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   92087篇
  免费   1225篇
  国内免费   1111篇
安全科学   3791篇
废物处理   3368篇
环保管理   14062篇
综合类   21220篇
基础理论   26533篇
环境理论   72篇
污染及防治   15436篇
评价与监测   5564篇
社会与环境   3833篇
灾害及防治   544篇
  2022年   812篇
  2021年   810篇
  2020年   653篇
  2019年   863篇
  2018年   1171篇
  2017年   1199篇
  2016年   2186篇
  2015年   1836篇
  2014年   2597篇
  2013年   9274篇
  2012年   2250篇
  2011年   2566篇
  2010年   3306篇
  2009年   3431篇
  2008年   2107篇
  2007年   1958篇
  2006年   2378篇
  2005年   2358篇
  2004年   2623篇
  2003年   2505篇
  2002年   2029篇
  2001年   2460篇
  2000年   2048篇
  1999年   1571篇
  1998年   1383篇
  1997年   1374篇
  1996年   1491篇
  1995年   1596篇
  1994年   1486篇
  1993年   1324篇
  1992年   1340篇
  1991年   1297篇
  1990年   1259篇
  1989年   1227篇
  1988年   1069篇
  1987年   987篇
  1986年   996篇
  1985年   1071篇
  1984年   1158篇
  1983年   1168篇
  1982年   1175篇
  1981年   1090篇
  1980年   945篇
  1979年   928篇
  1978年   819篇
  1977年   713篇
  1976年   643篇
  1975年   612篇
  1973年   637篇
  1972年   635篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
261.
262.
263.
Community evacuation following a chlorine release, Mississippi   总被引:1,自引:0,他引:1  
On 7th September 1986, four miles north of Collins, Mississippi, a train transporting chlorine derailed. Two cars ruptured and gas escaped. As a result, 100 families were evacuated. To study the evacuation process, we conducted person-to-person interviews with sixty-two families staying in the evacuation center. Only 52.5% of the families received their first directive to evacuate directly from police or other officials. Delays in evacuating tended to be shorter when people were warned by the police and were told the reason for evacuating. Lack of personal transportation and preexisting health problems resulted in delays in evacuation. Concerns about evacuation included fear of looting, lack of a place to go, lack of transportation, difficulty in moving with children and elderly persons, and the need to take care of pets. One third of the interviewees reported feeling panic. Community evacuation procedures would be improved if: (1) officials contact all households directly; (2) the warning message addresses people's concerns; and (3) transportation is provided.  相似文献   
264.
After several years of experimentation and demonstration, photovoltaic (PV) power is now firmly established for certain applications where reliable power is required in remote locations. The technology has recently matured to the point where PV is now an appropriate, cost-effective technology for village use. This paper reviews experience and presents economic comparisons between photovoltaic and conventional power systems. It is concluded that PV is cost-effective for individual home lighting and small loads such as radios, when compared with kerosene lamps and batteries. For mutiple uses PV is cost-effective compared with diesel generators for daily electricity demands up to around 20 kWh, depending on local conditions.  相似文献   
265.
ABSTRACT: This paper describes the formulation of an Index of Water Quality to evaluate the level of pollution in fresh water. A Four-Round Delphi equation, using a panel of seven nationally recognized water scientists, was performed to ascertain the pollutants to be included in the index, the relationship between the quantity of these pollutants in the water and the resulting quality of the water, and the importance of each pollution variable to each water use as well as to overall pollution. A multiplicative index was used to bring the pollutants together into one system.  相似文献   
266.
Living veligers of the Cassoidea have been observed to use a mantle appendage to form and resorb periostracum. Anatomical and histological examinations of a ranellid (Cymatium sp.) larva collected from the Red Sea in 1987 revealed the structure and location of the pallial appendage. The mantle edges of juvenile or adult species of the Cassoidea do not show a comparable specialization. It is demonstrated that cassoid larval conch characters are sufficient to prove the existence of a pallial appendage without anatomical confirmation. A mantle appendage is not known from teleplanic (long-living planktic) veligers of other gastropod superfamilies. In cases where the larval strategies of the latter are known they are totally different. Therefore it is suggested that the adaptation of cassoid larvae to pelagic life is unique among gastropods representing an autapomorphic character of the superfamily.  相似文献   
267.
268.
269.
   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   
270.
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