全文获取类型
收费全文 | 20416篇 |
免费 | 233篇 |
国内免费 | 1221篇 |
专业分类
安全科学 | 575篇 |
废物处理 | 855篇 |
环保管理 | 2151篇 |
综合类 | 7032篇 |
基础理论 | 4097篇 |
环境理论 | 2篇 |
污染及防治 | 5270篇 |
评价与监测 | 975篇 |
社会与环境 | 717篇 |
灾害及防治 | 196篇 |
出版年
2022年 | 275篇 |
2021年 | 210篇 |
2020年 | 160篇 |
2019年 | 181篇 |
2018年 | 314篇 |
2017年 | 336篇 |
2016年 | 435篇 |
2015年 | 380篇 |
2014年 | 615篇 |
2013年 | 1478篇 |
2012年 | 629篇 |
2011年 | 811篇 |
2010年 | 716篇 |
2009年 | 765篇 |
2008年 | 852篇 |
2007年 | 791篇 |
2006年 | 700篇 |
2005年 | 586篇 |
2004年 | 573篇 |
2003年 | 550篇 |
2002年 | 516篇 |
2001年 | 693篇 |
2000年 | 484篇 |
1999年 | 352篇 |
1998年 | 287篇 |
1997年 | 263篇 |
1996年 | 256篇 |
1995年 | 285篇 |
1994年 | 270篇 |
1993年 | 242篇 |
1992年 | 254篇 |
1991年 | 247篇 |
1990年 | 266篇 |
1989年 | 244篇 |
1988年 | 190篇 |
1987年 | 191篇 |
1986年 | 185篇 |
1985年 | 182篇 |
1984年 | 203篇 |
1983年 | 190篇 |
1982年 | 196篇 |
1981年 | 210篇 |
1980年 | 169篇 |
1979年 | 180篇 |
1974年 | 147篇 |
1968年 | 156篇 |
1967年 | 184篇 |
1966年 | 154篇 |
1965年 | 148篇 |
1964年 | 151篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
851.
852.
Waste oyster shell as a kind of active filler to treat the combined wastewater at an estuary 总被引:3,自引:0,他引:3
Hongbing Luo Gu Huang Xiaoying Fu Xiaoling Liu Daocai Zheng Jian Peng Ke Zhang Bo Huang Liangqian Fan Fenghui Chen Xiubo Sun 《环境科学学报(英文版)》2013,25(10):2047-2055
Estuaries have been described as one of the most difficult environments on Earth. It is difficult to know how to treat the combined wastewater in tidal rivers at the estuary, where the situation is very different from ordinary fresh water rivers. Waste oyster shell was used as the active filler in this study in a bio-contact oxidation tank to treat the combined wastewater at the Fengtang Tidal River. With a middle-experimental scale of 360 ma/day, the average removal efficiency of COD, BOD, NH3-N, TP and TSS was 80.05%, 85.02%, 86.59%, 50.58% and 85.32%, respectively, in this bio-contact oxidation process. The living microbes in the biofilms on the waste oyster shell in this bio-contact oxidation tank, which were mainly composed of zoogloea, protozoa and micro-metazoa species, revealed that waste oyster shell as the filler was suitable material for combined wastewater degradation. This treatment method using waste oyster shell as active filler was then applied in a mangrove demonstration area for water quality improvement near the experiment area, with a treatment volume of 5 × 10^3 m^3/day. Another project was also successfully applied in a constructed wetland, with a wastewater treatment volume of 1 ×10^3 m^3/day. This technology is therefore feasible and can easily be applied on a larger scale, 相似文献
853.
854.
855.
856.
857.
858.
F. Khodabakhshi M. Abbaszadeh H. Eskandari S.R. Mohebpour 《Journal of Manufacturing Processes》2013,15(4):533-541
A modified method of severe plastic deformation (SPD) entitled constrained groove pressing-cross route (CGP-CR) was introduced for imposing a high magnitude of equivalent strain of about 2.32 per pass on the sheet form samples. The major benefit of this improved route compared to previous common route was the more homogeneity of strain in the rolling (RD) and transverse (TD) directions of sheets. In this study, low carbon steel samples were used for examination of evolutions in microstructure and mechanical properties during SPD via CGP-CR process. Mechanical properties improvement were measured by tensile and macro hardness tests. The results indicate that CGP-CR process can effectively improve tensile strength; and also, yield stress and hardness of as-received low carbon steel samples were improved up to about 100% after two deformation passes. Also, high magnitude of inhomogeneity can be observed in hardness distribution through first pass of the process which diminishes in the subsequent passes. Microstructural evolutions during process were monitored by optical microscopy observations and X-ray diffraction analysis. The results demonstrate that initial ferritic microstructure with grain size of about 30 μm was refined to a 225 nm cell structure after two passes of CGP-CR process. 相似文献
859.
860.