全文获取类型
收费全文 | 4054篇 |
免费 | 18篇 |
国内免费 | 51篇 |
专业分类
安全科学 | 77篇 |
废物处理 | 137篇 |
环保管理 | 453篇 |
综合类 | 998篇 |
基础理论 | 893篇 |
环境理论 | 3篇 |
污染及防治 | 907篇 |
评价与监测 | 287篇 |
社会与环境 | 359篇 |
灾害及防治 | 9篇 |
出版年
2022年 | 36篇 |
2021年 | 66篇 |
2020年 | 31篇 |
2019年 | 35篇 |
2018年 | 63篇 |
2017年 | 57篇 |
2016年 | 90篇 |
2015年 | 53篇 |
2014年 | 118篇 |
2013年 | 319篇 |
2012年 | 121篇 |
2011年 | 180篇 |
2010年 | 122篇 |
2009年 | 163篇 |
2008年 | 155篇 |
2007年 | 174篇 |
2006年 | 141篇 |
2005年 | 117篇 |
2004年 | 111篇 |
2003年 | 130篇 |
2002年 | 119篇 |
2001年 | 134篇 |
2000年 | 95篇 |
1999年 | 63篇 |
1998年 | 33篇 |
1997年 | 41篇 |
1996年 | 25篇 |
1995年 | 55篇 |
1994年 | 33篇 |
1993年 | 37篇 |
1992年 | 38篇 |
1991年 | 37篇 |
1990年 | 49篇 |
1989年 | 40篇 |
1988年 | 28篇 |
1987年 | 31篇 |
1986年 | 23篇 |
1985年 | 31篇 |
1984年 | 26篇 |
1983年 | 38篇 |
1982年 | 26篇 |
1981年 | 41篇 |
1980年 | 30篇 |
1979年 | 30篇 |
1977年 | 25篇 |
1976年 | 28篇 |
1975年 | 25篇 |
1972年 | 23篇 |
1970年 | 23篇 |
1965年 | 23篇 |
排序方式: 共有4123条查询结果,搜索用时 859 毫秒
581.
582.
583.
584.
François Mermoud Fazil O. Gülaçar Samuel Siles Bernard Chassaing Armand Buchs 《Chemosphere》1982,11(6):557-567
Sediment cores from oxygen depleted zones of lake Léman (lake of Geneva) and from anoxic surface sediment from Voua de la Motte (France) were analyzed for their sterol compositions. 4-methylstanols were found to be major sterols in Motte lake sediment, which is rich in organic matter. In lake Léman, the relative abundances of the same 4-methylstanols increase with the depth in the core, but they remain always minor compounds. An extensive search for a possible external source for these compounds included the analysis of water, of the plankton and of the surrounding soil material. All these results, along with those of an in situ incubation experiment, give strong evidence in favor of their in situ bacterial biosynthesis. 相似文献
585.
Virus inactivation on clay particles in natural waters 总被引:2,自引:0,他引:2
586.
587.
Vrchotová N Tríska J Urban O Peknic L 《Environmental pollution (Barking, Essex : 1987)》2004,131(1):55-59
The amount of catechin and 4-hydroxyacetophenone in the methanolic extract of the Norway spruce needles at the locality Bíly Kríz (Moravian-Silesian Beskydy Mts.) was found in the range 2.8-12.1 mg g(-1) (dry weight) and 0.2-17.7 mg g(-1) (dry weight), respectively. Total amount of catechin (sum of the last three needle year-classes) is statistically higher (p<0.01) in the sparse areas compared to the dense ones and similar trends were recorded for catechin content in current and one-year-old needles. These results may support an idea about primary control of phenolic production by the incident solar radiation, which depends on the social position of the tree and canopy closure degree. 相似文献
588.
Multivariate statistical methods including pattern recognition (Principal Component Analysis--PCA) and modeling (Multiple Linear Regression--MLR, Partial Least Squares--PLS, as well as Principal Component Regression--PCR) methods were carried out to evaluate the state of ambient air in Miskolc (second largest city in Hungary). Samples were taken from near the ground at a place with an extremely heavy traffic. Although PCA is not able to determine the significance of variables, it can uncover their similarities and classify the cases. PCA revealed that it is worth to separate day and night data because different factors influence the ozone concentrations during all day. Ozone concentration was modeled by MLR and PCR with the same efficiency if the conditions of meteorological parameters were not changed (i.e. morning and afternoon). Without night data, PCR and PLS suggest that the main process is not a photochemical but a chemical one. 相似文献
589.
Reactions of lead sorption onto soil are largely affected by properties and composition of soil and its solution. In this study, the lead sorption onto regosol eutric soil from Francisco I. Madero, Zacatecas, Mexico is evaluated at different pH values. Soil samples were suspended in lead solutions of 10, 25, 50, 100, 150, 200, 300, and 400 mg/l (as Pb(NO3)2). The pH was adjusted at 2, 3, 4, and 5.5 with nitric acid for each of the lead solution concentrations. In all the cases the ionic strength was I=0.09 M with calcium nitrate. The solid-liquid-ratios were fixed in 1:100 and 1:200 g/ml. The results show that lead sorption increases when pH increases. Experimental isotherms were adjusted by both Langmuir and Freundlich models. The Langmuir affinity parameter, K, indicates that the lead sorption capacity of Francisco I. Madero soils is largely perceptible to pH changes. 相似文献
590.
Lalah JO Schramm KW Henkelmann B Lenoir D Behechti A Günther K Kettrup A 《Environmental pollution (Barking, Essex : 1987)》2003,122(2):195-203
A single tertiary isomer which is believed to be one of the major branched isomers of the isomeric nonylphenol was synthesized for use in investigations on its metabolism and estrogenicity in aquatic organisms. The physico-chemical properties of the isomer were determined to enable the prediction of its behaviour in aquatic environments. From laboratory investigations on its dissipation and distribution in lake water, which are reported in this paper, it was found that it had a half-life of dissipation of 38.1 days and 20.1 days in an open lake water and in an open lake water/ sediment system, respectively, and to be rapidly partitioned in to sediment giving a high concentration factor of 1.76 after 28 days with an initial dose concentration of 2.52 ppm. The main dissipation route was found to occur through volatilization and co-distillation. The isomer was, however, found to be resistant to biodegradation in both the lake water and sediment, showing only a slight 9% loss (after 56 days) and 4.2% loss (after 28 days), of the 14C-residues in lake water and lake water/sediment systems, respectively, by microbial activity. Transformation to other more polar metabolites possibly by hydroxylation was also found to be minimal in both lake water and sediment samples after 14 days by HPLC analysis. After 7 days, only 2.25 and 7.4% transformation to a more polar metabolite was detected in lake water and sediment samples, respectively. 相似文献