全文获取类型
收费全文 | 20454篇 |
免费 | 193篇 |
国内免费 | 141篇 |
专业分类
安全科学 | 594篇 |
废物处理 | 756篇 |
环保管理 | 2759篇 |
综合类 | 5620篇 |
基础理论 | 4358篇 |
环境理论 | 9篇 |
污染及防治 | 4792篇 |
评价与监测 | 1072篇 |
社会与环境 | 738篇 |
灾害及防治 | 90篇 |
出版年
2018年 | 239篇 |
2017年 | 245篇 |
2016年 | 362篇 |
2015年 | 281篇 |
2014年 | 386篇 |
2013年 | 1559篇 |
2012年 | 495篇 |
2011年 | 678篇 |
2010年 | 600篇 |
2009年 | 676篇 |
2008年 | 717篇 |
2007年 | 771篇 |
2006年 | 645篇 |
2005年 | 573篇 |
2004年 | 612篇 |
2003年 | 577篇 |
2002年 | 528篇 |
2001年 | 672篇 |
2000年 | 482篇 |
1999年 | 327篇 |
1998年 | 252篇 |
1997年 | 236篇 |
1996年 | 251篇 |
1995年 | 281篇 |
1994年 | 298篇 |
1993年 | 252篇 |
1992年 | 267篇 |
1991年 | 267篇 |
1990年 | 283篇 |
1989年 | 258篇 |
1988年 | 213篇 |
1987年 | 207篇 |
1986年 | 213篇 |
1985年 | 210篇 |
1984年 | 228篇 |
1983年 | 217篇 |
1982年 | 235篇 |
1981年 | 245篇 |
1980年 | 192篇 |
1979年 | 203篇 |
1978年 | 170篇 |
1977年 | 166篇 |
1976年 | 150篇 |
1974年 | 156篇 |
1973年 | 151篇 |
1968年 | 156篇 |
1967年 | 185篇 |
1966年 | 158篇 |
1965年 | 150篇 |
1964年 | 153篇 |
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
631.
632.
This paper shows that spent lubricating oils from automobile engines generate carboxylic acids on environmental exposure. Samples of exposed oils, isolated from polluted river water and shore muds obtained from various locations, showed a direct proportionality between carboxylic acid content and time of exposure. Carboxylic acids were isolated by solvent extraction and studied by infrared spectroscopy. 相似文献
633.
Marine Biology - The combined effects of temperature and salinity on the rate of oxygen consuption by the estuarine crab Panopeus herbstii Milne-Edwards (Crustacea: Decapoda: Xanthidae) were... 相似文献
634.
William Lin Robert L Spore Edmund A Nephew 《Journal of Environmental Economics and Management》1976,3(3):236-252
This study quantifies the short-run impacts of reclamation on strip mining costs, coal prices, production, and employment in Appalachia. A process analysis model is developed and used to estimate short-run strip-mined coal supply functions under conditions of alternative reclamation requirements. Then, an econometric model is developed and used to estimate coal demand relations. Our results show that full reclamation has rather minor impacts. In 1972, full reclamation would have increased strip-mined coal production costs an average of $0.35 per ton, reduced strip-mined coal production by 10 million tons, and cost approximately 1600 jobs in Appalachia. 相似文献
635.
636.
637.
Sadika M. Baladi Catherine M. Lewis Amitava Ganguly Alvin G. Morrow Lisel R. Shoffner Robert F. Blundy Patrick F. Nakagawa Sara T. Mundy Larry Anderson Karen Adams 《补救:环境净化治理成本、技术与工艺杂志》2003,14(1):5-20
Enhanced bioremediation is quickly developing into an economical and viable technology for the remediation of contaminated soils. Until recently, chlorinated organic compounds have proven difficult to bioremediate. Environmentally recalcitrant compounds, such as polychlorinated biphenyls (PCBs) and persistent organic pesticides (POPs) such as dichlorodiphenyl trichloroethane (DDT) have shown to be especially arduous to bioremediate. Recent advances in field‐scale bioremedial applications have indicated that biodegradation of these compounds may be possible. Engineers and scientists at the Savannah River Site (SRS), a major DOE installation near Aiken, South Carolina, are using enhanced bioremediation to remediate soils contaminated with pesticides (DDT and its metabolites, heptachlor epoxide, dieldrin, and endrin) and PCBs. This article reviews the ongoing remediation occurring at the Chemicals, Metals, and Pesticides (CMP) Pits using windrow turners to facilitate microbial degradation of certain pesticides and PCBs. © 2003 Wiley Periodicals, Inc. 相似文献
638.
