全文获取类型
收费全文 | 16126篇 |
免费 | 150篇 |
国内免费 | 119篇 |
专业分类
安全科学 | 358篇 |
废物处理 | 659篇 |
环保管理 | 1921篇 |
综合类 | 3648篇 |
基础理论 | 3701篇 |
环境理论 | 6篇 |
污染及防治 | 4006篇 |
评价与监测 | 1022篇 |
社会与环境 | 1019篇 |
灾害及防治 | 55篇 |
出版年
2022年 | 115篇 |
2021年 | 128篇 |
2019年 | 104篇 |
2018年 | 207篇 |
2017年 | 198篇 |
2016年 | 320篇 |
2015年 | 248篇 |
2014年 | 368篇 |
2013年 | 1097篇 |
2012年 | 410篇 |
2011年 | 618篇 |
2010年 | 477篇 |
2009年 | 560篇 |
2008年 | 640篇 |
2007年 | 678篇 |
2006年 | 615篇 |
2005年 | 511篇 |
2004年 | 535篇 |
2003年 | 521篇 |
2002年 | 491篇 |
2001年 | 624篇 |
2000年 | 394篇 |
1999年 | 307篇 |
1998年 | 191篇 |
1997年 | 215篇 |
1996年 | 227篇 |
1995年 | 234篇 |
1994年 | 233篇 |
1993年 | 220篇 |
1992年 | 200篇 |
1991年 | 207篇 |
1990年 | 198篇 |
1989年 | 169篇 |
1988年 | 172篇 |
1987年 | 156篇 |
1986年 | 158篇 |
1985年 | 150篇 |
1984年 | 171篇 |
1983年 | 170篇 |
1982年 | 173篇 |
1981年 | 146篇 |
1980年 | 133篇 |
1979年 | 123篇 |
1978年 | 135篇 |
1977年 | 117篇 |
1976年 | 104篇 |
1975年 | 107篇 |
1974年 | 118篇 |
1971年 | 99篇 |
1967年 | 101篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
M.G. Morgan S.C. Morris 《Journal of the Air & Waste Management Association (1995)》2013,63(7):670-673
The results from the regional air quality analysis for the Four Corners Study are discussed in this paper. This study was one of five regional studies conducted for the National Commission on Air Quality. Potential regional air quality impacts were evaluated through the year 1995 for alternative energy scenarios under current and alternative regulatory policies. The alternative regulatory policies include emission fees, technology standards, emission ceilings, and prevention of significant deterioration class elimination. The alternatives were compared in terms of their impacts on regional visibility and on the ambient concentrations of SO2, SO4, and primary fine particulates. The fate of the pollutants was estimated. The alternative regulatory policies were quite different with respect to their control of SOX emissions and their impacts on regional visibility. Sources located outside of the study region were estimated to have a major impact on regional air quality within the study region. 相似文献
992.
993.
G. Van Houte B. Delmon J.C. Maon Ph. Dumont 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1030-1033
This publication concerns the dry removal of SO2 from gases using limestone absorbents. It reports bench-scale experiments made with commercial samples of powdered limestone (CaCO3) activated by addition of a cheap substance, namely CaCl2. The absorption was carried out in a fluidized bed traversed by the flue gases, between 600° and 900° C. The degree and rate of transformation of CaCO3 to CaSO4 in the presence of SO2 and air have been compared for unmodified and modified absorbents. Initial rates of reaction, and the variation of the rate of absorption with time have been measured. The influence of the SO2 content of the gas has been assessed. At 700° C, the maximum degree of transformation of activated limestone to sulfate exceeds 90%, whereas untreated CaCO3 transforms only to 16–20%. At the same temperature, more than 90% of SO2 contained In a gas carrying 0.35% SO2 is removed. Because of the much smaller quantity of solid absorbent required, dry absorption processes based on the modified absorbents might get renewed interest. The modified absorbents might also be used for in situ absorption in fluidized bed combustion, in which the temperatures are in the range studied in the present paper. 相似文献
994.
995.
The dispersion of hot plumes emitted from a smelter complex located In the Columbia River Valley, British Columbia, was evaluated under stable and neutral conditions during two mornings In spring. Spatial measurements of SO2 and temperature within the plume were obtained by immersion probing using fast response helicopter and automobile mounted Instrumentation. In addition, meteorological measurements of vertical wind and temperature profiles at, and downwind from, the smelter were obtained from minisonde balloon releases. With weak down-valley winds, it was found that the plume axis elevations were generally lower during both stable and neutral conditions than would be predicted by Briggs plume-rise formulae. In contrast, plume dispersion, although confined in the horizontal by the steep valley walls during both stability regimes, was significantly enhanced by exceptionally good lateral mixing, particularly close to the source. 相似文献
996.
Richard G. Phelps 《Journal of the Air & Waste Management Association (1995)》2013,63(9):908-912
The problem of coke oven door leakage is generally recognized as one for which no proven solution exists. In 1974 the United States Environmental Protection Agency and the American Iron and Steel Institute entered into a jointly funded research project with Battelle Columbus Laboratories. The initial project was to define the problem by literature search, operator interviews and profile measurements of jambs and doors. Numerous concepts of seal designs were developed and then rated by industry and Battelle reviews. It was determined that a metal-to-metal seal offered the greatest probability of success. It was felt that jamb warpage was the most serious problem to be solved. In the fall of 1976 another contract was signed by EPA and AISI assigning Battelle the task of developing to the point of fabrication a system to eliminate or significantly reduce leakage from coke oven end closures. This program included mathematical modeling, physical modeling, field data collecting, analysis, and full scale unit design. A retrofittable door seal design has been developed and preparations are underway for operating evaluation at eight steel plants. The design is retrofittable to the two principal coke oven doors in service and should accommodate the worst jamb warpage usually found. 相似文献
997.
Larry G. Anderson 《Journal of the Air & Waste Management Association (1995)》2013,63(9):970-973
It has been recognized for several years that ozone in rural areas can exceed the National Ambient Air Quality Standard (NAAQS) for photochemical oxidant whirh was 0.08 ppm for one hour, not to be exceeded more than once per year. During the summer of 1973, the NAAQS was exceeded from 15 to 37% of the time at four rural monitoring sites in Maryland, Pennsylvania, Ohio, and West Virginia.1 This is a greater violation rate than is found in many urban areas. Dimitriades and Altshuller2 have enumerated four possible sources for this rural ozone: (a) transport from urban areas, (b) local photochemical generation from urban ozone precursors, (c) local photochemical generation from precursors of rural origin which may be man-made or natural, and (d) injection of stratospheric ozone into the rural area. This paper considers the chemistry pertinent to the first two of these possible sources of rural ozone, namely the long distance (overnight) transport of ozone and ozone precursors. 相似文献
998.
999.
1000.