全文获取类型
收费全文 | 21001篇 |
免费 | 240篇 |
国内免费 | 191篇 |
专业分类
安全科学 | 621篇 |
废物处理 | 845篇 |
环保管理 | 3058篇 |
综合类 | 2911篇 |
基础理论 | 5576篇 |
环境理论 | 13篇 |
污染及防治 | 5943篇 |
评价与监测 | 1325篇 |
社会与环境 | 973篇 |
灾害及防治 | 167篇 |
出版年
2022年 | 139篇 |
2021年 | 189篇 |
2020年 | 116篇 |
2019年 | 172篇 |
2018年 | 319篇 |
2017年 | 309篇 |
2016年 | 472篇 |
2015年 | 407篇 |
2014年 | 589篇 |
2013年 | 1755篇 |
2012年 | 733篇 |
2011年 | 942篇 |
2010年 | 738篇 |
2009年 | 864篇 |
2008年 | 974篇 |
2007年 | 1058篇 |
2006年 | 949篇 |
2005年 | 773篇 |
2004年 | 759篇 |
2003年 | 699篇 |
2002年 | 716篇 |
2001年 | 816篇 |
2000年 | 612篇 |
1999年 | 354篇 |
1998年 | 278篇 |
1997年 | 275篇 |
1996年 | 307篇 |
1995年 | 314篇 |
1994年 | 298篇 |
1993年 | 256篇 |
1992年 | 232篇 |
1991年 | 208篇 |
1990年 | 226篇 |
1989年 | 198篇 |
1988年 | 193篇 |
1987年 | 183篇 |
1986年 | 167篇 |
1985年 | 160篇 |
1984年 | 195篇 |
1983年 | 194篇 |
1982年 | 182篇 |
1981年 | 184篇 |
1980年 | 151篇 |
1979年 | 177篇 |
1978年 | 120篇 |
1977年 | 110篇 |
1976年 | 91篇 |
1975年 | 98篇 |
1973年 | 97篇 |
1972年 | 105篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
941.
Ronald C. Henry 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1353-1356
This paper describes incorporation of a human visual system model in the widely used plume visibility model PLUVUE. The results will be of interest to all involved with siting new sources for which visibility of the plume is a concern and to visibility researchers. The human visual system model allows inclusion of size and shape effects on the perceptibility of a plume. Example calculations are given for 2250- and 1600-MW power plants which show that size and shape effects can reduce the predicted perceptibility by up to a factor of three. 相似文献
942.
Andrew C. VanderZaag Hambaliou Baldé Jemaneh Habtewold Etienne L. Le Riche Stephen Burtt Kari Dunfield 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1096-1106
Liquid manure storages are a significant source of methane (CH4) emissions. Farmers commonly agitate (stir) liquid manure prior to field application to homogenize nutrients and solids. During agitation, manure undergoes mechanical stress and is exposed to the air, disrupting anaerobic conditions. This on-farm study aimed to better understand the effects of agitation on CH4 emissions, and explore the potential for intentional agitation (three times) to disrupt the exponential increase of CH4 emissions in spring and summer. Results showed that agitation substantially increased manure temperature in the study year compared to the previous year, particularly at upper- and mid-depths of the stored manure. The temporal pattern of CH4 emissions was altered by reduced emissions over the subsequent week, followed by an increase during the second week. Microbial analysis indicated that the activity of archaea and methanogens increased after each agitation event, but there was little change in the populations of methanogens, archaea, and bacteria. Overall, CH4 emissions were higher than any of the previous three years, likely due to warmer manure temperatures that were higher than the previous years (despite similar air temperatures). Therefore, intermittent manure agitation with the frequency, duration, and intensity used in this study is not recommended as a CH4 emission mitigation practice.Implications: The potential to mitigate methane emissions from liquid manure storages by strategically timed agitation was evaluated in a detailed farm-scale study. Agitation was conducted with readily-available farm equipment, and targeted at the early summer to disrupt methanogenic communities when CH4 emissions increase exponentially. Methane emissions were reduced for about one week after agitation. However, agitation led to increased manure temperature, and was associated with increased activity of methanogens. Overall, agitation was associated with similar or higher methane emissions. Therefore, agitation is not recommended as a mitigation strategy. 相似文献
943.
944.
