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   3286篇
  免费   14篇
  国内免费   47篇
安全科学   65篇
废物处理   144篇
环保管理   379篇
综合类   499篇
基础理论   1217篇
环境理论   2篇
污染及防治   634篇
评价与监测   213篇
社会与环境   190篇
灾害及防治   4篇
  2023年   9篇
  2022年   12篇
  2021年   18篇
  2020年   6篇
  2019年   10篇
  2018年   128篇
  2017年   132篇
  2016年   197篇
  2015年   72篇
  2014年   32篇
  2013年   48篇
  2012年   445篇
  2011年   236篇
  2010年   47篇
  2009年   48篇
  2008年   83篇
  2007年   94篇
  2006年   85篇
  2005年   410篇
  2004年   543篇
  2003年   412篇
  2002年   51篇
  2001年   47篇
  2000年   20篇
  1999年   35篇
  1998年   12篇
  1997年   12篇
  1996年   3篇
  1995年   20篇
  1994年   7篇
  1993年   7篇
  1992年   6篇
  1991年   10篇
  1990年   9篇
  1989年   7篇
  1988年   2篇
  1987年   4篇
  1986年   6篇
  1985年   2篇
  1975年   3篇
  1974年   3篇
  1973年   1篇
  1972年   2篇
  1971年   1篇
  1969年   1篇
  1968年   1篇
  1967年   1篇
  1966年   2篇
  1961年   1篇
  1957年   1篇
排序方式: 共有3347条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
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   
7.
Pyrite ash is created as waste from the roasting of pyrite ores during the production of sulphuric acid. These processes generate great amounts of pyrite ash waste that is generally land filled. This creates serious environmental pollution due to the release of acids and toxic substances. Pyrite ash waste can be utilized in the iron production industry as a blast furnace feed to process this waste and prevent environmental pollution. The essential parameters affecting the pelletization process of pyrite ash were studied using bentonite as a binder. Experiments were then carried out using bentonite and a mixture of bentonite with calcium hydroxide and calcium chloride in order to make the bentonite more effective. The metallurgical properties of pyrite ash, bentonite, calcium hydroxide, calcium chloride, a mixture of these and sintered pellets were studied using X-ray analysis. The crushing strength tests were carried out to investigate the strength of pyrite ash waste pellets. The results of these analyses showed that pyrite ash can be agglomerated to pellets and used in the iron production industry as a blast furnace feed. The crushing strength of the pellets containing calcium hydroxide and calcium chloride in addition to bentonite was better than the strength of pellets prepared using only bentonite binder.  相似文献   
8.
9.
10.
In this paper we apply graph theory in a reserve selection exercise to explore the tradeoffs between maintaining connectivity and minimizing the total area of a protected area network. Rather than focus on a single organism, we used a multi-species approach and looked at the tradeoff curves for organisms with varying dispersal abilities. We first generated the tradeoff curves using a graph-based metric to determine the importance of individual patches for maintaining connectivity. We then performed an analogous set of analyses using patch size as a surrogate measure of importance.  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