V. Krishna Prasad K.V.S. Badarinath H. Tsuruta S. Sudo S. Yonemura John Cardina Benjamin Stinner Richard Moore Deborah Stinner Casey Hoy 《The Environmentalist》2003,23(2):175-187
Forests and soils are a major sink of carbon, and land use changes can affect the magnitude of above ground and below ground carbon stores and the net flux of carbon between the land and the atmosphere. Studies on methods for examining the future consequences of changes in patterns of land use change and carbon flux gains importance, as they provide different options for CO2 mitigation strategies. In this study, a simulation approach combining Markov chain processes and carbon pools for forests and soils has been implemented to study the carbon flows over a period of time. Markov chains have been computed by converting the land use change and forestry data of India from 1997 to 1999 into a matrix of conditional probabilities reflecting the changes from one class at time t to another class time t+1. Results from Markov modeling suggested Indian forests as a potential sink for 0.94 Gt carbon, with an increase in dense forest area of about 75.93 Mha and decrease of about 3.4 Mha and 5.0 Mha in open and scrub forests, if similar land use changes that occurred during 1997–1999 would continue. The limiting probabilities suggested 34.27 percent as dense forest, 6.90 as open forest, 0.4 percent mangrove forest, 0.1 percent scrub and 58 percent as non-forest area. Although Indian forests are found to be a potential carbon sink, analysis of results from transition probabilities for different years till 2050 suggests that, the forests will continue to be a source of about 20.59 MtC to the atmosphere. The implications of these results in the context of increasing anthropogenic pressure on open and scrub forests and their contribution to carbon source from land use change and forestry sector are discussed. Some of the mitigation aspects to reduce greenhouse gas emissions from land use change and forestry sector in India are also reviewed in the study. 相似文献
639.
Egbert Kanis Ab F. Groen Karel H. De Greef 《Journal of Agricultural and Environmental Ethics》2003,16(2):137-162
Pork producers in Western Europe moreand more encounter a variety of societalconcerns about pork and pork production. Sofar, however, producers predominantly focusedon low consumer prices, therewith addressingjust one concern. This resulted in an intensiveand large-scale production system, decreasinglyrelated to the area of farm land, andaccompanied with increasing concerns aboutsafety and healthiness of pork, animal welfare,environmental pollution, and others.An overview was given of possible concernsabout West-European pork production with theconsumers, citizens, and producers, and thoseconcerns are traced back to the pork productionsystem. The various kinds and qualities ofinformation about the pork production system onwhich possible concerns are based have beenworked out extensively in this paper. Knowledgeabout the aspects of pork production that cangive rise to concerns can be used in two ways.First, the communication about those aspectstowards consumers and citizens can be adjustedor extended to give them better possibilitiesto make food choices or to develop their ownopinions about pork production. Second,producers could change the pork productionsystem such that it better satisfies consumersand citizens. Such adaptations are wellpossible, as three pork quality schemes, whichhave been evaluated, illustrate. However, mostof these adaptations can only be carried out atthe cost of the present low consumer prices andwill not occur spontaneously on a large scale.Therefore, accounting for the type andrelevance of the concerns, legislation isnecessary to address societal concerns in abalanced way such that pork production systemsbecome acceptable for the majority of oursociety. 相似文献
640.
This paper investigates the European Commission's decision to allow a merger between two Brazilian iron ore mining companies, CVRD and Caemi, using data on the Direct Reduced Iron pellet market. By using a simulation model, we can directly simulate the total welfare effects from the merger and hence evaluate the merger from a new perspective. The results from our simulations suggest that the welfare effects are negative from the merger between CVRD and Caemi, which supports the conclusion drawn by the European Commission decision. By performing different simulations between hypothetical merger candidates, our results show that only mergers between small candidates have the potential to be welfare enhancing. 相似文献