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   29160篇
  免费   268篇
  国内免费   217篇
安全科学   752篇
废物处理   976篇
环保管理   3806篇
综合类   7865篇
基础理论   6493篇
环境理论   9篇
污染及防治   7206篇
评价与监测   1418篇
社会与环境   982篇
灾害及防治   138篇
  2018年   346篇
  2017年   339篇
  2016年   484篇
  2015年   391篇
  2014年   541篇
  2013年   2047篇
  2012年   694篇
  2011年   993篇
  2010年   825篇
  2009年   963篇
  2008年   1026篇
  2007年   1083篇
  2006年   956篇
  2005年   783篇
  2004年   840篇
  2003年   810篇
  2002年   749篇
  2001年   1022篇
  2000年   689篇
  1999年   466篇
  1998年   350篇
  1997年   322篇
  1996年   369篇
  1995年   396篇
  1994年   414篇
  1993年   362篇
  1992年   388篇
  1991年   379篇
  1990年   409篇
  1989年   406篇
  1988年   319篇
  1987年   321篇
  1986年   295篇
  1985年   310篇
  1984年   317篇
  1983年   311篇
  1982年   328篇
  1981年   340篇
  1980年   291篇
  1979年   296篇
  1978年   258篇
  1977年   231篇
  1976年   248篇
  1974年   260篇
  1973年   238篇
  1972年   231篇
  1971年   217篇
  1968年   229篇
  1967年   263篇
  1966年   223篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
661.
662.
An investigation has been made of the suitability of a nondispersive infrared analyzer and two flame-ionization analyzers for measuring the total hydrocarbon concentrations of automobile exhaust gas. The investigation consisted of measuring relative responses of various hydrocarbons, checking for possible exhaust gas interferences and finally comparing exhaust hydrocarbon concentrations indicated by the flame-ionization analyzer to those indicated by the infrared analyzer. The infrared analyzer has high relative responses for parraffins and low responses for olefins, acetylenes, and aromatics. Also, the infrared indicated hydrocarbon concentrations must be corrected for exhaust water vapor interference. When the flameionization analyzers are operated at conditions that result in approximately uniform response to hydrocarbons and low oxygen interference, the exhaust hydrocarbon concentrations indicated by either flameionization analyzer are better approximations of the total hydrocarbon concentration than those indicated by the infrared analyzer.  相似文献   
663.
Recent studies of organic pyrolyses in the presence of nitric oxide have shown that various nitogen compounds, such as hydrogen cyanide (HCN) and aceto-nitrile (CH3CN) are formed. This suggests the possibility that such compounds will be found in internal combustion processes, and may be present in automobile exhaust gases. The present paper describes some gas-chromatographic and wet analyses of exhaust gases. It is concluded that the amounts of hydrogen cyanide are less than 1 ppm, but that various organic nitrogen compounds may reach a level of about 100 ppm. The significance of these results is discussed.  相似文献   
664.
A study was conducted to evaluate performance and cost comparisons of fabric filters and alternate fine particulate control techniques. In relating the removal of fine particulate to costs, due to the lack of fractional efficiency data, it was found necessary to treat a specific application in order to make the study manageable. The case chosen is that of the coal fired industrial boiler since Enviro-Systems has a pilot program in this application area.  相似文献   
665.
As many of you know, I previously served as Deputy Administrator of the Environmental Protection Agency at a time when the problem of air pollution control was reaching a peak of public awareness. The work of the Air Pollution Control Association in investigating facts and accelerating the development of solutions earned my high respect then and my continued admiration now.  相似文献   
666.
Two processes are currently being employed in North America for the desulfurization of coke oven gas, the Vacuum Carbonate System, and the Stretford System. A third, the Sulfi-ban Process, which was recently announced, now has several plants scheduled for construction. Overall operating requirements for each of these processes are considered in detail. Emphasis is placed on an identification of power and steam requirements, the types and amounts of solid and/or liquid waste streams produced together with methods for their treatment, and the net desulfurization efficiencies achieved by each process. Detailed estimates of capital and operating costs for desulfurization are considered, and equipment needs for environmental control requirements are discussed.  相似文献   
667.
668.
669.
670.
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