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基于无人机影像的荒漠地表类型信息提取
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作者 彭佳忆 王新军 +2 位作者 朱磊 赵成义 徐晓龙 《干旱区研究》 CSCD 北大核心 2019年第3期771-780,共10页
基于无人机可见光影像对古尔班通古特沙漠地表类型信息进行提取,运用面向对象的多尺度分割,在提取样本的光谱、形状、纹理、植被指数特征的基础上,建立规则提取地表类型信息。结果表明:(1)荒漠地表类型不同,最佳分割尺度不同;(2)不同荒... 基于无人机可见光影像对古尔班通古特沙漠地表类型信息进行提取,运用面向对象的多尺度分割,在提取样本的光谱、形状、纹理、植被指数特征的基础上,建立规则提取地表类型信息。结果表明:(1)荒漠地表类型不同,最佳分割尺度不同;(2)不同荒漠化程度地表类型特征相似,无法运用单个特征进行区分,需选用多种特征组合提取地表类型;(3)面向对象的多尺度分割方法相对于基于像元的最大似然法分类有明显提高,面向对象轻度沙漠区总体分类精度为93. 00%,中度沙漠化区为91. 83%,重度沙漠化区为93. 50%,较基于像元的最大似然方法分别提高了10. 34%、11. 86%和12. 50%。表明针对无人机可见光影像,面向对象的多尺度分割方法能高精度地提取荒漠地表类型信息。 展开更多
关键词 无人机影像 荒漠 地表类型 信息提取 古尔班通古特沙漠
Desert vegetation distribution and species-environment relationships in an oasis-desert ecotone of northwestern China
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作者 ZHAO Peng QU Jianjun +3 位作者 XU Xianying YU Qiushi JIANG Shengxiu ZHAO Heran 《干旱区科学:英文版》 SCIE CSCD 2019年第3期461-476,共16页
Environmental heterogeneity significantly affects the structure of ecological communities.Exploring vegetation distribution and its relationship with environmental factors is essential to understanding the abiotic mec... Environmental heterogeneity significantly affects the structure of ecological communities.Exploring vegetation distribution and its relationship with environmental factors is essential to understanding the abiotic mechanism(s)driving vegetation succession,especially in the ecologically fragile areas.In this study,based on the quantitative analysis of plant community and environmental factors in 68 plots at 10 different transects in the Minqin oasis-desert ecotone(ODE)of northwestern China,we investigated desert vegetation distribution and species-environment relationships using multivariate analysis.Two-way indicator species analysis(TWINSPAN),detrended correspondence analysis(DCA),and canonical correspondence analysis(CCA)methods were used.A total of 28 species,belonging to 27 genera in 8 families,were identified.Chenopodiaceae,Zygophyllaceae,Gramineae,and Leguminosae were the largest families.Annual and perennial herbs accounted for 28.60%of the total number of plants,while shrubs(42.90%)were the most dominant.Nitraria tangutorum was the constructive species of the desert plant community.We divided the 68 plots surveyed in this study into 7 community types,according to the results of TWINSPAN.The distribution of these 7 communities in the DCA ordination graph showed that species with a similar ecotype were clustered together.Results of CCA indicated that groundwater was the dominant factor influencing vegetation distribution,while distance between plot and oasis(Dis)and soil electrical conductivity(EC)were the local second-order factors.Our study suggests that optimizing the utilization of groundwater in oases is key to controlling the degradation of desert vegetation.The favorable topographic conditions of sand dunes should be fully utilized for vegetal dune stabilization,and the influence of soil salinity on the selection of afforestation tree species should be considered. 展开更多
关键词 TWINSPAN classification ORDINATION DESERT plant GROUNDWATER oasis-desert ECOTONE species-environment relationship Minqin
新疆荒漠类型特征及其保护利用
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作者 杨发相 李生宇 +4 位作者 岳健 张志伟 周杰 雷加强 尹惠妍 《干旱区地理》 CSCD 北大核心 2019年第1期12-19,共8页
新疆荒漠具有分布广泛、成因复杂、类型多样等特点。利用新疆数字地貌图结合Landsat卫星TM数据与GIS制图技术,通过长期野外调查结合有关资料编制荒漠类型图,获得荒漠类型面积数据,据此探讨荒漠分布规律、结构特征、形成演变,并提出利用... 新疆荒漠具有分布广泛、成因复杂、类型多样等特点。利用新疆数字地貌图结合Landsat卫星TM数据与GIS制图技术,通过长期野外调查结合有关资料编制荒漠类型图,获得荒漠类型面积数据,据此探讨荒漠分布规律、结构特征、形成演变,并提出利用和保护荒漠的建议。结果显示:(1)新疆荒漠具有水平地带性分布与垂直地带性分布的规律及非地带性分布特点,荒漠多分布于干旱程度较高的南疆和东部吐鲁番及哈密地区,东部荒漠占新疆面积的45. 86%,占东部区域面积的91. 77%。(2)荒漠分布广,面积大,总面积达1. 31×10^6km^2,占新疆面积的80. 55%。荒漠类型面积最大的是沙漠为42. 7×10^4km^2,占荒漠面积32. 49%,泥漠面积仅1. 06×10^4km^2,占0. 81%。(3)荒漠类型复杂多样,成因各异,有沙漠、砾漠、盐漠等11种类型,分别主要由气候、地貌、地表物质组成、人为作用等因素单独或共同作用所形成。(4)受自然环境变化与人为作用,荒漠类型之间、荒漠类型与其他地物之间可发生演变。(5)各种荒漠类型的要素特征不同,宜合理利用荒漠资源,划分荒漠环境退化敏感区,保护荒漠环境,针对不同荒漠类型采取适应保护措施,以保障区域可持续发展。 展开更多
关键词 荒漠 类型 特征 保护 新疆
Holocene climatic change reconstructed from trace elements of an aeolian deposit in the southeastern Mu Us Desert, northern China 预览
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作者 Bing Liu HeLing Jin +2 位作者 LiangYing Sun WenPing Xue ZhenYu Liu 《寒旱区科学:英文版》 CSCD 2019年第2期126-138,共13页
