期刊文献+
共找到88,284篇文章
< 1 2 250 >
每页显示 20 50 100
Improving remote sensing-based net primary production estimation in the grazed land with defoliation formulation model
1
作者 YE Hui HUANG Xiao-tao +3 位作者 LUO Ge-ping WANG Jun-bang ZHANG Miao WANG Xin-xin 《山地科学学报:英文版》 SCIE CSCD 2019年第2期323-336,共14页
Remote sensing(RS) technologies provide robust techniques for quantifying net primary productivity(NPP) which is a key component of ecosystem production management. Applying RS, the confounding effects of carbon consu... Remote sensing(RS) technologies provide robust techniques for quantifying net primary productivity(NPP) which is a key component of ecosystem production management. Applying RS, the confounding effects of carbon consumed by livestock grazing were neglected by previous studies, which created uncertainties and underestimation of NPP for the grazed lands. The grasslands in Xinjiang were selected as a case study to improve the RS based NPP estimation. A defoliation formulation model(DFM) based on RS is developed to evaluate the extent of underestimated NPP between 1982 and 2011. The estimates were then used to examine the spatiotemporal patterns of the calculated NPP. Results show that average annual underestimated NPP was 55.74 gC·m-2yr-1 over the time period understudied, accounting for 29.06% of the total NPP for the Xinjiang grasslands. The spatial distribution of underestimated NPP is related to both grazing intensity and time. Data for the Xinjiang grasslands show that the average annual NPP was 179.41 gC·m-2yr-1, the annual NPP with an increasing trend was observed at a rate of 1.04 gC·m-2yr-1 between 1982 and 2011. The spatial distribution of NPP reveals distinct variations from high to low encompassing the geolocations of the Tianshan Mountains, northern and southern Xinjiang Province and corresponding with mid-mountain meadow, typical grassland, desert grassland, alpine meadow, and saline meadow grassland types. This study contributes to improving RS-based NPP estimations for grazed land and provides a more accurate data to support the scientific management of fragile grassland ecosystems in Xinjiang. 展开更多
关键词 Remote SENSING DEFOLIATION FORMULATION model Net primary production Grazed LAND Spatial-temporal patterns XINJIANG
Radiation therapy for extrahepatic bile duct cancer: Current evidences and future perspectives 预览
2
作者 Taeryool Koo Hae Jin Park Kyubo Kim 《世界临床病例杂志》 2019年第11期1242-1252,共11页
Extrahepatic bile duct cancer (EBDC) is a rare malignancy that involves neoplastic changes extending from both hepatic ducts to the common bile duct. The treatment of choice is surgical resection, but the predominant ... Extrahepatic bile duct cancer (EBDC) is a rare malignancy that involves neoplastic changes extending from both hepatic ducts to the common bile duct. The treatment of choice is surgical resection, but the predominant pattern of initial treatment failure is locoregional recurrence. Accordingly, adjuvant radiotherapy has been administered after surgical resection based on these rationales. At this time, there is minimal evidence supporting adjuvant radiotherapy, because there have been no phase III trials evaluating its benefit. Relatively small retrospective studies have tried to compare outcomes associated with EBDC treated with or without radiotherapy. We aimed to review studies investigating adjuvant radiotherapy for resected EBDC. Because less than onethird of EBDC cases are amenable to curative resection at diagnosis, other locoregional treatment modalities need to be considered, including radiotherapy. The next aim of this review was to summarize reports of definitive radiotherapy for unresectable EBDC. Patients with advanced EBDC often experience biliary obstruction, which can lead to jaundice and progress to death. Biliary stent insertion is an important palliative procedure, but stents are prone to occlusion after subsequent ingrowth of the EBDC. Radiotherapy can be effective for maintaining the patency of inserted stents. We also reviewed the benefit of palliative radiotherapy combined with the biliary stent insertion. Lastly, we discuss the existing gaps in the evidence supporting radiotherapy in the management of EBDC. 展开更多
