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   21568篇
  免费   384篇
  国内免费   381篇
安全科学   858篇
废物处理   875篇
环保管理   3629篇
综合类   3357篇
基础理论   5603篇
环境理论   15篇
污染及防治   5380篇
评价与监测   1264篇
社会与环境   1174篇
灾害及防治   178篇
  2023年   132篇
  2022年   209篇
  2021年   207篇
  2020年   226篇
  2019年   199篇
  2018年   390篇
  2017年   368篇
  2016年   547篇
  2015年   417篇
  2014年   584篇
  2013年   1749篇
  2012年   791篇
  2011年   1129篇
  2010年   841篇
  2009年   959篇
  2008年   1041篇
  2007年   1092篇
  2006年   911篇
  2005年   769篇
  2004年   777篇
  2003年   681篇
  2002年   649篇
  2001年   718篇
  2000年   596篇
  1999年   374篇
  1998年   267篇
  1997年   275篇
  1996年   275篇
  1995年   332篇
  1994年   271篇
  1993年   263篇
  1992年   222篇
  1991年   218篇
  1990年   210篇
  1989年   212篇
  1988年   177篇
  1987年   167篇
  1986年   187篇
  1985年   178篇
  1984年   229篇
  1983年   182篇
  1982年   212篇
  1981年   196篇
  1980年   157篇
  1979年   163篇
  1978年   117篇
  1977年   112篇
  1975年   93篇
  1974年   97篇
  1972年   102篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
971.
Inequalities in exposure and awareness of flood risk in England and Wales   总被引:1,自引:0,他引:1  
Fielding JL 《Disasters》2012,36(3):477-494
This paper explores the environmental inequalities of living in the floodplains of England and Wales and the differences in flood awareness of those 'at risk'. An area comparison is made between an etic, objective flood risk exposure, and an emic, subjective perception of that risk by social class. In all areas except the Midlands, the working classes were more likely to reside in the floodplains; the greatest exposure inequality is seen in the North East and Anglian regions. Flood awareness in the Anglian regions was much lower than average, but there were no significant class differences. In the Thames region, despite equal flood risk exposure between classes, the most deprived displayed the least awareness of flood risk. In the North East, inequalities in the distribution of flood risk exposure accompanied inequalities in perception, resulting in the least aware and most deprived experiencing the greatest flood risk.  相似文献   
972.
The current state of the ecology of the impact regions is outlined. It is argued that the complex of ecosystems situated around a point polluter (an impact region) is an appropriate model for solving several fundamental and applied ecological problems related to the exploration of strong external impacts on biota. Typical methodological errors resulting from insufficient attention to specific features of passive experiments are analysed, and ways to avoid them are proposed. The principles of spatial arrangements of study sites within the impact region and of the selection of experimental and evaluation units are discussed.  相似文献   
973.
Integrated studies on the temperature regime in a limestone outcrop area have been performed, including analysis of the latitudinal trends and dynamics of direct solar radiation input onto slopes of different exposures and the redistribution of temperatures depending on mesotopographic features of the slopes. Assessment of the diversity of ecological conditions in this model landscape has shown that about 3.3% of its area is potentially suitable for the formation of a relict lithophytic floristic assemblage.  相似文献   
974.
Commercial cattle-feeding is a large industry in the United States. In California, for instance, there are more than 500 commercial feedlots. Each of these lots handles from less than 500 to more than 50,000 head of cattle at one time. With the urban and suburban explosion, feedlots that were at one time many miles from residential centers are now “just across the street.” Naturally the high odor level from improperly operated yards gives rise to considerable complaint and citizen indignation.

A variety of methods to reduce odor to an acceptable level have been tried with varying results. A highly satisfactory procedure is based on “good housekeeping” practices, frequent removal of fecal material, and abatement of residual odor by spraying the lots at designated intervals with a solution of potassium permanganate. Details of the method are discussed.  相似文献   
975.
In conjunction with a 15-month air quality survey of Jacksonville, Fia., a mathematical model has been developed to describe the dispersion of atmospheric pollutants. The source inventory used with the model was compiled, in part, from the data obtained from the sampling of all major sources within the area. The major sources were considered separately from the one-mile square area sources which accounted for the remainder of the emissions. Meteorological data was recorded continuously in the city including vertical temperature observations to 750 ft. The model was compiled in FORTRAN and can be used for both gaseous and particulate pollutants, by utilizing proper decay rates. The variant nature of meteorological parameters and emission rates are considered. The ground level concentrations of several pollutants which were determined for 24 hr periods at 11 sites and continuously at two other sites were used to check the model. A limited tracer study was carried out in conjunction with the project.  相似文献   
976.
977.
The importance of fuels combustion was brought into sharp focus recently in a report on air pollution to the United States Senate in which it was stated, “These processes replace usable air with potentially harmful pollutants, and the capability of the atmosphere to disperse and dilute these pollutants—especially in urban areas where people, vehicles, and industries congregate in even greater numbers—is strictly limited.”1 The overwhelming burden of emissions of sulfur compounds, as well as nitrogen compounds and particulate matter in the U. S. today, originates from the burning of coal and fuel oil in stationary combustion sources. Thus, combustion has a large influence on the quality of the atmosphere in most urban areas. The air pollution effects of these contaminants are many and varied and all are objectionable and undesirable. Without a doubt, the most serious air pollution problem in the nation today is that created by the combustion of fossil fuels.  相似文献   
978.
979.
980.
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