In semi-arid and arid desert regions of northern China, aeolian deposits document the framework variation of an Asian monsoon during the late Quaternary. However, there is still a lack of detailed data pertaining to H... In semi-arid and arid desert regions of northern China, aeolian deposits document the framework variation of an Asian monsoon during the late Quaternary. However, there is still a lack of detailed data pertaining to Holocene Asian monsoonal variation especial in the modern Asian summer monsoonal boundary belt. In this study, we reconstructed Holocene millennial- scale climatic changes in the Mu Us Desert, northern China, through systematic analysis of the variation of trace elements (324 samples) in different lithological units of the palaeosol-aeolian sand deposit, in combination with 14C and OSL chronology. Statistical results, correlation and clustering analysis indicate that the high content of 11 trace elements (V, Y, Cr, Nb, P, Mn, Cu, Zr, As, Ni and Rb, represented by P) and lower Sr content corresponding to periods of palaeosol development, marked increase of vegetation, weathering degree, and enhanced Asian summer monsoonal strength. In contrast, their opposed variation are coincident with accumulated aeolian sand layers, implying weaker summer monsoons and less geochemical weathering and degraded vegetation. These associations can be considered as signaling regional humid and dry changes of the Holocene environment. Accordingly, relatively arid conditions dominated the region before 7.2 ka, and there was an optimal humid climate in 7.2?4.6 ka. Afterwards, the climate became obviously dry, accompanied with several cycles of relatively wet and dry, such as relatively wet intervals around 4.1?3.7 ka, 3.5?3.3 ka and 2.5 ka. In addition, six millennial-scale dry events were recorded, and these events were consistent with weaker Asian summer monsoonal intervals in low latitudes, declined palaeosol development and precipitation in middle latitudes, as well as increased winter monsoon and periodic ice-rafting events in high latitudes of the Northern Hemisphere, within limits of accuracy of existing dating ages. This possibly suggests a noteworthy synchronism between millennial-scale climatic changes in this reg 展开更多
关键词 HOLOCENE climatic change MU Us DESERT Aeolian DEPOSIT trace element synchronism
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Hyper-spectral characteristics of rolled-leaf desert vegetation in the Hexi Corridor,China
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作者 WEI Huaidong YANG Xuemei +4 位作者 ZHANG Bo DING Feng ZHANG Weixing LIU Shizeng CHEN Fang 《干旱区科学:英文版》 SCIE CSCD 2019年第3期332-344,共13页
Desert plants survive harsh environment using a variety of drought-resistant structural modifications and physio-ecological systems.Rolled-leaf plants roll up their leaves during periods of drought,making it difficult... Desert plants survive harsh environment using a variety of drought-resistant structural modifications and physio-ecological systems.Rolled-leaf plants roll up their leaves during periods of drought,making it difficult to distinguish between the external structures of various types of plants,it is therefore necessary to carry out spectral characteristics analysis for species identification of these rolled-leaf plants.Based on hyper-spectral data measured in the field,we analyzed the spectral characteristics of seven types of typical temperate zone rolled-leaf desert plants in the Hexi Corridor,China using a variety of mathematical transformation methods.The results show that:(1)during the vigorous growth period in July and August,the locations of the red valleys,green peaks,and three-edge parameters,namely,the red edge,the blue edge,and the yellow edge of well-developed rolled-leaf desert plants are essentially consistent with those of the majority of terrestrial vegetation types;(2)the absorption regions of liquid water,i.e.,1400-1500 and 1600-1700 nm,are the optimal bands for distinguishing various types of rolled-leaf desert plants;(3)in the leaf reflectance regions of 700-1250 nm,which is controlled by cellular structure,it is difficult to select the characteristic bands for differentiation rolled-leaf desert vegetation;and(4)after processing the spectral reflectance curves using a first-order differential,the envelope removal method,and the normalized differential ratio,we identify the other characteristic bands and parameters that can be used for identifying various types of temperate zone rolled-leaf desert plants,i.e.,the 510-560,650-700 and 1330-1380 nm regions,and the red edge amplitude.In general,the mathematical transformation methods in the study are effective tools to capture useful spectral information for species identification of rolled-leaf plants in the Hexi Corridor. 展开更多
关键词 rolled-leaf desert VEGETATION spectral CHARACTERISTICS mathematical transformation VEGETATION identification Hexi CORRIDOR
ENJOYING THESAND
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作者 Wei Yao(Text/photos) 《北京周报:英文版》 2019年第36期18-19,共2页
On August 3, Beijing Review reporters visited the Suwu Desert Scenic Area in Minqin County, northwest China's Gansu Province, where sculptures of various shapes dot the sand dunes.
