全文获取类型
收费全文 | 4629篇 |
免费 | 42篇 |
国内免费 | 190篇 |
专业分类
安全科学 | 147篇 |
废物处理 | 259篇 |
环保管理 | 481篇 |
综合类 | 824篇 |
基础理论 | 1040篇 |
环境理论 | 4篇 |
污染及防治 | 1471篇 |
评价与监测 | 349篇 |
社会与环境 | 265篇 |
灾害及防治 | 21篇 |
出版年
2023年 | 36篇 |
2022年 | 108篇 |
2021年 | 76篇 |
2020年 | 42篇 |
2019年 | 64篇 |
2018年 | 156篇 |
2017年 | 84篇 |
2016年 | 116篇 |
2015年 | 115篇 |
2014年 | 136篇 |
2013年 | 328篇 |
2012年 | 156篇 |
2011年 | 233篇 |
2010年 | 190篇 |
2009年 | 224篇 |
2008年 | 221篇 |
2007年 | 268篇 |
2006年 | 193篇 |
2005年 | 169篇 |
2004年 | 199篇 |
2003年 | 179篇 |
2002年 | 159篇 |
2001年 | 273篇 |
2000年 | 161篇 |
1999年 | 87篇 |
1998年 | 61篇 |
1997年 | 60篇 |
1996年 | 50篇 |
1995年 | 56篇 |
1994年 | 56篇 |
1993年 | 51篇 |
1992年 | 44篇 |
1991年 | 44篇 |
1990年 | 42篇 |
1989年 | 39篇 |
1988年 | 29篇 |
1987年 | 21篇 |
1986年 | 28篇 |
1985年 | 24篇 |
1984年 | 29篇 |
1983年 | 32篇 |
1982年 | 30篇 |
1981年 | 19篇 |
1980年 | 12篇 |
1979年 | 16篇 |
1978年 | 14篇 |
1977年 | 10篇 |
1975年 | 14篇 |
1973年 | 11篇 |
1972年 | 14篇 |
排序方式: 共有4861条查询结果,搜索用时 703 毫秒
71.
72.
73.
74.
Y. Ginetti 《Die Naturwissenschaften》1954,41(14):333-334
75.
76.
吉林省的风能潜力(英文) 总被引:2,自引:0,他引:2
近两年我国电力突然短缺,已经引起政府的高度重视。由于我国风电发展的紧迫性和风电发展的潜力,特别是国际上正在如火如荼地开发风电的情景,中国- 奥地利政府间双边合作计划将风电评估列入2001~2003 年度合作计划,论文是该计划的成果之一。以我国吉林省为研究对象,采用广泛使用的风机选址算法和空间分布诊断程序( WAsP和ZAWIMOD2),运用数字地形图和遥感资料获得的土地利用图,进而得到数字化的表面粗糙度,再对吉林省的风能潜力进行估算。完成了近1km2 分辨率的距地面60m高度的风速和风能密度计算,并制作了它们的分布图。这是我国第一次在较大区域上估算距地面60m 高度的风速和风能密度,其方法对我国风电资源的评估有重要的借鉴作用。结果显示最有效的风能资源在吉林省的中西部地区,而南部和东部的高风资源区位于山脊和山顶,对风能的开发有一定的限制。 相似文献
77.
A laboratory scale study was conducted to assess the feasibility of the new coupling of rotating biological contactor (RBC) plus porous biomass support system (PBSS) using polyurethane foam as porous support media to biodegrade petroleum refinery wastewater. Polyurethane foam was attached on disks of two four-stage laboratory scale cascade connected RBC units.The two RBC units were operated simultaneously at different but constant, flowrates giving hydraulic loading rates of 0.01, 0.02, 0.03, 0.04 m3/m2/d in two runs keeping the same rotational speed 10 r/min throughout. Organic loading was a less controllable factor in this study.For all of the hydraulic loadings, it was found that the removal efficiency of total chemical oxygen demand (TCOD) and oil were above 80 percent. Ammonia nitrogen and phenol removal were above 90 and 80 percent respectively. The maximum biomass concentration within polyurethane foam was about 30 g/m2 in the first stage for 0.03 m3/m2/d hydraulic loading.The results show that t 相似文献
78.
Wu Jin Wang Anpu Huang Yanchu Ma ciguang Y. Ii S. Daishim K. Furuy T. Kikuchi H. Matsushit K. Tanabe 《环境科学学报(英文版)》1990,2(1):27-39
A study has been made on elements organic constituents, TSP, SO2,NO2 of atmospheric pollutants in Beijing. 17 elements, and some PAHs, e. g. B(a)P, B(b, j, k)P, and B(g, h, i)P, in airborne particles by X-ray fluorescence spectroscopy and HPLC, GC/MS, have been determined respectively. It has been shown that the elements Pb, Zn, S and Cu were more enriched in fine particles and different valence states of sulfur at various sites. It was found that the concentrations of S6+ and S2-were more than 85% and less than 15% of the total sulfur respectively. Concentrations of major PAHs and sulfur-containing compounds increased in winter and in urban area. High values for Pb and Zn in city, Fe and Mn at industrial area and Cu, Al rural sites were obtained respectively. This implies the functions of different elemental sources of various sites. Thus, elements can be from distingushed anthropogenic and natural sources.The main contribution of SO2 was found of to have same seasonal variation as the anthropogenic el 相似文献
79.
The application of ultrasonic-electrolysis process for the removal of copper is studied.In the ultrasonic field cavitation acts as jets and agitates the solution and breaks the barrier layer between the cathode surface and the bulk of the solution.Thus increases metal deposition on the cathode surface.The results show that an ultrasonic field is successful for the removal of low copper concentrations in solution. 相似文献
80.
Zhang YJ Bryan ND Livens FR Jones MN 《Environmental pollution (Barking, Essex : 1987)》1997,96(3):361-367
The interactions of a range of actinide elements (Th, U, Np, Pu, Am) with humic substances from the Needle's Eye natural analogue site were studied by gel permeation chromatography. Bulk humic substances were isolated by ammonia extraction, followed by dialysis against distilled water and freeze-drying. The gel permeation results suggest that Needle's Eye humic substances can be fractionated into three incompletely resolved fractions with average molecular weights determined by analytical ultracentrifugation around 49 000 for Fraction 1, around 14 700 for Fraction 2 and around 8000 for Fraction 3. Although there are significant differences between the organic matter elution patterns in individual gel permeation experiments, presumably due to differences in column packing, these are much smaller than the differences between metal ions. The uranium that is naturally present in these humic substances is largely bound in the late-eluting fraction. Spikes of the early actinides, including Np and Pu in controlled valency states, have been added to the humic substances, and gel permeation of the spiked humic substances shows that the three humic fractions vary greatly in their effectiveness and selectivity as ligands for early actinides. 相似文献