关键词 EXTRAHEPATIC BILE duct cancer Patterns of failure ADJUVANT RADIOTHERAPY Definitive RADIOTHERAPY PALLIATIVE RADIOTHERAPY BILIARY stent
在线阅读 免费下载
Hexagonal Patterns in the 2-D Lengyel-Epstein System
3
作者 Li-na ZHANG Fei XU 《数学研究及应用:英文版》 CSCD 2019年第3期269-276,共8页
Some qualitative behaviors of stationary solutions for the 2-D Lengyel-Epstein system are considered from the local bifurcation viewpoint in this paper. First, local bifurcation branches of hexagonal stationary soluti... Some qualitative behaviors of stationary solutions for the 2-D Lengyel-Epstein system are considered from the local bifurcation viewpoint in this paper. First, local bifurcation branches of hexagonal stationary solutions are constructed in the special case when the habitat domain is a rectangle. Next, the type of the bifurcation diagram near the bifurcation points is discussed. 展开更多
关键词 Lengyel-Epstein SYSTEM BIFURCATION HEXAGONAL PATTERNS
Sedimentary Facies, Sequence Stratigraphic Patterns in Pre-Cenozoic Inland Compressional Basin: Example from Early Yanshanian Succession of Eastern Yihezhuang Salient, Jiyang Depression, Bohai Bay Basin, China
4
作者 Guangzeng Song Hua Wang +2 位作者 Meng Xu Jinda Xu Guoqing Sang 《地球科学学刊:英文版》 SCIE CAS CSCD 2019年第1期194-205,共12页
To improve the success rate of locating hydrocarbon reservoirs in pre-Cenozoic inland compressional basins, taking the Early Yanshanian succession of eastern Yihezhuang salient as an example, this paper studied the se... To improve the success rate of locating hydrocarbon reservoirs in pre-Cenozoic inland compressional basins, taking the Early Yanshanian succession of eastern Yihezhuang salient as an example, this paper studied the sedimentary facies and sequence stratigraphic patterns. First, through seismic profiles, well logs, cores and outcrops, the sequence framework was established and internal sedimentary facies were identified. Further, according to analysis of single-wells and connecting-wells, the vertical evolution and horizontal distribution of sedimentation inside the sequence frameworks were discussed. The following results were acquired:(1) meandering river characterized by dual structures superposing each other was developed, and the dual structures can be further divided into three kinds;(2) the entire Early Yanshanian succession was interpreted as one first-order sequence, composed of three third-order sequences, including SQ-Fz1, SQ-Fz2 and SQ-St from bottom to top. Each third-order sequence can be further divided into three system tracts;(3) in different system tracts, different types of dual structures developed separately, and sedimentary bodies showed different horizontal distribution scales and vertical superposition patterns. Finally, the model of sequence stratigraphic patterns was established. This study enhanced the use of sequence stratigraphy to inland tectonically active basins, and would be helpful to predict reservoirs in pre-Cenozoic residual basins. 展开更多
关键词 Early YANSHANIAN SUCCESSION SEQUENCE STRATIGRAPHIC PATTERNS INLAND compressional basin meandering river dual structure
京津冀干旱时空演变规律分析(英文)
5
作者 章杰 孙福宝 +2 位作者 刘文彬 刘家宏 王红 《地理学报:英文版》 SCIE CSCD 2019年第6期863-876,共14页
