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   64620篇
  免费   708篇
  国内免费   794篇
安全科学   2125篇
废物处理   3020篇
环保管理   8346篇
综合类   10281篇
基础理论   16801篇
环境理论   35篇
污染及防治   16503篇
评价与监测   4637篇
社会与环境   3936篇
灾害及防治   438篇
  2023年   307篇
  2022年   717篇
  2021年   762篇
  2020年   489篇
  2019年   591篇
  2018年   1085篇
  2017年   1105篇
  2016年   1656篇
  2015年   1200篇
  2014年   1805篇
  2013年   5281篇
  2012年   2265篇
  2011年   2979篇
  2010年   2436篇
  2009年   2446篇
  2008年   2919篇
  2007年   2973篇
  2006年   2617篇
  2005年   2231篇
  2004年   2205篇
  2003年   2229篇
  2002年   1988篇
  2001年   2407篇
  2000年   1691篇
  1999年   1069篇
  1998年   783篇
  1997年   770篇
  1996年   805篇
  1995年   911篇
  1994年   845篇
  1993年   724篇
  1992年   739篇
  1991年   721篇
  1990年   711篇
  1989年   689篇
  1988年   630篇
  1987年   543篇
  1986年   482篇
  1985年   511篇
  1984年   562篇
  1983年   539篇
  1982年   584篇
  1981年   480篇
  1980年   389篇
  1979年   436篇
  1978年   379篇
  1977年   298篇
  1975年   298篇
  1973年   287篇
  1972年   287篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
22.
23.
24.
Developers are often required by law to offset environmental impacts through targeted conservation actions. Most offset policies specify metrics for calculating offset requirements, usually by assessing vegetation condition. Despite widespread use, there is little evidence to support the effectiveness of vegetation-based metrics for ensuring biodiversity persistence. We compared long-term impacts of biodiversity offsetting based on area only; vegetation condition only; area × habitat suitability; and condition × habitat suitability in development and restoration simulations for the Hunter Region of New South Wales, Australia. We simulated development and subsequent offsetting through restoration within a virtual landscape, linking simulations to population viability models for 3 species. Habitat gains did not ensure species persistence. No net loss was achieved when performance of offsetting was assessed in terms of amount of habitat restored, but not when outcomes were assessed in terms of persistence. Maintenance of persistence occurred more often when impacts were avoided, giving further support to better enforce the avoidance stage of the mitigation hierarchy. When development affected areas of high habitat quality for species, persistence could not be guaranteed. Therefore, species must be more explicitly accounted for in offsets, rather than just vegetation or habitat alone. Declines due to a failure to account directly for species population dynamics and connectivity overshadowed the benefits delivered by producing large areas of high-quality habitat. Our modeling framework showed that the benefits delivered by offsets are species specific and that simple vegetation-based metrics can give misguided impressions on how well biodiversity offsets achieve no net loss.  相似文献   
25.
26.
Biomethane production through biogas upgrading is a promising renewable energy for some industries which could be part of the equilibrium needed with fossil fuels consumption to achieve a sustainable society. This paper presents a comprehensive list of biogas upgrading technologies focused on carbon dioxide removal as well as recent advances reported by researcher with wide expertise in this topic. Additionally, an extensive costs–performance comparison among the technologies studied is discussed. Among the different alternatives, chemical scrubbing stood out to achieve high biomethane purities while cryogenic technologies proved to be effective against methane losses. Regarding the different costs, water scrubbing and membrane separation seem to be the most affordable techniques.  相似文献   
27.
Journal of Material Cycles and Waste Management - The present research work focused on fabricating Biodegradable Plate (BD plate) composed of rice husk ash, bagasse and corn starch which is...  相似文献   
28.
29.
Quantitative methods have been applied to the study of floristic structure and diversity in Samarskaya Luka. The results show that Samarskaya Luka is a floristically heterogeneous area in which six elementary floras can be distinguished. This area has been assessed as a floristically autonomous formation, and its floristic representativeness was estimated.  相似文献   
30.
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