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   38580篇
  免费   417篇
  国内免费   302篇
安全科学   1110篇
废物处理   1311篇
环保管理   5395篇
综合类   7226篇
基础理论   10608篇
环境理论   27篇
污染及防治   9813篇
评价与监测   2106篇
社会与环境   1462篇
灾害及防治   241篇
  2021年   225篇
  2019年   269篇
  2018年   471篇
  2017年   466篇
  2016年   687篇
  2015年   593篇
  2014年   799篇
  2013年   2834篇
  2012年   1045篇
  2011年   1560篇
  2010年   1242篇
  2009年   1310篇
  2008年   1554篇
  2007年   1624篇
  2006年   1470篇
  2005年   1212篇
  2004年   1211篇
  2003年   1176篇
  2002年   1139篇
  2001年   1518篇
  2000年   1050篇
  1999年   697篇
  1998年   527篇
  1997年   527篇
  1996年   572篇
  1995年   587篇
  1994年   568篇
  1993年   505篇
  1992年   534篇
  1991年   497篇
  1990年   514篇
  1989年   538篇
  1988年   456篇
  1987年   410篇
  1986年   384篇
  1985年   422篇
  1984年   394篇
  1983年   430篇
  1982年   431篇
  1981年   390篇
  1980年   354篇
  1979年   373篇
  1978年   336篇
  1977年   284篇
  1976年   299篇
  1975年   261篇
  1974年   282篇
  1973年   268篇
  1972年   288篇
  1970年   223篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
Four small- to medium-sized municipalities in the south-east of Sweden were chosen for a 5-year study of their Local Agenda 21 (LA21) processes. The study shows that the LA21 processes have instigated many new ideas, brought fields together and introduced new subjects into the municipal world. In the decisions of the local governments environmental considerations are treated seriously. There are signs of an extended dialogue and of public influence, especially within fields where citizens are directly involved. LA21 does not seem to have great influence on which natural resources are dealt with, but does on how they are dealt with. New stakeholders within and outside the municipal organization have been identified through the LA21 processes, and more comprehensive ways of solving problems and a positive climate for testing new ideas have been created. In these respects LA21 has been and will be a significant support to the development of appropriate natural resource management at the local level.  相似文献   
143.
144.
In a 1981 survey of 436 Florida citrus growers, 27 pesticide related poisoning incidents were reported that were to have taken place within one year of the interview date. From these reports it is possible to estimate that there are 376 citrus fieldworker related poisonings per year in Florida. This number of estimated poisonings may be developed into an incidence rate of 113 fieldworker poisonings per 10,000 fieldworkers.  相似文献   
145.
146.
   Global change, i.e. the mega-process radically transforming the relationship between nature and human civilization since the end of World War II, is investigated from the point of view of systems analysis. It is argued that this unbridled process should rather be domesticated by planetary control strategies transpiring from a new science called “geocybernetics”. The formal aspects of geocybernetic theory are sketched and illustrated in a tutorial theatre world reflecting the overall environment and development problematic. Within this setting a straightforward operationalization of the sweeping “sustainable development” ideal through a set of concise paradigms can be achieved. Evidence is provided that geocybernetics is actually feasible on the basis of earth system modelling and fuzzy-control techniques.  相似文献   
147.
148.
149.
The effectiveness of inorganic alumino-silicate sorbents (alumina and kaolinite) to adsorb airborne lead and cadmium from the effluent stream of a simulated waste incinerator was studied. A 20 kW (68,000 BTU/h) flow reactor was used to achieve the temperature and residence times typical of a waste incinerator. Solutions containing lead or cadmium were introduced yielding airborne metals concentrations between 15 and 150 ppm. Gas samples were drawn into a particle impactor that collected the airborne particles and condensed phase metal aerosols, separating them into ten size ranges from 0.2 μm to greater than 10 μm. Metals to sorbent mass ratios between 0.03 and 1.56 were investigated. Scavenging efficiency increased as the ratio of sorbent to injected metal mass was increased. The scavenging efficiencies were as high as 76% for lead scavenged by kaolinite to as low as 14% for cadmium scavenged by alumina.  相似文献   
150.
5p deletion syndrome commonly known as cri du chat is well described in affected neonates with catlike cry and hypotonia. Karyotyping will usually show a deletion of the short arm of one chromosome 5 with variable breakpoints. Only a few cases have been reported prenatally, and the fetal form of the syndrome has not been clearly individualised. We report a new case of 5p deletion syndrome diagnosed prenatally in association with Dandy–Walker syndrome and agenesis of the corpus callosum. Other brain anomalies have been reported previously, but this unusual association suggests the use of a specific probe in the investigation of these malformations. Copyright © 2005 John Wiley & Sons, Ltd.  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