全文获取类型
收费全文 | 2503篇 |
免费 | 89篇 |
国内免费 | 708篇 |
专业分类
安全科学 | 133篇 |
废物处理 | 170篇 |
环保管理 | 195篇 |
综合类 | 1116篇 |
基础理论 | 441篇 |
环境理论 | 1篇 |
污染及防治 | 965篇 |
评价与监测 | 113篇 |
社会与环境 | 56篇 |
灾害及防治 | 110篇 |
出版年
2023年 | 37篇 |
2022年 | 108篇 |
2021年 | 104篇 |
2020年 | 66篇 |
2019年 | 69篇 |
2018年 | 73篇 |
2017年 | 110篇 |
2016年 | 131篇 |
2015年 | 122篇 |
2014年 | 209篇 |
2013年 | 254篇 |
2012年 | 229篇 |
2011年 | 230篇 |
2010年 | 172篇 |
2009年 | 163篇 |
2008年 | 164篇 |
2007年 | 143篇 |
2006年 | 146篇 |
2005年 | 97篇 |
2004年 | 68篇 |
2003年 | 80篇 |
2002年 | 68篇 |
2001年 | 50篇 |
2000年 | 49篇 |
1999年 | 57篇 |
1998年 | 50篇 |
1997年 | 52篇 |
1996年 | 31篇 |
1995年 | 33篇 |
1994年 | 28篇 |
1993年 | 19篇 |
1992年 | 23篇 |
1991年 | 12篇 |
1990年 | 18篇 |
1989年 | 13篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1958年 | 2篇 |
排序方式: 共有3300条查询结果,搜索用时 437 毫秒
921.
922.
Winfried Schröder Cordula Englert Roland Pesch Harald G. Zechmeister Lotti Thöni Ivan Suchara Blanka Maňkovská Zvonka Jeran Harry Harmens Krystyna Grodzinska Renate Alber 《Environmental Sciences Europe》2008,20(2):120-132
Goal and Scope
Several studies show that the concentration of metals in mosses depends not only on metal deposition but also on factors such as moss species, canopy drip, precipitation, altitude, distance to the sea and the analytical technique used. However, contrasting results have been reported and the interpretation of the spatial variability of the metal accumulation in mosses remains difficult. In the presented study existing monitoring data from the European Heavy Metals in Mosses Surveys together with surface data on precipitation, elevation and land use are statistically analysed to assess factors other than emissions that have an influence on the metal accumulation in the mosses.Main Features
Inference statistics and Spearman correlation analysis were applied to examine the association of the metal accumulation and the distance of the monitoring sites to the sea as well as the altitude. Whether or not significant differences of the metal loads in the mosses exist at national borders was examined with help of the U-test after Mann and Whitney. In order to identify and rank the factors that are assumed to have an influence on the metal uptake of the mosses Classification and Regression Trees (CART) were applied.Results
No clear tendency could be derived from the results of the inference statistical calculations and the correlation analyses with regard to the distance of the monitoring site to the sea and the altitude. According to the results of the CART-analyses mainly the moss species, potential emission sources around the monitoring sites, canopy drip and precipitation have an effect on the metal bioaccumulation. Assuming that each participating country followed strictly the manual for sampling and sample preparation the results of the inference statistical calculations furthermore suggest that in most cases different techniques for digestion and analysis bias the measurements significantly.Discussion
For the first time a national monitoring data base consisting of measurement data and metadata as well as surface information on precipitation, land use and elevation was applied to examine influence factors on the metal bioaccumulation in mosses. The respective results mirror existing knowledge from other national studies to a large extend, although further analyses are necessary to affirm the findings. These analyses should include data from other national monitoring programmes and should additionally be carried out with other decision tree algorithms than CART.Conclusions
The local variability in the metal concentration in mosses can be uncovered in terms of predictors or underlying hidden causes by using CART. Ideally, such an approach should be applied across the whole of Europe. This will only be feasible if all participating countries provide additional information about site characteristics as currently is done in for example the German moss surveys.Recommendations
The UNECE Metals in Mosses Survey experimental protocol should be improved in order to reduce the observed influences, to enhance standardisation, and to strengthen the quality control. This implies the integration of sampling site describing metadata into the assessment. Furthermore, basis research is needed to test the hypothesis concerning moss species-specific accumulation of depositions.Perspectives
Provided that the presented results hold true in further analyses correction factors should be applied on the moss data in order to get the depicted spatial patterns and temporal trends of metal bioaccumulation unbiased. Such factors should be calculated for natural landscape units or ecoregions that are homogeneous with regard to climate, vegetation and altitude. 相似文献923.
黄土高原地区水资源承载力动态变化及灰色拓扑预测——以山西、陕西、宁夏、甘肃四省为例 总被引:1,自引:0,他引:1
研究水资源承载力对促进区域水资源的合理开发和保证经济可持续发展具有十分重要的作用.文章采用模糊综合评价方法,以水资源利用率、降水量、人均占有水量和生态用水量作为评价因素,首次对黄土高原水资源承载力进行了大尺度综合评价,并建立灰色拓扑预测模型对其动态变化进行预测,在此基础上提出了黄土高原水资源可持续利用对策.结果表明:黄土高原四省水资源承载力在1994-2004年间总体上呈缓慢上升趋势,水资源开发潜力呈微弱增大趋势;但值得注意的是,黄土高原水资源开发已有一定规模,其水环境仍十分脆弱,需要进一步作好节水和水资源的保护工作. 相似文献
924.
925.
926.
Ma Li Yu Zhuo Jiao Yan Lin Lin Zhong Wei Day Sara W. Postlethwaite Arnold Chen Hong Li Qiang Yin Heliang Wang Gang 《Environmental science and pollution research international》2021,28(28):37498-37505
Environmental Science and Pollution Research - The widespread epidemic of the COVID-19 in developed countries such as Europe and the USA has sparked many speculations. What factors caused the rapid... 相似文献
927.
928.
选用代表性蒙囿剂甲酸和柠檬酸以及皮胶原的水解产物明胶为对象,研究了这3种有机配体对Cr(Ⅲ)碱沉淀过程和耐碱性的影响分析,同时采用紫外可见光光谱及凝胶渗透色谱(GPC)对不同pH条件下的配合物变化进行了识别,分析了相应碱沉淀物热失重特点.研究结果表明:3种有机配体对Cr(Ⅲ)有不同程度的络合作用,形成的配合物的稳定性有较大差异,其稳定性与配合物的耐碱性顺序一致,依次顺序为:柠檬酸明胶甲酸.鞣制废水中铬与羟基羧酸型蒙囿剂络合是其难以去除的主要原因,胶原水解产物也会影响沉淀效果,同时发现有机配体与Cr(Ⅲ)可协同沉淀,鞣制废水中铬的彻底去除需先破除铬的络合物稳定性问题. 相似文献
929.
930.
Ao Ran Ma Liping Guo Zhiying Yang Jing Mu Liusen Yang Jie Wei Yi 《Environmental science and pollution research international》2021,28(6):6929-6940
Environmental Science and Pollution Research - Perovskite is an efficient and emerging catalyst for NO oxidation. In this study, BaMnO3 and BaCoO3 perovskite catalysts were synthesized by the... 相似文献