全文获取类型
收费全文 | 11884篇 |
免费 | 109篇 |
国内免费 | 90篇 |
专业分类
安全科学 | 336篇 |
废物处理 | 442篇 |
环保管理 | 1638篇 |
综合类 | 2117篇 |
基础理论 | 3129篇 |
环境理论 | 7篇 |
污染及防治 | 2969篇 |
评价与监测 | 735篇 |
社会与环境 | 625篇 |
灾害及防治 | 85篇 |
出版年
2022年 | 103篇 |
2021年 | 98篇 |
2020年 | 80篇 |
2019年 | 93篇 |
2018年 | 164篇 |
2017年 | 142篇 |
2016年 | 222篇 |
2015年 | 194篇 |
2014年 | 268篇 |
2013年 | 881篇 |
2012年 | 356篇 |
2011年 | 497篇 |
2010年 | 409篇 |
2009年 | 478篇 |
2008年 | 521篇 |
2007年 | 518篇 |
2006年 | 453篇 |
2005年 | 420篇 |
2004年 | 352篇 |
2003年 | 366篇 |
2002年 | 351篇 |
2001年 | 472篇 |
2000年 | 346篇 |
1999年 | 209篇 |
1998年 | 131篇 |
1997年 | 157篇 |
1996年 | 163篇 |
1995年 | 190篇 |
1994年 | 192篇 |
1993年 | 159篇 |
1992年 | 132篇 |
1991年 | 169篇 |
1990年 | 163篇 |
1989年 | 157篇 |
1988年 | 115篇 |
1987年 | 114篇 |
1986年 | 118篇 |
1985年 | 91篇 |
1984年 | 108篇 |
1983年 | 110篇 |
1982年 | 118篇 |
1981年 | 108篇 |
1980年 | 96篇 |
1979年 | 112篇 |
1978年 | 73篇 |
1977年 | 76篇 |
1975年 | 76篇 |
1973年 | 72篇 |
1972年 | 65篇 |
1967年 | 66篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
791.
James N. Galloway Ellis B. Cowling 《Journal of the Air & Waste Management Association (1995)》2013,63(3):229-235
Precipitation is one of the most important factors determining the nature and productivity of terrestrial and aquatic ecosystems. Detailed historical and contemporary records are available indicating the amount of water deposited at thousands of locations throughout the world. Comparatively, however, knowledge of the changing chemistry of precipitation has developed only recently and is still very fragmentary. Our present ignorance of the total impact of changes in precipitation quality on the productivity and stability of ecosystems is especially profound. This paper has a fourfold purpose: (1) to describe the myriad of trace chemical constituents transferred from the atmosphere into the biosphere of the earth; (2) to define the range of beneficial and injurious ecological effects of perturbations in atmospheric deposition; (3) to explain the concepts of sensitive areas, life stages, and life forms; and (4) to describe briefly plans for a National Deposition Network and associated research on the terrestrial and aquatic ecosystems of the United States. 相似文献
792.
James B. Homolya James L. Cheney 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1000-1004
A study was carried out to investigate the emissions of SO2 and primary sulfate materials (H2SO4 and inorganic particulate matter) from a boiler burning fossil fuel and using a wet-limestone scrubber for SO2 removal. Experiments were designed to assess the scrubbing efficiency for SO2 and sulfate, as well as the potential for scrubber liquor reentrainment. The boiler studied was an 820 MW cyclone-fired unit equipped with a wet, limestone scrubber, consisting of eight two-stage venturi-absorber modules designed to treat a flue gas flow rate of 2,760,000 acfm. The boiler fuel was a low-grade sub-bituminous coal with ash and sulfur contents of 25 and 5%, respectively. Multiple-sampling methods were employed concurrently on the inlet and outlet of a candidate absorber module to measure SO2, total water-soluble sulfate, and free H2SO4. Samples were collected during three field experiments from September 1977 through April 1978. The average SO2 scrubbing efficiency was 76% and was observed to decrease over the 5 day operation/maintenance cycle of the module. The total water-soluble sulfate input to the scrubber amounted to approximately 1% of the total sulfur oxides and was composed of a 5:1 ratio of H2SO4 to particulate sulfate. The total sulfate scrubbing efficiency, averaging about 29%, was invariant with respect to SO2 removal. The sulfate emissions measured in the scrubber exit gas consisted of about 85 % H2SO4 as a fine aerosol. Mass emissions of acid and particulate sulfate were calculated as 1730 Ib/hr and 305 Ib/hr, respectively. 相似文献
793.
T. Y. Chang J. M. Norbeck B. Weinstock 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1022-1025
The distribution of mutagenic activity and nitroaromatic components of polycyclic organic matter (POM) in ambient air at industrial, urban, suburban, rural, and remote sites was studied using organic extracts from high volume aerosol samples. Direct-acting mutagens including 1-nitropyrene (1-NP), dinitropyrenes (DNP), and hydroxynitropyrenes (HNP) were measured by high performance liquid chromatography while the mutagenicity was determined in the Salmonella bioassay with strain TA-98. Benzo(a)pyrene (BaP), one of the possible precursors of nitroaromatic compounds in POM, was also measured. In comparing samples from a range of sites, TSP and the concentration of BaP per mass of particulate matter decreased, as expected, at greater distances from urban and industrial combustion sources. However, the concentrations of polar nitroaromatic POM compounds per mass of particles were higher at a remote site than in nonindustrial urban and suburban areas. The mutagenicity in particulate matter extracts from the remote area was predominantly (>90 percent) in the very polar fractions. There were also high atmospheric levels of nitroaromatic compounds and mutagenicity in heavily industrialized areas. These observations may reflect the influences of source emissions, atmospheric transformations of POM compounds, and ther atmospheric processes on the composition of ambient suspended particulate matter. 相似文献
794.
