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   20848篇
  免费   315篇
  国内免费   334篇
安全科学   647篇
废物处理   948篇
环保管理   2810篇
综合类   3478篇
基础理论   5194篇
环境理论   11篇
污染及防治   5752篇
评价与监测   1311篇
社会与环境   1212篇
灾害及防治   134篇
  2023年   122篇
  2022年   272篇
  2021年   272篇
  2020年   221篇
  2019年   190篇
  2018年   413篇
  2017年   350篇
  2016年   571篇
  2015年   415篇
  2014年   635篇
  2013年   1715篇
  2012年   822篇
  2011年   1082篇
  2010年   829篇
  2009年   883篇
  2008年   1017篇
  2007年   1063篇
  2006年   895篇
  2005年   714篇
  2004年   719篇
  2003年   656篇
  2002年   621篇
  2001年   691篇
  2000年   553篇
  1999年   340篇
  1998年   223篇
  1997年   240篇
  1996年   227篇
  1995年   287篇
  1994年   224篇
  1993年   216篇
  1992年   181篇
  1991年   188篇
  1990年   185篇
  1989年   187篇
  1988年   157篇
  1987年   139篇
  1986年   160篇
  1985年   147篇
  1984年   190篇
  1983年   150篇
  1982年   175篇
  1981年   157篇
  1980年   132篇
  1979年   152篇
  1978年   94篇
  1977年   100篇
  1975年   93篇
  1974年   94篇
  1972年   97篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
43.
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   
44.
New data on the composition of surface assemblages of plant macroremains from soil and swamp samples have been obtained in the study of geomorphologically different localities in the middle reaches of the Nizhnyaya Tunguska River. The results of paleocarpological analysis of forest soil sections supported by relevant palynological and geochronological data are presented. Natural changes of the forest cover over the past 2400 years and quantitative characteristics of the paleoclimate during each stage are described.Translated from Ekologiya, No. 1, 2005, pp. 3–10.Original Russian Text Copyright © 2005 by Koshkarova, Koshkarov.  相似文献   
45.
46.
Prader–Willi syndrome (PWS) results from either paternal deletion of 15q11–q13, or maternal uniparental disomy (UPD) of chromosome 15 or imprinting center mutation. Prenatal diagnosis of PWS is currently indicated for chromosomal parental translocation involving chromosome 15 and for decreased fetal movements during the third trimester of gestation. Here we present the prenatal diagnosis of PWS during the first trimester of gestation and autopsy findings. Chorionic villus sampling (CVS) was performed for advanced maternal age at 13 weeks' gestation. CVS showed mosaicism including cells with a normal karyotype and cells with trisomy 15. Amniocentesis showed cells with a normal karyotype. Molecular analysis demonstrated that the fetus had a typical PWS abnormal methylation profile and maternal disomy for chromosome 15. Fetal ultrasound examination showed slightly enlarged lateral ventricles and hypoplasic male external genitalia without intra-uterine growth retardation. The autopsy showed a eutrophic male fetus with facial dysmorphy, hypoplasic genitalia, abnormal position of both feet and posterior hypoplasia of the corpus callosum. This report points out that in a karyotypically normal fetus with ambiguous male external genitalia and cerebral anomalies, extensive cytogenetic and molecular biology studies are strongly recommended because of risk of PWS. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
47.
48.
49.
50.
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