关键词 BEIJING DESERT COUNTY
Remote Sensing Monitoring of Surface Characteristics in the Badain Jaran, Tengger, and Ulan Buh Deserts of China 预览
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作者 LIU Qingsheng LIU Gaohuan +1 位作者 HUANG Chong LI He 《中国地理科学:英文版》 SCIE CSCD 2019年第1期151-165,共15页
Deserts and sandy land in northern China are very susceptible to sandy desertification and are the main source of sand-dust storms of Asian dust. However, because of the complex factors involved, descriptions of the r... Deserts and sandy land in northern China are very susceptible to sandy desertification and are the main source of sand-dust storms of Asian dust. However, because of the complex factors involved, descriptions of the relationship between sandy desertification and surface characteristics in these regions are lacking. We monitored the surface characteristics and their changes in time using information about soil, vegetation, and landforms in the Badain Jaran Desert(BJD), Tengger Desert(TD), and Ulan Buh Desert(UBD) in the northern China. The monitoring was done using tasseled cap angle(TCA), disturbance index(DI), and topsoil grain size index(TGSI) from Moderate Resolution Imaging Spectroradiometer(MODIS) images combined with a decision tree classification. Results showed that the TD had higher topsoil fine sand content, and the ratio of non-vegetated to vegetated areas was similar with that in the UBD. Northeast-southwest coarse sand dunes with thin interdune(NECTI) dominated the BD, fine sand dunes(FSD) dominated the TD, and a combination of northeast-southwest coarse sand dunes with wide interdune(NECWI) and northwest-southeast coarse sand dunes with wide interdune(NWCWI) dominated the UBD. From 2000 to 2015, in the BJD the area of the NECTI, non-sand dune(Non) and potential sand sources(PSS) increased, whereas the area of the NECWI, FSD and NWCWI decreased, indicating a improve process in the BJD. In the TD, the area covered by Non increased, whereas the area covered by PSS, NECWI, NECTI, FSD, and NWCWI decreased from 2000 to 2015. The area covered by the various surface characteristic types fluctuated annually in the UBD from 2000 to 2015. Changes in surface characteristics reflect the combined effects of natural conditions and human activity. The findings of our study will assist scientists and policy makers in proposing different management techniques to combat sandy desertification for the different surface characteristics of these regions. 展开更多
关键词 surface characteristics MODIS DESERT tasseled CAP angle DISTURBANCE INDEX TOPSOIL GRAIN size INDEX
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Geochemical characterization of major elements in desert sediments and implications for the Chinese loess source
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作者 Wancang ZHAO Lianwen LIU +1 位作者 Jun CHEN Junfeng JI 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2019年第9期1428-1440,共13页
Mineral dust released from the desert is one of the important components of atmospheric aerosols. Arid and semi-arid deserts, sandy lands in northern China and their adjacent Gobi Desert lands in northern China and ne... Mineral dust released from the desert is one of the important components of atmospheric aerosols. Arid and semi-arid deserts, sandy lands in northern China and their adjacent Gobi Desert lands in northern China and neighboring Mongolia(hereinafter referred to as Gobi) are potential sources of mineral dust in Asia. However, there is currently a lack of systematic studies on the characteristics of major elements in the potential mineral dust source area. This study investigates the major elements of 310 surficial sand samples in the stabilized and semi-stabilized dune fields from 12 deserts/sandy land and Gobi in northern China and southern Mongolian Gobi and compiles published data. We identify four regions with distinct geochemical characteristics:(1) Taklimakan, Kumtag and Qaidam deserts in western China;(2) Badain Jaran, Tengger, Hobq, and Mu Us deserts in the central and western regions of northern China;(3) Hulun Buir, Onqin Daga and Horqin sandy lands in northeast China;and(4) Gobi and Gurbantunggut deserts. The spatial distributions of the SiO2 and CaO contents in Chinese deserts are highly variable. The average content of SiO2 generally reflects an increasing trend from west to east, while the average content of CaO shows a decreasing trend from west to east. We demonstrate that the spatial variation of major elements is likely controlled by two key scenarios: the composition of source rocks and the mineral maturity caused by the supply of fresh materials. The SiO2/(Al2O3+K2O+Na2O) ratio of desert sediments is relatively lower in western China and may be caused by high ferricmagnesia and high carbonate minerals;this ratio is relatively higher in the northeast sandy lands and may be linked to a lack of fresh material supply and the presence of high K-feldspar minerals in source rocks. The deserts can be further distinguished by ternary diagrams with SiO2/10-CaO-Al2O3,(K2O+Na2O)-CaO-Fe2O3 and CaO-Na2O-K2O. The comparison of major elements between desert sediments and loess suggests that the western and/or ce 展开更多
