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   1928篇
  免费   23篇
  国内免费   25篇
安全科学   56篇
废物处理   65篇
环保管理   263篇
综合类   441篇
基础理论   366篇
环境理论   2篇
污染及防治   555篇
评价与监测   104篇
社会与环境   110篇
灾害及防治   14篇
  2023年   18篇
  2022年   18篇
  2021年   31篇
  2020年   24篇
  2019年   25篇
  2018年   51篇
  2017年   54篇
  2016年   63篇
  2015年   75篇
  2014年   77篇
  2013年   98篇
  2012年   86篇
  2011年   124篇
  2010年   106篇
  2009年   105篇
  2008年   93篇
  2007年   100篇
  2006年   82篇
  2005年   64篇
  2004年   84篇
  2003年   52篇
  2002年   67篇
  2001年   75篇
  2000年   33篇
  1999年   17篇
  1998年   18篇
  1997年   29篇
  1996年   22篇
  1995年   31篇
  1994年   22篇
  1993年   8篇
  1992年   16篇
  1991年   24篇
  1990年   13篇
  1989年   19篇
  1988年   8篇
  1987年   6篇
  1985年   9篇
  1984年   7篇
  1983年   4篇
  1982年   12篇
  1981年   12篇
  1980年   5篇
  1979年   9篇
  1978年   4篇
  1970年   6篇
  1969年   4篇
  1965年   4篇
  1960年   4篇
  1954年   3篇
排序方式: 共有1976条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
This article reviews the application of environmental impact assessment (EIA) procedures and practices to three watershed modification projects situaled in western Canada. These ventures were justified for accelerating regional economic development, and cover the period during which public concerns for protecting the environment rapidly made their way into the national political agenda. An historical account and analysis of the situation, therefore, seems desirable in order to understand the development of EIA processes, practices, and methodologies since the start of construction of the first project in 1961. This study concludes that there has been good progress in predicting and evaluating environmental and related social impacts of watershed modification proposals. However, a number of obstacles need to be overcome before EIA can firmly establish itself as an effective planning tool. These difficulties include jurisdictional confusions and conflicts, division of authority and responsibility in designing and implementing appropriate mitigative and monitoring measures, lack of tested EIA methodologies, and limited availability of qualified human resources. A number of conclusions and suggestions are offered so that future watershed modification proposals may be planned and implemented in a more environmentally sustainable fashion. These include: (1) EIA processes must be completed before irrevocable decisions are made. (2) Any major intrusion into a watershed is likely to impact on some major components of the ecosystem(s). (3) Mitigation costs must form part of the benefit-cost analysis of any project proposal. (4) Interjurisdictional cooperation is imperative where watersheds cross political boundaries. (5) The EIA process is a public process, hence public concerns must be dealt with fairly. (6) The role of science in the EIA process must be at arms length from project proponents and regulators, and allowed to function in the interest of the protection of the environment and public health and safety. The views expressed here are the authors’ own and do not necessarily reflect those of FEARO and/or other government agencies and officials involved in the review of these projects.  相似文献   
5.
6.
7.
8.
9.
Passive samplers provide an excellent opportunity to perform indicative measurements or establish a dense network of measuring sites. A drawback compared with conventional active measuring methods is the larger spread of results. This variation can, to a large extent, be attributed to the influence of temperature, sampler geometry and wind on sampling results. A proper design of sampler geometry and optimum choice of draught shield can reduce the influence of wind velocity on a badge type sampler to less than 10%. Wire mesh screens prove to be inadequate in damping turbulence. Filters give good results. Attention should be paid to the size and isolation value of the walls of the sampler to prevent thermal updrafts occurring within the sampler. Tube type samplers are less influenced by wind, provided that turbulence is prevented from influencing diffusion within the sampler.  相似文献   
10.
In order to control the quality of rare earth determinations in environmental matrices, the Standards, Measurements and Testing Programme (formerly Community Bureau of Reference, BCR) of the European Commission has started a project, the final aim of which is to certify four types of matrices (tuna muscle, mussel tissue, aquatic plant and estuarine sediment) for their contents of a range of rare earth elements (Sc, Y and the lanthanides: La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu). The elements U and Th were added to the study. The first part of this project consisted of an interlaboratory study which aimed to test the feasibility of preparation of environmental reference materials and to detect and remove most of the pitfalls observed in rare earth determinations. This paper presents the preparation of the four matrices for the intercomparison study and for the candidate reference material. The main results are presented of the interlaboratory study that was carried out prior to the certification campaign. This collaborative trial is the first attempt ever carried out at this scale to evaluate the state-of-the-art of rare earth determinations in the environment. Its impact on the improvement of chemical measurements will have positive effects on the comparability of data necessary for environmental monitoring.  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