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排序方式: 共有349条查询结果,搜索用时 453 毫秒
321.
Richard Lowrance Lee S. Altier J. Denis Newbold Ronald R. Schnabel Peter M. Groffman Judith M. Denver David L. Correll J. Wendell Gilliam James L. Robinson Russell B. Brinsfield Kenneth W. Staver William Lucas Albert H. Todd 《Environmental management》1997,21(5):687-712
/ Maryland, Virginia, and Pennsylvania, USA, have agreed to reduce nutrient loadings to Chesapeake Bay by 40% by the year 2000. This requires control of nonpoint sources of nutrients, much of which comes from agriculture. Riparian forest buffer systems (RFBS) provide effective control of nonpoint source (NPS) pollution in some types of agricultural watersheds. Control of NPS pollution is dependent on the type of pollutant and the hydrologic connection between pollution sources, the RFBS, and the stream. Water quality improvements are most likely in areas of where most of the excess precipitation moves across, in, or near the root zone of the RFBS. In areas such as the Inner Coastal Plain and Piedmont watersheds with thin soils, RFBS should retain 50%-90% of the total loading of nitrate in shallow groundwater, sediment in surface runoff, and total N in both surface runoff and groundwater. Retention of phosphorus is generally much less. In regions with deeper soils and/or greater regional groundwater recharge (such as parts of the Piedmont and the Valley and Ridge), RFBS water quality improvements are probably much less. The expected levels of pollutant control by RFBS are identified for each of nine physiographic provinces of the Chesapeake Bay Watershed. Issues related to of establishment, sustainability, and management are also discussed.KEY WORDS: Riparian forest buffers; Chesapeake Bay; Nonpoint source pollution; Nitrogen; Phosphorus; Sediment 相似文献
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Albert Rango 《Journal of the American Water Resources Association》1980,16(6):1066-1073
ABSTRACT: Several federal and state water resources agencies and NASA have recently completed an Applications Systems Verification and Transfer (ASVT) project on the operational applications of satellite snow cover observations. When satellite snow cover data were tested in both empirical seasonal runoff estimation and short term modeling approaches, a definite potential for reducing forecast error was evident. Three years of testing in California resulted in reduction of seasonal stream flow forecast error was evident. Three years of testing in California resulted in reduction of seasonal stream flow forecast error from 15 percent to 10 percent on three study basins; and modeling studies on the Boise River basin in Idaho indicated that satellite snow cover could be used to reduce short term forecast error by up to 9.6 percent (5 day forecast). Potential benefits from improved satellite snow cover based predictions across the 11 western states total 10 million dollars for hydropower and 28 million dollars for irrigation annually. The truly operational application of the new technology in the West, however, will only be possible when the turnaround time for all data is reduced to 72 hours, and the water management agencies can be assured of a continuing supply of operational snow cover data from space. 相似文献
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Albert C. Achudume 《Environment, Development and Sustainability》2009,11(2):459-469
Sustainable development is a process that has social, cultural, economic and ecological dimensions. The necessity of improving
the quality of life of rural women in terms of socio-economic aspects in developing countries like Nigeria is the aim of this
study. The study was carried out in four villages of Tonkere district (Okeake, Abagboro, Elefon and Akiri), situated on expansive
university land at Ile-Ife and typical of rural settings in Nigeria. Data were generated from group meetings, local government
and individual interviews and surveys. In rural Nigeria, women’s essential contributions to overall environmental health,
development and economy are negatively influenced by domestic tasks such as gathering of fuel woods and biomass for cooking.
In reality, wood burning, kerosene stoves, and open fireplaces emit significant quantities of known health-damaging pollutants.
The significant emissions of health-damaging pollutants per unit activity, combined with daily use in close proximity to rural
human populations mean household biomass fuel use exposes total population to important pollutants resulting in ill-health
and premature dead. Application of solar energy collectors and hosts of solar devices is an alternative energy sources in
rural areas that could best improve women’s health, socially and economically, and positively add to ecological dimensions.
Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
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It is predicted that climate change will drive extinctions of some reptiles and that the number of these extinctions will depend on whether reptiles are able to change their distribution. Whether the latitudinal distribution of reptiles may change in response to increases in temperature is unknown. We used data on reptile distributions collected during the 20th century to analyze whether changes in the distributions of reptiles in Spain are associated with increases in temperature. We controlled for biases in sampling effort and found a mean, statistically significant, northward shift of the northern extent of reptile distributions of about 15.2 km from 1940-1975 to 1991-2005. The southern extent of the distributions did not change significantly. Thus, our results suggest that the latitudinal distributions of reptiles may be changing in response to climate change. 相似文献