关键词 DESERT LOESS Major elements EOLIAN DUST CARBONATE
Alleviating freshwater shortages with combined desert-based large-scale renewable energy and coastal desalination plants supported by Global Energy Interconnection
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作者 Hengxu Zhang Yuzheng Xie 《全球能源互联网:英文版》 2019年第3期205-213,共9页
Under the background of sustainable energy transition and environmental protection,Global Energy Interconnection(GEI),which features an innovative combination of clean energy(e.g.,solar power) and ultra-high voltage(U... Under the background of sustainable energy transition and environmental protection,Global Energy Interconnection(GEI),which features an innovative combination of clean energy(e.g.,solar power) and ultra-high voltage(UHV) transmission technologies,provides a means to realize global climate governance.China is a large country with unevenly distributed water resources,energy production,and energy consumption,and the large areas of desert in northern and western China have the potential for installing large-scale solar power plants.This study analyzed the potential of using large-scale solar power from deserts to coastal seawater desalination plants,which could alleviate the freshwater crisis and control desertification in China.First,the measurement data from NASA were used to estimate the potential exploitable amount of solar energy in desert areas.A macro idea was proposed for the transmission of electrical power from inland integrated energy bases to coastal seawater desalination and pumping of freshwater to western China to combat desertification and alleviate the freshwater crisis.Based on this,the electricity demands for desalination and water redistribution were estimated.As a huge interruptible load,desalination and pumping systems could be used to suppress power fluctuations of the integrated energy bases.Finally,the fundamental support roles of UHV grids in large-scale renewable energy allocation and utilization were discussed.This analysis offers a theoretical framework to help realize efficient renewable energy generation and consumption and alleviate freshwater shortage. 展开更多
关键词 DESERT DESALINATION ENERGY crisis Freshwater GLOBAL ENERGY INTERCONNECTION (GEI) Solar ENERGY Ultra-high voltage (UHV).
Image Perception and Emotional Evaluation of Tourists for Desert Tourism Destinations in Inner Mongolia—Content Analyses Based on Network Travel Notes 预览
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作者 AO Hongyan LI Meng 《景观研究:英文版》 2019年第1期95-103,共9页
Recent years have witnessed the popularity of desert tourism as a fashion tourism product in the 21^st century along with the increasing demand for personalized tourism for tourists.The academic community is paying gr... Recent years have witnessed the popularity of desert tourism as a fashion tourism product in the 21^st century along with the increasing demand for personalized tourism for tourists.The academic community is paying growing attention to desert tourism research,but there is little research on the perception of tourists about the image of desert tourism destinations in Inner Mongolia.With Inner Mongolia as the object of the study,this paper analyzed the image perception and evaluation of tourists for Inner Mongolia desert tourism destinations from three aspects of cognitive image perception,emotional image perception,and overall image perception according to the“cognitive-emotional”model,with the help of relevant network text analysis methods,and proposed some suggestions for the future development of desert tourism destinations in Inner Mongolia from the aspects of increasing desert humanities tourism resources and product development,improving scenic spot management ability,improving tourism service quality,improving tourism infrastructure construction and strengthening environmental protection.It is hoped that this paper can provide a reference for improving the image of Inner Mongolia desert tourism destinations and improving the tourist experience. 展开更多
