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不整合面和砂体配置对镇北长3及以上低渗透油藏油气富集的影响 预览
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作者 张庆洲 孙燕妮 +2 位作者 武迪生 杨子清 曾山 《西安石油大学学报:自然科学版》 CAS 北大核心 2019年第5期31-36,共6页
通过大量的测井和岩心等资料分析,采用古地貌恢复等方法,探讨了鄂尔多斯盆地侏罗系和三叠系间的不整合面及砂体的配置关系对镇北地区长3及以上低渗透油藏油气富集的影响。研究表明:前侏罗系古地貌将镇北地区划分为若干个古河流域,每个... 通过大量的测井和岩心等资料分析,采用古地貌恢复等方法,探讨了鄂尔多斯盆地侏罗系和三叠系间的不整合面及砂体的配置关系对镇北地区长3及以上低渗透油藏油气富集的影响。研究表明:前侏罗系古地貌将镇北地区划分为若干个古河流域,每个流域的主河谷深切延长组地层,通过油气运移所形成的低渗透油藏在平面上主要局限于其古河流域内;不整合面为油气运移的主要通道,由于地层纵向相态转化快,油气运移困难,同一古河流域的长3及以上低渗透油藏纵向上主要局限于一个统一的构造附近,即油气主要聚集于不整合面附近古河流域内砂体连片性较好的构造基准域内。 展开更多
关键词 长3及以上 低渗透油藏 古河流域 构造基准域 不整合面 镇北地区
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Re-assessing Vegetation Carbon Storage and Emissions from Land Use Change in China Using Surface Area 预览
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作者 HE Qingsong TAN Shukui +2 位作者 XIE Peng LIU Yaolin LI Jing 《中国地理科学:英文版》 SCIE CSCD 2019年第4期601-613,共13页
Land surface area estimation can provide basic information for accurately estimating vegetation carbon storage under complex terrain. This study selected China, a country dominated by mountains, as an example, and cal... Land surface area estimation can provide basic information for accurately estimating vegetation carbon storage under complex terrain. This study selected China, a country dominated by mountains, as an example, and calculated terrestrial vegetation carbon storage(VCS) for 2000 and 2015 using land surface area and traditional ellipsoid area. The land surface area is estimated by a triangular network on the high precision digital elevation model.The results showed that: 1) The VCS estimated by the surface area measurement in 2000 and 2015 were 0.676 and0.692 Pg C(1 Pg = 1015 g) higher than the VCS calculated using the ellipsoid area, respectively. 2) As the elevation increases, the differences between VCS estimated by surface area measurement and ellipsoid area measurement are expanding. Specially, a clear gap was present starting from an elevation of 500 m, with the relative error exceeds8.99%. 3) The total amount of carbon emitted due to land use change reached 0.114 Pg C. The conversions of forestland and grassland to other land use type are the main reasons of the loss of vegetation carbon storage, resulting in a total amount of biomass carbon storage decreased by 0.942 and 0.111 Pg C, respectively. This study was a preliminary exploration of incorporating land surface area as a factor in resource estimation, which can help more accurately understand the status of resources and the environment in the region. 展开更多
关键词 carbon storage LAND use CHANGE surface area RESOURCE estimation ellipsoidal area China
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球形水果表面斑块成像失真度控制与实验 预览
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作者 刘婷 芮成杰 +1 位作者 李海涛 张绍英 《农业机械学报》 EI CAS CSCD 北大核心 2019年第9期221-228,共8页
