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   101871篇
  免费   1244篇
  国内免费   1161篇
安全科学   4039篇
废物处理   3813篇
环保管理   15456篇
综合类   21564篇
基础理论   28044篇
环境理论   74篇
污染及防治   19826篇
评价与监测   6116篇
社会与环境   4660篇
灾害及防治   684篇
  2022年   825篇
  2021年   858篇
  2020年   675篇
  2019年   891篇
  2018年   1363篇
  2017年   1407篇
  2016年   2318篇
  2015年   1875篇
  2014年   2611篇
  2013年   9294篇
  2012年   2715篇
  2011年   3450篇
  2010年   3530篇
  2009年   3695篇
  2008年   3081篇
  2007年   3006篇
  2006年   3101篇
  2005年   2916篇
  2004年   3192篇
  2003年   3017篇
  2002年   2597篇
  2001年   3029篇
  2000年   2339篇
  1999年   1682篇
  1998年   1435篇
  1997年   1434篇
  1996年   1570篇
  1995年   1661篇
  1994年   1535篇
  1993年   1382篇
  1992年   1390篇
  1991年   1353篇
  1990年   1307篇
  1989年   1274篇
  1988年   1121篇
  1987年   1042篇
  1986年   1016篇
  1985年   1093篇
  1984年   1195篇
  1983年   1195篇
  1982年   1192篇
  1981年   1115篇
  1980年   958篇
  1979年   968篇
  1978年   849篇
  1977年   739篇
  1976年   672篇
  1974年   655篇
  1973年   687篇
  1972年   691篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
 The Australian buprestid beetle Merimna atrata (Coleoptera: Buprestidae) approaches forest fires because its larvae develop in freshly burnt wood. So far nothing is known about possible sensory systems enabling the beetles to detect fires and to cope with the thermal environment close to the flames. We found that M. atrata has two pairs of infrared (IR) organs on the ventrolateral sides of the abdomen. Each IR organ consists of a specialized IR-absorbing area which is innervated by one thermosensitive multipolar neuron. The primary dendritic branches ramify into more than 800 closely packed terminal endings which contain a large number of mitochondria. We called the special morphology of the dendritic region a terminal dendritic mass. The type of IR receptor found in M. atrata is unique in insects and can best be compared with the IR organs of boid snakes. Received: 14 August 2000 / Accepted in revised form: 18 October 2000  相似文献   
992.
IntroductionSiberiaandtheFarEastaretheoldestandtherichestgold miningareasofRussia .Intensivegold miningherestartedinthebeginningofthe 19thcentury(Vyazelshchikov ,1963) .Forthemostpartgold bearingoresandsandswereprocessedwiththeuseofamalgamationmethodforgolde…  相似文献   
993.
Stadtökologie     
Within the cities, natural environmental conditions become manifold modified. Thereby, together with the high density of population, enduring effects upon human feeling results. In order to ensure reasonable conditions of life, in spite of the many effective factors in the cities, enforced interdisciplinary research and teaching will be necessary.  相似文献   
994.
995.
996.
997.
998.
999.
The abundance patterns of ant communities were monitored with pitfall traps during 14 weeks in four northern California, dry farmed, apple orchards: an abandoned orchard undisturbed for 25 years, two ‘organically’ managed orchards, one with a cover crop of bell beans (Vicia faba) and grasses and the other kept clean of cover by discing, and a ‘commercial’ clean cultivated orchard sprayed with organophosphate insecticides. Six species of ants coexisted in the abandoned orchard, whereas only two species were found in the managed orchards. In both the organic and sprayed, clean cultivated systems, ants were more abundant in the orchard edges than in the vegetation-free centers. This trend was not apparent in the abandoned or organic cover orchards, where plant diversity in the center was similar to that of the edges. Ant predation on potato tuberworm larvae, Phthorimaea operculella, artificially placed on the orchard floor, declined with the intensity of management and vegetational simplication. A higher incidence of larval removal occurred in the edges than in the centers of the clean cultivated orchards. No noticeable populations of ants were detected on the trees in any of the orchards. Increased vegetational diversity and lack of disturbance appeared to affect ant locomotory activity and foraging efficiency by creating preferred sheltering and feeding sites.  相似文献   
1000.
Sexual selection and red-winged blackbirds   总被引:1,自引:0,他引:1  
  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