Judith C. Chow John G. Watson Richard T. Egami Clifton A. Frazier Zhiqiang Lu Andrew Goodrich 《Journal of the Air & Waste Management Association (1995)》2013,63(8):1134-1142
Street sweeping is often proposed as a means of reducing the emissions from paved roads. The objective of this study was to evaluate the effectiveness of street sweeping on ambient particulate matter concentrations and to determine the difference In source contributions to PM10 concentrations between street sweeping and non-street sweeping periods. Chemically-speciated measurements of PM10 and PM2.5 were taken in the commercial section of Reno, Nevada, for a one-month sampling period. The Chemical Mass Balance (CMB) model was applied to these data and an average of approximately 50 percent of the PM10 was apportioned to resuspended geological material. During half of the sampling period, streets In the vicinity of the sampling site were completely swept with a regenerative-air vacuum sweeper, while no sweeping was performed during the remainder of the experiment. Ratios of primary geological contributions divided by primary motor vehicle contributions to PM10 were compared between sweeping and non-sweeping periods using analysis of variance. This ratio of source contributions minimizes the effects of variations in traffic volume and meteorological dispersion. No significant differences in geological contributions to PM10 were detected as a result of regenerative-air vacuum street sweeping. 相似文献
945.
946.
Stephen C. James 《Journal of the Air & Waste Management Association (1995)》2013,63(5):801-806
This paper will focus on the demonstration of hazardous waste cleanup technologies in the field. The technologies will be at the pilot- or full-scale, and further referred to as field-scale. The main objectives of demonstration at the field-scale are development of reliable performance and cost data. Technology demonstrations provide performance, cost effectiveness, and reliability data so that potential technology users have sufficient information to make effective decisions as to the applicability of the technology to a specific situation. The demonstration and evaluation of a technology should be conducted with the purpose of characterizing performance, need for pre- and post-processing of the waste feed, identification of waste type and constituents applicable to the technology, system throughput, problems and limitations of the technology, and operating and maintenance costs. Table I provides a summary of remediation activities for demonstration projects. 相似文献
947.
Arijit Pakrasi Wayne T. Davis Gregory D. Reed Timothy C. Keener 《Journal of the Air & Waste Management Association (1995)》2013,63(7):987-992
The removal of SO2 with atomization of a slaked lime slurry and supplemental injection of gaseous NH3 were tested in a conventional spray dryer/baghouse system for SO2 concentrations of 2000 ppm and 3000 ppm and a 30° F approach to saturation. Results at 3000 ppm of SO2 showed an average SO2 removal efficiency of 90.3 percent at a combined stoichiometric ratio of 0.95-1.10 and an average overall sorbent utilization of 91.6 percent. The overall molal ratio of NH3/SO2 reaction was found to be 2:1 under the test conditions Particle size analyses, and EP toxicity tests were conducted on the products of the reactions. 相似文献
948.
Peter A. Gabele 《Journal of the Air & Waste Management Association (1995)》2013,63(3):296-304
In response to the occurrence of the increasingly severe ambient ozone exceedances, regional environmental managers are examining the possibility of a cleaner fuel for automobiles. At this time the leading candidate appears to be methanol. In anticipation of a shift to methanol, flexible-fueled automobiles capable of operating on gasoline and/or methanol are being developed. This study examines both the exhaust and evaporative emissions from a prototype General Motors Variable Fuel Corsica. Results are reported for tests conducted at temperatures of 40°, 75°, and 90° F, and for fuels MO M25, M50, M85, and M100. In addition to regulated emissions and fuel economy, emission rates for methanol, aldehydes, and a large number of hydrocarbon compounds were measured. The data indicate that increasing the fuel's methanol content does not affect the exhaust organic emission rate (calculated in accordance with the regulation) from flexible-fueled cars, but formaldehyde and methanol comprise increasingly greater portions of the organic material while hydrocarbons comprise less. Increasing fuel methanol content has no significant effect on exhaust regulated emission rates (organic material, carbon monoxide, and nitrogen oxides) nor on the composition of total hydrocarbons, except for methane, which increases substantially. The effect of ambient temperature on both exhaust and evaporative emissions is similar to its effect on gasoline cars: organic and carbon monoxide exhaust emissions increase substantially at the lower temperatures, and evaporative emissions increase steadily with increases in temperature. 相似文献
949.
950.
Bert Brunekreef Mieke Lumens Gerard Hoek Peter Hofschreuder Paul Fischer Klaas Biersteker 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1444-1447
In January 1987, an air pollution episode occurred In central and western Europe. Levels of SO2, NO2, black smoke, sulphates and other components were elevated, with 24 hour average concentrations of SO2 reaching a maximum of close to 300 μg/m3 In an area In the southeast of the Netherlands. Pulmonary function was measured In a group of children of 6- 12 years old at the end of the episode, and also two and three and a half weeks after the episode. A baseline lung function value was obtained about three months before the episode. Pulmonary function growth between baseline and retest dates was estimated from a simple growth model which was validated using measured pulmonary function growth data from a longitudinal study. A decline of pulmonary function (FVC, FEV1 and PEF) from predicted baseline levels was observed, starting on the last day of the episode. Two weeks after the episode, FVC, FEV1 PEF and MMEF were all decreased, and three and a half weeks after the episode, there was still a deficit compared to predicted baseline levels for FVC and FEV1 相似文献