针对机器视觉在线分选时球形水果表面缺陷斑块在图像中形状、尺寸失真的问题,依据射影几何原理和通用成像配置,建立了斑块的成像普遍方程及斑块成像面积的通用算法,分析了斑块图像的面积失真规律;利用Matlab建立了满足特定分选准确度要... 针对机器视觉在线分选时球形水果表面缺陷斑块在图像中形状、尺寸失真的问题,依据射影几何原理和通用成像配置,建立了斑块的成像普遍方程及斑块成像面积的通用算法,分析了斑块图像的面积失真规律;利用Matlab建立了满足特定分选准确度要求下有效采像区域与成像系统参数的配置关系,提出了一种有效采像区域的简化划定方法;分别以半球块和埃及甜橙为实验对象,利用NI Vision Assistant对工业相机采集到的、位于划定区域内的缺陷斑块进行了面积失真度校验。实验结果表明,特定采像条件下,当失真度阈值 A 为20%时,求得最小球心角λ 0 min 为79.32°来划定有效采像区域,采集到的5个半球块位于不同采像工位及其对应的采像姿态下的图像,有效采像区域内各缺陷斑块面积失真度均小于20%,满足失真度控制要求;同样地,5个埃及甜橙样本中,满足失真度要求的缺陷斑块比例分别达:97.38%、97.33%、94.22%、96.44%、97.78%。可见,利用球形水果表面缺陷斑块成像普遍方程预测结果进行图像的有效采像区域分割,即可实现对分选准确率的有效控制;通过测定有效采像区域中缺陷斑块面积进行分选阈值判断,有利于简化图像处理计算,为球形水果成像系统成像参数配置提供理论指导. 展开更多
关键词 球形水果 表面成像 缺陷斑块 面积失真度
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低品质海泡石提纯及吸附性能研究 预览
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作者 贺洋 《非金属矿》 CAS CSCD 北大核心 2019年第4期56-57,共2页
对低品质海泡石原矿进行纯化、均化、活化等处理,制备了超细海泡石粉体吸附材料。采用元素分析、比表面积、SEM、XRD等方法对吸附材料进行表征,并对材料的吸附性能进行了分析。结果表明:该海泡石吸附材料粒度细,比表面积大,吸附能力强。
关键词 海泡石 提纯 比表面积 吸附性能
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微造型面积占有率对滑动轴承摩擦性能的影响 预览
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作者 丁林 权秀敏 《南阳理工学院学报》 2019年第4期54-59,共6页
利用激光打标系统配合标准旋转工作台在滑动轴承轴颈圆周表面制备了微造型,研究了表面微造型面积占有率对滑动轴承摩擦磨损性能的影响,并探讨IS025178表面形貌三维表征参数与摩擦系数之间的相关性。结果表明:随着表面微造型面积占有率... 利用激光打标系统配合标准旋转工作台在滑动轴承轴颈圆周表面制备了微造型,研究了表面微造型面积占有率对滑动轴承摩擦磨损性能的影响,并探讨IS025178表面形貌三维表征参数与摩擦系数之间的相关性。结果表明:随着表面微造型面积占有率的增大,摩擦副接触表面的摩擦系数、温升及磨损量均先减小后增大,在表面微造型面积占有率为10%时均为最小值。随表面偏态和表面峰态增加,不同表面微造型面积占有率摩擦副接触表面的摩擦系数分别逐渐增大和减小;随表面谷处平均空体体积和表面中心处平均空体体积增加,不同表面微造型面积占有率摩擦副接触表面的摩擦系数先减小后增大。 展开更多
关键词 微造型 表面形貌参数 面积占有率 摩擦特性
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Discussion on“Effects of lime addition on geotechnical properties of sedimentary soil in Curitiba,Brazil”[J Rock Mech Geotech Eng 10(2018)188e194] 预览
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作者 Amin Soltani Mehdi Mirzababaei 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第1期214-218,共5页
The present discussion aims at complementing the original work published by Baldovino et al.(2018)by outlining a novel point of view.In light of the inherent limitations associated with the empirical model suggested i... The present discussion aims at complementing the original work published by Baldovino et al.(2018)by outlining a novel point of view.In light of the inherent limitations associated with the empirical model suggested in the original article,the dimensional analysis technique was introduced to the soil-lime strength problem,thereby leading to the development of simple and physically meaningful dimensional models capable of predicting the unconfined compressive and splitting tensile strengths of compacted soil-lime mixtures as a function of the mixture’s index properties,i.e.lime content,initial placement(or compaction)condition,initial specific surface area and curing time.The predictive capacity of the proposed dimensional models was examined and validated by statistical techniques.The proposed dimensional models contain a limited number of fitting parameters,which can be calibrated by minimal experimental effort and hence implemented for predictive purposes. 展开更多
