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   40837篇
  免费   272篇
  国内免费   275篇
安全科学   795篇
废物处理   2216篇
环保管理   4887篇
综合类   6113篇
基础理论   10680篇
环境理论   13篇
污染及防治   10314篇
评价与监测   3316篇
社会与环境   2873篇
灾害及防治   177篇
  2023年   143篇
  2022年   376篇
  2021年   371篇
  2020年   211篇
  2019年   269篇
  2018年   1829篇
  2017年   1718篇
  2016年   1869篇
  2015年   670篇
  2014年   937篇
  2013年   2701篇
  2012年   1520篇
  2011年   2554篇
  2010年   1783篇
  2009年   1692篇
  2008年   2182篇
  2007年   2576篇
  2006年   1351篇
  2005年   1106篇
  2004年   1118篇
  2003年   1122篇
  2002年   1077篇
  2001年   1265篇
  2000年   905篇
  1999年   568篇
  1998年   382篇
  1997年   359篇
  1996年   383篇
  1995年   418篇
  1994年   385篇
  1993年   348篇
  1992年   344篇
  1991年   334篇
  1990年   319篇
  1989年   328篇
  1988年   306篇
  1987年   255篇
  1986年   201篇
  1985年   230篇
  1984年   285篇
  1983年   267篇
  1982年   305篇
  1981年   220篇
  1980年   205篇
  1979年   244篇
  1978年   192篇
  1977年   181篇
  1976年   164篇
  1975年   171篇
  1974年   177篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
102.
103.
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   
104.
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   
105.
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   
106.
107.
Material suppliers and industrial metabolism   总被引:1,自引:1,他引:0  
Life Cycle Assessment (LCA) is not sufficiently tailored to the analysis of strategic environmental problems of material suppliers. Sustainable development calls for a reduction by a factor of 10 to 20 in the material intensity of the economy, a situation which leads to dramatic shifts in markets for raw materials. Furthermore, a material supplier might have major improvement options in the material’s numerous downstream uses. LCAs, however, can’t cover these two aspects. An adapted form of Substance Flow Analysis (SFA) may be an answer. This approach defines a system in relation to the flow of a specific material through society. All environmental interventions related to the material are inventoried. An emission evaluation indicates the dominant environmental bottlenecks, given the current market volume of each application of the material. This helps to identify improvement options and strategic choices in market portfolios. Scenario analysis on potential measures can further indicate changes of material flows — and thus markets — in the system. The approach is illustrated with a case study on chlorine.  相似文献   
108.
The situation and the latest findings of forest damage research in Germany are discussed. A newly developed concept for this research is described. This concept allows to identify the drawbacks of the recent damage research concept but also the integration of results compiled up to now. The importance for including natural occurring stress factors such as climate, soil conditions or local situation of individual species is outlined.  相似文献   
109.
Indices of abundance and reproduction rate are considered in some groups of aquatic and terrestrial vertebrates from the zones of technogenic disasters. Upon a critical population decline caused by external destructive factors, such as emissions of acute ecotoxicants, the ecophysiological and behavioral compensatory mechanisms are activated, which provide for restoration of the total population size to the optimum within a short period of time. Environmental pollution with substances disturbing the reproductive function has the gravest consequences for animals. In this case, population size may remain fairly high, and, therefore, the effect of enhanced reproduction as a response to population decline does not take place, which eventually leads to a gradual but irreversible destruction of the population. Pathologies of reproduction should be used as a criterion for assessing the state of animals in the zones of technogenic disasters.Translated from Ekologiya, No. 1, 2005, pp. 32–38.Original Russian Text Copyright © 2005 by Shilova, Shatunovskii.  相似文献   
110.
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