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   3121篇
  免费   17篇
  国内免费   70篇
安全科学   90篇
废物处理   150篇
环保管理   307篇
综合类   517篇
基础理论   1117篇
污染及防治   613篇
评价与监测   211篇
社会与环境   194篇
灾害及防治   9篇
  2023年   4篇
  2022年   17篇
  2021年   16篇
  2020年   7篇
  2019年   7篇
  2018年   121篇
  2017年   127篇
  2016年   188篇
  2015年   62篇
  2014年   25篇
  2013年   40篇
  2012年   436篇
  2011年   222篇
  2010年   38篇
  2009年   46篇
  2008年   56篇
  2007年   79篇
  2006年   77篇
  2005年   399篇
  2004年   535篇
  2003年   421篇
  2002年   60篇
  2001年   57篇
  2000年   36篇
  1999年   38篇
  1998年   13篇
  1997年   12篇
  1996年   5篇
  1995年   12篇
  1994年   4篇
  1993年   3篇
  1992年   3篇
  1991年   8篇
  1990年   4篇
  1989年   6篇
  1986年   3篇
  1979年   1篇
  1978年   1篇
  1975年   2篇
  1974年   2篇
  1973年   1篇
  1972年   2篇
  1971年   1篇
  1969年   1篇
  1968年   1篇
  1967年   1篇
  1966年   2篇
  1961年   1篇
  1957年   1篇
  1917年   1篇
排序方式: 共有3208条查询结果,搜索用时 31 毫秒
641.
Among chemical industries, petroleum refineries have been identified as large emitters of a wide variety of pollutants. Benzene, toluene, ethylbenzene, and xylene (BTEX) form an important group of aromatic volatile organic compounds (VOCs) because of their role in the troposphere chemistry and the risk posed to human health. A very large crude oil refinery of the Baltic States (200,000 bbl/day) is situated in the northern, rural part of Lithuania, 10 km from the town of Ma?eikiai (Lithuania). The objectives of this study were: (1) to determine of atmospheric levels of BTEX in the region rural and urban parts at the vicinity of the crude oil refinery; and (2) to investigate the effect of meteorological parameters (wind speed, wind direction, temperature, pressure, humidity) on the concentrations measured. The averaged concentration of benzene varied from 2.12 ppbv in the rural areas to 2.75 ppbv in the urban areas where the traffic was determined to be a dominant source of BTEX emissions. Our study showed that concentration of benzene, as strictly regulated air pollutant by EU Directive 2008/50/EC, did not exceed the limit of 5 ppbv in the region in the vicinity of the crude oil refinery during the investigated period. No significant change in air quality in the vicinity of the oil refinery was discovered, however, an impact of the industry on the background air quality was detected. The T/B ratio (0.50-0.81) that was much lower than 2.0, identified other sources of pollution than traffic.  相似文献   
642.
This study compares the social costs and environmental benefits of collecting single use drink containers through the Danish deposit system with the social costs and benefits of treating the containers as part of the municipal waste-disposal system. It focuses on single use polyethylene terphthalate and glass bottles, and steel and aluminium cans. The social costs of handling these containers in the deposit system includes the costs of collection, sorting, and transportation, adjusted against the profit from selling the collected material for recycling. The social cost of incinerating these containers as municipal waste consists of the expenses for the collection, incineration of the containers and disposal of ashes. If there is any income from energy generation accompanying incineration, this is adjusted against costs. The main environmental effects related to both strategies are quantified, valuated and included in the assessment. The results of the analysis show that there are significant social costs compared to the benefits connected with the new deposit system. This is true for all four types of single use drink containers examined. All in all, Denmark bears a net social cost of 6.7 to 8.1 million Euros per year compared to a baseline of incineration with energy recovery.  相似文献   
643.
Landfill processes were simulated in laboratory-scale bioreactors--lysimeters. The changes in leachate characteristics as well as the influence of advanced oxidation processes (AOPs) on the processes taking place in the sanitary landfill were investigated. Lysimeters were filled with material simulating municipal waste in the city of Lodz, Poland. Compost in the amount of 30% w/w and the methanogens inoculum were added in order to enhance development of a methanogenic phase. The leachate produced in lysimeters was recirculated. In order to investigate the influence of AOPs implementation on processes taking place in landfills two runs in lysimeters were performed, each lasting about 250 days. The leachate composition and biogas composition and production changes showed trends that confirmed that the bench-scale lysimeters appeared suitable to simulate processes taking place in the landfill. The application of AOPs to the leachate recirculated into the lysimeters did not bring about unequivocally positive effects. The ozonation of the leachate, implemented at the beginning of the methanogenic phase, caused slight acceleration (about 2 weeks) of the biodegradation, whereas employment of H2O2/UV led to the inhibition of anaerobic processes.  相似文献   
644.
