农业生态系统可持续性评价研究进展   总被引：5，自引：0，他引：5  

翟胜  王巨媛  张二勋  董杰  戴全厚 《地域研究与开发》2010,29(1)

在大量查阅国内外文献资料的基础上,阐述了国内外农业可持续性评价指标体系的选取标准与选取方法,在此基础上,综述了国内外农业可持续评价方法及评价尺度等研究进展情况。发现国内农业可持续性评价指标过多且以农业经济方面的指标为主,指标之间重叠现象严重,对生态环境、政策性和指导性指标重视不够,而且评价方法有待进一步完善。最后,针对农业可持续性评价中存在的问题提出了一些建议,以期对国内农业的可持续评价研究有所借鉴。  相似文献   

一种适用于各向异性土体的破坏准则     

苏栋 《岩土力学》2010,31(6):1681-1686

自然界的土体通常具有各向异性的特点,而传统的破坏准则大多只适用于各向同性的土体。结合应力张量和反映材料各向异性状态的组构张量,定义了修正偏应力及其不变量,提出了适用于各向异性土体材料的破坏准则。给出了共轴条件下正交各向异性和横向各向异性材料在一般应力空间的破坏曲线以及不同应力区中主应力系数b与摩擦角的关系曲线,并分析了它们的特性以及与各向同性材料相应曲线的区别。通过与真三轴试验数据的比较,表明该准则能很好地描述各向异性土体材料的强度特点。  相似文献   

基于MODIS遥感数据地表水汽压估算   总被引：1，自引：0，他引：1  

黄耀欢  江东  庄大方  付晶莹 《地理科学进展》2010,29(9)

地表水汽压是大气科学、水文学等多项研究中的一个重要输入参数.鉴于常规观测方法对于地面气象站点依赖性强且空间不连续的缺点,采用MODIS遥感数据对海河流域的日平均地表水汽压进行估算.通过相关分析得出日平均地表水汽压与MOD07低空可降雨量数据具有很强的相关性,并通过对比采用二次曲线进行建模.选取2009年1-4月数据对二次曲线模型的验证结果表明,估箅结果与实测日平均地表水汽压1∶1曲线的相关系数R2为0.83.本文的研究结果提供了一种实用的基于遥感数据估算日平均地表水汽压的方法.  相似文献   

中国土壤动物生态地理研究进展(英文)   总被引：7，自引：0，他引：7  

殷秀琴  宋博  董炜华  辛未冬  王野乔 《地理学报(英文版)》2010,20(3):333-346

This review summarizes main research findings in soil fauna eco-geography in China in the past 30 years.The subject areas and main results were overviewed including biodiversity and eco-geological distribution of soil fauna communities.Studies of ecological distributions of soil fauna and dynamic ranges in space from tropical,subtropical to temperate regions,and in categories from forest,grassland,desert,wetland,farmland to urban ecosystems,the responses and indications of soil fauna to soil environments.Ef...  相似文献   

张家口地区应变参数变化及其特征研究     

马栋  陈建国  陈晓燕 《华北地震科学》2010,28(2):1-5

根据1988—2009年张家口伸缩仪3方向的线应变资料计算出最大主应变、最大剪应变以及主应变方向等平面应变参数,分析张家口地区的断层特征、张家口伸缩仪观测环境的变化,结合1988—2009年张家口地区Ms≥4.0级以上地震,研究张家口地区应变参数的变化特征。  相似文献   

Residual curvature migration velocity analysis for angle domain common imaging gathers   总被引：2，自引：0，他引：2  

Kai Zhang  Zhen-Chun Li  Tong-Sheng Zeng  Xiao-Chun Dong 《应用地球物理》2010,7(1):49-56

Pre-stack depth migration velocity analysis is one of the keys to influencing the imaging quality of pre-stack migration. In this paper we cover a residual curvature velocity analysis method on angle-domain common image gathers (ADCIGs) which can depict the relationship between incident angle and migration depth at imaging points and update the migration velocity. Differing from offset-domain common image gathers (ODCIGs), ADCIGs are not disturbed by the multi-path problem which contributes to imaging artifacts, thus influencing the velocity analysis. On the basis of horizontal layers, we derive the residual depth equation and also propose a velocity analysis workflow for velocity scanning. The tests to synthetic and field data prove the velocity analysis methods adopted in this paper are robust and valid.  相似文献   