Spatio-temporal patterns of drought from 1961 to 2013 over the Beijing-Tianjin-Hebei(BTH) region of China were analyzed using the Palmer Drought Severity index(PDSI) based on 21 meteorological stations. Overall, chang... Spatio-temporal patterns of drought from 1961 to 2013 over the Beijing-Tianjin-Hebei(BTH) region of China were analyzed using the Palmer Drought Severity index(PDSI) based on 21 meteorological stations. Overall, changes in the mean-state of drought detected in recent decades were due to decreases in precipitation and potential evapotranspiration. The Empirical Orthogonal Functions(EOF) method was used to decompose drought into spatio-temporal patterns, and the first two EOF modes were analyzed. According to the first leading EOF mode(48.5%), the temporal variability(Principal Components, PC1) was highly positively correlated with annual series of PDSI(r=+0.99). The variance decomposition method was further applied to explain the inter-decadal temporal and spatial variations of drought relative to the total variation. We find that 90% of total variance was explained by time variance, and both total and time variance dramatically decreased from 1982 to 2013. The total variance was consistent with extreme climate events at the inter-decadal scale(r=0.71, p<0.01). Comparing the influence of climate change on the annual drought in two different long-term periods characterized by dramatic global warming(P1: 1961–1989 and P2: 1990–2013), we find that temperature sensitivity in the P2 was three times more than that in the P1. 展开更多
关键词 PDSI SPATIAL and TEMPORAL PATTERNS sensitivity analysis GLOBAL WARMING
Precipitation differences cause contrast patterns of glacier-melt water supplied discharge of two glacier basins between northern and southern Third Pole
6
作者 Ruzhen Yao Jiancheng Shi 《科学通报:英文版》 SCIE EI CSCD 2019年第7期431-434,共4页
In the Third Pole (TP) region, there are about 100,000 km2of glaciers [1], distributed mainly in the Tibetan Plateau and its surroundings. Glacier melt-water from these glaciers not only feeds rivers, such as the Indu... In the Third Pole (TP) region, there are about 100,000 km2of glaciers [1], distributed mainly in the Tibetan Plateau and its surroundings. Glacier melt-water from these glaciers not only feeds rivers, such as the Indus, Brahmaputra, Ganges, Yellow and Yangtze, which finally reach the seas, but also feeds the rivers, such as the Tarim River, Heihe River and a lot of other rivers, which finally reach the arid areas or deserts. The Asian Water Tower [2]is, therefore, proposed to characterize the significance of the glaciers and glacier melt water at all the river heads in the TP, which is important water resource both for regulating seasonal water demands in the arid areas or deserts and for sea level rising. In addition, they also change the water cycle at a large scale [3]. 展开更多
关键词 TP Precipitation DIFFERENCES cause contrast patterns of glacier-melt water supplied DISCHARGE of two GLACIER BASINS between NORTHERN and SOUTHERN Third Pole
小组教学模式在手术室临床教学中的应用 预览
7
作者 唐立平 李开红 倪小丽 《中国继续医学教育》 2019年第14期41-43,共3页
目的采用小组教学模式对手术室实习护士进行临床教学,以培养师生团队合作的能力,弥补一对一教学的不足。方法选取2018年1-12月来我院手术室实习的护理实习生(护生)120名作为研究对象,将其随机分成对照组和观察组。对照组采用传统一对一... 目的采用小组教学模式对手术室实习护士进行临床教学,以培养师生团队合作的能力,弥补一对一教学的不足。方法选取2018年1-12月来我院手术室实习的护理实习生(护生)120名作为研究对象,将其随机分成对照组和观察组。对照组采用传统一对一教学模式,观察组采用小组教学带教模式,对比两组护生实习后出科考核成绩。结果观察组护生出科理论考核成绩和操作考核成绩均高于对照组,差异均具有统计学意义(P<0.05)。实习满意度的比较,观察组中激发兴趣、技能提升、思维拓展、应对能力、团队协作5项评分均高于对照组,差异均具有统计学意义(P<0.05)。结论在手术室护理带教中采用小组教学模式,可有效提高护生的实习成绩,实习满意度提升,带教老师教学水平大幅度提高,达到了教学相长的目的。 展开更多
关键词 小组教学 实习护士 临床教学 手术室 模式 应用
在线阅读 免费下载
Ecosystem Service Flow Insights into Horizontal Ecological Compensation Standards for Water Resource: A Case Study in Dongjiang Lake Basin, China 预览
8
作者 XU Jie XIAO Yu +1 位作者 XIE Gaodi JIANG Yuan 《中国地理科学:英文版》 SCIE CSCD 2019年第2期214-230,共17页
