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   18841篇
  免费   293篇
  国内免费   332篇
安全科学   654篇
废物处理   805篇
环保管理   2739篇
综合类   3048篇
基础理论   4751篇
环境理论   10篇
污染及防治   5073篇
评价与监测   1139篇
社会与环境   1116篇
灾害及防治   131篇
  2023年   97篇
  2022年   205篇
  2021年   209篇
  2020年   201篇
  2019年   159篇
  2018年   312篇
  2017年   302篇
  2016年   464篇
  2015年   361篇
  2014年   516篇
  2013年   1535篇
  2012年   707篇
  2011年   993篇
  2010年   726篇
  2009年   824篇
  2008年   913篇
  2007年   944篇
  2006年   794篇
  2005年   658篇
  2004年   669篇
  2003年   604篇
  2002年   588篇
  2001年   662篇
  2000年   529篇
  1999年   326篇
  1998年   219篇
  1997年   233篇
  1996年   230篇
  1995年   277篇
  1994年   220篇
  1993年   213篇
  1992年   177篇
  1991年   186篇
  1990年   181篇
  1989年   182篇
  1988年   153篇
  1987年   133篇
  1986年   158篇
  1985年   144篇
  1984年   191篇
  1983年   151篇
  1982年   173篇
  1981年   158篇
  1980年   131篇
  1979年   149篇
  1978年   95篇
  1977年   100篇
  1975年   89篇
  1974年   93篇
  1972年   96篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
41.
42.
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   
43.
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   
44.
We report the prenatal diagnosis at 16 weeks' gestation of bilateral split-hand/split-foot malformation (SHSFM) with severe lobster claw deformity of hands and feet in a male fetus without associated malformations. A minor manifestation of SHSFM was present in the father with only mild bilateral foot involvement (syndactyly I–II; cleft II–III; left cutaneous syndactyly III–IV). Mutation analysis of the p63 gene on chromosome 3q27 showed a missense mutation 577A→G (predicting amino acid substitution K193E) in the father. This mutation has not been reported so far in SHSFM but resembles the previously reported 580A→G (predicting amino acid substitution K194E) in a family with SHSFM. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
45.
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   
46.
47.
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   
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