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   33275篇
  免费   387篇
  国内免费   236篇
安全科学   906篇
废物处理   1355篇
环保管理   4559篇
综合类   5895篇
基础理论   8982篇
环境理论   18篇
污染及防治   8251篇
评价与监测   2046篇
社会与环境   1644篇
灾害及防治   242篇
  2022年   234篇
  2021年   238篇
  2019年   241篇
  2018年   396篇
  2017年   440篇
  2016年   673篇
  2015年   534篇
  2014年   764篇
  2013年   2683篇
  2012年   968篇
  2011年   1331篇
  2010年   1086篇
  2009年   1136篇
  2008年   1304篇
  2007年   1395篇
  2006年   1282篇
  2005年   1056篇
  2004年   1020篇
  2003年   1019篇
  2002年   946篇
  2001年   1167篇
  2000年   898篇
  1999年   532篇
  1998年   416篇
  1997年   431篇
  1996年   440篇
  1995年   493篇
  1994年   464篇
  1993年   447篇
  1992年   441篇
  1991年   431篇
  1990年   440篇
  1989年   408篇
  1988年   372篇
  1987年   347篇
  1986年   346篇
  1985年   328篇
  1984年   369篇
  1983年   354篇
  1982年   379篇
  1981年   348篇
  1980年   304篇
  1979年   321篇
  1978年   267篇
  1977年   248篇
  1975年   199篇
  1974年   244篇
  1973年   230篇
  1972年   231篇
  1971年   214篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
751.
752.
753.
The assumptions and empirical evidence linking climate change adaptation to development cooperation have led to the emergence of a range of climate change adaptation tools aiming at improving the quality of development cooperation initiatives in times of global change. In order to assess the quality of these tools, we develop an analytic framework to critically assess the social learning and sustainable development outcomes of climate change adaptation tools. The analytic framework defines project objectives, participation typology, participation tools, participation stages, scenarios development, modelling exercises, stakeholder analysis and risk communication strategies that support quality participation outcomes.  相似文献   
754.
The aim of the present study is to determine the effect of blood lead on the health of industrial workers in United Arab Emirates (UAE). This is a cross-sectional pilot survey of blood lead levels (BLL) of 100 industrial workers (exposed) and 100 non-industrial workers (nonexposed), matched for age, sex and nationality selected from Al-Ain, Abu-Dhabi Emirate. Industrial workers had significantly higher mean of BLL (77.5+/-42.8 microg/dl and median 80.9 microg/dl) than non-industrial workers (19.8+/-12.3 microg/dl and median 11.0 microg/dl). In the present study, reported symptoms among industrial workers were strongly associated with BLL nausea/vomiting, muscular symptoms, dizziness, fatigue, irritability, memory disturbances, insomnia and allergic conjuctivitis, rhinitis and dermatitis. Furthermore, the present study revealed that industrial workers had higher prevalence of respiratory symptoms for phlegm, shortness of breath and diagnosed asthma. In conclusion, this study determined that occurrence of certain symptoms might be associated with lead exposure among industrial workers.  相似文献   
755.
This paper analyzes day-of-week variations in concentrations of particulate matter (PM) in California. Because volatile organic compounds (VOCs) and oxides of nitrogen (NOx) are not only precursors of ozone (O3) but also of secondary PM, it is useful to know whether the variations by day of week in these precursors are also evident in PM data. Concentrations of PM < or = 10 microm (PM10) and < or = 2.5 microm in aerodynamic diameter (PM2.5) were analyzed. PM concentrations exhibit a general weekly pattern, with the maximum occurring late in the workweek and the minimum occurring on weekends (especially Sunday); however, this pattern does not prevail at all sites and areas. PM nitrate (NO3-) data from Size Selective Inlet (SSI) samplers in the South Coast Air Basin (SoCAB) tend to be somewhat lower on weekends compared with weekdays. During 1988-1991, the weekend average was lower than the weekday average at 8 of 13 locations, with an average decrease of 1%. During 1997-2000, the weekend average was lower than the weekday average at 10 of 13 locations, with an average decrease of 6%. The weekend averages are generally lower than weekday averages for sulfates, organic carbon, and elemental carbon. Because heavy-duty trucks typically represent a major source of elemental carbon, the weekend decrease in heavy-duty truck traffic may also result in a decrease in ambient elemental carbon concentrations.  相似文献   
756.
Estuarine sediments from a USEPA Superfund site in coastal Georgia were extensively contaminated with Aroclor 1268, a mixture of highly chlorinated polychlorinated biphenyls used by a former chlor-alkali plant. Batch slurries of contaminated sediment were incubated for 1 yr with amendments of 2,6-dibromobiphenyl (26-BB) and 2,3,4,5,6-pentachlorobiphenyl (23456-CB) under anaerobic, sulfate-reducing conditions and different pH (5.5-7.5). Organic extracts of slurry sub-samples in a time series were analyzed by congener-specific GC-MS. Dechlorination of 23456-CB was pH dependent and occurred via two routes with the sequential loss of (1) meta and para chlorines and (2) para, ortho, and meta chlorines. Quantitative dehalogenation of 26-BB was observed at all pH. Supplementation of nonachlorobiphenyls (as primers) did not induce dechlorination of native Aroclor 1268 nor of the primers themselves. While contaminated estuarine sediments possess microbial consortia with diverse dehalogenating activities, lack of dechlorination of Aroclor 1268 and spiked nonachlorobiphenyl congeners suggests a bioavailability limitation or enzyme-substrate incompatibilities.  相似文献   
757.
758.
Hunt MR 《Disasters》2011,35(3):606-622
Expatriate health care professionals frequently participate in international responses to natural disasters and humanitarian emergencies. This field of practice presents important clinical, logistical and ethical challenges for clinicians. This paper considers the ethics of health care practice in humanitarian contexts. It examines features that contribute to forming the moral landscape of humanitarian work, and discusses normative guidelines and approaches that are relevant for this work. These tools and frameworks provide important ethics resources for humanitarian settings. Finally, it elaborates a set of questions that can aid health care professionals as they analyse ethical issues that they experience in the field. The proposed process can assist clinicians as they seek to establish their moral bearings in situations of ethical complexity and uncertainty. Identifying and developing ethics resources and vocabulary for clinical practice in humanitarian work will help health care professionals provide ethically sound care to patients and communities.  相似文献   
759.
Earthquake hazard assessment after Mexico (1985)   总被引:1,自引:0,他引:1  
Degg MR 《Disasters》1989,13(3):237-246
The 1985 Mexican earthquake ranks foremost amongst the major earthquake disasters of the twentieth century. One of the few positive aspects of the disaster is that it provided massive quantities of data that would otherwise have been unobtainable. Every opportunity should be taken to incorporate the findings from these data in earthquake hazard assessments. The purpose of this paper is to provide a succinct summary of some of the more important lessons from Mexico. It stems from detailed field investigations, and subsequent analyses, conducted by the author on the behalf of reinsurance companies.  相似文献   
760.
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