关键词 Dimensional analysis LIME content CURING time Specific surface area Unconfined compressive STRENGTH SPLITTING tensile STRENGTH
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Examining the Relationship Between Spatial Configurations of Urban Impervious Surfaces and Land Surface Temperature 预览
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作者 WU Xiangli LI Binxia +3 位作者 LI Miao GUO Meixin ZANG Shuying ZHANG Shouzhi 《中国地理科学:英文版》 SCIE CSCD 2019年第4期568-578,共11页
The urban heat island(UHI) effect has significant effects on the quality of life and public health. Numerous studies have addressed the relationship between UHI and the increase in urban impervious surface area(ISA), ... The urban heat island(UHI) effect has significant effects on the quality of life and public health. Numerous studies have addressed the relationship between UHI and the increase in urban impervious surface area(ISA), but few of them have considered the impact of the spatial configuration of ISA on UHI. Land surface temperature(LST) may be affected not only by urban land cover, but also by neighboring land cover. The aim of this research was to investigate the effects of the abundance and spatial association of ISAs on LST. Taking Harbin City, China as an example, the impact of ISA spatial association on LST measurements was examined. The abundance of ISAs and the LST measurements were derived from Landsat Thematic Mapper(TM) imagery of 2000 and 2010, and the spatial association patterns of ISAs were calculated using the local Moran’s I index. The impacts of ISA abundance and spatial association on LST were examined using correlation analysis. The results suggested that LST has significant positive associations with both ISA abundance and the Moran’s I index of ISAs, indicating that both the abundance and spatial clustering of ISAs contribute to elevated values of LST. It was also found that LST is positively associated with clustering of high-ISA-percentage areas(i.e.,>50%) and negatively associated with clustering of low-ISA-percentage areas(i.e.,<25%). The results suggest that, in addition to the abundance of ISAs,their spatial association has a significant effect on UHIs. 展开更多
关键词 impervious surface area urban heat ISLAND LAND sruface temperature SPATIAL CONFIGURATION local Moran’s I index
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Experimental evaluation of activated carbon derived from South Africa discard coal for natural gas storage 预览
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作者 Jibril Abdulsalam Jean Mulopo +2 位作者 Bilainu Oboirien Samson Bada Rosemary Falcon 《国际煤炭科学技术学报:英文版》 2019年第3期459-477,共19页
