全文获取类型
收费全文 | 3350篇 |
免费 | 68篇 |
国内免费 | 33篇 |
专业分类
安全科学 | 122篇 |
废物处理 | 102篇 |
环保管理 | 617篇 |
综合类 | 523篇 |
基础理论 | 875篇 |
环境理论 | 9篇 |
污染及防治 | 810篇 |
评价与监测 | 196篇 |
社会与环境 | 150篇 |
灾害及防治 | 47篇 |
出版年
2023年 | 13篇 |
2022年 | 18篇 |
2021年 | 39篇 |
2020年 | 21篇 |
2019年 | 32篇 |
2018年 | 79篇 |
2017年 | 76篇 |
2016年 | 83篇 |
2015年 | 87篇 |
2014年 | 96篇 |
2013年 | 243篇 |
2012年 | 159篇 |
2011年 | 205篇 |
2010年 | 149篇 |
2009年 | 165篇 |
2008年 | 177篇 |
2007年 | 206篇 |
2006年 | 212篇 |
2005年 | 152篇 |
2004年 | 108篇 |
2003年 | 104篇 |
2002年 | 116篇 |
2001年 | 66篇 |
2000年 | 59篇 |
1999年 | 49篇 |
1998年 | 50篇 |
1997年 | 61篇 |
1996年 | 46篇 |
1995年 | 55篇 |
1994年 | 49篇 |
1993年 | 30篇 |
1992年 | 33篇 |
1991年 | 23篇 |
1990年 | 23篇 |
1989年 | 12篇 |
1988年 | 16篇 |
1987年 | 14篇 |
1986年 | 19篇 |
1985年 | 18篇 |
1984年 | 20篇 |
1983年 | 21篇 |
1982年 | 18篇 |
1981年 | 16篇 |
1980年 | 18篇 |
1979年 | 20篇 |
1978年 | 13篇 |
1977年 | 10篇 |
1965年 | 11篇 |
1963年 | 8篇 |
1957年 | 10篇 |
排序方式: 共有3451条查询结果,搜索用时 296 毫秒
521.
A three-dimensional model for the migration of colloids in a saturated fracture is presented, which considers the motion of colloids as a result of advection and diffusion, as well as colloid-surface interactions at the fracture walls. This model is successfully incorporated into a three-dimensional particle tracking algorithm that tracks particles within a continuum and allows consideration of the migration of colloids in symmetrical, three-dimensional, non-uniform fractures. The framework is general enough to incorporate non-local interactions that provide colloid motion relative to the fluid. The algorithm is verified against classical Taylor dispersion, and its generalization to a sorbing phase, in a uniform fracture and shows excellent agreement with theory. A simple, non-uniform fracture that has an analytically tractable velocity field is also considered, and both quantitative and qualitative comparisons are made with the uniform fracture case. The modelling of more complex fracture geometries is also discussed and a particular case is implemented within the particle tracking framework. 相似文献
522.
523.
Books
The age of the molecule 相似文献524.
525.
Peter Orris M.D. John R. Kominsky M.S. Daniel Hryhorczuk M.D. James Melius M.D. 《Chemosphere》1986,15(9-12):1305-1311
A Polychlorinated Biphenyl (PCB) containing transformer released approximately 50 gallons of askarel oil. No polychlorinated dibenzofurans (PCDF) or polychlorinated dibenzodioxins (PCDD) were detected in a sample of the askarel (analytical limit of detection of 40 parts per billion per isomer group). Skin irritation, unusual tiredness, and headaches occurred in approximately 20% of the individuals at the scene of the incident. Serum PCB levels, and mean values for blood and urine tests were within normal ranges. 相似文献
526.
527.
528.
529.
530.
Contamination of the environment from atmospheric deposition during the twentieth century is pervasive even in areas ostensibly considered pristine or remote from point sources. In this study, Pb concentrations in a 210Pb-dated peat core collected from the Okefenokee Swamp, GA were used to assess historical contaminant input via atmospheric deposition. Lead isotope ratios were determined by dynamic reaction cell ICP-MS (DRC-ICP-MS). Increases in Pb concentration occurred in the late nineteenth century and a marked rise in Pb concentrations pre-dated the widespread use of leaded gasoline within the US. The 206Pb/207Pb ratios of 1.19 during this period were consistent with coal combustion emissions. A later increase in Pb concentration, concurrent with a trend toward more radiogenic 206Pb/207Pb ratios in gasoline is consistent with an increased input of Pb from leaded gasoline emissions. However, it appears that coal combustion emissions remain a major source of Pb to the Okefenokee. 相似文献