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   90920篇
  免费   1231篇
  国内免费   1111篇
安全科学   3762篇
废物处理   3239篇
环保管理   14012篇
综合类   21344篇
基础理论   26360篇
环境理论   79篇
污染及防治   14865篇
评价与监测   5426篇
社会与环境   3637篇
灾害及防治   538篇
  2022年   803篇
  2021年   820篇
  2020年   658篇
  2019年   883篇
  2018年   1152篇
  2017年   1179篇
  2016年   2187篇
  2015年   1850篇
  2014年   2614篇
  2013年   9303篇
  2012年   2167篇
  2011年   2422篇
  2010年   3278篇
  2009年   3392篇
  2008年   1999篇
  2007年   1850篇
  2006年   2275篇
  2005年   2227篇
  2004年   2594篇
  2003年   2395篇
  2002年   1931篇
  2001年   2297篇
  2000年   2007篇
  1999年   1503篇
  1998年   1383篇
  1997年   1368篇
  1996年   1481篇
  1995年   1590篇
  1994年   1500篇
  1993年   1335篇
  1992年   1332篇
  1991年   1300篇
  1990年   1250篇
  1989年   1192篇
  1988年   1047篇
  1987年   984篇
  1986年   993篇
  1985年   1065篇
  1984年   1162篇
  1983年   1172篇
  1982年   1182篇
  1981年   1100篇
  1980年   941篇
  1979年   923篇
  1978年   825篇
  1977年   717篇
  1976年   640篇
  1975年   611篇
  1973年   643篇
  1972年   647篇
排序方式: 共有10000条查询结果,搜索用时 562 毫秒
261.
262.
263.
264.
265.
266.
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   
267.
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   
268.
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   
269.
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   
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