全文获取类型
收费全文 | 679篇 |
免费 | 57篇 |
国内免费 | 64篇 |
专业分类
安全科学 | 71篇 |
废物处理 | 9篇 |
环保管理 | 228篇 |
综合类 | 236篇 |
基础理论 | 97篇 |
环境理论 | 1篇 |
污染及防治 | 25篇 |
评价与监测 | 13篇 |
社会与环境 | 113篇 |
灾害及防治 | 7篇 |
出版年
2024年 | 1篇 |
2023年 | 12篇 |
2022年 | 28篇 |
2021年 | 23篇 |
2020年 | 27篇 |
2019年 | 26篇 |
2018年 | 25篇 |
2017年 | 40篇 |
2016年 | 36篇 |
2015年 | 31篇 |
2014年 | 25篇 |
2013年 | 41篇 |
2012年 | 42篇 |
2011年 | 53篇 |
2010年 | 18篇 |
2009年 | 29篇 |
2008年 | 21篇 |
2007年 | 32篇 |
2006年 | 30篇 |
2005年 | 24篇 |
2004年 | 28篇 |
2003年 | 19篇 |
2002年 | 29篇 |
2001年 | 17篇 |
2000年 | 15篇 |
1999年 | 18篇 |
1998年 | 16篇 |
1997年 | 15篇 |
1996年 | 19篇 |
1995年 | 14篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有800条查询结果,搜索用时 32 毫秒
531.
532.
古建筑火灾会造成重大财产和文化损失,一直是我国消防工作中的重点和难点问题。我国古建筑消防相关法规与技术体系建设起步较晚,发展速度较慢。近年来我国文物保护部门与消防部门加强对古建筑消防法规与技术体系建设,颁布了一系列法规与规范,为我国古建筑消防事业发展提供了法律和技术依据。本文对我国古建筑火灾特点进行分析,阐述了我国古建筑消防法规与技术规范发展历程,并对其中存在制度单一,灵活性差;发展滞后,内容不完善;体系封闭,社会参与不足等问题进行了分析与探讨,为进一步研究提供了一定的参考价值。 相似文献
533.
Benjamin L. Harding Taiye B. Sangoyomi Elizabeth A. Payton 《Journal of the American Water Resources Association》1995,31(5):815-824
ABSTRACT: The impacts of a severe sustained drought on Colorado River system water resources were investigated by simulating the physical and institutional constraints within the Colorado River Basin and testing the response of the system to different hydrologic scenarios. Simulations using Hydrosphere's Colorado River Model compared a 38-year severe sustained drought derived from 500 years of reconstructed streamflows for the Colorado River basin with a 38-year streamflow trace extracted from the recent historic record. The impacts of the severe drought on streamflows, water allocation, storage, hydropower generation, and salinity were assessed. Estimated deliveries to consumptive uses in the Upper Basin states of Colorado, Utah, Wyoming, New Mexico, and northern Arizona were heavily affected by the severe drought, while the Lower Basin states of California, Nevada, and Arizona suffered only slight shortages. Upper Basin reservoirs and streamflows were also more heavily affected than those in the Lower Basin by the severe drought. System-wide, total hydropower generation was 84 percent less in the drought scenario than in the historical stream-flow scenario. Annual, flow-weighted salinity below Lake Mead exceeded 1200 ppm for six years during the deepest portion of the severe drought. The salinity levels in the historical hydrology scenario never exceeded 1100 ppm. 相似文献
534.
Douglas S. Kenney 《Journal of the American Water Resources Association》1995,31(5):837-850
ABSTRACT: In many interstate river basins, the institutional arrangements for the governance and management of the shared water resource are not adequately designed to effectively address the many political, legal, social, and economic issues that arise when the demands on the resource exceed the available supplies. Even under normal hydrologic conditions, this problem is frequently seen in the Colorado River Basin. During severe sustained drought, it is likely that the deficiencies of the existing arrangements would present a formidable barrier to an effective drought response, interfering with efforts to quickly and efficiently conserve and reallocate available supplies to support a variety of critical needs. In the United States, several types of regional arrangements are seen for the administration of interstate water resources. These arrangements include compact commissions, interstate councils, basin interagency committees, interagency-interstate commissions, federal-interstate compact commissions, federal regional agencies, and the single federal administrator. Of these options, the federal-interstate compact commission is the most appropriate arrangement for correcting the current deficiencies of the Colorado River institution, under all hydrologic conditions. 相似文献
535.
