全文获取类型
收费全文 | 20461篇 |
免费 | 234篇 |
国内免费 | 188篇 |
专业分类
安全科学 | 634篇 |
废物处理 | 846篇 |
环保管理 | 3175篇 |
综合类 | 2665篇 |
基础理论 | 5364篇 |
环境理论 | 6篇 |
污染及防治 | 5818篇 |
评价与监测 | 1309篇 |
社会与环境 | 924篇 |
灾害及防治 | 142篇 |
出版年
2022年 | 147篇 |
2021年 | 183篇 |
2020年 | 126篇 |
2019年 | 169篇 |
2018年 | 292篇 |
2017年 | 289篇 |
2016年 | 480篇 |
2015年 | 388篇 |
2014年 | 564篇 |
2013年 | 1807篇 |
2012年 | 678篇 |
2011年 | 894篇 |
2010年 | 712篇 |
2009年 | 827篇 |
2008年 | 947篇 |
2007年 | 1009篇 |
2006年 | 870篇 |
2005年 | 702篇 |
2004年 | 752篇 |
2003年 | 695篇 |
2002年 | 687篇 |
2001年 | 800篇 |
2000年 | 595篇 |
1999年 | 349篇 |
1998年 | 262篇 |
1997年 | 253篇 |
1996年 | 306篇 |
1995年 | 313篇 |
1994年 | 288篇 |
1993年 | 265篇 |
1992年 | 225篇 |
1991年 | 211篇 |
1990年 | 235篇 |
1989年 | 208篇 |
1988年 | 206篇 |
1987年 | 192篇 |
1986年 | 183篇 |
1985年 | 167篇 |
1984年 | 206篇 |
1983年 | 199篇 |
1982年 | 193篇 |
1981年 | 188篇 |
1980年 | 149篇 |
1979年 | 177篇 |
1978年 | 119篇 |
1977年 | 108篇 |
1976年 | 96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 15 毫秒
991.
The Clean Air Act Amendments of 1977 designated national parks and wilderness areas larger than 1894 ha to be class I areas
for air quality management, setting more restrictive criteria than the National Ambient Air Quality Standards. Class I areas
are afforded the greatest degree of air quality protection under the Clear Air Act of 1970. In recent years, several studies
have documented air pollution effects in the Great Smoky Mountains National Park (GSMNP), the second-largest class I area
in the eastern United States. Air pollution problems of greatest concern in the GSMNP are effects of acid deposition, visibility
impairment, and tropospheric ozone. Several recent events have increased concerns about air quality management in the class
I area of the GSMNP. A forum, sponsored by the Southern Appalachian Man and the Biosphere Cooperative (SAMAB), was held in
March 1992, which involved representative. parties-at-interest and began to address strategies for better management of air
resources in the Southern Appalachians. This paper summarizes those discussions and recommendations and reports actions occurring
as a result of the forum. Another objective of this paper is to present a conceptual framework for more effective management
of the class I area of the GSMNP. 相似文献
992.
E. Worrell A. P. C. Faaij G. J. M. Phylipsen K. Blok 《Resources, Conservation and Recycling》1995,13(3-4)
Material efficiency improvement saves energy and reduces the consumption of primary resources and reduces the volume of waste. In this article an approach for analysing the potential for material efficiency improvement is proposed and discussed. In this approach the product functions performed by the materials and various improvement measures are taken into account. The potential for material saving and associated energy saving is assessed and evaluated economically. In this paper the approach is tested in an analysis of the potential for material efficiency improvement with respect to plastic packaging in the Netherlands. The technical reduction potential is found to be 34 ± 7% (157 ± 30 ktonne virgin plastics). Realization of this potential would improve the energy efficiency of the lifecycle of plastic packaging by 31% (10 PJ in 1988). From our study we conclude that our approach can indeed be used to investigate the potential for material efficiency improvement. However, a reliable technical and particularly an economical assessment of reduction measures cannot be made until more detailed data become available. 相似文献
993.