Water supply services(WSSs) are critical for the regional water balance and water circulation, but relevant studies have not established the relationship between WSSs and human well-being. This research identifies the... Water supply services(WSSs) are critical for the regional water balance and water circulation, but relevant studies have not established the relationship between WSSs and human well-being. This research identifies the scope of areas that benefit from WSSs from an ecosystem service flow perspective. Moreover, the path and quantity of the flow of WSSs are simulated to provide a scientific theoretical basis for ecosystem service management and ecological compensation. The Dongjiang Lake Basin is a national priority river basin in China where ecological compensation pilot programmes concerning water resources are top priorities. Dongjiang Lake Basin experienced an increase and then a decrease in the overall supply of water, with an average net water supply of 1096–1500 mm for the years 1995, 2000, 2005 and 2010. The water demand increased each year in service beneficiary areas(SBAs), varying from 387 to 580 mm. Overall, Dongjiang Lake Basin met the net water demands of the actual SBAs in the lower reaches, but a gap in the water supply and demand emerged gradually. This research provides an understanding of the functional mechanisms for the provision, demand and flow of WSSs and provides a scientific theoretical basis for ecosystem service management and ecological compensation. 展开更多
关键词 ECOSYSTEM service flow water supply services Dongjiang Lake Basin SPATIOTEMPORAL patterns HORIZONTAL ecological COMPENSATION
在线阅读 下载PDF
Genome-wide analysis of odorant-binding proteins and chemosensory proteins in the sweet potato whitefly, Bemisia tabaci
9
作者 Yang Zeng Yu-Ting Yang +3 位作者 Qing-Jun Wu Shao-Li Wang Wen Xie You-Jun Zhang 《昆虫科学:英文版》 SCIE CAS CSCD 2019年第4期620-634,共15页
Odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) of insects are thought to play roles in olfactory recognition affecting host choice, copulation, reproduction and other behaviors. Previous descriptions... Odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) of insects are thought to play roles in olfactory recognition affecting host choice, copulation, reproduction and other behaviors. Previous descriptions of OBPs and CSPs in the whitefly Bemisia tabaci often provided no or incomplete genetic information. In this study, we present a genome-wide and transcriptome-wide investigation of the OBPs and CSPs in B. tabaci MEAMl (Middle East-Asia Minorl species). Eight OBP and 19 CSP genes were identified that covered all previous sequences. Phylogenetic analyses showed that the CSP genes had a lineage-specific expansion (BtabBCSP人 BtabBCSP3, BtabBCSPl3, BtabBCSPl 7, BtabBCSP18 and BtabBCSP 19). Expression profiling of OBPs and CSPs by transcriptome sequencing and quantitative real-time polymerase chain reaction (qPCR) revealed that expression patterns differed among developmental stages of B. tabaci MEAM 1. Five OBP genes and 11 CSP genes significantly differed between males and females;four of the 19 CSP genes were highly expressed in adults, while two were highly expressed in nymphs. The expression profiles of the OBP and CSP genes in different tissues of B. tabaci MEAM1 adults were analyzed by qPCR. Four OBP genes found in B. tabaci MEAM 1 were highly expressed in the head. Conversely, only two CSPs were enriched in the head, while the other six CSPs were specifically expressed in other tissues. Our results provide a foundation for future research on OBPs and CSPs in B. tabaci. 展开更多
关键词 BEMISIA TABACI CSPs expression PATTERNS GENOME-WIDE identification OBPs PHYLOGENETIC
彩瓷纹饰在现代纺织品中的应用 预览
10