Lacking in literature is the use of discard coal to produce activated carbon and in its subsequent use in the storage of natural gas. In this study, the characterization and gas storage evaluation of a largely porous ... Lacking in literature is the use of discard coal to produce activated carbon and in its subsequent use in the storage of natural gas. In this study, the characterization and gas storage evaluation of a largely porous activated carbon with large surface area synthesized from discard coal were investigated. Discard coals are waste material generated from coal beneficiation process. In developing the activated carbon, chemical activation route with the use of KOH reagent was applied. The effects of KOH/discard coal weight ratio (1:1, 2.5:1, 4:1), temperature (400-800 ℃) and particle size (0.15-0.25 mm, 0.25-0.5 mm, 0.5-1 mm) on the adsorptive properties of the activated carbon were methodically evaluated and optimized using response surface methodology. The synthesized activated carbon was characterized using BET, SEM/EDS, and XRD. The results showed that for each activation process, the surface area and pore volume of the resulting activated carbon increased with increased temperature and KOH/discard coal weight ratio. The maximum surface area of 1826.41 m2/g, pore volume of 1.252 cm^3/g and pore size of 2.77 nm were obtained at carbonization temperature of 800 ℃ and KOH/discard coal weight ratio of 4:1. Methane and nitrogen adsorption data at high pressure were fitted to Toth isotherm model with a predictive accuracy of about 99%. Adsorption parameters using the Toth model provides useful information in the design of adsorbed natural gas storage system. According to the requirements of adsorbent desired for natural gas storage, it could be stated that the synthesized activated carbon could well be applied for natural gas storage. 展开更多
关键词 DISCARD COAL ACTIVATED carbon Surface area METHANE ADSORPTION
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One-step synthesis of robust carbon nanotube foams with ultrahigh surface area for high-performance lithium ion battery
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作者 YU PengCheng YUAN YanChao 《中国科学:技术科学英文版》 SCIE EI CAS CSCD 2019年第3期464-471,共8页
A novel three-dimensional(3D) carbon nanotube foams(CNTF) with ultrahigh specific surface area have been fabricated through a unique but facile one-step synthesis by using CO2 as both carbon source and activating agen... A novel three-dimensional(3D) carbon nanotube foams(CNTF) with ultrahigh specific surface area have been fabricated through a unique but facile one-step synthesis by using CO2 as both carbon source and activating agent. The activation temperature and time have been adjusted, and the best sample demonstrates a specific surface area of 1959.8 m2 g–1 and a total pore volume of 3.23 cm3 g–1. A reversible capacity of about 870 mAhg–1 is maintained at 50 mAg–1 when the CNTF used as cathode materials. Meanwhile, the capacity is as large as 320 mAhg–1 at the current density of 2 A g–1 and the capacity retention is nearly 100% after 500 cycles. These excellent and highly stable battery performances should be attributed to the structural advantages of as-synthesized CNTFs generated by using a facile CO2-assisted strategy, which may potentially be applied in large scale production of porous 3D carbon materials in the fields of energy storage and conversion. 展开更多
