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   52735篇
  免费   579篇
  国内免费   650篇
安全科学   1686篇
废物处理   2169篇
环保管理   7224篇
综合类   8542篇
基础理论   14404篇
环境理论   36篇
污染及防治   13568篇
评价与监测   3339篇
社会与环境   2638篇
灾害及防治   358篇
  2022年   453篇
  2021年   458篇
  2020年   369篇
  2019年   454篇
  2018年   785篇
  2017年   763篇
  2016年   1172篇
  2015年   933篇
  2014年   1344篇
  2013年   4159篇
  2012年   1688篇
  2011年   2359篇
  2010年   1900篇
  2009年   1959篇
  2008年   2326篇
  2007年   2443篇
  2006年   2121篇
  2005年   1775篇
  2004年   1742篇
  2003年   1751篇
  2002年   1622篇
  2001年   2083篇
  2000年   1448篇
  1999年   924篇
  1998年   698篇
  1997年   697篇
  1996年   711篇
  1995年   788篇
  1994年   771篇
  1993年   659篇
  1992年   675篇
  1991年   636篇
  1990年   675篇
  1989年   657篇
  1988年   577篇
  1987年   514篇
  1986年   443篇
  1985年   492篇
  1984年   504篇
  1983年   516篇
  1982年   502篇
  1981年   462篇
  1980年   377篇
  1979年   422篇
  1978年   368篇
  1977年   287篇
  1976年   292篇
  1975年   295篇
  1974年   263篇
  1972年   295篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
In studies of occupational risks, severity, which is a component of the estimation of every risk, appears as a multifaceted entity assessable according to numerous criteria. A method of measuring the degree of severity of the consequences of potentially dangerous events would be of undeniable value to organisations seeking to improve their understanding of the complexity of such events. The need to control severity is highlighted by scientifically acquired improvements in the understanding of occupational risks, by certain new regulatory obligations in Europe, and by some requirements in the financial management of organisations. We put forward a statistical way of integrating several constituent elements of severity and hence of determining a relevant, synthetic, one-dimensional index. This is achieved by means of principal component analysis (PCA), which is used here to calculate a resultant severity, as in some physical measurements. We also investigate how severity may be statistically modelled, with the aim of contributing to the quantitative assessment of occupational risks. The choice of parametric models is detailed and illustrated by the search for a suitable model for workplace accidents in an organisational setting. The practical value of modelling severity is two-fold. First, one is able to study the distribution of the numerical values of severity over a continuum (a theoretically infinite numerical set) rather than through a limited number of arbitrarily defined categories. Second, with a generally applicable parametric model, one can estimate the law of probability of a measurement of severity in a particular situation, notably recent or new. Lastly, the statistical concept of risk curve is defined and discussed. The goal is to incorporate the severity component into the risk assessment in the form of a probability law, thus circumventing the difficulties associated with an analysis of scenarios.  相似文献   
992.
Russian Journal of Ecology - Technogenic pollution can accelerate microevolutionary processes in natural populations. We estimated the nuclear DNA content of 10 Bromus inermis Leyss. samples from...  相似文献   
993.
Russian Journal of Ecology - Abstract—Long-term observations (1968–2019) on the dynamics of infection by the cestode Eubothrium rugosum in the burbot (Lota lota) have been performed in...  相似文献   
994.
Russian Journal of Ecology - The variability of the ecological and morphological characteristics of the field vole was studied on samples collected in its two localities of the Southern Urals and...  相似文献   
995.
Environment, Development and Sustainability - The COVID-19 pandemic has caused a global emergence, and the absence of a proven vaccine or medicine has led to the implementation of measures to...  相似文献   
996.
Environment, Development and Sustainability - The current study explores the role of green trust, green perceived risk and green perceived quality in changing green purchase intention....  相似文献   
997.
Russian Journal of Ecology - The long-term dynamics (over more than 70 years) of pike infection by cestodes Triaenophorus crassus and T. nodulosus in the Rybinsk Reservoir (the Volga River) has...  相似文献   
998.
Allergic respiratory disease due to common allergens of organic origin is wwell known. Less familiar, but of increasing importance, are chemicals of organic and inorganic nature, met as dusts, vapours, and fumes. Their relevance is shown in occupational respiratory allergic disorders. Confirmation is given by “real life,” simulated, occupational-type provocation tests. Controlled exposure with minute amounts for brief periods, thus closely simulating allergic sensitivity, can precisely identify etiological causes in often complex exposures. The capacity of these widely different agents in different forms to elicit the different patterns of asthmatic reactions, is a pointed example of their potential role, as well as the role of chemical agents in general. The introduction into indoor environments of such materials demands consideration of their possible allergenic ffects and of the need to recognise the various forms of allergic respiratory reaction they may cause.  相似文献   
999.
A 566 m3/m (20,000 acfm) permanent installation demonstration system, consisting of the Air Pollution Systems' High Intensity Ionizer and a variable throat venturi scrubber (called the Scrub-E) has been installed on a magnesium recovery furnace. The furnace produces submicron fume particles of MgO, MgCl2, and ZrCl4. The system is designed to demonstrate the effectiveness of the High Intensity Ionizer versus high venturi pressure drop on the furnace emissions. The High Intensity Ionizer array operates stably at field strengths of 10–15 kV/cm and at velocities in excess of 18 m/sec (60 fps) while maintaining high charging efficiencies. The report covers the system design, technology, applications, and project developments. An Environmental Protection Agency proposed charged droplet Scrub-E is also discussed covering the design, technology, and proposed demonstration program.  相似文献   
1000.
The recovery of energy from the combustion of municipal solid wastes is becoming an attractive alternative as landfill space becomes scarce and the availability of fossil fuels decreases. Particulate emissions from “waste-as-fuel” processes, however, may differ significantly in chemical and physical properties from particulate emissions produced by firing only coal. Such differences can affect the design and operation of air pollution control equipment. Presented in this paper are the results of a 2-month test program at Ames, Iowa, with a mobile electrostatic precipitator (ESP) and a mobile scrubber supplied by the U.S. Environmental Protection Agency (EPA), Industrial Environmental Research Laboratory (IERL), Research Triangle Park. PEDCo Environmental, Inc., and Acurex Corporation jointly conducted the test program to examine the effect of burning refuse-derived fuel (RDF) on particulate and heavy metal control efficiencies. The mobile ESP was used only as a primary control device, whereas the mobile scrubber was tested both upstream and downstream of the existing full-scale ESP. This paper also presents a status report on a PEDCo test program with a pilot fabric filter at Ames.  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