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   31706篇
  免费   357篇
  国内免费   468篇
安全科学   986篇
废物处理   1503篇
环保管理   3816篇
综合类   5195篇
基础理论   8222篇
环境理论   21篇
污染及防治   8519篇
评价与监测   2210篇
社会与环境   1874篇
灾害及防治   185篇
  2023年   151篇
  2022年   362篇
  2021年   358篇
  2020年   261篇
  2019年   301篇
  2018年   508篇
  2017年   526篇
  2016年   805篇
  2015年   613篇
  2014年   962篇
  2013年   2548篇
  2012年   1147篇
  2011年   1546篇
  2010年   1227篇
  2009年   1262篇
  2008年   1511篇
  2007年   1561篇
  2006年   1332篇
  2005年   1136篇
  2004年   1032篇
  2003年   1114篇
  2002年   999篇
  2001年   1257篇
  2000年   873篇
  1999年   530篇
  1998年   353篇
  1997年   365篇
  1996年   368篇
  1995年   432篇
  1994年   456篇
  1993年   357篇
  1992年   377篇
  1991年   355篇
  1990年   390篇
  1989年   342篇
  1988年   296篇
  1987年   278篇
  1986年   225篇
  1985年   249篇
  1984年   266篇
  1983年   260篇
  1982年   243篇
  1981年   224篇
  1980年   176篇
  1979年   194篇
  1978年   177篇
  1975年   141篇
  1974年   117篇
  1972年   130篇
  1971年   131篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
  1. The Air Polluttion Monitoring System has got a significant development of late, which is in direct relation with a considerable extention and improvement of the observation network in cities and industrial areas, with creation of a new network for assessing regional and global background of the atmosphere pollution, as well as with the wide involvement of meteorologists to monitoring organization.
  2. While developing a new global monitoring system, it is necessary to take into account its relationship with the local monitoring within the region of air pollution sources, i.e. at the \lsimpact\rs level. The need in such an account is dictated first of all by the physics of pollutant spreading that states: changes in air pollution over large territories must be in a certain agreement with greater changes in the vicinity of emission sources. Methods applied in the global and local monitoring have also a number of common peculiarities. White organizing regional network for observations of the background pollution of the atmosphere twin stations (one of the pair of stations located outside the city boundaries in a small community, and the other, in the nearest city with the population of 200–400 thousand inhabitants) were established in the U.S.S.R. and in a number of socialist countries in Europe.
  3. Implementation of the twin-station principles in the U.S.S.R. has contributed to data interpretation and representativity assessment as well as to correction of the station location. Observation results from the Soviet background stations and those abroad have been compared by now according to a number of indices.
  4. The correlation of monitoring systems of various scales tells positively both on mutual improvement and completion of observational methods. The methods of obtaining integral characteristics of air pollution were used for the global monitoring, in particular spectral actinometric observations and chemical analysis of the precipitation composition. Now they find still wider employment. Thus methods of spectral actinometric measurements and data processing were used to estimate the degree of aerosol pollution of a number of industrial centres. The theory of solar radiation spreading and aerosol contents determination in urban atmosphere has also been developed. It is a generalization of an earlier developed theory, used to estimate global atmosphere pollution basing on actinometric data. The organization of precipitation collection and analysis on a network of stations around Leningrad and in Donbass area enables us to compare the admixture content in precipitations falling in industrial and agricultural areas.
  5. A considerable increase of possibilities to measure microconcentrations of sulphur dioxide, nitrogen oxides and of a number of other pollutants is connected with the use of solid solvents for sampling. Their use will allow to avoid establishment of special laboratories at background stations and only send samples by post for their analysis in centralized laboratories.
They will also allow to considerably increase precision and accuracy of measurements. The international comparisons of methods of air pollution measurements on the background level allow to judge about the effiency of these methods.  相似文献   
42.
43.
44.
45.
46.
47.
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