全文获取类型
收费全文 | 8503篇 |
免费 | 1029篇 |
国内免费 | 1678篇 |
专业分类
安全科学 | 2059篇 |
废物处理 | 130篇 |
环保管理 | 1134篇 |
综合类 | 4572篇 |
基础理论 | 1208篇 |
污染及防治 | 530篇 |
评价与监测 | 366篇 |
社会与环境 | 706篇 |
灾害及防治 | 505篇 |
出版年
2024年 | 57篇 |
2023年 | 191篇 |
2022年 | 354篇 |
2021年 | 411篇 |
2020年 | 393篇 |
2019年 | 331篇 |
2018年 | 270篇 |
2017年 | 414篇 |
2016年 | 434篇 |
2015年 | 471篇 |
2014年 | 387篇 |
2013年 | 473篇 |
2012年 | 722篇 |
2011年 | 753篇 |
2010年 | 608篇 |
2009年 | 634篇 |
2008年 | 433篇 |
2007年 | 535篇 |
2006年 | 539篇 |
2005年 | 384篇 |
2004年 | 287篇 |
2003年 | 276篇 |
2002年 | 271篇 |
2001年 | 209篇 |
2000年 | 205篇 |
1999年 | 158篇 |
1998年 | 152篇 |
1997年 | 130篇 |
1996年 | 111篇 |
1995年 | 102篇 |
1994年 | 88篇 |
1993年 | 72篇 |
1992年 | 64篇 |
1991年 | 40篇 |
1990年 | 29篇 |
1989年 | 27篇 |
1988年 | 27篇 |
1987年 | 19篇 |
1986年 | 18篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1981年 | 16篇 |
1980年 | 14篇 |
1979年 | 18篇 |
1978年 | 11篇 |
1977年 | 6篇 |
1973年 | 7篇 |
1972年 | 9篇 |
1971年 | 11篇 |
1970年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
901.
Robert G. Bailey 《Environmental management》1988,12(1):11-17
As part of the planning process, maps of natural factors are often superimposed in order to identify areas which are suitable or unsuitable for a particular type of resource management. Overlay maps may also be used to identify analysis areas for predictive modeling of resource productivity and ecological response to management. Current interest in applying computer-assisted mapping technology to making overlay maps is drawing attention to geographic information systems for this purpose. The resultant maps, however, may be so inaccurate or unable to capture significant units of productivity and ecological response that they could lead to imperfect or false conclusions. Recommendations are made on how to proceed in light of these problems. 相似文献
902.
John E. Keith Rangesan Narayanan 《Journal of the American Water Resources Association》1988,24(6):1247-1256
ABSTRACF: Examination of a series of studies of the economically efficient water allocations in the Upper Colorado River, Yellowstone River, and Great Basins indicate that water is not a serious general physical constraint on the development of energy resources, so long as public institutions do not hinder the exchange of water rights in markets. Energy development will cause limited impacts on other water-using sectors, principally agriculture. There appears to be little reason to develop large-scale water storage facilities, even during periods of reduced water production. Water storage developments appear to be necessary only when institutional constraints severely restrict water rights markets and transfers. 相似文献
903.
探讨了微波辐射的致热生物效应,研究了微波辐射与人体热调节的关系,建立了考虑微波辐射致热效应的人体热调节系统模型。采用数值模拟方法能方便地定量分析微波辐射的致热生物效应。 相似文献
904.
Fuzzy数学在人-机-环境系统工程研究中的应用 总被引:1,自引:0,他引:1
孙洪元 《中国安全科学学报》1995,5(6):33-33
综述了模糊数学在航天人机环境系统工程中的应用和发展。内容包括急性缺氧反应综合评定,人机系统中的控制模型,通风服研制和鉴定以及人体。心脏功能评价等研究领域中模糊数学的应用方法和作用。其研究方法对于一般人机工程的建模和分析具有积极意义。 相似文献
905.
按照校验费和损失费最小以及有效度最大的原则分别给出了安全监测系统校验的等周期模型。当安全监测系统的无故障工作时间服从威布尔分布时,给出了模型的解法。 相似文献
906.
本文由我们已往提出的三个地震模式讨论了1995年日本阪神大震(M7.2)的预报问题。这些模式是立交模式、组合模式和调制模式。此外还用柯里奥利力(Corrioli)的效应讨论了主震3年后最强余震的预报。 相似文献
907.
908.
灰色系统方法在城市生活垃圾量预测中的应用 总被引:2,自引:0,他引:2
利用灰色关联分析方法分析了影响城市生活垃圾量的因素,建立了生活垃圾量的GM(1,1)预测模型,预测了未来的城市生活垃圾量。该法具有较高的精度,简便,可行。 相似文献
909.
ABSTRACT: The Hallett Quarry gravel pit lakes are an active sand and gravel extraction operation located 0.4 km north of the City of Ames, Iowa. During periods of drought, these lakes serve as a supplemental water supply for Ames. A modified version of the Vollenweider input-output model was used to predict future water quality under various watershed land use, drainage, and lake configurations. The dominant factor controlling the future water quality of the lakes was found to be the nutrient input. It is recommended that a management plan to protect the future water quality should be oriented towards reducing the sources of phosphorus to the lakes. 相似文献
910.
W. L. Nutter T. Tkacs P. B. Bush D. G. Neary 《Journal of the American Water Resources Association》1984,20(6):851-858
The breakpoint rainfall hydrology and pesticide options of the field scale model CREAMS (Chemicals, Runoff, and Erosion from Agricultural Management Systems) were used to predict average concentrations of hexazinone [3 cyclohexyl-6-(dimethyl-amino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione] in stormflow from four forested watersheds in the upper Piedmont region of Georgia. Predicted concentrations were compared with measured concentrations recorded over a 13-month period. CREAMS accurately predicted hexazinone concetrations in the initial stormflow events which also contained the highest concentrations. The model underestimated the hexazinone concentrations in stormflow two months and greater following pesticide application. In a companion study, the daily rainfall option of the CREAMS model was used to evaluate the reltive risk associated with the maximum expected concentration of hexazinone, bromacil (5-bromo-3 sec-butyl-6 methyuracil), picloram (4-amino-3,5,6 trichloropicolinic acid), dicamba (3,6-dichloro-0-anisic acid), and triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid} in stormflow from small forested watersheds. The model predicted the following order of potential residue appearance in stormflow: bromacil>triclopyr>hexazinone>picloram>dicamba. Subsurface movement of residues via interflow and deep leaching losses are not simulated by the version of CREAMS used in these studies. 相似文献