全文获取类型
收费全文 | 955篇 |
免费 | 91篇 |
国内免费 | 194篇 |
专业分类
安全科学 | 18篇 |
废物处理 | 15篇 |
环保管理 | 301篇 |
综合类 | 535篇 |
基础理论 | 227篇 |
污染及防治 | 41篇 |
评价与监测 | 32篇 |
社会与环境 | 59篇 |
灾害及防治 | 12篇 |
出版年
2024年 | 4篇 |
2023年 | 23篇 |
2022年 | 43篇 |
2021年 | 50篇 |
2020年 | 43篇 |
2019年 | 19篇 |
2018年 | 21篇 |
2017年 | 39篇 |
2016年 | 44篇 |
2015年 | 41篇 |
2014年 | 53篇 |
2013年 | 54篇 |
2012年 | 59篇 |
2011年 | 71篇 |
2010年 | 62篇 |
2009年 | 65篇 |
2008年 | 52篇 |
2007年 | 81篇 |
2006年 | 84篇 |
2005年 | 42篇 |
2004年 | 53篇 |
2003年 | 38篇 |
2002年 | 50篇 |
2001年 | 17篇 |
2000年 | 25篇 |
1999年 | 15篇 |
1998年 | 14篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 9篇 |
1994年 | 8篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有1240条查询结果,搜索用时 31 毫秒
611.
612.
三唑酮在水体系中的光化学降解研究 总被引:2,自引:0,他引:2
系统研究了在天然日光和高压汞灯照射下三唑酮在蒸馏水、人工海水和天然海水中的光降解情况.结果表明,天然日光照射下,三唑酮在三种介质中降解较慢.高压汞灯较天然日光能够更有效地激发三唑酮的降解,且降解符合一级动力学规律.在300 W高压汞灯照射下,三唑酮在蒸馏水、人工海水和天然海水中的半寿期分别为54.14 min、144.38 min、177.69 min.三唑酮在蒸馏水中的光降解速率大于其在天然海水中的,这主要是由于天然海水中存在的阴、阳离子和其它特殊的物质所引起的.同蒸馏水中的光反应相比,人工海水中的离子抑制了三唑酮的光降解反应.在500 W高压汞灯照射下,三唑酮的反应速率明显提高.实验发现溶液中加入重金属离子(Cu2+、Pb2+、Cd2+)能够改变三唑酮的光降解速率. 相似文献
613.
614.
615.
Biological nitrogen fixing is an important source of nitrogen input in the natural ecological restoration of mine wastelands. The
diversity of nifH genes in tailings samples under di erent plant communities in Yangshanchong and Tongguanshan wastelands
in Tongling, was analyzed using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) approach. The
nitrogen-fixing microorganism community in the upper layer of tailings of Tongguanshan wasteland discarded in 1980 showed
higher Shannon-Wiener diversity index than that in Yangshanchong wasteland discarded in 1991. The diversity of nifH genes in
Yangshanchong wasteland of copper mine tailings did not display a consistent successional tendency with development of plant
communities during the process of natural ecological restoration. Phylogenetic analysis of 25 sequences of nifH gene fragments
retrieved from the DGGE gels indicated that there were mainly two taxa of free-living nitrogen-fixing microorganisms, Proteobacteria
and Cyanobacteria living in the wastelands investigated, most of which were unique and uncultured. Canonical correspondence analysis
(CCA) based on the relationship between band patterns of DGGE profile and physico-chemical properties of tailings samples showed
that the diversity of nifH genes in di erent tailing samples was mainly a ected by loss of ignition, water content, pH and available Zn
contents of wastelands. The dominant plant species and development period of plant communities by ameliorating pH, reducing the
toxicity of heavy metals, increasing organic matter and water content a ected the diversity and structure of the free-living nitrogenfixing
microorganisms in wastelands of copper mine tailings. 相似文献
616.
617.
结合新疆煤炭资源开发利用的特点,通过分析煤炭资源大规模开发利用导致的主要生态环境问题,提出健全生态环境恢复法律法规、严格执行环评和"三同时"制度、实行开采许可证制度、明确生态恢复经费来源、推广煤矿绿色开采技术和洁净煤技术、强化生态恢复科研力度等治理生态环境破坏的对策。 相似文献
618.
Evaluating the Eco‐Geomorphological Condition of Restored Streams Using Visual Assessment and Macroinvertebrate Metrics
下载免费PDF全文
![点击此处可从《Journal of the American Water Resources Association》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Barbara A. Doll Gregory D. Jennings Jean Spooner David L. Penrose Joseph L. Usset 《Journal of the American Water Resources Association》2015,51(1):68-83
The Stream Performance Assessment (SPA), a new rapid assessment method, was applied to 93 restored, 21 impaired, 29 reference, and 13 reference streams with some incision throughout North Carolina. Principal component analysis (PCA) indicated restored streams align more closely with reference streams rather than impaired streams. Further, PCA‐based factor analysis revealed restored streams were similar to reference streams in terms of morphologic condition, but exhibited a greater range of scores relative to aquatic habitat and bedform. Macroinvertebrate sampling and GIS watershed analyses were conducted on 84 restored streams. SPA and watershed data were compared to Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa to determine which factors indicate stream health. SPA and watershed factors were used in least squares, ridge, and principal component regression (PCR) to develop a prediction model for EPT taxa. All three methods produced reasonable predictions for EPT taxa. Cross‐validation indicated ridge regression resulted in the lowest prediction error. The ridge model was then used to predict EPT taxa numbers for 21 impaired and 25 reference streams in addition to the 84 restored streams. Statistical comparisons of the predicted scores indicated urban streams (>10% impervious watershed cover) have lower expected numbers of EPT taxa. Rural restored streams have macroinvertebrate metric scores similar to those predicted for rural reference streams. 相似文献
619.
Bernd Klauer Johannes Schiller Frauke Bathe 《Journal of Environmental Planning and Management》2015,58(11):1944-1960
The EU Water Framework Directive calls for cost effective measures to achieve a “good status” in all European ground, surface and coastal waters. Besides eutrophication, the degradation of hydromorphology is the main reason for failing this objective. In this paper, we conceptualise the interactive decision support process BASINFORM-M for finding proper locations for river restoration. The concept combines the recently proposed “stepping stone approach” from aquatic ecology with elements from cost effectiveness analysis, multi-criteria analysis and participatory approaches. BASINFORM-M exemplifies a shift away from the isolated restoration of single river reaches towards a consideration of functional relationships within river networks. 相似文献
620.
滇池受损湖滨带堤岸处置及基底修复工程技术研究 总被引:1,自引:0,他引:1
1970年滇池实施了规模浩大的围海造田工程,使滇池湿地面积减少约23.8 km2,使湖滨带原有的天然湿地大量消失,水生动植物栖息地不复存在,1980-1990年间,滇池环湖修建防浪堤113 km,使湖滨带生境条件进一步急剧恶化,彻底切断了湖泊水体生态系统和陆地生态系统的连续性,消落带消失,湖滨带湿生、挺水和沉水等大型水生植物难以生存,湖泊生态系统遭到重创,对湖泊生态系统带来极其不利的负面影响,文章重点分析了滇池湖滨陡岸带防浪堤处置及基底修复对湖滨带生态修复的重要作用及技术研究,为受损湖泊湖滨带生态修复创造良好的生境条件提供借鉴。 相似文献