全文获取类型
收费全文 | 617篇 |
免费 | 66篇 |
国内免费 | 254篇 |
专业分类
安全科学 | 48篇 |
废物处理 | 52篇 |
环保管理 | 152篇 |
综合类 | 472篇 |
基础理论 | 56篇 |
污染及防治 | 139篇 |
评价与监测 | 9篇 |
社会与环境 | 8篇 |
灾害及防治 | 1篇 |
出版年
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 15篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 15篇 |
2016年 | 22篇 |
2015年 | 43篇 |
2014年 | 32篇 |
2013年 | 41篇 |
2012年 | 69篇 |
2011年 | 58篇 |
2010年 | 34篇 |
2009年 | 42篇 |
2008年 | 22篇 |
2007年 | 60篇 |
2006年 | 66篇 |
2005年 | 46篇 |
2004年 | 52篇 |
2003年 | 50篇 |
2002年 | 37篇 |
2001年 | 33篇 |
2000年 | 29篇 |
1999年 | 18篇 |
1998年 | 21篇 |
1997年 | 20篇 |
1996年 | 15篇 |
1995年 | 15篇 |
1994年 | 10篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有937条查询结果,搜索用时 62 毫秒
31.
32.
根据瓜尔豆胶在生产食品添加剂的过程中产生的废水COD的值高迭216000mg/l的特点,分别用如下方法进行处理①调pH=6.84,按0.5%质量比加入活性炭吸附剂,静止20天,此时去除率为87.7%;②用饱和硫酸铝2mL 适量的聚丙烯酰胺絮凝,去除率为36.5%;③原液先蒸馏出1/4体积后在釜液中按3%的质量比加入Ca(OH)2,计算去除率为89.6%④利用铁炭屑以5:1的质量比形成微电池的方法作用两小时后再按3%的质量比加Ca(OH)2絮凝,此条件下去除率高达91.7%.经过比较得出第四种方法是最经济有效的,对该特种废水起到了很好的预处理作用. 相似文献
33.
34.
35.
James R Payne John R Clayton Jr. Bruce E Kirstein 《Spill Science & Technology Bulletin》2003,8(2):201-221
The interactions of physically dispersed oil droplets with suspended particulate material (SPM) can be important for the transport of bulk quantities of spilled crude oil and polycyclic aromatic hydrocarbons (PAH) to subtidal sediments. The literature regarding oil/SPM interactions is reviewed, and results from whole-oil droplet/SPM interaction kinetics and pure-component (Prudhoe Bay crude oil distillate cut) equilibrium partitioning experiments are presented. The effects of oil type, SPM characteristics, and salinity on the interaction rates are examined, and the importance of whole-oil droplet/SPM interactions on particle agglomeration and settling behavior are discussed. Whole-oil droplet/SPM interactions are retarded as oil droplet dispersion into the water column is inhibited by oil viscosity increases due to evaporation weathering and water-in-oil emulsification. Compared to whole oil droplet/SPM interactions, dissolved-component/SPM adsorption is not as significant for transport of individual components to sediments. The information presented in this paper can be used to augment computer-based models designed to predict oil-spill trajectories, oil-weathering behavior, and spilled oil impacts to the marine environment. 相似文献
36.
37.
采用絮凝法对味精发酵生产过程中发酵液中的菌体进行研究,得到无机凝聚剂与高分子絮凝剂复合配比使用是发酵液去除菌体的有效办法。对复合用药除菌后的谷氨酸发酵液和原谷氨酸发酵液进行谷氨酸回收的比较,谷氨酸的回收率提高了8.8%。 相似文献
38.
39.
Christopher I. Thornton Steven R. Abt Warren P. Clary 《Journal of the American Water Resources Association》1997,33(6):1279-1288
ABSTRACT: A meandering stream channel was simulated in the Hydraulics Laboratory at Colorado State University and a series of tests was conducted using four types of vegetation to evaluate the potential effects of vegetation on sediment deposition and retention in a stream channel. The data collected included average flow velocity, flow depth, length of vegetation, density of vegetation, cross-sectional area of the vegetative stem, wetted perimeter of the vegetative stem, and injection and flushing time. The findings indicated that the vegetation could retain from 30 to 70 percent of the deposited sediments. The ability of vegetation to entrap and retain sediment is related to the length and cross-sectional area of the vegetation. The variables describing the flow and the vegetative properties were combined to form a predictive parameter, the sedimentation factor (Sd) that can be compared with the amount of sediment entrapped by vegetation in a stream system. A relation was developed correlating vegetation length to sediment retention after flushing for flexibility and rigid vegetation. 相似文献
40.