作者 尚亚力 徐跃帼 吴增波 《纺织科技进展》 CAS 2019年第4期20-25,共6页
研究了青花瓷、斗彩、五彩、珐琅彩和粉彩瓷器的工艺艺术,介绍了彩瓷与非彩瓷的渊源。通过对蕴涵某一朝代政治、经济、文化、科技等代表性瓷器纹饰的深刻领悟,采用直接应用或提取重构,根据织物配色原理、织物组织结构及其肌理视觉原理,... 研究了青花瓷、斗彩、五彩、珐琅彩和粉彩瓷器的工艺艺术,介绍了彩瓷与非彩瓷的渊源。通过对蕴涵某一朝代政治、经济、文化、科技等代表性瓷器纹饰的深刻领悟,采用直接应用或提取重构,根据织物配色原理、织物组织结构及其肌理视觉原理,化繁为简设计出反映现代文化元素、工艺技术及符合市场需求的各种纹饰,将其应用于纺织品以承载和传承华夏文明。 展开更多
关键词 彩瓷 艺术 纹饰 应用 纺织品
在线阅读 下载PDF
FunctionFlow:coordinating parallel tasks
11
作者 Xuepeng FAN Xiaofei LIAO Hai JIN 《中国计算机科学前沿:英文版》 SCIE EI CSCD 2019年第1期73-85,共13页
With the growing allel programming,nowadays popularity of task-based partask-parallel programming libraries and languages are still with limited support for coordinating parallel tasks.Such limitation forces programme... With the growing allel programming,nowadays popularity of task-based partask-parallel programming libraries and languages are still with limited support for coordinating parallel tasks.Such limitation forces programmers to use additional independent components to coordinate the parallel tasks -the components can be third-party libraries or additional components in the same programming library or language.Moreover,mixing tasks and coordination components increase the difficulty of task-based programming,and blind schedulers for understanding tasks'dependencies. In this paper,we propose a task-based parallel programming library,Function Flow,which coordinates tasks in the purpose of avoiding additional independent coordination components.First,we use dependency expression to represent ubiquitous tasks'termination.The key idea behind dependency expression is to use && for both task's termination and Ⅱ for any task termination,along with the combination of dependency expressions.Second,as runtime support,we use a lightweight representation for dependency expression. Also,we use suspended-task queue to schedule tasks that still have prerequisites to run. Finally,we demonstrate Function Flow's effectiveness in two aspects,case study about implementing popular parallel patterns with FunctionFIow,and performance comparision with state-of-the-art practice,TBB.Our demonstration shows that FunctionFIow can generally coordinate parallel tasks without involving additional components,along with comparable performance with TBB. 展开更多
关键词 TASK parallel PROGRAMMING TASKS DEPENDENCY FunctionFlow COORDINATION PATTERNS
Direct observation of epitaxial alignment of Au on M0S2 at atomic resolution
12
作者 Yinghui Sun Haofei Zhao +3 位作者 Dan Zhou Yuchen Zhu Huanyu Ye Yan Aung Moe 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第4期947-954,共8页
The morphology and structural stability of metal/2D semic on ductor interfaces strongly affect the performa nee of 2D electronic devices and synergistic catalysis. However, the structural evolution at the interfaces h... The morphology and structural stability of metal/2D semic on ductor interfaces strongly affect the performa nee of 2D electronic devices and synergistic catalysis. However, the structural evolution at the interfaces has not been well explored particularly at atomic resolution. In this work, we study the structural evoluti on of Au nan oparticles (NPs) on few-layer MoS2 by high resol utio n transmissi on electro n microscopy (HRTEM) an d quan titative high-angle annular dark field seanning TEM. It is found that in the transition of Au from nan oparticles to den drites, a dynamically epitaxial align ment betwee n Au and MoS2 lattices is formed, and Moirc patter ns can be directly observed in HRTEM images due to the mismatch between Au and M0S2 lattices. This epitaxial alignment can occur in ambient conditions, and can also be accelerated by the irradiation of high-energy electron beam. In situ observation clearly reveals the rotation of Au NPs, the atom migration inside Au NPs, and the transfer of Au atoms between neighboring Au NPs, finally leading to the formation of epitaxially aligned Au dendrites on M0S2. The structural evoluti on of metal/2D semico nductor in terfaces at atomic scale can provide valuable information for the design and fabricatio n of the metal/2D semicon ductorn ano-devices with desired physical and chemical performa nces. 展开更多
