全文获取类型
收费全文 | 10565篇 |
免费 | 841篇 |
国内免费 | 2303篇 |
专业分类
安全科学 | 894篇 |
废物处理 | 173篇 |
环保管理 | 1910篇 |
综合类 | 6960篇 |
基础理论 | 1165篇 |
环境理论 | 11篇 |
污染及防治 | 721篇 |
评价与监测 | 1086篇 |
社会与环境 | 441篇 |
灾害及防治 | 348篇 |
出版年
2024年 | 55篇 |
2023年 | 217篇 |
2022年 | 309篇 |
2021年 | 428篇 |
2020年 | 445篇 |
2019年 | 363篇 |
2018年 | 290篇 |
2017年 | 391篇 |
2016年 | 396篇 |
2015年 | 501篇 |
2014年 | 517篇 |
2013年 | 684篇 |
2012年 | 677篇 |
2011年 | 795篇 |
2010年 | 630篇 |
2009年 | 618篇 |
2008年 | 503篇 |
2007年 | 730篇 |
2006年 | 717篇 |
2005年 | 547篇 |
2004年 | 493篇 |
2003年 | 523篇 |
2002年 | 452篇 |
2001年 | 407篇 |
2000年 | 390篇 |
1999年 | 297篇 |
1998年 | 219篇 |
1997年 | 203篇 |
1996年 | 167篇 |
1995年 | 132篇 |
1994年 | 120篇 |
1993年 | 87篇 |
1992年 | 84篇 |
1991年 | 61篇 |
1990年 | 45篇 |
1989年 | 19篇 |
1988年 | 14篇 |
1987年 | 29篇 |
1986年 | 15篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1982年 | 17篇 |
1981年 | 18篇 |
1980年 | 13篇 |
1979年 | 10篇 |
1978年 | 16篇 |
1977年 | 6篇 |
1973年 | 8篇 |
1972年 | 8篇 |
1971年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
361.
362.
露天深孔爆破环境污染的危害与防治 总被引:1,自引:0,他引:1
在全面分析爆破所带来的地震效应、噪声以及废气等污染的同时,结合某矿山生产爆破的具体情况,提出了些防治爆破环境污染的措施和建议。 相似文献
363.
364.
Jon E. Schoonover Karl W. J. Williard 《Journal of the American Water Resources Association》2003,39(2):347-354
ABSTRACT: Ground water contamination by excess nitrate leaching in row‐crop fields is an important issue in intensive agricultural areas of the United States and abroad. Giant cane and forest riparian buffer zones were monitored to determine each cover type's ability to reduce ground water nitrate concentrations. Ground water was sampled at varying distances from the field edge to determine an effective width for maximum nitrate attenuation. Ground water samples were analyzed for nitrate concentrations as well as chloride concentrations, which were used as a conservative ion to assess dilution or concentration effects within the riparian zone. Significant nitrate reductions occurred in both the cane and the forest riparian buffer zones within the first 3.3 m, a relatively narrow width. In this first 3.3 m, the cane and forest buffer reduced ground water nitrate levels by 90 percent and 61 percent, respectively. Approximately 40 percent of the observed 99 percent nitrate reduction over the 10 m cane buffer could be attributed to dilution by upwelling ground water. Neither ground water dilution nor concentration was observed in the forest buffer. The ground water nitrate attenuation capabilities of the cane and forest riparian zones were not statistically different. During the spring, both plant assimilation and denitrification were probably important nitrate loss mechanisms, while in the summer nitrate was more likely lost via denitrification since the water table dropped below the rooting zone. 相似文献
365.
分析了膨胀岩的胀缩机理及影响因素,总结了近几年的理论研究成果。着重论述了巷道和边坡工程中的膨胀 岩所造成的灾害形式,通过分析诱发灾害的机理,有针对性地提出了一些防治措施。 相似文献
366.
367.
