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   19891篇
  免费   190篇
  国内免费   173篇
安全科学   444篇
废物处理   827篇
环保管理   2441篇
综合类   4126篇
基础理论   5057篇
环境理论   9篇
污染及防治   4747篇
评价与监测   1281篇
社会与环境   1256篇
灾害及防治   66篇
  2022年   135篇
  2021年   158篇
  2019年   131篇
  2018年   341篇
  2017年   349篇
  2016年   532篇
  2015年   331篇
  2014年   421篇
  2013年   1217篇
  2012年   843篇
  2011年   909篇
  2010年   554篇
  2009年   659篇
  2008年   773篇
  2007年   817篇
  2006年   738篇
  2005年   924篇
  2004年   1069篇
  2003年   937篇
  2002年   557篇
  2001年   668篇
  2000年   422篇
  1999年   330篇
  1998年   202篇
  1997年   227篇
  1996年   242篇
  1995年   247篇
  1994年   253篇
  1993年   229篇
  1992年   212篇
  1991年   219篇
  1990年   204篇
  1989年   182篇
  1988年   174篇
  1987年   158篇
  1986年   158篇
  1985年   150篇
  1984年   173篇
  1983年   175篇
  1982年   179篇
  1981年   151篇
  1980年   139篇
  1979年   124篇
  1978年   140篇
  1977年   116篇
  1976年   105篇
  1975年   111篇
  1974年   121篇
  1971年   99篇
  1967年   102篇
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
501.
502.
Involuntary eye movements in salamanders   总被引:1,自引:0,他引:1  
  相似文献   
503.
504.
505.
506.
507.
508.
Enhanced bioremediation is quickly developing into an economical and viable technology for the remediation of contaminated soils. Until recently, chlorinated organic compounds have proven difficult to bioremediate. Environmentally recalcitrant compounds, such as polychlorinated biphenyls (PCBs) and persistent organic pesticides (POPs) such as dichlorodiphenyl trichloroethane (DDT) have shown to be especially arduous to bioremediate. Recent advances in field‐scale bioremedial applications have indicated that biodegradation of these compounds may be possible. Engineers and scientists at the Savannah River Site (SRS), a major DOE installation near Aiken, South Carolina, are using enhanced bioremediation to remediate soils contaminated with pesticides (DDT and its metabolites, heptachlor epoxide, dieldrin, and endrin) and PCBs. This article reviews the ongoing remediation occurring at the Chemicals, Metals, and Pesticides (CMP) Pits using windrow turners to facilitate microbial degradation of certain pesticides and PCBs. © 2003 Wiley Periodicals, Inc.  相似文献   
509.
In the UK for the period 1994-99, a broad range of environmental projects were given financial support through the European Agriculture Guidance and Guarantee Fund under the Objective 1 and Objective 5b programmes. This paper is concerned with the ex-post evaluation of these projects set within a Sustainable Development framework. The aim was to identify project types or characteristics that offered the greatest return on investment. A classification of six broad project types was adopted. The evaluation revealed that there were significant differences between individual projects with respect to the type and scale, and temporal and social distribution of the benefits they delivered. In particular, as well as delivering environmental and economic benefits, many projects made a significant contribution to the development of human and social capital. The paper concludes that it is possible to improve the basis for future project selection in order to maximise the returns on environmental investments in the context of sustainable development.  相似文献   
510.
ABSTRACT: A synthetic relationship is developed between nutrient concentrations and discharge rates at two river gauging sites in the Illinois River Basin. Analysis is performed on data collected by the U.S. Geological Survey (USGS) on nutrients in 1990 through 1997 and 1999 and on discharge rates in 1988 through 1997 and 1999. The Illinois River Basin is in western Arkansas and northeastern Oklahoma and is designated as an Oklahoma Scenic River. Consistently high nutrient concentrations in the river and receiving water bodies conflict with recreational water use, leading to intense stakeholder debate on how best to manage water quality. Results show that the majority of annual phosphorus (P) loading is transported by direct runoff, with high concentrations transported by high discharge rates and low concentrations by low discharge rates. A synthetic relationship is derived and used to generate daily phosphorus concentrations, laying the foundation for analysis of annual loading and evaluation of alternative management practices. Total nitrogen (N) concentration does not have as clear a relationship with discharge. Using a simple regression relationship, annual P loadings are estimated as having a root mean squared error (RMSE) of 39.8 t/yr and 31.9 t/yr and mean absolute percentage errors of 19 percent and 28 percent at Watts and Tahlequah, respectively. P is the limiting nutrient over the full range of discharges. Given that the majority of P is derived from Arkansas, management practices that control P would have the most benefit if applied on the Arkansas side of the border.  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