795.
James L. Littlejohn David B. Shaver William C. Malm 《Journal of the Air & Waste Management Association (1995)》2013,63(8):879-880
This study includes an application of the first two phases of a new three-phased decision-making structure that was developed to overcome the problems related to ecological safety and social justice in site selection applications. It was conducted on a current site selection problem related to the municipal solid waste disposal facilities in Kocaeli, the most industrialized region of Turkey. In order to assess the deficiencies of the legal site selection procedures related to ecological safety, two different decision tree modes were applied separately. The first mode (“Legislation”) concerns the current buffer zone applications given in the regulations, while the second one (“Proposed”) includes the applications of the new decision-making structure proposed in this study. Since it was assumed that the subjective tendencies of the decision makers on the weightings would have a significant effect on the final decision, these two modes were assessed by employing two different weighting models. The results were obtained from all of the scenarios related to selection of suitable sites with three different area requirements (15, 250, and 500 acres) for the solid wastes generated in the Kocaeli region. The results showed that the possible changes in the decision structure could cause significant differences in the final decision related to selection of the most suitable sites. The most highest and lowest differences were at the “Legislation” mode for 15 acres and 500 acres, respectively. Furthermore, the results obtained in the study showed that the possible differentiations in the criteria weightings could also cause significant differences in the suitability ranking. Therefore, to get a reliable final decision, a statistical assessment of these differentiations should be made.
Implications: The results showed that the possible changes in the decision structure could cause significant differences in the final decision related to selection of the most suitable sites. Furthermore, the results obtained in the study showed that the possible differentiations in the criteria weightings could also cause significant differences in the suitability ranking. Therefore, to get a reliable final decision, a statistical assessment of these differentiations should be made. 相似文献
796.
S. Witz M. Smith M. Shu A. B. Moore 《Journal of the Air & Waste Management Association (1995)》2013,63(3):276-278
Air monitoring In the San Francisco Bay Area was carried out to measure outdoor community air concentrations of poly cyclic aromatic hydrocarbons (PAH) and mutagenlc activity (mutagenlclty) In participate organic matter (POM). Monitoring began In 1979 and Is currently conducted at six stations. PAH and mutagenlclty tests were performed on organic extracts prepared from high volume (hl-vol) filters composited every four months, by meteorological season. PAH were determined by high pressure liquid chromatography (HPLC) with fluorescence and ultraviolet detection. Mutagenlclty was measured In the Ames Salmonella bloas-say using strain TA98 with and without metabolic activation. The nine-year mean concentration of benzo(a)pyrene (BaP) was 0.4 ng/m3. The mutagenlcfty of this amount of BaP accounted for only about 0.2% of the observed mutagenicity In POM and other measured PAH accounted for even less. Concentrations of PAH and mutagenlclty were three to nine times higher during the winter than during other seasons. Year-to-year wintertime trends In several PAH were also seen. Early In the 1980s, winter concentrations of BaP and benzo (g,h,i)perylene Increased. However since the mld-1980’s, their concentrations have fallen. The decrease In PAH concentrations may be the result of an Increasing proportion of vehicles with relatively low organic emissions. In contrast to PAH, mutagenlcfty did not show significant year-to-year time trends. 相似文献
797.
A. R. Hawthorne R. B. Gammage 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1126-1131
An important potential source of formaldehyde in the home is ureaformaldehyde foam insulation (UFFI). This study measures the long-term release of formaldehyde through the interior wall of test panels foamed with commercial urea-formaldehyde insulation. The measurements, made approximately 16 mo after initial foaming, were conducted under both static and dynamic air conditions with air flow selected to simulate a typical air exchange found in houses. Estimated room concentrations based on a simple model of uniform mixing within a room and measured emission rates are presented. Measurements of formaldehyde in the air from within the UFFI cavities are also reported. 相似文献
798.
G. B. Howe R. K. M. Jayanty A. V. Rao W. F. Gutknecht C. E. Decker D. J. von Lehmden 《Journal of the Air & Waste Management Association (1995)》2013,63(9):823-826
A repository of 38 gaseous organic compounds in compressed gas cylinders has been established by EPA. This repository was established to provide standards for source test performance audits, that is, quantitative quality assurance tests. Among these compounds are ten halogenated organic species, which are the focus of this paper. Stability studies of all ten compounds have been performed to determine the feasibility of using them as performance audit standards. Results indicate that all of the halocarbons tested are adequately stable to be used as reliable audit standards. Subsequent to completion of stability studies, four of the ten halocarbons were used in source test performance audits. Results are available at this time for two of the four compounds; the results show agreement within 10% of the concentrations previously established by Research Triangle Institute. 相似文献
799.
800.
R.M. Adams S.A. Hamilton B. A. McCarl 《Journal of the Air & Waste Management Association (1995)》2013,63(9):938-943
Past attempts to measure the economic consequences of ozone on agriculture have been based on limited plant science information. This paper reports on an economic assessment of ozone on U.S. agriculture using recent crop response data from the National Crop Loss Assessment Network (NCLAN). The results are derived from a U.S. agricultural sector model that includes major crop and livestock production as well as domestic consumption, livestock feeding and export uses. The economic effects of four hypothetical ambient ozone levels are investigated. The analysis Indicates that the benefits to society of moderate (25%) ozone reductions are approximately $1.7 billion. A 25% Increase in ozone pollution results in costs (negative benefits) of $2.1 billion. These estimates do not reflect compliance costs of achieving the ozone changes and hence are not net benefits. 相似文献