In recent years the issue of the municipal waste in Poland has become increasingly topical, with a considerable rise in the waste generation, much of which can be attributed to a boom in product packaging (mainly plastic). The annual production of plastics packaging has been constantly increasing over the last 20 to 30 years, and now exceeds 3.7 million tons. Due to a lack of processing technologies and poorly developed selective segregation system, packaging waste is still treated as a part of the municipal solid waste (MSW) stream, most of which is landfilled. As a result of Poland's access to the European Union, previous legal regulations governing municipal waste management have been harmonized with those binding on the member countries. One of the main changes, the most revolutionary one, is to make entrepreneurs liable for environmental risks resulting from the introduction of packaging to the market, and for its recycling. In practice, all entrepreneurs are to ensure recovery, and recycling, of used packaging from products introduced to the market at the required level. In recent year, the required recycling levels were fulfilled for all types of materials but mainly by large institutions using grouped and transport packaging waste for that matter. Household packaging gathered in the selective segregation system at the municipalities was practically left alone. This paper is an attempt to describe the system and assess the first year of functioning of the new, revamped system of packaging waste management in Poland. Recommendations are made relating to those features that need to be included in packaging waste management systems in order to maximize their sustainability and harmonization with the EU legal system.  相似文献   
645.
646.
Summary This paper presents data from an educational study of acid rain in Greater Manchester, UK, and Greater Lisbon and Setúbal, Portugal, which was carried out between October and December, 1989. A simple, specified methodology was employed by ten schools in each of the two countries to generate reliable, comparative rainfall acidity data. The results have been described and related to emission sources and meteorological conditions over the three-month experimental period. It is apparent that there are considerable differences in rainfall quantity and quality in the two contrasting areas, and the results are broadly consistent with those derived from the European Monitoring and Evaluation Programme. The paper concludes with a short review of rainfall acidity in the UK and Portugal.Sue Hare and Dr James W.S. Longhurst are respectively Education Officer and Director of the Acid Rain Information Centre, Department of Environmental and Geographical Studies at Manchester Polytechnic. Mr A. Marques da Costa is a teacher in the Chemistry Department at the Colégio Militar, Largo da Luz, 1600 Lisboa, Portugal.  相似文献   
647.
The Dead Sea is a severely disturbed ecosystem, greatly damaged by anthropogenic intervention in its water balance. During the 20th century, the Dead Sea level dropped by more than 25 meters, and presently (2003) it is at about 416 meters below mean sea level. This negative water balance is mainly due to the diversion of water from the catchment area of the lake by Israel, Jordan and Syria. During the 2002 World Summit on Sustainable Development Israel and Jordan jointly announced their interest in saving the Dead Sea by constructing the “Peace Conduit” that will pipe water from the Red Sea to the Dead Sea. The inflow of seawater (or reject brine after desalinization) into the Dead Sea will have a major impact on its limnology, geochemistry and biology. During the filling stage, relatively diluted surface water will form and the rate of evaporation will therefore increase. Dilution of the surface water will most likely result in microbial blooming whose duration is not known, while the lower water layer is likely to develop reducing conditions, including bacterial sulfate reduction and presence of hydrogen sulfide (H2S). Mixing between the calcium-rich Dead Sea brine and the sulfate-rich seawater will result in gypsum precipitation (CaSO4⋅ 2H2O). Once the target level is reached, inflow will be outbalanced by evaporation and salinity of the surface water will increase due to accumulation of seawater-salts. The water column will re-mix when the density of the surface water will equal that of the lower water column. In spite of its large volume and high salinity relative to that of the inflowing water, over the long run the composition of this unique lake will change. Before a decision is made on the planning and construction of the Conduit, it is essential that the long term evolution and characteristics of the “renewed” Dead Sea be known and anticipated changes examined. Once decided upon, the planning and construction of the Conduit should be conducted so as to minimize possible negative impacts of seawater introduction on the Dead Sea. This can only be achieved through a thorough understanding of the expected changes in the limnological physical/chemical characteristics of the Dead Sea and its unique brine.  相似文献   
648.
Ernst Mayr: the doyen of twentieth century evolutionary biology   总被引:1,自引:0,他引:1  
  相似文献   
649.
650.
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