关键词 ATOM migration M0S2 in SITU transmission electron MICROSCOPY (TEM) metal-semiconductor interface MOIRE patterns
Spatial and temporal patterns of drought in Zambia
13
作者 Brigadier LIBANDA ZHENG Mie Chilekana NGONGA 《干旱区科学:英文版》 SCIE CSCD 2019年第2期180-191,共12页
Drought acutely affects economic sectors, natural habitats and communities. Understanding the past spatial and temporal patterns of drought is crucial because it facilitates the forecasting of future drought occurrenc... Drought acutely affects economic sectors, natural habitats and communities. Understanding the past spatial and temporal patterns of drought is crucial because it facilitates the forecasting of future drought occurrences and informs decision-making processes for possible adaptive measures. This is especially important in view of a changing climate. This study employed the World Meteorological Organization(WMO)-recommended standardized precipitation index(SPI) to investigate the spatial and temporal patterns of drought in Zambia from 1960 to 2016. The relationship between the occurrence of consecutive dry days(CDD;consecutive days with less than 1 mm of precipitation) and SPI was also investigated. Horizontal wind vectors at 850 hPa during the core of the rainy season(December–February)were examined to ascertain the patterns of flow during years of extreme and severe drought;and these were contrasted with the patterns of flow in 2007, which was a generally wet year. Pressure vertical velocity was also investigated. Based on the gamma distribution, SPI successfully categorized extremely dry(with a SPI value less than or equal to –2.0) years over Zambia as 1992 and 2015, a severely dry(–1.9 to –1.5) year as 1995, moderately dry(–1.4 to –1.0) years as 1972, 1980, 1987, 1999 and 2005, and 26 near normal years(–0.9 to 0.9). The occurrence of CDD was found to be strongly negatively correlated with SPI with a coefficient of –0.6. Further results suggest that, during wet years, Zambia is influenced by a clockwise circulating low-pressure zone over the south-eastern Angola, a second such zone over the northern and eastern parts, and a third over the Indian Ocean. In stark contrast, years of drought were characterized by an anti-clockwise circulating high-pressure zone over the south-western parts of Zambia,constraining precipitation activities over the country. Further, wet years were characterized by negative pressure vertical velocity anomalies, signifying ascending motion;while drought years were dominate 展开更多
关键词 standardized precipitation index PATTERNS of DROUGHT consecutive dry DAYS vertical VELOCITY GAMMA distribution RAINFALL
On-site stormwater detention for Australian development projects: Does it meet frequent flow management objectives? 预览
14
作者 Rodney Ronalds Alex Rowlands Hong Zhang 《水科学与水工程:英文版》 EI CAS CSCD 2019年第1期1-10,共10页