关键词 carbon NANOTUBE foam CO2-assisted activation ultrahigh surface area lithium ion battery
Dominant role of wettability in improving the specific capacitance 预览
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作者 Tongtong Liu Kai Wang +2 位作者 Yongxiu Chen Shuangliang Zhao Yongsheng Han 《绿色能源与环境:英文版》 CSCD 2019年第2期171-179,共9页
Here we report a strategy to enhance the energy density of supercapacitors by increasing the utilization rate of the specific surface area(SSA)via wettability improvement.The nonporous gold(NPG)film is used as the ele... Here we report a strategy to enhance the energy density of supercapacitors by increasing the utilization rate of the specific surface area(SSA)via wettability improvement.The nonporous gold(NPG)film is used as the electrodes and the ionic liquid[EMIM]BF4 is the electrolyte.When the electrode is coated by paraffin,an increase of the contact angle leads to a remarkable reduction of the specific capacitance.While when acetonitrile is added into the electrolyte,the contact angle is decreased and the utilization rate of SSA is improved,which results in an increase of the specific capacitance.The addition of isopropyl acetate into the electrolyte leads to a further increase of the specific capacitance.To generalize the role of the wettability in improving the energy density,a carbon-based electrode is evaluated in the solution of potassium hydroxide.An addition of propyl alcohol into the potassium hydroxide solution leads to an increase of the specific capacitance,as well as a long-term stability of the supercapacitor.The role of conductivity in this study is excluded by designing experiments.This paper highlights the significance of wettability in determining the specific capacitance,showing an alternative to improve the energy density of supercapacitors. 展开更多
关键词 SUPERCAPACITOR Energy density Specific CAPACITANCE EFFECTIVE surface area WETTABILITY
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非规则金属制品表面积计算三维扫描法 预览
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作者 母宇渊 蔡小先 +2 位作者 彭建兵 唐瑶 郭力嘉 《检验检疫学刊》 2019年第4期39-40,共2页
采用三维扫描仪对不规则金属制品如碗、勺、锅、筷子等样品进行检测,能快速、准确地获得其样品表面积。与传统测量手段相比,其特点是不受样品形状的限制、速度快、稳定性好、精度高,可以解决日常生活中不规则金属用品表面积检验情况。
关键词 三维扫描仪 不规则金属制品 表面积 3D
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四面体的Bonnesen型等周不等式 预览
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作者 彭璐 马磊 曾春娜 《湖北民族学院学报:自然科学版》 CAS 2019年第3期287-290,共4页
主要通过研究平面上四面体的表面积、体积和内切球半径之间的关系,并借助一系列几何不等式、均值不等式等,获得了四面体的几个新的Bonnesen型不等式.进一步还给出了四面体的等周不等式的新的证明方法.最后猜想获得用ri与re表示新的四面... 主要通过研究平面上四面体的表面积、体积和内切球半径之间的关系,并借助一系列几何不等式、均值不等式等,获得了四面体的几个新的Bonnesen型不等式.进一步还给出了四面体的等周不等式的新的证明方法.最后猜想获得用ri与re表示新的四面体的Bonnesen型不等式. 展开更多
