全文获取类型
收费全文 | 883篇 |
免费 | 42篇 |
国内免费 | 344篇 |
专业分类
安全科学 | 73篇 |
废物处理 | 50篇 |
环保管理 | 49篇 |
综合类 | 539篇 |
基础理论 | 156篇 |
污染及防治 | 295篇 |
评价与监测 | 47篇 |
社会与环境 | 24篇 |
灾害及防治 | 36篇 |
出版年
2023年 | 16篇 |
2022年 | 39篇 |
2021年 | 32篇 |
2020年 | 30篇 |
2019年 | 27篇 |
2018年 | 40篇 |
2017年 | 35篇 |
2016年 | 41篇 |
2015年 | 42篇 |
2014年 | 62篇 |
2013年 | 92篇 |
2012年 | 79篇 |
2011年 | 71篇 |
2010年 | 71篇 |
2009年 | 77篇 |
2008年 | 56篇 |
2007年 | 63篇 |
2006年 | 45篇 |
2005年 | 26篇 |
2004年 | 31篇 |
2003年 | 36篇 |
2002年 | 30篇 |
2001年 | 33篇 |
2000年 | 33篇 |
1999年 | 16篇 |
1998年 | 23篇 |
1997年 | 20篇 |
1996年 | 21篇 |
1995年 | 23篇 |
1994年 | 18篇 |
1993年 | 14篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 8篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1961年 | 1篇 |
排序方式: 共有1269条查询结果,搜索用时 187 毫秒
591.
592.
593.
Anaerobic acidogenic fermentation with high-solid sludge is a promising method for volatile fatty acid (VFA) production to realize resource recovery. In this study, to model inhibition by free ammonia in high-solid sludge fermentation, the anaerobic digestion model No. 1 (ADM1) was modified to simulate the VFA generation in batch, semi-continuous and full scale sludge. The ADM1 was operated on the platform AQUASIM 2.0. Three kinds of inhibition forms, e.g., simple inhibition, Monod and non-inhibition forms, were integrated into the ADM1 and tested with the real experimental data for batch and semi-continuous fermentation, respectively. The improved particle swarm optimization technique was used for kinetic parameter estimation using the software MATLAB 7.0. In the modified ADM1, the Ks of acetate is 0.025, the km,ac is 12.51, and the KI_NH3 is 0.02, respectively. The results showed that the simple inhibition model could simulate the VFA generation accurately while the Monod model was the better inhibition kinetics form in semi-continuous fermentation at pH 10.0. Finally, the modified ADM1 could successfully describe the VFA generation and ammonia accumulation in a 30 m3 full-scale sludge fermentation reactor, indicating that the developed model can be applicable in high-solid sludge anaerobic fermentation. 相似文献
594.
选择武陵山区域黔江区的2个城市集中式饮用水源地为研究对象,通过2010-2014年每月进行水质监测,获取120组有效数据,运用US EPA推荐的健康风险评价模型对13项水质指标(如Cd、As、Hg等)进行健康风险评估.结果表明:2010-2014年,黔江区小南海、洞塘水库监测指标均满足GB 3838-2002《地表水环境质量标准》 Ⅲ标准,水质状况良好.2个饮用水源地的成人总致癌风险均在0.87×10-7~1.19×10-7 a-1之间,儿童总致癌风险均在2.86×10-7~3.91×10-7 a-1之间,成人和儿童的水质总健康风险均值低于US EPA和ICRP(1×10-4和5×10-5 a-1)的最大可接受风险水平2个数量级以上.健康风险排序为致癌物>非致癌物.计算健康风险指标贡献率表明,通过饮水暴露途径引起健康风险应优先控制Cr6+.黔江区2个城市饮用水源地对儿童产生的人体健康总风险值大于成人,因此儿童更易受到化学物质引起的健康危害.不确定分析结果表明,该研究健康风险评价结果具有可信性,但污染物浓度、人体单位体质量、日均饮水量以及暴露时间的变动将会影响健康风险水平的高低. 相似文献
595.
596.
The microwave radiation oxidation process, Fenton as catalytic agent, was used to remove the thiocyanate from the industrial wastewater. The effects of microwave power, radiation time, pH and the feeding in ways of catalyst on the degradation rate of synthetic wastewater were investigated using the microwave radiation oxidation process by orthogonal experiment. The results show Fenton catalyst ratio was 1:20, the microwave radiation power was 900 W, the microwave radiation time was 7 min and the value of pH was 3. Under the optimum conditions, the removal of KSCN can reach over 90%. The apparent kinetics of removal was studied, which conformed to kinetics first-class reaction. In short, for the thiocyanate from the industrial wastewater, microwave-Fenton oxidation method is feasible and effective. 相似文献
597.
东北地区粮食生产及其可持续性因子分析 总被引:3,自引:0,他引:3
通过对东北地区耕地面积、粮食单产及总产的时间序列分析,揭示了该地区粮食生产发展趋势,并结合粮食生产发展的影响因子分析,探该区粮食生产可持续发展的影响因子,指出今后提高粮食生产的途径。 相似文献
598.
Bai Wei Hao Jinmin Zhang Qiuping Department of Land Resource Management China Agricultural University Beijing China 《中国人口.资源与环境(英文版)》2006,4(4)
This paper aims at establishing the operation idea based on the analysis of the connotation,principles and reference indexes for programming standard for ecological rescue.The paper puts forward that the programming standard should take into account the natural,social and economic reference indexes,and modifies the scale and distribution of the ecological rescue according to the order of ecological safety,social safety and economic development.The paper suggests that the land planning department should strengthen the study and datum accumulation in order to establish the technology regulations of programming standard of the ecological rescue. 相似文献
599.
600.
论证限期治理是可诉的具体行政行为,探讨限期治理及其行政处罚的主体适格问题,通过对相关法律规范的剖析和质疑,澄清多种模糊认识,并提出一些建设性意见。 相似文献