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   93958篇
  免费   1561篇
  国内免费   2162篇
安全科学   4074篇
废物处理   3529篇
环保管理   14178篇
综合类   23450篇
基础理论   26860篇
环境理论   73篇
污染及防治   15222篇
评价与监测   5715篇
社会与环境   3894篇
灾害及防治   686篇
  2022年   977篇
  2021年   952篇
  2020年   815篇
  2019年   1001篇
  2018年   1284篇
  2017年   1367篇
  2016年   2334篇
  2015年   2039篇
  2014年   2822篇
  2013年   9599篇
  2012年   2490篇
  2011年   2787篇
  2010年   3612篇
  2009年   3683篇
  2008年   2244篇
  2007年   2059篇
  2006年   2460篇
  2005年   2431篇
  2004年   2718篇
  2003年   2507篇
  2002年   2093篇
  2001年   2383篇
  2000年   2103篇
  1999年   1571篇
  1998年   1429篇
  1997年   1401篇
  1996年   1512篇
  1995年   1609篇
  1994年   1495篇
  1993年   1345篇
  1992年   1332篇
  1991年   1303篇
  1990年   1232篇
  1989年   1218篇
  1988年   1045篇
  1987年   980篇
  1986年   989篇
  1985年   1058篇
  1984年   1154篇
  1983年   1167篇
  1982年   1170篇
  1981年   1093篇
  1980年   943篇
  1979年   917篇
  1978年   820篇
  1977年   714篇
  1976年   637篇
  1975年   601篇
  1973年   629篇
  1972年   634篇
排序方式: 共有10000条查询结果,搜索用时 660 毫秒
821.
介绍了目前对环境样品中总汞及其各形态未的分析方法以及大气和水生生态系统中汞的研究进展,并指出,燃煤、汞齐法采金和人造水库等引起的环境汞污染问题以及汞在热带地区水生生态系统中的迁移转化规律等是目前的研究热点。  相似文献   
822.
823.
824.
The boll weevil (Anthonomus grandis Boheman), generally considered to be native to Mexico or Central America, spread into the southern United States of America in the late 1800s and seriously threatened the cotton industry. As there were no effective alternatives, pest control specialists studied the insect's ecology and advocated cultural practices that would disrupt its environment and maximize the benefits of natural biological and environmental controls. An ecologically orientated pest management scheme founded on cultural practices emerged well before suitable chemical control technology became available and allowed farmers to live with the weevil problem.Despite the ingenuity of the early management scheme, it frequently did not provide satisfactory boll weevil control gauged by present standards. Control of the pest thus shifted largely from an ecological to a chemical approach as effective synthetic organic insecticides became available after World War II. The chemical approach was successful for a number of years, but problems of insecticide-resistant strains of pests, secondary pest outbreaks, environmental quality, and increased costs of the insecticides have forced pest control specialists to re-emphasize the nonchemical techniques used widely against the boll weevil before World War II and to revive the ecological approach to weevil management.This article examines boll weevil ecology as related to management of the insect and reviews the status and prospects of ecologically-based weevil management techniques in the United States.  相似文献   
825.
826.
Pheromones — semiochemicals used by insects for intraspecific chemical communication — can be isolated and with special analytical techniques their chemical structure elucidated. With stereoselective synthesis methods, presented by the preparation of sex attractants and aggregating pheromones of moths and beetles, respectively, a synthetic access to compounds is given which can be used for behavior manipulation of insects. Aside the importance of these compounds for investigations of the sensoric process the possibility of their application in an integrated and biological pest control is discussed.  相似文献   
827.
828.
829.
Research in molecular neurobiology has recently entered a new phase of rapid development as a result of the application of the techniques of molecular genetics. This is illustrated by recent work on the electric ray (Torpedo marmorata and T. californica), whose electric organ is a rich source of cholinergic synapses. Other examples from recent literature of the application of the recombinant DNA technique to the mammalian central nervous system are given and possible future developments are discussed.  相似文献   
830.
The female silkmoth Bombyx mori L. emits a second pheromone component bombykal (E-10, Z-12-hexade-cadien-1-al) in addition to the well-known sexual attractant bombykol (E-10, Z-12-hexadecadien-1-ol). Bombykal stimulates its own specialized and highly sensitive olfactory cells of the male moth. Surprisingly, the aldehyde inhibits the release of the male's wing-fluttering response to bombykol.  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