关键词 Inner Mongolia DESERT tourism DESTINATION Image perception CONTENT analysis
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Microbial Water Source for the Desert Plants 预览
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作者 Ahmed Z.Abdel Azeiz Abeer Elhalwagi +1 位作者 Sameh E.Hassanein Lobna A.Moussa 《农业科学与技术:A》 2019年第2期71-80,共10页
Finding water resources for the desert plants is one of the important research areas since it enables saving water resources.Bromus inermis plant was noticed to keep 5%of moisture in its rhizosphere zone;therefore,thi... Finding water resources for the desert plants is one of the important research areas since it enables saving water resources.Bromus inermis plant was noticed to keep 5%of moisture in its rhizosphere zone;therefore,this study aimed to identify this source of water.Thirteen endophytic bacteria were isolated from the root of B.inermis and identified.Their specific respiration rate was determined.Alcaligenes faecalis showed the highest specific respiration rate.It is a facultative chemoautotrophic hydrogen-fixing bacterium that utilizes the hydrogen gas as energy source and the water is produced as an end product.The source of hydrogen gas for this bacterium is not only from air and soil gases but also from the hydrogen-producing bacteria such as Enterobacter spp.,which was among the isolated bacteria.The hydrogenases synthesizing genes(HoxC,HypA and HypB)were detected in most of the isolated bacteria and roots of four wild plants,out from 18 wild plant samples,epically the grains of the wild wheat plant.This result suggests that the hydrogen-fixing and hydrogen-producing bacteria transfer from the root through the plant to inhabit the grain/seeds.This can help the grain/seeds to germinate in drought environment. 展开更多
关键词 DESERT plants ALCALIGENES spp. ENTEROBACTER spp. HYDROGENASE HoxC HypA HypB
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姜黄素对模拟沙漠干热环境中暑大鼠外周血CD11b和CD19表达的影响
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作者 姜婧 刘江伟 +5 位作者 李佳佳 陶林 王铮 杨柳 是文辉 马娜 《中华危重病急救医学》 CAS CSCD 北大核心 2019年第2期221-224,共4页
目的探讨不同剂量姜黄素对模拟沙漠干热环境中暑大鼠外周血免疫因子CD11b和CD19水平的影响。方法选取SPF级健康雄性SD大鼠160只,按随机数字表法分为生理盐水(NS)对照组(给予NS)、溶剂对照组〔给予羧甲基纤维素钠(CMCNa)〕以及姜黄素低... 目的探讨不同剂量姜黄素对模拟沙漠干热环境中暑大鼠外周血免疫因子CD11b和CD19水平的影响。方法选取SPF级健康雄性SD大鼠160只,按随机数字表法分为生理盐水(NS)对照组(给予NS)、溶剂对照组〔给予羧甲基纤维素钠(CMCNa)〕以及姜黄素低、中、高剂量预处理组(给予0.05、0.10、0.20 mg/g姜黄素+ 0.5% CMCNa溶液),每组32只,均按10 mL·kg-1·d-1灌胃,连续给药7 d。第8天将大鼠置于环境温度(41.0±0.5)℃、相对湿度(10±1)%的西北特殊环境人工实验舱中,于放置0(常温放置)、50、100和150 min时,用流式细胞仪检测各组大鼠外周血CD19和CD11b水平。结果随着在模拟干热环境中放置时间的延长,各组大鼠外周血CD11b水平逐渐升高,于150 min时达峰值,NS对照组、溶剂对照组以及姜黄素低、中、高剂量预处理组分别为0.346±0.013、0.342±0.013、0.342±0.012、0.325±0.012、0.281±0.012;而各组CD19水平先升高后降低,于100 min时达峰值,NS对照组、溶剂对照组以及姜黄素低、中、高剂量预处理组分别为0.586±0.010、0.601±0.014、0.684±0.009、0.613±0.012、0.604±0.006。姜黄素中、高剂量预处理组于干热环境下50 min和100 min时CD11b水平明显低于NS对照组和溶剂对照组(50 min:0.237±0.011、0.188±0.006比0.283±0.009、0.289±0.012,100 min:0.260±0.010、0.248±0.008比0.293±0.008、0.290±0.007,均P<0.05),150 min时姜黄素高剂量预处理组CD11b水平均明显低于NS对照组、溶剂对照组以及姜黄素低剂量组(0.281±0.012比0.346±0.013、0.342±0.013、0.342±0.012,均P<0.05)。干热环境下50 min时,姜黄素低、中、高剂量预处理组CD19水平均明显高于NS对照组和溶剂对照组(0.394±0.001、0.436±0.009、0.553±0.011比0.205±0.005、0.197±0.003,均P<0.05),100 min时仅姜黄素低剂量预处理组CD19水平明显高于NS对照组和溶剂对照组(0.684±0.009比0.586±0.010、0.601±0.014,均P<0.05),其余各剂量预处理组CD19水平与NS� 展开更多
关键词 沙漠 干热环境 中暑 姜黄素 免疫 流式细胞术 CD11B CD19
Geochemistry of an Alaskan-type mafic-ultramafic complex in Eastern Desert, Egypt: New insights and constraints on the Neoproterozoic island arc magmatism 预览
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作者 Shehta E. Abdallah Shehata Ali Mohamed A. Obeid 《地学前缘:英文版》 CAS CSCD 2019年第3期941-955,共15页
Mikbi intrusion (MI) is a part of the Neoproterozoic Nubian Shield located along the NEeSW trending major fracture zones prevailing southern Eastern Desert of Egypt. In this study, we present for the first time detail... Mikbi intrusion (MI) is a part of the Neoproterozoic Nubian Shield located along the NEeSW trending major fracture zones prevailing southern Eastern Desert of Egypt. In this study, we present for the first time detailed mineralogical and bulk-rock geochemical data to infer some constraints on the parental magma genesis and to understand the tectonic processes contributed to MI formation. Lithologically, it is composed of fresh peridotite, clinopyroxenite, hornblendite, anorthosite, gabbronorite, pyroxene amphibole gabbro, amphibole gabbro and diorite. All rocks have low Th/La ratios (mostly <0.2) and lack positive Zr and Th anomalies excluding significant crustal contamination. They show very low concentrations of Nb, Ta, Zr and Hf together with sub-chondritic ratios of Nb/Ta (2-15) and Zr/Hf (19-35), suggesting that their mantle source was depleted by earlier melting extraction event. The oxygen fugacity (logfO2) estimated from diorite biotite is around the nickel-nickel oxide buffer (NNO) indicating crystallization from a relatively oxidized magma. Amphiboles in the studied mafic-ultramafic rocks indicate relative oxygen fugacity (i.e. DNNO;nickel-nickel oxide) of 0.28e3 and were in equilibrium mostly with 3.77-8.24 wt.