全文获取类型
收费全文 | 17466篇 |
免费 | 1309篇 |
国内免费 | 4524篇 |
专业分类
安全科学 | 1238篇 |
废物处理 | 347篇 |
环保管理 | 4555篇 |
综合类 | 10399篇 |
基础理论 | 1993篇 |
环境理论 | 4篇 |
污染及防治 | 1825篇 |
评价与监测 | 1351篇 |
社会与环境 | 1203篇 |
灾害及防治 | 384篇 |
出版年
2024年 | 85篇 |
2023年 | 335篇 |
2022年 | 537篇 |
2021年 | 541篇 |
2020年 | 596篇 |
2019年 | 534篇 |
2018年 | 485篇 |
2017年 | 730篇 |
2016年 | 919篇 |
2015年 | 944篇 |
2014年 | 899篇 |
2013年 | 1286篇 |
2012年 | 1295篇 |
2011年 | 1396篇 |
2010年 | 999篇 |
2009年 | 980篇 |
2008年 | 780篇 |
2007年 | 1232篇 |
2006年 | 1169篇 |
2005年 | 918篇 |
2004年 | 759篇 |
2003年 | 794篇 |
2002年 | 689篇 |
2001年 | 556篇 |
2000年 | 516篇 |
1999年 | 443篇 |
1998年 | 307篇 |
1997年 | 290篇 |
1996年 | 261篇 |
1995年 | 229篇 |
1994年 | 203篇 |
1993年 | 185篇 |
1992年 | 130篇 |
1991年 | 108篇 |
1990年 | 87篇 |
1989年 | 87篇 |
1988年 | 76篇 |
1987年 | 74篇 |
1986年 | 48篇 |
1984年 | 47篇 |
1983年 | 59篇 |
1982年 | 59篇 |
1981年 | 76篇 |
1980年 | 85篇 |
1979年 | 76篇 |
1978年 | 56篇 |
1977年 | 50篇 |
1973年 | 46篇 |
1972年 | 40篇 |
1971年 | 61篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
水入渗条件下边坡破坏离心模型试验研究 总被引:3,自引:0,他引:3
水的人渗能对土体强度产生较大的影响,它是造成边坡破坏的一个主要因素.不同含水量土质边坡的离心模型试验表明:边坡的破坏类型与其含水量大小有关,且主要存在两种破坏类型:一种是含水量较小时形成的拉裂缝破坏,另一种是含水量较大时形成的整体滑塌破坏;同时,含水量与边坡的最大稳定高度呈非线性关系.进一步的损伤力学分析表明,随着土体含水量的增加,损伤变量增大,并存在一个突变点;通过同离心模型试验结果比较,发现该突变点对应的含水量可作为两种破坏类型的判据. 相似文献
132.
济南市是资源型缺水城市,地表水遭到严重污染,已成为水质型缺水城市,导致地下水超采、地面沉降、泉水停涌等一系列环境、生态、经济问题,水资源已成为制约济南市发展的瓶颈因素.在对济南市水资源现状及相关问题进行详细分析的基础上,提出加强客水资源调用与管理、水资源循环利用、合理制定水价等水资源可持续利用的措施和对策. 相似文献
133.
刘铁英 《中国环境管理干部学院学报》2004,14(2):15-20
污水深度处理后回用不仅节约水资源,也减少了大量污染物的排放,是一项一举多得的益事。秦皇岛港污水深度处理回用工程利用城市二级处理的污水,经深度生物处理后用于煤炭除尘,解决了除尘水源紧张的局面。本文就如何确定回用工程的出水水质指标及其标准进行了讨论,阐述了制定出水水质标准的基本原则。 相似文献
134.
135.
136.
137.
The article states the case for greatly enhanced reliance on desalination in the provision of freshwater. It argues that the concept of integrated water resource management (IWRM), should be expanded to routinely include desalination, and that sea water and brackish water should be listed among available sources of freshwater. In recent years, the price per m3 of freshwater obtained from desalination has steadily declined, and is now within competitive range of conventional sources, especially as extracting water from surface sources (rivers, lakes) is becoming increasingly expensive as well as ecologically harmful, and groundwater in many locations is saline or depleted. With the expectation that by 2020, five billion people will reside in megacities, today's conventional water resources are likely to become insufficient. As many of these megacities are located near ocean coasts, sea water seems a logical solution. 相似文献
138.
