首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   766篇
  免费   23篇
  国内免费   6篇
安全科学   54篇
废物处理   15篇
环保管理   211篇
综合类   80篇
基础理论   209篇
环境理论   3篇
污染及防治   152篇
评价与监测   40篇
社会与环境   21篇
灾害及防治   10篇
  2023年   7篇
  2022年   5篇
  2021年   7篇
  2020年   14篇
  2019年   17篇
  2018年   19篇
  2017年   22篇
  2016年   28篇
  2015年   25篇
  2014年   27篇
  2013年   59篇
  2012年   45篇
  2011年   50篇
  2010年   44篇
  2009年   43篇
  2008年   54篇
  2007年   55篇
  2006年   48篇
  2005年   35篇
  2004年   28篇
  2003年   39篇
  2002年   17篇
  2001年   18篇
  2000年   8篇
  1999年   4篇
  1998年   7篇
  1997年   4篇
  1996年   8篇
  1995年   9篇
  1994年   2篇
  1993年   1篇
  1992年   3篇
  1991年   1篇
  1990年   2篇
  1989年   4篇
  1987年   3篇
  1986年   2篇
  1985年   2篇
  1984年   7篇
  1983年   1篇
  1982年   2篇
  1981年   4篇
  1980年   4篇
  1979年   2篇
  1978年   5篇
  1977年   2篇
  1976年   1篇
  1975年   1篇
排序方式: 共有795条查询结果,搜索用时 15 毫秒
61.
Land tenure plays a primary role in sustainable development efforts. However armed conflict and its repercussions reconfigure the network of social relations upon which all land tenure systems depend. In post‐conflict settings new laws have the opportunity to address tenure issues in the context of what people are already doing ‘on the ground’, with a view to moving from the fluidity of post‐conflict situations to a more solidified and peaceful social and legal environment. However there exists a lack of tools to analyze postwar land tenure and the prospects for reconstituting tenure systems to support recovery and development. This paper uses the Sustainable Livelihoods framework to examine postwar land tenure issues in order to draw out latent opportunities within emergent informal smallholder tenure constructs which may have utility in the reconstitution of national tenure systems.  相似文献   
62.
63.
Bossio JP  Harry J  Kinney CA 《Chemosphere》2008,70(5):858-864
The objective of this research was the development, optimization, and demonstration of an ultrasonic assisted extraction (UAE) based method for organic anthropogenic waste indicators (AWIs) with a range of physicochemical properties from soil and sediment samples. The optimized method was designed to be cost effective compared to existing extraction methods, which may require large quantities of consumables, produce substantial volumes of organic waste, or require costly instrumentation or equipment. Reagent grade sand, soil collected from the native grassland in proximity to Eastern Washington University (EWU), and sediment samples collected from the Spokane river were used as sample matrices during method development. These matrices were fortified with eight AWIs of varying chemical properties that are representative of a variety of household, industrial, and agricultural sources. The recoveries of the AWIs spiked onto these matrices were determined in the extracts using gas chromatography/mass spectrometry (GC/MS). These values reflect the efficiency of the method for extraction of these analytes from representative environmental matrices. Recoveries ranged from 46.1% to 110% in the fortified soil and from 49.2% to 118.6% in the fortified sediment samples, which is comparable with existing methods for the study analytes. The optimized method was then used to quantify AWIs in a biosolid-amended soil. Indole and p-cresol were detected in the biosolid-amended soil.  相似文献   
64.
65.
66.
67.
68.
69.
The Vegetation of Wet Meadows in Relation to Their Land-use   总被引:5,自引:0,他引:5  
Wetland biomonitoring approaches are needed to determine when changes in response to stressors are occurring and to predict the consequences of proposed land-use changes. These approaches require an understanding of shifts in biota that occur in response to land-use, data that are lacking for most kinds of wetlands. Changes in floristic composition corresponding to land-use differences at multiple scales (site to 2500 m radius) were characterized for 40 wet meadows associated with prairie glacial marshes in Minnesota (U.S.A.). In general, guild was more useful than species composition for indicating land-use impacts. Site impacts (stormwater, cultivation) and landscape disturbance (agriculture and urbanization, combined), coincide with a reduction in native graminoid and herbaceous perennial abundance (e.g., Carex lasiocarpa, Calamagrostis canadensis, Spartina pectinata). This vegetation is replaced with annuals (e.g, Bidens cernua, Polygonum pensylvanicum) in recently cultivated sites or introduced perennials (e.g., Phalaris arundinacea, Typha angustifolia) and floating aquatics (lemnids) in stormwater impacted wetlands. Ditches also reduce native perennial importance and increase perennials, but only when they are in highly impacted landscapes.  相似文献   
70.
Urinary copper (Cu), nickel (Ni) and cobalt (Co) concentrations were determined for 127 Cu refinery workers (40 females, 87 males), with values of the 95% upper confidence interval of the geometric mean in nmol per mmol creatinine of 89 (Ni), 42 (Cu) and 3.4 (Co) for electrorefinery workers. In the pyrometallurgical departments, the corresponding concentrations were 37 (Ni), 99 (Cu) and 11 (Co). Female workers had higher Co urinary concentrations than males (p< or = 0.05) while no gender difference was observed for Cu and Ni. Inter-elemental correlations were moderate to weak. Based on the inhalable aerosol levels reported previously for the same workers, the observed urinary Cu concentrations were considerably lower than expected, relative to Co and Ni. This is interpreted in terms of the current understanding of Cu homeostasis.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号