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   228篇
  免费   0篇
安全科学   1篇
废物处理   6篇
环保管理   4篇
综合类   164篇
基础理论   21篇
污染及防治   19篇
评价与监测   12篇
社会与环境   1篇
  2013年   4篇
  2011年   3篇
  2009年   11篇
  2007年   5篇
  2006年   5篇
  2005年   4篇
  2003年   2篇
  2002年   3篇
  2001年   3篇
  1999年   4篇
  1997年   4篇
  1996年   3篇
  1991年   2篇
  1985年   3篇
  1984年   3篇
  1983年   2篇
  1982年   2篇
  1977年   2篇
  1969年   2篇
  1967年   3篇
  1966年   5篇
  1965年   6篇
  1964年   5篇
  1963年   4篇
  1962年   5篇
  1961年   8篇
  1960年   6篇
  1959年   4篇
  1958年   12篇
  1957年   6篇
  1956年   2篇
  1955年   5篇
  1954年   4篇
  1953年   3篇
  1952年   6篇
  1951年   5篇
  1950年   3篇
  1949年   2篇
  1943年   4篇
  1940年   2篇
  1938年   3篇
  1935年   2篇
  1933年   2篇
  1932年   2篇
  1928年   5篇
  1927年   2篇
  1926年   3篇
  1923年   4篇
  1922年   5篇
  1921年   3篇
排序方式: 共有228条查询结果,搜索用时 15 毫秒
71.
72.
Based upon several years of experience in investigations with macrozoobenthos in rivers in the states of Minas Gerais and Rio de Janeiro, a biological assessment system has been developed to indicate pollution levels caused by easily degradable organic substances from sewers. The biotic index presented here is aimed at determining water’s saprobic levels and was, therefore, named the “Saprobic Index for Brazilian Rivers in Minas Gerais and Rio de Janeiro states” (ISMR). For this purpose, saprobic valences and weights have been established for 122 taxa of tropical macrozoobenthos. Investigations were carried out in little, medium sized and big rivers in mountains and plains. Through ISMR, a classification of water quality and the respective cartographic representation can be obtained. Data collection and treatment methods, as well as the limitations of the biotic index, are thoroughly described. ISMR can also be used as an element to establish complex multimetric indexes intended for an ecological integrity assessment, where it is essential to indicate organic pollution.  相似文献   
73.
ABSTRACT

For the evaluation of air quality improvement strategies, emission data in high temporal and spatial resolution is necessary, including all emission sources and all relevant pollutant species. Computer aided models are usually used to generate this emission data because it is not possible to obtain measurements from all sources, and, furthermore, a large amount of data has to be handled. For the development of emission modeling systems, a software tool called CAREAIR has been created. The intention of this paper is to introduce CAREAIR to the international community dealing with emission inventories and air quality improvement strategies.

CAREAIR is not just a single emission model but a flexible modeling toolbox. The database contains data and formulas for data manipulation, which is performed by using a set of flexible operators with different specifications. The emission calculation is carried out by combining several data manipulation operators. The CAREAIR modeling toolbox allows model implementation for the calculation of emissions from different pollutants in a high spatial and temporal resolution. The application of CAREAIR within various investigation projects in Germany, Europe, and Nigeria shows that CAREAIR is an appropriate instrument for the development of flexible emission models by meeting the various demands of these projects. The function and the data structures of this modeling toolbox are described and, towards the end of the paper, an example of an emission calculation with CAREAIR is given.  相似文献   
74.
Monitoring personal exposure to particle matter (PM(2.5)) in ambient air requires performing measurements using portable monitors. In this work, the portable nephelometer SidePak? AM510 Personal Aerosol Monitor manufactured by TSI Inc. was evaluated against a Tapered Element Oscillating Microbalance (TEOM) equipped with a Filter Dynamics Measurements System (FDMS). Conventionally, the SidePak is calibrated with respect to the Arizona Road Test Dust and then multiplied by an environmental calibration factor to yield mass concentration. To adapt this calibration to specific field conditions, we present an implementation of this calibration by introducing a growing factor correction which takes into account relative humidity and the dry and wet portions of the refractive index estimated from TEOM-FDMS measurements. PM(2.5) sampling with several SidePaks AM510 was carried out in background and rural sites in the Po Valley (Italy). Modeled SidePak data were plotted vs. reference TEOM-FDMS data which show a good agreement.  相似文献   
75.
76.
77.
78.
79.
80.
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