Twenty-two metals for which secondary recovery is important, in terms of quantity and/or value, were compared and ranked for rate and efficiency of recycling, and availability of recycled metal. In general, their recycling rates trended upward over the period 1970–1993. Iron, aluminum, copper, gold, platinum, and lead accounted for most of the value of all secondary metal produced, while iron and steel dominated in terms of quantity produced and exported. The factors most influential on recycling rates are profitability, public support, organization of infrastructure, sortability, legislative support, and scrap purity. The share of supply accounted for by secondary metals is expected to surpass that of primary metals sometime in the next decade. 相似文献
994.
Interest in the concept—and implementation—of environmental excellence is at an all-time high. A wealth of examples from individual companies, trade associations, states, industry coalitions, and the federal government illustrate the growing acceptance by a wide range of stakeholders of a management systems approach to environmental issues. Perhaps nowhere is this more clear than in the collection of public comments submitted to EPA in response to its January 15, 1993, Federal Register notice, which proposed the creation of an Environmental Leadership Program (ELP). The authors, both of whom worked on the ELP, review these public comments and offer a set of “do's and don'ts” for organizations interested in establishing an environmental excellence program. In addition, the authors outline the Green Track proposal, a plan to structure an alternate regulatory pathway based on environmental excellence. 相似文献
995.
Lawrence J. MacDonnell David H. Getches William C. Hugenberg 《Journal of the American Water Resources Association》1995,31(5):825-836
ABSTRACT: The waters of the Colorado River are divided among seven states according to a complex ‘Law of the River’ drawn from interstate compacts, international treaties, statutes, and regulations. The Law of the River creates certain priorities among the states and the Republic of Mexico, and in the event of a severe sustained drought, the Law of the River dictates the distribution of water and operation of the elaborate reservoir system. Earlier work indicated that there is remarkable resilience in the system for established uses of water in the Lower Basin of the Colorado River. This work shows, based on an application of the Law of the River using computer modeling of operations of facilities on the Colorado River, that there may be serious environmental consequences and related legal restraints on how the water is used in times of shortage and that the existing legal and institutional framework governing the Colorado River does not adequately address all the issues that would be raised in a severe sustained drought. Several possible legal options for dealing with drought in the context of the Law of the River are identified. 相似文献
996.
997.
Letitia C. Langord 《The Environmentalist》1984,4(3):185-193
Summary The author presents the results of a pilot study which explored the voluntary support given by seven Pittsburgh multinationals
to environmental goals and objectives through their foundations and operations. While much of the information is national
in scope, the findings have international significance. Fundamental common key factors and patterns were identified which
already have and will continue to guide most corporate international environmental activities. As interest grows in developing
cooperative undertakings with the corporate community, it is important for environmental organizations, government, and academia
to understand these patterns. Based on the findings and on suggestions by corporate representatives, recommendations are given
as to how support of the goal of creating sustainable societies by the corporate and environmental communities can be improved
and increased.
Dr Langord's interest in urban and environmental policies range from issues dealing with coastal zone and floodplain management
to urban waterfront re-vitalization and environmental aesthetics. Most recently she is studying the role of industry in helping
to meet critical resource and environmental needs. She is exploring new patterns of cooperation with government, industry
and environmental organizations. Currently Director of the International Environment Program, Center for International Studies,
University of Pittsburgh, Dr Langord has held a number of academic positions, served as a resource policy analyst for the
US Department of Interior, and has acted as a consultant to government and industry. 相似文献
998.
999.
1000.
Three approaches to using aerial photography are evaluated for searching for open dumps in the state of Indiana. Photography with hand-held cameras from a small airplane proved more effective and flexible than either photo-interpretation of existing air photos or subcontracting to a federal agency for new aerial photography. The rationale for our choice of aerial reconnaissance, other uses of low-level aerial surveillance, the utility of small-format camera aerial photography for environmental analysis, and methods used for locating open dumps are discussed. 相似文献