当今社会面临的日趋严重且类型众多的灾害,构成了对生态环境安全的巨大威胁,为此各国都在致力于发挥法制手段在灾害防治中的不可替代的作用。我国是个多灾国家,在减灾法治方面虽已取得了一定成就,但总体上还比较薄弱,因此进一步加强该领域的法制建设十分重要。从我国环境安全保障角度及与国际经验的比较来看,完善我国减灾法制建设的基本工作涉及到减灾法制体系的理论研究、立法模式的选择及其充实方向、行政体制的理顺及执法司法功能的强化等多个方面。 相似文献
368.
/ Land use/land cover classifications for 1973 and 1991, derived from the interpretation of satellite imagery, are quantified on the basis of biophysical land units in a study area in southeastern Australia. Nutrient export potentials are estimated for each land unit based on their composition of land use/land cover classes. Spatial and temporal comparisons are made of the land units based on the calculated pollution hazard indicators to provide an insight into changes in the state of the environment and the regional significance of land use changes. For example, one ecosystem, unique to the study, showed a large increase in pollution hazard over the study period as a manifestation of an 11-fold rise in cleared area and an expansion of cropping activities. The benefits to environmental management in general are discussed.KEY WORDS: Land cover change; Nutrient export; Environmental condition; Pollution hazard; Agricultural pollution; Nonpoint source pollution; Diffuse pollution; Environmental degradation 相似文献
369.
A Sensitivity Analysis of Nitrogen Losses from Dairy Farms 总被引:2,自引:0,他引:2
International attention has focused on agricultural production systems as non-point sources of pollution affecting the quality of streams, estuaries and ground water resources. The objective of the current study was to develop a model of nitrogen management on the dairy farm, and to perform sensitivity analyses in order to determine the relative importance of manipulating herd nutrition, manure management and crop selection in reducing nitrogen (N) losses from the farm. The importance of the method of N input to the farm (purchased feed, legume fixation, inorganic fertilizer, imported manure) was investigated, and the potential to reduce N losses from dairy farms was evaluated. Nitrogen balance equations were derived, and related efficiency coefficients were set to reference values representing common management practices. Total farm N efficiency (animal product N per N input), and N losses per product N were determined for different situations by solving the set of simultaneous equations. Improvements in animal diet and management that increase the conversion of feed N to animal product by 50% would increase total farm N efficiency by 48% and reduce N losses per product by 36 to 40%. In contrast, reducing losses from manure collection, storage and application to improve the percentage of manure N that becomes available in soil by 100% would only improve total farm N efficiency by 13% and reduce total N losses by 14%. Selecting crops and management that can use soil nutrients 50% more efficiently would improve total farm efficiency by up to 59% and reduce N losses by up to 41% depending on the predominant nitrogen sources to the farm. Legume production would reduce N losses per product compared with non-legumes. There was more than a five fold difference in N losses per animal product N between the most extreme scenarios suggesting considerable opportunity to reduce N losses from dairy farms. 相似文献
370.
洗涤法处理含油土壤的研究 总被引:12,自引:1,他引:12
研究了用洗涤法处理含油土壤,考察了洗涤剂种类与浓度、洗涤温度、液固比、洗涤时间、表面活性剂、洗涤液直接循环使用次数对洗涤效果的影响,结果表明:当混合减浓度为10000mg/L、洗涤温度为70℃、液固比2:1、洗涤时间20min时,可将含油量为30%的土壤洗至残油率仅为0.3%左右。OP、EL型表面活性剂的加入对洗涤效果没有改善,特别有意义的是洗涤液能够直接循环使用而对洗涤效果基本无影响,这不仅能够减少用水量,还可以大大减少废水的排放量,降低操作费用及废水处理费用。该洗涤法不涉及物质的相变过程,混合碱由廉价的无机碱和无机盐组成,故能量消耗低,处理费用也低,且洗脱下来的原油可回收。 相似文献