% H2Omelt (i.e. water content in the melt), consistent with the typical values of subduction-related magmas. Moreover, pressure estimates (0.53-6.79 kbar) indicate polybaric crystallization and suggest that the magma chamber(s) was located at relatively shallow crustal levels. The enrichment in LILE (e.g., Cs, Ba, K and Sr) and the depletion in HFSE (e.g., Th and Nb) relative to primitive mantle are consistent with island arc signature. The olivine, pyroxene and amphibole compositions also reflect arc affinity. These inferences suggest that their primary magma was derived from partial melting of a mantle source that formerly metasomatized in a subduction zone setting. Clinopyroxene and bulkrock data are consistent with orogenic tholeiitic affinity. Consequently, the mineral and bulk-rock chemistr 展开更多
关键词 Alaskan-type complex NEOPROTEROZOIC Arc MAGMATISM Eastern DESERT EGYPT
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How changes of groundwater level affect the desert riparian forest ecosystem in the Ejina Oasis,Northwest China 预览
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作者 HaiYang Xi JingTian Zhang +3 位作者 Qi Feng Lu Zhang JianHua Si TengFei Yu 《寒旱区科学:英文版》 CSCD 2019年第1期62-80,共19页
Groundwater is a key factor controlling the growth of vegetation in desert riparian systems.It is important to recognise how groundwater changes affect the riparian forest ecosystem.This information will not only help... Groundwater is a key factor controlling the growth of vegetation in desert riparian systems.It is important to recognise how groundwater changes affect the riparian forest ecosystem.This information will not only help us to understand the ecological and hydrological process of the riparian forest but also provide support for ecological recovery of riparian forests and water-resources management of arid inland river basins.This study aims to estimate the suitability of the Water Vegetation Energy and Solute Modelling(WAVES)model to simulate the Ejina Desert riparian forest ecosystem changes,China,to assess effects of groundwater-depth change on the canopy leaf area index(LAI)and water budgets,and to ascertain the suitable groundwater depth for preserving the stability and structure of desert riparian forest.Results demonstrated that the WAVES model can simulate changes to ecological and hydrological processes.The annual mean water consumption of a Tamarix chinensis riparian forest was less than that of a Populus euphratica riparian forest,and the canopy LAI of the desert riparian forest should increase as groundwater depth decreases.Groundwater changes could significantly influence water budgets for T.chinensis and P.euphratica riparian forests and show the positive and negative effects on vegetation growth and water budgets of riparian forests.Maintaining the annual mean groundwater depth at around 1.7-2.7 m is critical for healthy riparian forest growth.This study highlights the importance of considering groundwater-change impacts on desert riparian vegetation and water-balance applications in ecological restoration and efficient water-resource management in the Heihe River Basin. 展开更多
关键词 groundwater CHANGES DESERT RIPARIAN forest EJINA OASIS WAVES leaf area index(LAI) water budgets
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Antimicrobial Activities of Desert Truffle Extracts and Their Chemical Identification 预览
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作者 Dib-Bellahouel S. Fortas Z. 《药剂与药理学:英文版》 2019年第11期593-597,共5页
