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   3672篇
  免费   63篇
  国内免费   33篇
安全科学   204篇
废物处理   132篇
环保管理   963篇
综合类   332篇
基础理论   902篇
环境理论   7篇
污染及防治   830篇
评价与监测   234篇
社会与环境   134篇
灾害及防治   30篇
  2023年   18篇
  2022年   23篇
  2021年   28篇
  2020年   30篇
  2019年   35篇
  2018年   44篇
  2017年   66篇
  2016年   90篇
  2015年   73篇
  2014年   79篇
  2013年   461篇
  2012年   137篇
  2011年   181篇
  2010年   120篇
  2009年   135篇
  2008年   162篇
  2007年   201篇
  2006年   138篇
  2005年   126篇
  2004年   131篇
  2003年   134篇
  2002年   112篇
  2001年   73篇
  2000年   81篇
  1999年   52篇
  1998年   56篇
  1997年   44篇
  1996年   64篇
  1995年   57篇
  1994年   67篇
  1993年   56篇
  1992年   48篇
  1991年   39篇
  1990年   39篇
  1989年   33篇
  1988年   40篇
  1987年   31篇
  1986年   35篇
  1985年   34篇
  1984年   31篇
  1983年   40篇
  1982年   49篇
  1981年   47篇
  1980年   25篇
  1979年   30篇
  1978年   25篇
  1977年   30篇
  1976年   14篇
  1974年   11篇
  1972年   11篇
排序方式: 共有3768条查询结果,搜索用时 15 毫秒
201.
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   
202.
203.
204.
The study considers a range of possible effects on the transportation industry, satellite industries, the labor market, and the economy which may be anticipated in the event mass production of unconventional low emission automotive propulsion systems should occur, whether as a consequence of federal intervention, or not. A postulated 1 976 Otto Cycle Internal Combustion Engine equipped with a dual catalyst manifold reactor and other “conventional” emission control devices was compared in detail with a Regenerative Free Turbine Engine and a Rankine Cycle Engine, as specified by the contracting agency. Manufacturing costs, operating and ownership costs, consumer demand, inter-industry effects, employment, resource requirements, and international trade implications were analyzed in depth under a number of plausible sets of policy constraints and parametric variations. Principal conclusions are that conversion over a 10 year period is feasible, that manufacturing cost differentials are less critical than fuel consumption and cost differentials, that industry/employment impacts are minor, and that resource/trade effects are dominated by petroleum imports. Implications for federal policy are discussed.  相似文献   
205.
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   
206.
207.
A mass transfer approach is used in developing a practical mathematical model of gaseous pollutant uptake by leaves in which a series of resistances is summed across a concentration difference. The body of information presented in this paper is directed to plant pathologists or physiologists in the field of vegetal-pollutant effects and to people interested in the natural removal of air pollutants by vegetation. Correlations are given to calculate the aerodynamic and the stomatal resistances to uptake, while both a qualitative investigation and quantitative estimates are made of the mesophyllic resistance. The factors which control the aerodynamic resistance, ra, are leaf size and wind speed, while the leaf physiology is the determinant of the stomatal resistance, rs . It is noted that the chemical reaction rate and pollutant diffusivity in the mesophyll control the mesophyllic resistance, rm, though the overall gas phase mesophyllic resistance, Hrm, is strongly a function of pollutant solubility in water. Finally, the overall model is compared to earlier experimental work on vegetal uptake of SO2.  相似文献   
208.
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   
209.
Calculations of pollutant concentrations at various downwind and crosswind distances from an elevated point source are frequently based on diffusion models and parameter values contained in Turner’s Workbook of Atmospheric Dispersion Estimates.1 These calculations can be made much more speedily on a computer or on a currentgeneration, programmable desk calculator, if the values of the horizontal and vertical standard deviations of plume concentrations distributions are stated explicitly as a mathematical function of downwind distance. The alternative is to read the values from Turner’s Figures 3-2 and 3-3 and input them into the calculation for each individual value of downwind distance.  相似文献   
210.
Measurements conducted on full-scale hazardous waste incinerators have occasionally shown a relationship between carbon monoxide (CO) emissions and emissions of toxic organic compounds. In this study, four mixtures of chlorinated C1 and C2 hydrocarbons were diluted in commercial-grade heptane and burned in a water-cooled turbulent flame reactor (TFR) under two different excess air levels. No correlation between CO and organic emissions could be discerned. Reasons for this lack of observable correlations are discussed in terms of combustion and chemical reaction kinetic theory.  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