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   96675篇
  免费   1247篇
  国内免费   1124篇
安全科学   3828篇
废物处理   3560篇
环保管理   14635篇
综合类   21579篇
基础理论   27278篇
环境理论   76篇
污染及防治   17640篇
评价与监测   5834篇
社会与环境   4026篇
灾害及防治   590篇
  2022年   885篇
  2021年   885篇
  2020年   685篇
  2019年   900篇
  2018年   1289篇
  2017年   1303篇
  2016年   2317篇
  2015年   1895篇
  2014年   2694篇
  2013年   9432篇
  2012年   2500篇
  2011年   2946篇
  2010年   3403篇
  2009年   3532篇
  2008年   2519篇
  2007年   2399篇
  2006年   2664篇
  2005年   2539篇
  2004年   2845篇
  2003年   2672篇
  2002年   2240篇
  2001年   2638篇
  2000年   2180篇
  1999年   1586篇
  1998年   1405篇
  1997年   1398篇
  1996年   1525篇
  1995年   1618篇
  1994年   1510篇
  1993年   1353篇
  1992年   1347篇
  1991年   1318篇
  1990年   1261篇
  1989年   1240篇
  1988年   1084篇
  1987年   1002篇
  1986年   1005篇
  1985年   1082篇
  1984年   1171篇
  1983年   1184篇
  1982年   1183篇
  1981年   1104篇
  1980年   951篇
  1979年   937篇
  1978年   833篇
  1977年   730篇
  1976年   658篇
  1974年   630篇
  1973年   656篇
  1972年   671篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
171.
 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   
172.
IntroductionSiberiaandtheFarEastaretheoldestandtherichestgold miningareasofRussia .Intensivegold miningherestartedinthebeginningofthe 19thcentury(Vyazelshchikov ,1963) .Forthemostpartgold bearingoresandsandswereprocessedwiththeuseofamalgamationmethodforgolde…  相似文献   
173.
174.
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   
175.
176.
177.
A short account is given of the events leading to the creation, after Alfred Nobel's death 1896, of the Nobel Foundation for the management of the funds, and of the Nobel committees in charge of the selection of the Prize winners in the five areas mentioned in the will. The impact of the various and partly recently added activities of the Nobel organizations on contemporary international scientific and cultural life is briefly discussed.  相似文献   
178.
179.
180.
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