Desert truffles are edible mushrooms and they belong to groupe of ascomycetes. In Algeria, we find them in arid and semiarid area. They are represented by two most genuses: Tirmania (white terfez) and Terfezia (red te... Desert truffles are edible mushrooms and they belong to groupe of ascomycetes. In Algeria, we find them in arid and semiarid area. They are represented by two most genuses: Tirmania (white terfez) and Terfezia (red terfez). The aim of our work is to present extraction technics of the bioactive substances from gleba (ascoms) of Tirmania pinoyi (Maire) Malen?on and from the culture filtrate of mycelium of Terfezia claveryi Chatin. Also, we present antifungal and antibacterial activity of these substances in vitro and their identification. There is antifungal activity of different extracts on solid medium, in vitro, against species of Aspergillus, Fusarium, Gliocladium, Candida. Also, there is antibacterial activity against species of Staphylococus, Streptococcus, Bacillus, Enterococcus, Escherichia, and Salmonella. Results show that extracts inhibition varies according to microbial tested species. Bioactive substances of the different extracts were analyzed by GC (gas chromatography)-mass, RMN (Nuclear Magnetic Resonance) and infrared in order to determine the chemical identity. Results show that these substances contain pyrazines and cyclic compounds like quinones. 展开更多
关键词 DESERT TRUFFLE ANTIMICROBIAL ACTIVITY bioactive substances CHEMICAL identification
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沙漠地区大口径长距离顶管施工关键技术
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作者 陈军 《施工技术》 CAS 2019年第1期121-123,131共4页
某工程顶管施工的钢筋混凝土管道直径大,一次性顶距长,穿越地层主要为无水粉砂层,具有较大施工技术难度及组织难度。介绍了在沙漠地质条件下大口径长距离顶管工程施工中,顶管工艺的选择、顶管设备选型设计以及特殊减阻浆液的配制等关键... 某工程顶管施工的钢筋混凝土管道直径大,一次性顶距长,穿越地层主要为无水粉砂层,具有较大施工技术难度及组织难度。介绍了在沙漠地质条件下大口径长距离顶管工程施工中,顶管工艺的选择、顶管设备选型设计以及特殊减阻浆液的配制等关键技术。 展开更多
关键词 沙漠地区 顶管 刀盘 注浆 施工技术
Is bi-seasonal germination an optimal choice for an ephemeral plant living in a cold desert?
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作者 YANG Shanlin SHI Xiang +3 位作者 WANG Shaoming LIU Jiashu MENG Fanxiang PANG Wei 《干旱区科学:英文版》 SCIE CSCD 2019年第2期280-291,共12页
Research on germination strategies has been proposed as a tool for understanding the evolutionary patterns of plant species living in extreme climate conditions. Previous research has concentrated on spring-germinated... Research on germination strategies has been proposed as a tool for understanding the evolutionary patterns of plant species living in extreme climate conditions. Previous research has concentrated on spring-germinated plants, while there has been little investigation on the ecological significance of ephemeral plants that germinate in both autumn and spring. The biological characteristics and life history strategies of autumn-and spring-germinated plants of Hypecoum erectum L. that belongs to Hypecoum in Papaveraceae family in the southern part of the Gurbantunggut Desert, China, were investigated from 2016 to 2017. Results showed that:(1) the interval from seedling emergence to the end of the life cycle in autumn-germinated plants(202–208 d) was significantly longer than that in spring-germinated plants(53–65 d);(2) the height, crown, principal axis and the number of leaves of autumn-germinated plants were much greater than those of spring-germinated plants;(3) allocation of dry mass to reproduction was 30.24%(±2.41%) and 10.12%(±0.68%) in autumn-and spring-germinated plants, respectively. Autumn-germinated seedlings of H. erectum had an advantage in avoiding the competition between annual and perennial herbs that had longer periods of vegetative growth.Spring-germinated seedlings need to ensure the survival of population when only a fewer autumn-germinated seedlings successfully overwinter. In an unpredictable environment, the germination strategy of bet hedging not only utilizes the resources and reduces the competition intensity in offspring,but also ensures the survival of the plant population. 展开更多
关键词 EPHEMERAL plant Gurbantunggut DESERT Hypecoum erectum L. spring-germinated PLANTS autumn-germinated PLANTS
沙漠沙尘粒径对太阳能光伏组件性能影响的实验研究
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作者 赵明智 苗一鸣 +1 位作者 张旭 孙浩 《太阳能学报》 EI CAS CSCD 北大核心 2019年第3期803-808,共6页
通过选用不同粒径的沙漠沙尘颗粒沉积于太阳能光伏组件表面,对太阳能光伏组件的背板温度变化及输出特性进行实验研究。结果表明:随着沉积在光伏组件表面的沙尘粒径(0.05~0.3 mm)变化,组件的开路电压变化较小,其最大差值为0.25 V,变化幅... 通过选用不同粒径的沙漠沙尘颗粒沉积于太阳能光伏组件表面,对太阳能光伏组件的背板温度变化及输出特性进行实验研究。结果表明:随着沉积在光伏组件表面的沙尘粒径(0.05~0.3 mm)变化,组件的开路电压变化较小,其最大差值为0.25 V,变化幅度约1.2%;对短路电流和输出功率有较大影响,短路电流的最大差值大约为13%,输出功率的最大差值约为17%。 展开更多
关键词 沙尘粒径 光伏组件 沙漠地区 温度变化 输出特性
Estimation of maximum mass velocity from macroseismic data: A new method and application to archeoseismological data
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作者 M.V.Rodkin A.M.Korzhenkov 《大地测量与地球动力学:英文版》 2019年第4期321-330,共10页