On-site stormwater detention (OSD) is a conventional component of urban drainage systems, designed with the intention of mitigating the increase to peak discharge of stormwater runoff that inevitably results from urba... On-site stormwater detention (OSD) is a conventional component of urban drainage systems, designed with the intention of mitigating the increase to peak discharge of stormwater runoff that inevitably results from urbanization. In Australia, singular temporal patterns for design storms have governed the inputs of hydrograph generation and in turn the design process of OSD for the last three decades. This paper raises the concern that many existing OSD systems designed using the singular temporal pattern for design storms may not be achieving their stated objectives when they are assessed against a variety of alternative temporal patterns. The performance of twenty real OSD systems was investigated using two methods:(1) ensembles of design temporal patterns prescribed in the latest version of Australian Rainfall and Runoff, and (2) real recorded rainfall data taken from pluviograph stations modeled with continuous simulation. It is shown conclusively that the use of singular temporal patterns is ineffective in providing assurance that an OSD will mitigate the increase to peak discharge for all possible storm events. Ensemble analysis is shown to provide improved results. However, it also falls short of providing any guarantee in the face of naturally occurring rainfall. 展开更多
关键词 STORMWATER DETENTION Frequent flow management Temporal patterns RUNOFF routing Continuous simulation South East Queensland
在线阅读 下载PDF
美丽乡村建设背景下的精准扶贫模式与路径研究——以西安航空学院结对帮扶陕西镇坪县千山村为例 预览
15
作者 张鹏 雷颖颐 田驰 《西安航空学院学报》 2019年第2期41-45,共5页
精准扶贫是国家打赢脱贫攻坚战,全面建成小康社会,实现民族伟大复兴“中国梦”的战略部署,也是促进美丽乡村建设,构建乡村富裕、生态文明、和谐可持续发展的重要途径。高校承担着服务地方经济社会建设发展的职责,参与精准扶贫有着显著... 精准扶贫是国家打赢脱贫攻坚战,全面建成小康社会,实现民族伟大复兴“中国梦”的战略部署,也是促进美丽乡村建设,构建乡村富裕、生态文明、和谐可持续发展的重要途径。高校承担着服务地方经济社会建设发展的职责,参与精准扶贫有着显著的优势。依托高校自身优势和资源,通过实施教育扶贫、人才扶贫、产业扶贫、科技扶贫、党建扶贫和文化扶贫模式,提升了贫困人口的经济收入,大幅度降低了贫困人口数量,使更多贫困人口走上了致富之路。以西安航空学院结对帮扶陕西省镇坪县千山村为例,研究探索高校精准扶贫的模式与路径。 展开更多
关键词 美丽乡村 精准扶贫 模式 路径
在线阅读 下载PDF
Turing pattern in the fractional Gierer–Meinhardt model
16
作者 王语 张荣培 +1 位作者 王震 韩子健 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第5期57-63,共7页
It is well-known that reaction–diffusion systems are used to describe the pattern formation models.In this paper,we will investigate the pattern formation generated by the fractional reaction–diffusion systems.We fi... It is well-known that reaction–diffusion systems are used to describe the pattern formation models.In this paper,we will investigate the pattern formation generated by the fractional reaction–diffusion systems.We first explore the mathematical mechanism of the pattern by applying the linear stability analysis for the fractional Gierer–Meinhardt system.Then,an efficient high-precision numerical scheme is used in the numerical simulation.The proposed method is based on an exponential time differencing Runge–Kutta method in temporal direction and a Fourier spectral method in spatial direction.This method has the advantages of high precision,better stability,and less storage.Numerical simulations show that the system control parameters and fractional order exponent have decisive influence on the generation of patterns.Our numerical results verify our theoretical results. 展开更多
关键词 TURING PATTERNS FRACTIONAL Gierer–Meinhardt MODEL FOURIER SPECTRAL method
DYNAMICAL PREDICTION OF WEST CHINA AUTUMN RAINFALL BY THE NCEP CLIMATE FORECAST SYSTEM
17
作者 董少柔 杨崧 +1 位作者 张团团 冯业荣 《热带气象学报:英文版》 SCIE 2019年第1期114-128,共15页
This study investigates the variation and prediction of the west China autumn rainfall(WCAR) and their associated atmospheric circulation features, focusing on the transitional stages of onset and demise of the WCAR.O... This study investigates the variation and prediction of the west China autumn rainfall(WCAR) and their associated atmospheric circulation features, focusing on the transitional stages of onset and demise of the WCAR.Output from the 45-day hindcast by the National Centers for Environmental Prediction(NCEP) Climate Forecast System version 2(CFSv2) and several observational data sets are used. The onset of WCAR generally occurs