关键词 四面体 体积 表面积 内切球半径 Bonnesen型等周不等式
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Facile Preparation of Al2O3 Hollow Microspheres Via a Urea-nietliated Precipitation Process
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作者 徐东 姜洪义 +2 位作者 LI Ming DONG Xuecheng LUO Ting 《武汉理工大学学报:材料科学英文版》 SCIE EI CAS 2019年第3期579-586,共8页
Al2O hollow microspheres without noticeable aggregation have been prepared via a facile templating route with urea-mediated precipitation. The precipitation process is different from the surfaceadsorption method which... Al2O hollow microspheres without noticeable aggregation have been prepared via a facile templating route with urea-mediated precipitation. The precipitation process is different from the surfaceadsorption method which is confined to the adsorption capacity of the template surface. TEM and SEM images indicate that most of these Al2O hollow microspheres with shell thickness of tens of nanometers and diameters in a narrow range of 100-200 nm consist of a shell of closely packed nanoparticles. The optimal amount of H2O and EtOH are 40 and 120 mL, respectively. The specific surface area, average pore size and pore volume of the Al2O hollow microspheres (calcinated at 600 °C) are 328.52 m2/g, 17.496 nm and 1.985 cm'/g, respectively. As the calcination temperature increases from 600 to 1 100 °C, the phase composition changes from y-Al2O3 to &-AI2O3 and a-Al2O3, and the surface morphology appears to change from a relatively rough surface formed by nanoparticles to a smooth surface formed by lamellar, which lead to the closure of pore channels and the reduction of specific surface. 展开更多
关键词 Al2O HOLLOW MICROSPHERES PRECIPITATION NANOPARTICLES SPECIFIC surface area
一种求解三维激光扫描后不规则体的体积及表面积方法 预览
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作者 王伟 段虎荣 +1 位作者 张德成 贾荣超 《测绘与空间地理信息》 2019年第8期172-175,共4页
三维激光扫描技术在测绘中的应用日渐广泛,针对如何利用三维扫描数据直接计算出不规则模型的体积和表面积的问题,本文提出利用投影法计算模型体积,利用投影面积平方和的算术平方根来计算空间模型的表面积。首先对扫描得到的空间离散点... 三维激光扫描技术在测绘中的应用日渐广泛,针对如何利用三维扫描数据直接计算出不规则模型的体积和表面积的问题,本文提出利用投影法计算模型体积,利用投影面积平方和的算术平方根来计算空间模型的表面积。首先对扫描得到的空间离散点的三维坐标进行处理,通过利用X和Y坐标实现不规则Delaunay三角网的构建;然后实现逐个三角形顶点点号的输出,将输出的点号和原始参与计算的点号使用Tecplot软件实现空间模型的构建;最后通过简单的四面体模型、第一卦限球体表面模型和扫描出的假山数据通过模拟数据,实现了模型的构建及体积和表面积的计算,并经过与理论结果进行比对,误差均可接受。 展开更多
关键词 三维激光扫描仪 DELAUNAY三角网 数值模拟 体积 表面积
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三维激光扫描技术在假山雕塑表面积计算中的应用
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作者 姜赟 陈宜金 《工程勘察》 2019年第4期66-69,共4页
采用三维激光扫描技术可以快速准确地获取物体表面的三维数据。本文给出了基于三维激光扫描仪对假山雕塑进行扫描所获取的数据来计算假山雕塑表面积的方法。介绍了三维激光扫描技术的原理,并用青岛啤酒节黄岛会场的一处不规则假山雕塑... 采用三维激光扫描技术可以快速准确地获取物体表面的三维数据。本文给出了基于三维激光扫描仪对假山雕塑进行扫描所获取的数据来计算假山雕塑表面积的方法。介绍了三维激光扫描技术的原理,并用青岛啤酒节黄岛会场的一处不规则假山雕塑的扫描实例,给出了点云数据的获取、处理和计算的基本方法和结果。 展开更多
关键词 三维激光扫描 假山雕塑 表面积
氢氧化钠改性玉米秸秆性状 预览
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作者 陈娟 刘元 +2 位作者 闫秦生 张智芳 刘皓 《化工科技》 CAS 2019年第5期6-9,共4页