工程结构柱式构件的抗震性能试验研究进展     

董正方  王君杰  韩鹏 《震灾防御技术》2010,5(1):43-52

为研究工程结构中柱式构件的抗震性能,本文对国内外普通混凝土柱、高强混凝土柱、钢管混凝土柱和钢骨混凝土柱的抗震拟静力试验结果进行了总结,得出了影响柱式构件抗震性能的几个关键因素,并对研究中存在的不足以及今后需要探讨的问题进行了讨论。  相似文献   

Anti-proliferative activity of phlorotannin extracts from brown algae Laminaria japonica Aresch     

杨会成  曾名湧  董士远  刘尊英  李瑞雪 《中国海洋湖沼学报》2010,28(1):122-130

In this study, we evaluated the anti-proliferative activity of phlorotannins derived from brown algae Laminaria japonica Aresch extracts on the human hepatocellular carcinoma cell (BEL-7402) and on murine leukemic cells (P388) by MTT assay. Cells were incubated with 100 μg/mL of the phlorotannin extract (PE) for 48 h. The inhibitory rate of PE on BEL-7402 and P388 cells was 30.20±1.16% and 43.44±1.86%, respectively, and the half-inhibitory concentration of PE (IC₅₀) on P388 and BEL-7402 cells was 120 μg/mL and >200 μg/mL, respectively. Microscopic observation shows that the morphologic features of tumor cells treated with PE and 5-fluorouracil are markedly different from the normal control group. The inhibitory rate of fraction A₂ isolated from PE by sephadex LH-20 for BEL-7402 and P388 cells at the sample concentration of 70.42 μg/mL was 61.96±7.02% and 40.47±8.70%, respectively. The apoptosis peak for fraction A₂ was the most profound of all fractions used in the flow cytometry assay. The results indicate that the anti-proliferative of this algal extract is associated with the total phlorotannin content.  相似文献   

Chemical characteristics and environmental significance of fresh snow deposition on Urumqi Glacier No. 1 of Tianshan Mountains, China   总被引：2，自引：0，他引：2  

Zhongqin Li  Huilin Li  Zhiwen Dong  Mingjun Zhang 《中国地理科学(英文版)》2010,20(5):389-397

Ice and snow chemistry of alpine glaciers is crucial for the research of regional atmospheric environment change. Fresh snow samples were weekly collected from Urumqi Glacier No.1 in the Tianshan Mountains, Xin- jiang, China, and the chemical characteristics and seasonal variations of major ions, mineral dust, δ18O and trace metals were measured. Results show that the concentrations of major ions in the snow are Ca2+ SO42- NH4+ NO3- Cl- Na+ Mg2+ K+, in which Ca2+ is the dominant cation, and SO42-is the dominant anion. All major ions have close positive correlations with each other except NO3-. δ18O shows positive correlation with air temperature change during the study period. Mineral dust particle and major ionic concentrations in fresh snow have obvious seasonal change, with high concentration in spring but low concentration in summer and autumn, which indicates that the chemical mass input from Asian dust activity to snow is very significant. Temporal changes of trace metals in fresh snow, e.g., Cd, Pb, Zn, Al, Fe, have shown that human-induced pollution of central Asian region also has large contribution to the snow chemistry on alpine glaciers of the Tianshan Mountains.  相似文献   

海底透水通道发育带隧道施工注浆技术研究   总被引：1，自引：0，他引：1  

王永红  马栋  凌树云  陈鹰 《岩土力学》2011,32(12):3660-3666

通过对海底透水通道的特征分析,采用裂隙超前预注浆和裂隙补充注浆方法成功地解决了裂隙注浆堵水难题,为海底隧道安全施工提供了保障。提出了适于海水条件下的裂隙注浆原则、参数、设备、方法、工艺、材料及注浆效果检查方法,并成功地应用于胶州湾海底隧道穿越断裂破碎带时裂隙岩体注浆实践,其研究结果可为类似工程提供参考  相似文献