at pentad 46 and decays at pentad 56, with heavy rainfall over the northwestern China and moderate rainfall over the south. Before that,southerly wind changes into southeasterly wind, accompanied by a westward expansion and intensification of the western Pacific subtropical high(WPSH), favoring rainfall over west China. On the other hand, during the decay of WCAR, a continental cold high develops and the WPSH weakens and shifts eastward, accompanied by a demise of southwest monsoon flow, leading to decay of rainfall over west China. The CFSv2 generally well captures the variation of WCAR owing to the high skill in capturing the associated atmospheric circulation, despite an overestimation of rainfall. This overestimation occurs at all time leads due to the overestimated low-level southerly wind. The CFSv2 can pinpoint the dates of onset and demise of WCAR at the leads up to 5 days and 40 days, respectively. The lower prediction skill for WCAR onset is due to the unrealistically predicted northerly wind anomaly over the lower branch of the Yangtze River and the underestimated movement of WPSH after lead time of 5 days. 展开更多
关键词 west China AUTUMN RAINFALL NCEP CFSv2 PREDICTION predictable patterns
Dendritic branching patterns in platforms of complex Ni-based single crystal castings
18
作者 Min Huang Gong Zhang +4 位作者 Dong Wang Zhi-cheng Ge Yu-zhang Lu Xiang-wei Jiang Lang-hong Lou 《中国铸造:英文版》 SCIE 2019年第2期110-117,共8页
Dendritic branching patterns at variable cross-sections in Ni-based single crystal(SX) castings of different generations were investigated using optical microscope(OM), electro probe microanalyzer(EPMA),differential s... Dendritic branching patterns at variable cross-sections in Ni-based single crystal(SX) castings of different generations were investigated using optical microscope(OM), electro probe microanalyzer(EPMA),differential scanning calorimeter(DSC), Thermo-Cal software and Pro-CAST software. Results show that the dendritic branching patterns are similar in outward platform in SXs of different generations. That is, the primary dendrites(PDs) are introduced into the platform by developing a series of secondary dendrites(SDs) to occupy the bottom of the platform, and the ternary dendrites(TDs) originating from these SDs grow upward to fill up the platform. With the SX generation increasing, the undercooling of melts in the inward platform increases significantly due to the increasing alloying elements and the segregation in the directional solidification(DS)process, and the growth velocity of the dendrite tip increases according to the dynamic model of dendrite growth,which is beneficial for the high-order dendrite development. The stronger dendritic branching ability is shown in the inward platform of the higher generation Ni-based SX. 展开更多
关键词 DENDRITIC branching patterns platform UNDERCOOLING
“祥云”图案在鞋靴设计中的应用 预览
19
作者 金渝萍, 谢松军, +1 位作者 柳鑫, 杨轩 《西部皮革》 2018年第17期46-48,共3页
从“祥云”纹中提取设计元素;将祥云进行变形处理,用简洁的线条提炼出祥云飘逸的形态;将其运用到鞋靴当中,寓意美好、吉祥的开始.从古至今,人们对吉祥、幸福充满了向往.“祥云”纹有着很多美好的寓意,是人们对万事万物希冀祝福的心理意... 从“祥云”纹中提取设计元素;将祥云进行变形处理,用简洁的线条提炼出祥云飘逸的形态;将其运用到鞋靴当中,寓意美好、吉祥的开始.从古至今,人们对吉祥、幸福充满了向往.“祥云”纹有着很多美好的寓意,是人们对万事万物希冀祝福的心理意愿和生活追求.“祥云”图案来源于我国古代的云纹.古人出于对云的敬畏,在纹饰上变化出各种和云有关的图案,运用于器物、服饰、建筑等. 展开更多
关键词 祥云 鞋靴 元素 图案 纹饰 风格
在线阅读 下载PDF
Amy Lowell诗“Patterns”多模式话语分析 预览
20
作者 陈洁娜 朱怡 《陇东学院学报》 2018年第4期18-22,共5页
立足于Halliday系统功能理论中的三大元语言功能,结合Kress和Leeuwen多模态话语的社会符号学分析,对AmyLowell的名篇“Patterns”进行了多模式话语分析。研究聚焦于概念功能中的及物系统、人际功能中的情态系统和语篇功能中的主位系... 立足于Halliday系统功能理论中的三大元语言功能,结合Kress和Leeuwen多模态话语的社会符号学分析,对AmyLowell的名篇“Patterns”进行了多模式话语分析。研究聚焦于概念功能中的及物系统、人际功能中的情态系统和语篇功能中的主位系统,从印刷体诗歌文字和非文字多模式中探讨了诗歌主题意义、主人公内心情感以及作者态度评价的诠释过程,进一步增强了该诗的独特魅力。 展开更多
关键词 元语言功能 PATTERNS 多模式话语分析
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部 意见反馈