人体温度调节的计算机数值模拟 总被引:1,自引:0,他引:1
在研究人体温度调节生理机制的基础上,通过必要的近似简化方法,对一维人体温度调节数学模型进行某些改进,用控制容积法推导出微分方程的有限差分格式,并利用相应的计算程序对人体温度调节进行数值模拟 相似文献
536.
John C. Bergstrom Kevin J. Boyle Charles A. Job Mary Jo Kealy 《Journal of the American Water Resources Association》1996,32(2):279-291
ABSTRACT: The full range of environmental and economic services of ground water need to be accounted for in policy decisions. Non-recognition of these services imputes a lower value for the ground water resource in establishing policies. We describe a conceptual framework for identifying and measuring the economic value of groundwater. The valuation framework links changes in physical characteristics of ground water to services provided by ground water and the economic effects of changes in ground water services. In addition to the framework, we develop a general protocol to follow for assessing the benefits of ground water policies. Application of the protocol will aid in establishing structure and consistency across policy assessments and improve the accuracy and completeness of benefit estimates, avoid double-counting problems, and eliminate duplication of ground water valuation efforts. 相似文献
537.
J. Walter Milon 《Journal of the American Water Resources Association》1987,23(3):387-396
ABSTRACT: A stochastic programming framework is developed to evaluate the economic implications of reliability criteria and multiple effluent controls on nonpoint source pollution. An integrated watershed simulation model is used to generate probability distributions for agricultural effluents in surface and ground water resulting from agricultural practices. Results from the planning model indicate that reliability and multiple effluent constraints significantly increase the cost of nonpoint controls but the effects vary by control alternative. The analysis indicates that an evaluation of multiple water quality objectives can be an important planning tool for designing nonpoint source controls for innovative programs to promote cost-effective water quality regulation. 相似文献
538.
Marsh creation is currently receiving wide attention in the United States as an important tool for mitigating the impacts of development in coastal wetlands. The perception that there is no net loss in valuable coastal wetlands when development is mitigated by the creation of man-made marshes can have a substantial impact on the permitting and decision-making processes. The effective result may be the trading of natural salt marshes for man-made marshes.Techniques for marsh creation were developed by the US Army Corps of Engineers to enhance and stabilize dredge spoil materials. Most research sponsored by the Corps has been directed at determining whether these goals have been accomplished. A survey of the research indicates that there is insufficient evidence to conclude that man-made marshes function like natural salt marshes or provide the important values of natural marshes. It is necessary, therefore, for decision-makers to understand the limitations of present knowledge about man-made marshes, realistically evaluate the trade-offs involved, and relegate mitigation to its proper role in the permitting process—post facto conditions imposed on developments that clearly meet state qualifications and policies. 相似文献
539.
This assessment of the environmental protection regulatory system for the $2.2 billion iron and steel plant, oil refinery, and thermal generating station composing the core of the greenfield Nanticoke industrial complex is based upon: the use of governmental and industrial research in project management; technology and institutional arrangements for environmental protection; evidence of environmental changes to date; analysis of government and industrial approval files; and interviews with government, industry, and interest group representatives. Planning, regulation, and management have been reasonably efficient and effective to the beginning of the operational stage for all three major industries as of spring 1980. Of major future concern, however, is management of the cumulative and synergistic impacts of the industries and associated development on air quality as well as the lands, waters, and sensitive ecosystems of the nearby Lake Erie coast. Continuous monitoring, more comprehensive research, and better overall coordination of government, industrial, and public interests are required if Nanticoke benefits are to be achieved without undue cost to pre-project resource users within and outside the Haldimand-Norfolk region. 相似文献
540.
Paul J. Trimble Jorge A. Marban 《Journal of the American Water Resources Association》1989,25(6):1249-1257
ABSTRACT: The current Lake Okeechobee regulation schedule is two feet higher than previous schedules that were in operation during the early 1970's. Its implementation was in response to prolonged periods of drought that occurred during the 1960's and early 1970's and the large increases in consumptive uses that were projected, and are presently occurring in south Florida. The additional storage provided by the schedule undoubtedly helped prevent more severe water shortages during the record setting 1980–1982 drought. However, two environmental concerns associated with the present schedule surfaced in recent years with the return to more normal rainfall conditions. First, the present schedule allows frequent high water conditions to exist in the lake that appear to be stressful to the unique littoral zone habitat of the lake. Second, the allowable buildup of storage prior to the dry season, combined with the large required decrease in storage prior to the hurricane (wet) season, contribute to the need for large regulation releases to tidewater. These large discharges have undesirable impacts on ecosystems of the downstream estuaries. This paper presents an alternative schedule that better meets the needs of the estuarine habitats without negatively impacting the other objectives of managing the lake. 相似文献