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   20696篇
  免费   189篇
  国内免费   219篇
安全科学   563篇
废物处理   1026篇
环保管理   2448篇
综合类   2705篇
基础理论   5330篇
环境理论   4篇
污染及防治   5745篇
评价与监测   1685篇
社会与环境   1476篇
灾害及防治   122篇
  2023年   94篇
  2022年   222篇
  2021年   226篇
  2020年   142篇
  2019年   185篇
  2018年   344篇
  2017年   336篇
  2016年   548篇
  2015年   371篇
  2014年   593篇
  2013年   1774篇
  2012年   699篇
  2011年   887篇
  2010年   818篇
  2009年   808篇
  2008年   911篇
  2007年   1010篇
  2006年   895篇
  2005年   734篇
  2004年   734篇
  2003年   712篇
  2002年   687篇
  2001年   911篇
  2000年   631篇
  1999年   395篇
  1998年   275篇
  1997年   247篇
  1996年   294篇
  1995年   270篇
  1994年   250篇
  1993年   233篇
  1992年   240篇
  1991年   208篇
  1990年   214篇
  1989年   219篇
  1988年   197篇
  1987年   158篇
  1986年   126篇
  1985年   140篇
  1984年   170篇
  1983年   154篇
  1982年   193篇
  1981年   134篇
  1980年   119篇
  1979年   152篇
  1978年   118篇
  1977年   107篇
  1976年   100篇
  1975年   83篇
  1974年   88篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
141.
Environmental Science and Pollution Research - The objective of this study was to monitor a newly constructed wetland (CW) in north Wales, UK, to assess whether it contributes to an improvement in...  相似文献   
142.
The population of foxes in the central regions of Yakutia has grown by a factor of four to five during the period from 2000 to 2011–2012, following an increase in the abundance of voles from the genus Microtus. A total of 130 carcasses of foxes taken in 2007–2012 have been examined. Age- and sex-related variation in morphological features has been described. The demographic structure of the population has been studied by estimating animal age from annual layers in the recording structures. Changes in female fertility and involvement in reproduction depending on age and feeding conditions have been analyzed. Changes in the composition of fox diet caused by long-term population depression in the mountain hare and their effect on the dynamics of fox abundance have been revealed. Age- and sex-related characteristics of the condition factor in foxes and sex-related differences in their dietary preferences have been demonstrated.  相似文献   
143.
The probable source of stone moroko, Pseudorasbora parva (Temminck & Schlegel, 1846), populations in lake- and stream-type Dnieper reservoirs was revealed. The dynamics and specific growth rates of these populations over 20 years were analyzed. The dynamic phase portrait method was used to determine the timing of stages in the process of invader naturalization and the periods when its populations were in equilibrium. The potential growth rates of P. parva populations in the Kremenchug and Dneprodzerzhinsk reservoirs were estimated.  相似文献   
144.
Value stream mapping (VSM) is a well-accepted tool within lean manufacturing concept which is often used for analysing and designing the flow of materials and information required to manufacture a product. However, the analysis is static and single product oriented, which fails to cope with either the variation of production plan or a multi-product environment. In addition, the environmental impact of a manufacturing system is highly associated with the dynamic consumption of energy and resources. Despite the recent integration of VSM with simulation or environmental studies (in the domain of energy efficiency), still neglected is the dynamic assessment of all the resources involved in a multi-product production environment. This paper presents a methodology for modelling multi-product manufacturing systems with dynamic material, energy and information flows with the aim to generate economic and environmental value stream maps (E2VSM). The proposed methodology is validated with an industrial case.  相似文献   
145.
This paper considers the evolution of attempts to control and manage air pollution, principally but not exclusively focussing upon the challenge of managing air pollution in urban environments. The development and implementation of a range of air pollution control measures are considered. Initially the measures implemented primarily addressed point sources, a small number of fuel types and a limited number of pollutants. The adequacy of such a source-control approach is assessed within the context of a changing and challenging air pollution climate. An assessment of air quality management in the United Kingdom over a 50-year timeframe exemplifies the range of issues and challenges in contemporary air quality management. The need for new approaches is explored and the development and implementation of an effects-based, risk management system for air quality regulation is evaluated.  相似文献   
146.
The US EPA has exempted t-butyl acetate from VOC regulations, which increases the likelihood that it may replace other solvents in some settings. This investigation probes its chemosensory properties. In Study 1, subjects (n = 29) sought to detect the odor of t-butyl acetate and of n-butyl acetate in forced-choice testing of stable concentrations, analytically confirmed. Subjects sniffed from cones with a high enough volumetric flow to insure against dilution by nonodorized air. A subject made hundreds of judgments, enough for a psychometric function for each material. The points of 50% detection above chance (“threshold”) occurred at 8 and 2 ppb for t-butyl acetate and n-butyl acetate, respectively. In study 2, subjects (n = 26) sought to detect vapor with the eye via chemesthesis (sensory irritation) in 10-s exposures. Detection at 50% occurred at 177 and 113 ppm for t-butyl acetate and n-butyl acetate, respectively, more than 10,000 times above that for odor detection. The protocols produced results of uncommon precision compared to those in often-misleading archival databases. The nose exhibits much higher sensitivity than the databases indicate. The collections rarely exhibit accuracy better than ±1000%. Collection of accurate data for a VOC can ironically bring on stricter regulation for just it, a situation that calls for a strategy to improve the database by collection of new data, importation of better data, and development of quantitative structure–activity modeling.  相似文献   
147.
148.
The paper describes results obtained in the development of a previous research. We study here, in fast firing, the sintering behaviour and measure some properties of tiles containing a mixture of 60 wt% of paper mill sludge and 40 wt% of glass cullet. The behaviour of this material is compared to those displayed by materials obtained by the same mixture added with 10, 20 and 30 wt% of a natural red clay. In parallel, the same properties are measured also on a reference blend, which is presently used to produce commercial tiles. We show that powders containing 60 wt% of paper sludge and 40 wt% of glass cullet to which 30 wt% of clay is added give rise to materials that display a stable sintering process and have good hardness and strength and therefore could be used for the industrial production of tiles.  相似文献   
149.
150.
The paper describes a programme to develop the profile of major accident risk across a large multi national oil company. It describes the concepts, tools and processes for constructing the risk profile and some of the key learnings from the exercise.  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