全文获取类型
收费全文 | 1981篇 |
免费 | 114篇 |
国内免费 | 157篇 |
专业分类
安全科学 | 281篇 |
废物处理 | 30篇 |
环保管理 | 450篇 |
综合类 | 737篇 |
基础理论 | 283篇 |
污染及防治 | 107篇 |
评价与监测 | 74篇 |
社会与环境 | 201篇 |
灾害及防治 | 89篇 |
出版年
2024年 | 4篇 |
2023年 | 17篇 |
2022年 | 24篇 |
2021年 | 40篇 |
2020年 | 53篇 |
2019年 | 50篇 |
2018年 | 38篇 |
2017年 | 58篇 |
2016年 | 66篇 |
2015年 | 39篇 |
2014年 | 77篇 |
2013年 | 107篇 |
2012年 | 108篇 |
2011年 | 131篇 |
2010年 | 98篇 |
2009年 | 91篇 |
2008年 | 101篇 |
2007年 | 146篇 |
2006年 | 133篇 |
2005年 | 102篇 |
2004年 | 100篇 |
2003年 | 89篇 |
2002年 | 71篇 |
2001年 | 52篇 |
2000年 | 51篇 |
1999年 | 55篇 |
1998年 | 40篇 |
1997年 | 48篇 |
1996年 | 36篇 |
1995年 | 36篇 |
1994年 | 22篇 |
1993年 | 22篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1986年 | 4篇 |
1985年 | 10篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1973年 | 4篇 |
1972年 | 5篇 |
1971年 | 3篇 |
排序方式: 共有2252条查询结果,搜索用时 437 毫秒
591.
水泥土搅拌桩复合地基静载试验检测法的安全度分析 总被引:2,自引:1,他引:1
在检测水泥土搅拌桩复合地基的承载力能否达到设计要求时 ,最常用的方法是单桩静载试验法和复合地基静载试验法。工程实践中发现 ,采用这两种静载试验方法得到的检测结果存在较大差异。笔者根据水泥土搅拌桩的基本特性 ,结合工程实例 ,对这两种静载试验检测结果存在的差异及其安全度进行比较分析 ,得出单桩静载试验法结果的安全度高于复合地基试验法结果的结论 ,因此 ,提出了一些合理化建议 相似文献
592.
593.
重庆市旅游资源开发与旅游产业发展对策 总被引:6,自引:0,他引:6
本文在列举了重庆旅游资源的优势和特点的基础上,阐述了旅游业对发展重庆经济的功能;并就重庆市旅游规划的格局,以及如何保持该市旅游业持续、健康地发展提出了相应的对策。 相似文献
594.
Mark A. Hooker Wendy E. Alexander 《Journal of the American Water Resources Association》1998,34(3):497-505
ABSTRACT: This paper computes estimates of the demand for surface irrigation water directly from disaggregated profit functions for fields in the San Joaquin Valley of California. It finds that treating delivered surface water and pumped ground water as separate, imperfectly substitutable inputs to production matters a great deal. We find substantial ranges of inelastic demand for delivered water, and thresholds across which demand then becomes highly elastic. The results imply that moves toward freer water markets could lead to large quantities reallocated from agriculture to urban uses in the Western U.S., but would require large price increases and would induce extensive ground water mining and major changes in cropping patterns. While these results are dependent on our particular model and simplifying assumptions, evidence exists that they may be robust. 相似文献
595.
Michel C. Boufadel 《Journal of the American Water Resources Association》1998,34(1):167-177
ABSTRACT: Unit hydrograph ordinates are often estimated by deconvoluting excess rainfall pulses and corresponding direct runoff. The resulting ordinates are given at discrete times spaced evenly at intervals equal to the duration of the rainfall pulse. If the new duration is not a multiple of the parent duration, hydrograph interpolation is required. Linear interpolation, piece-wise nonlinear interpolation and graphical smoothing have been used. These interpolation schemes are expedient but they lack theoretical basis and can lead to undesirable results. Interpolation can be avoided if the instantaneous unit hydrograph (IUH) for the watershed is known. Here two issues connected with the classic Nash IUH are examined: (1) how should the Nash parameters be estimated? and (2) under what conditions is the resulting hydrograph able to reasonably represent watershed response? In the first case, nonlinear constrained optimization provides better estimates of the IUH parameters than does the method of moments. In the second case, the Nash IUH gives good results on watersheds with mild shape unit hydrographs, but performs poorly on watersheds having sharply peaked unit hydrographs. Overall, in comparison to empirical interpolation alternatives, the Nash IUH offers a theoretically sound and practical approach to estimate unit hydrographs for a wide variety of watersheds. 相似文献
596.
防灾减灾系统工程的国际对比分析及建议 总被引:11,自引:2,他引:9
针对我国现存的灾害状况,本文通过国际对比的方法,对其他国家已有的减灾系统工程作了简单介绍,并结合我国实际,对未来建立减灾系统工程中应着重加强的薄弱环节作了分析,提出了加强立法工作,增加减灾投入,建立全国统一的减灾通讯系统的建议。 相似文献
597.
超大规模工业厂越来越多地应用于工业生产,但与我国现行防火技术规范存在突出的矛盾,有些地方甚至突破了我国现行防火技术规范。本文即对这一矛盾进行典型事例分析,并研究上应的安全措施。 相似文献
598.
COD分光光度法与标准方法对比实验 总被引:3,自引:0,他引:3
CODcr分光光度快速测定法具有简便,快速,节能,省试剂等优点。其测定结果与标准方法之间有良好的可比性,最低检测限为5.0mg/l 。 相似文献
599.
Thomas S. Maddock Walter G. Hines 《Journal of the American Water Resources Association》1995,31(2):317-329
ABSTRACT: Most southwestern cities were founded along rivers or in areas having springs or readily available ground water. Because of the generally sparse precipitation, the renewable fresh water supply in the Southwest is smaller than most other areas of the United States. Despite the arid climate, water use has increased rapidly, first in the form of irrigation, and more recently the use in cities. This has caused extensive development of local water resources and overdraft of ground water basins in some areas. It is difficult to implement new local supplies and importation projects due to a myriad of environmental and legal constraints and a general shortage of public funds. Various opportunities and plans for water management, both on the demand and supply sides, are discussed. Evolving water strategies in four metropolitan areas - El Paso, Albuquerque, Las Vegas, and Phoenix - and issues regarding the Central Arizona Project are presented. 相似文献
600.
Bernard E. Rollin 《Journal of Agricultural and Environmental Ethics》1989,2(3):225-234
It is patent that society is evolving an ethic for the treatment of animals which goes well beyond the standard prohibitions against cruelty. This new ethic for animals takes the consensus ethic for the treatment of humans in society and extends it,mutatis mutandis, to the treatment of animals. Though this ethic has been applied first to research animals, its extension to agricultural animals is inevitable, and has already begun. This article explores the extent to which veterinary medicine and animal science, the major scientific fields relevant to animal agriculture, can accommodate the emerging ethic. 相似文献