玉米秸秆粉末经不同w(NaOH)改性处理后分离出固相部分为改性玉米秸秆,采用SEM、BET及热重分析技术手段表征改性玉米秸秆的基本性状。结果表明,改性玉米秸秆的热解以第2阶段挥发分的析出和燃烧为主,失重率高达61.16%,330℃呈现最大失重尖... 玉米秸秆粉末经不同w(NaOH)改性处理后分离出固相部分为改性玉米秸秆,采用SEM、BET及热重分析技术手段表征改性玉米秸秆的基本性状。结果表明,改性玉米秸秆的热解以第2阶段挥发分的析出和燃烧为主,失重率高达61.16%,330℃呈现最大失重尖峰,失重速率为0.738%/℃。w(NaOH)=2.0%改性玉米秸秆平均孔径(31.23nm)较w(NaOH)=1.5%改性玉米秸秆的平均孔径(14.79nm)偏大,比表面积与孔体积偏小。w(NaOH)越高,对玉米秸秆的改性作用越强。 展开更多
关键词 改性玉米秸秆 热解 比表面积 孔径
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江汉平原沙洋地区表层土壤中硒的分布特征及富硒原因分析 预览
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作者 陈秋菊 甘义群 张若雯 《安全与环境工程》 CAS 北大核心 2019年第4期8-14,43共8页
以江汉平原沙洋地区为研究区,采集154个表层土壤样品,综合表层土壤样品的主微量元素含量、pH值和有机碳(TOC)等地球化学指标,系统地探讨了沙洋地区表层土壤中硒(Se)含量的分布特征、硒来源以及土壤理化性质对硒分布的影响。结果表明:沙... 以江汉平原沙洋地区为研究区,采集154个表层土壤样品,综合表层土壤样品的主微量元素含量、pH值和有机碳(TOC)等地球化学指标,系统地探讨了沙洋地区表层土壤中硒(Se)含量的分布特征、硒来源以及土壤理化性质对硒分布的影响。结果表明:沙洋地区表层土壤中Se含量介于0.07~1.48mg/kg之间,90%以上表层土壤样点呈足硒状态;富硒土壤主要分布于西荆河东岸的李市镇和官垱镇,面积约为80km2;沙洋富硒区土壤中主微量元素含量及主要参数与汉江沉积物相近,而与长江沉积物和沙洋过渡区土壤有一定的差异,指示其物源为汉江沉积物;表层土壤中硒的含量与土壤酸碱度(pH值)、TOC含量以及铁铝氧化物(Fe2O3、Al2O3)含量具有良好的相关关系,说明沙洋地区表层土壤中硒分布不仅受控于成土母质,还受土壤理化性质的影响。 展开更多
关键词 江汉平原 表层土壤 硒分布 富硒成因 沙洋地区
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3000m^3液化石油气球罐检验与缺陷分析 预览
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作者 陈赫 曾旭 《石化技术》 CAS 2019年第6期33-34,共2页
某大型炼化企业一台3000m3液化石油气球罐进行首次定期检验,内表面上大环焊缝经磁粉检测发现多处表面裂纹缺陷.对其成因进行分析,为在湿硫化氢环境下发生的应力导向氢致开裂,经维修单位打磨消除后投入使用.下大环焊缝缺陷为非活性缺陷.... 某大型炼化企业一台3000m3液化石油气球罐进行首次定期检验,内表面上大环焊缝经磁粉检测发现多处表面裂纹缺陷.对其成因进行分析,为在湿硫化氢环境下发生的应力导向氢致开裂,经维修单位打磨消除后投入使用.下大环焊缝缺陷为非活性缺陷.针对球罐检验,提出了检验建议及注意事项. 展开更多
关键词 首次检验 表面裂纹 敏感区域 返修处理
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地表覆被对岩溶区鲜土无机三氮累积的影响
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作者 李仰征 何斌 +5 位作者 杨梦 沈驰华 曹熙 彭建宇 高峰 王小二 《环境科学与技术》 CAS CSCD 北大核心 2019年第6期44-51,共8页
通过对毕节市七星关区地表覆被差异明显的3个样地逐月采样,文章检测了土壤的铵态氮、亚硝态氮、硝态氮及有机质含量等指标,研究表明:(1)3个样地无机三氮季节差异明显,总体上表层土壤变异程度强于深层。凉亭样地为乔灌草地,植被覆盖良好... 通过对毕节市七星关区地表覆被差异明显的3个样地逐月采样,文章检测了土壤的铵态氮、亚硝态氮、硝态氮及有机质含量等指标,研究表明:(1)3个样地无机三氮季节差异明显,总体上表层土壤变异程度强于深层。凉亭样地为乔灌草地,植被覆盖良好,整个剖面年均有机质含量为最高,微生物底物充足导致铵态氮含量最大。3样地土壤有机质与铵态氮相关分析表征两者存在显著性相关(r2=0.549,p<0.05)。(2)对雨量充沛的中国南方区域新鲜土壤,其铵态氮均在夏季出现全年最低值,这主要是夏季强淋溶作用所致。而在北方非(弱)季风区,全年淋溶有限且夏季氨化作用强,铵态氮恰与南方相反,为全年高浓度时段。其他学者使用风干土此规律则被掩盖,这是因为矿质化作用会导致氮素出现流转。为精准评价原位土壤氮素含量应使用鲜土检测。(3)亚硝态氮全年最大的为农地鲜土,剖面均值达到2.39 mg/kg,最小的为撂荒疏草地。这与肥料施加和地表生物返还差异有关。3样地均在夏季出现了峰值,这除了与该季节腐殖质矿质化作用加强导致土壤转为弱碱性,进而为氨氧化细菌提供了游离氨基质有关,还受夏季土壤毛管孔隙长期被水充斥形成的微域缺氧环境,反硝化作用被激发、硝酸还原酶活性增大而亚硝酸还原酶活性被抑制等因素所制约。(4)3样地硝态氮含量曲线4月以后即表现显著下降态势,最低值出现在7月。这与硝态氮自身不易被土壤胶体吸附、春季以来逐步增强的淋溶和硝酸还原酶活性增大等因素有关。 展开更多
关键词 新鲜土壤 铵态氮 亚硝态氮 硝态氮 地表覆被 岩溶区
The Shephard Type Problems for General Lp-Centroid Bodies 预览
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作者 Zhang Juan Wang Wei-Dong Rong Xiao-chun 《数学研究通讯:英文版》 CSCD 2019年第1期27-34,共8页
In this paper,combining with the Lp-dual geominimal surface area and the general Lp-centroid bodies,we research the Shephard type problems for general Lp-centroid bodies.
关键词 Shephard TYPE problem general Lp-centroid BODY Lp-dual geominimal surface area
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