Magdalena Svanstrm Morgan Frling Michael Modell William A. Peters Jefferson Tester 《Resources, Conservation and Recycling》2004,41(4):573
Environmental aspects of using supercritical water oxidation (SCWO) to treat sewage sludge were studied using a life cycle assessment (LCA) methodology. The system studied is the first commercial scale SCWO plant for sewage sludge in the world, treating sludge from the municipal wastewater treatment facility in Harlingen, TX, USA. The environmental impacts were evaluated using three specific environmental attributes: global warming potential (GWP), photo-oxidant creation potential (POCP) and resource depletion; as well as two single point indicators: EPS2000 and EcoIndicator99. The LCA results show that for the described process, gas-fired preheating of the sludge is the major contributor to environmental impacts, and emissions from generating electricity for pumping and for oxygen production are also important. Overall, SCWO processing of undigested sewage sludge is an environmentally attractive technology, particularly when heat is recovered from the process. Energy-conserving measures and recovery of excess oxygen from the SCWO process should be considered for improving the sustainability potential. 相似文献
139.
Mohammad N. Almasri Jagath J. Kaluarachchi 《Journal of the American Water Resources Association》2004,40(1):165-186
ABSTRACT: This paper presents a modeling approach based on a geographic information system (GIS) to estimate the variability of on‐ground nitrogen loading and the corresponding nitrate leaching to ground water. The methodology integrates all point and nonpoint sources of nitrogen, the national land cover database, soil nitrogen transformations, and the uncertainty of key soil and land use‐related parameters to predict the nitrate mass leaching to ground water. The analysis considered 21 different land use classes with information derived from nitrogen sources such as fertilizer and dairy manure applications, dairy lagoons, septic systems, and dry and wet depositions. Simulations were performed at a temporal resolution of one month to capture seasonal trends. The model was applied to a large aquifer of 376 square miles in Washington State that serves more than 100,000 residents with drinking water. The results showed that dairy manure is the main source of nitrogen in the area followed by fertilizers. It was also seen that nitrate leaching is controlled by the recharge rate, and there can be a substantial buildup of soil nitrogen over long periods of time. Uncertainty analysis showed that denitrification rate is the most influential parameter on nitrate leaching. The results showed that combining management alternatives is a successful strategy, especially with the use of nitrification inhibitors. Also, change in the land use pattern has a noticeable impact on nitrate leaching. 相似文献
140.
Aida Mendez Gary R. Sands Berangere Basin Chang‐Xing Jin Paul J. Wotzka 《Journal of the American Water Resources Association》2004,40(2):385-400
ABSTRACT: Surface and subsurface drainage make crop production economically viable in much of southern Minnesota because drainage allows timely field operations and protects field crops from extended periods of flooded soil conditions. However, subsurface drainage has been shown to increase nitrate/nitrogen losses to receiving waters. When engaging in drainage activities, farmers are increasingly being asked to consider, apart from the economic profit, the environmental impact of drainage. The Agricultural Drainage and Pesticide Transport model (ADAPT) was used in this study to evaluate the impact of subsurface drainage design on the soil water balance over a two‐year period during which observed drainage discharge data were available. Twelve modeling scenarios incorporated four drainage coefficients (DC), 0.64 cm/d, 0.95 cm/d, 1.27 cm/d, and 1.91 cm/d, and three drain depths, 0.84 m, 1.15 m, and 1.45 m. The baseline condition corresponded to the drainage system specifications at the field site: a drain depth and spacing of 1.45 m and 28 m, respectively (DC of 0.64 cm/d). The results of the two‐year simulation suggested that for a given drainage coefficient, soils with the shallower drains (but equal DC) generally have less subsurface drainage and can produce more runoff (but reduced total discharge) and evapotranspiration. The results also suggested that it may be possible to design for both water/nitrate/nitrogen reduction and crop water needs. 相似文献