An important task in seismic hazard assessment is the estimation of intensity and frequency of rare strong seismic shaking, in particular, the long-term peak ground velocity values(PGVs). A recently proposed method is... An important task in seismic hazard assessment is the estimation of intensity and frequency of rare strong seismic shaking, in particular, the long-term peak ground velocity values(PGVs). A recently proposed method is suitable for simply estimating PGVs based on the examination of the magnitude of displacements of rock blocks. The effectiveness of this method is demonstrated by results of studies on the source zones of two large earthquakes and a vicinity of one strong explosion. In this study, the method is applied to the examination of archeoseismological data from the ancient Rehovot-ba-Negev city and other ancient cities from the Negev desert(in Southern Israel) where numerous evidences of presumable seismic damage were found earlier. The cities and also a sophisticated irrigation system within the region, which existed in the Negev desert, were abandoned however in the middle of the seventh century. The abandonment could be caused by a combined effect, from not only the cessation of the state support from Byzantium as a result of the Arab conquest but also the severe destruction from the strong earthquake that hit the area at that time. The intensities of the seismic events that hit the cities were estimated earlier, which are within the range of 8 e9. Our estimates indicate that the PGV values are about 1.5 m/s. Hence, the magnitude of the causative earthquake could be in the range M z 6.5 e7.5, and the location of the epicenter might be at a distance of a few dozens of kilometers from the ancient Rehovot-ba-Negev city, while the other variants associated with the earthquake seem to be less probable. 展开更多
关键词 ANCIENT earthquakes ANCIENT cities in the NEGEV DESERT PGV ESTIMATION from macroseismic DATA Earthquake hazard assessment for southern Israel
Shrub modulates the stoichiometry of moss and soil in desert ecosystems, China
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作者 LI Yonggang ZHOU Xiaobing ZHANG Yuanming 《干旱区科学:英文版》 SCIE CSCD 2019年第4期579-594,共16页
Desert mosses, which are important stabilizers in desert ecosystems, are distributed patchily under and between shrubs. Mosses differ from vascular plants in the ways they take up nutrients. Clarifying their distribut... Desert mosses, which are important stabilizers in desert ecosystems, are distributed patchily under and between shrubs. Mosses differ from vascular plants in the ways they take up nutrients. Clarifying their distribution with ecological stoichiometry may be useful in explaining their mechanisms of living in different microhabitats. In this study, Syntrichia caninervis, the dominant moss species of moss crusts in the Gurbantunggut Desert, China, was selected to examine the study of stoichiometric characteristics in three microhabitats(under living shrubs, under dead shrubs and in exposed ground). The stoichiometry and enzyme activity of rhizosphere soil were analyzed. The plant function in the above-ground and below-ground parts of S. caninervis is significantly different, so the stoichiometry of the above-ground and below-ground parts might also be different. Results showed that carbon(C), nitrogen(N) and phosphorus(P) contents in the below-ground parts of S. caninervis were significantly lower than those in the above-ground parts. The highest N and P contents of the two parts were found under living shrubs and the lowest under dead shrubs. The C contents of the two parts did not differ significantly among the three microhabitats. In contrast, the ratios of C:N and C:P in the below-ground parts were higher than those in the above-ground parts in all microhabitats, with significant differences in the microhabitats of exposed ground and under living shrubs. There was an increasing trend in soil organic carbon(SOC), soil total nitrogen(STN), soil available phosphorous(SAP), and C:P and N:P ratios from exposed ground to under living shrubs and to under dead shrubs. No significant differences were found in soil total phosphorous(STP) and soil available nitrogen(SAN), or in ratios of C:N and SAN:SAP. Higher soil urease(SUE) and soil nitrate reductase(SNR) activities were found in soil under dead shrubs, while higher soil sucrase(STC) and soil β-glucosidase(SBG) activities were respectively found in exposed ground and 展开更多
关键词 MOSS STOICHIOMETRY Syntrichia caninervis MICROHABITATS SOIL STOICHIOMETRY SOIL enzyme Gurbantunggut DESERT
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