全文获取类型
收费全文 | 1230篇 |
免费 | 179篇 |
国内免费 | 2617篇 |
专业分类
安全科学 | 25篇 |
废物处理 | 41篇 |
环保管理 | 57篇 |
综合类 | 2675篇 |
基础理论 | 439篇 |
污染及防治 | 598篇 |
评价与监测 | 71篇 |
社会与环境 | 102篇 |
灾害及防治 | 18篇 |
出版年
2024年 | 8篇 |
2023年 | 50篇 |
2022年 | 105篇 |
2021年 | 185篇 |
2020年 | 159篇 |
2019年 | 134篇 |
2018年 | 104篇 |
2017年 | 130篇 |
2016年 | 189篇 |
2015年 | 197篇 |
2014年 | 222篇 |
2013年 | 291篇 |
2012年 | 312篇 |
2011年 | 250篇 |
2010年 | 152篇 |
2009年 | 188篇 |
2008年 | 127篇 |
2007年 | 250篇 |
2006年 | 174篇 |
2005年 | 145篇 |
2004年 | 128篇 |
2003年 | 71篇 |
2002年 | 51篇 |
2001年 | 66篇 |
2000年 | 20篇 |
1999年 | 50篇 |
1998年 | 50篇 |
1997年 | 42篇 |
1996年 | 37篇 |
1995年 | 40篇 |
1994年 | 19篇 |
1993年 | 34篇 |
1992年 | 24篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1988年 | 1篇 |
1987年 | 9篇 |
排序方式: 共有4026条查询结果,搜索用时 281 毫秒
31.
讨论了铜在淡水藻(Scenedesmus subspicatus86.81SAG)细胞壁和细胞内分布规律,以及乙二胺四乙酸(EDTA)和水体腐殖酸(FA)存在下对铜分布的影响,研究结果表明,EDTA和FA的存在显著降低了细胞表面铜的吸附量,但是不影响细胞内铜的浓度,对测定数据进行分析。可以认为溶液相铜与EDTA或FA形成的铜络合物是生物无效形态,不参与铜在藻细胞壁上特定位点或生物配体的竞争结合反应。 相似文献
32.
运用评价化学品毒性藻类测试的标准实验方法,得到铜、锌和锰对月形藻生长的最小无显著差异浓度(LNOEC)分别为31.8μg/L、16.4μg/L和2.7mg/L,抑制月形藻生长的96h半效应浓度(96h-EC50)分别为199.5μg/L、38.0μg/L和12.6mg/L。实验结果表明无论从LNOEC还是从96h-EC50考虑,都证明抑制月形藻生长的毒性由大到小的顺序是锌>铜>锰。此结果对铜抑制藻类生长的毒性远远大于锌的毒性这一人们普遍认同的观点构成挑战。月形藻细胞壁表面可能含有较少的硫代基团但包含较多与锌有很强结合能力的官能团可能是导致月形藻对铜的敏感性弱而对锌敏感性强的主要原因。 相似文献
33.
34.
The effects of land use and its patterns on soil properties in a small catchment of the Loess Plateau 总被引:3,自引:0,他引:3
Due to relatively strong human activities in the hilly area of Loess Plateau,the natural vegetation has been destroyed,and landscape pattern based on agricultural land matrix was land use mosaic composing of shrub land,grassland,woolland and orchard.This pattern has an important effect on soil moisture and soil nutrients.The Danangou catchment,a typical small catchment,was selected to study the effects of land use and its patterns on soil moisture and nutrients in this paper.The results are as follows:The comparisons of soil moisture among seven land uses for wet year and dry year were performed:(1)the average of soil moisture content for whole catchment was 12.11% in wet year,while it was 9.37% in dry year;(2)soil moisture among seven land uses was significantly different in dry year,but not in wet year;(3) form wet year to dry year,the profile type of soil moisture changed from decreasing type to fluctuation-type and from fluctuant type to increasing type;(4)the increasing trend in soil moisture from the top to foot of hillslope occurred in simple land use along slope,while complicated distribution of soil moisture was observed in multiple land uses along slope.The relationships between soil nutrients and land uses and landscape positions were analysed:(1)five nutrient contents of soil organic matter(SOM),total N(TN),available N(AN),total P(TP) and available P(AP) in hilly area were lower than that in other areas.SOM content was less than 1%,TN content less than 0.07%,and TP fallow land and cropland,and higher level in soil fertility was found in crop-fruit intercropping land among croplands;(3)soil nutrient distribution and responses to landscape positions were variable depending on slope and the location of land use types. 相似文献
35.
36.
37.
The mixture of five yeast strains obtained from soil could remove about 85% TOC of oil-rich wastewater in batch test.While the highest MLSS was obtained at an N:C of 1:5,the oil removal decreased with the increase of N:C during yeast sludge cultivation.Ammonium chloride was the best nitrogen source for yeast cultivation from the viewpoint of yeast growth and oil utilizxation.An ammonia concentration of over 1300 mg/L led to mass death of yeast at a pH of 5.The ammonia concentration should be controlled at a level of 1000 mg/L or lower. 相似文献
38.
The studied agriculture-pasture interlacing zone has its specific natural conditions,at which the natural systems are unstable ,their self-regulation capability is low and the equilibrium is easily broken, and hence the habitat is fairly vulnerable.During last 20 years the increasing population and livestock ,over-reclamation,over-pasturing,over-deforesting, and other intensified negative human activities in the zone resulted in coarsening of surface soil,decrease of organic mater content in soil, reduction of vegetation coverage ,variation and degradation of flora structure, and hence in desertization of the land, although average of gales and sandstorms some decreased and the climate tended to be better in the region.However, the frequent sandstorms occurring in the springs of last and present years has attracted much attention.Investigations confirmed that the main cause for the phenomena is the unreasonable human activites rater than the natural factors. 相似文献
39.
40.
以作者近年来的研究结果为中心 ,综合地介绍过氧化氢 (H2 O2 )、单线态氧 ( 1O2 )、超氧阴离子自由基 ( .O-2 )以及羟自由基 ( .OH)等活性氧化学发光研究的最新动态 .侧重介绍活性氧的鲁米诺、光泽精、甲壳动物荧光素化学发光测定体系 ,比较了这几种方法的各自特点和应用情况 相似文献