全文获取类型
收费全文 | 898篇 |
免费 | 115篇 |
国内免费 | 259篇 |
专业分类
安全科学 | 215篇 |
废物处理 | 23篇 |
环保管理 | 94篇 |
综合类 | 545篇 |
基础理论 | 138篇 |
环境理论 | 4篇 |
污染及防治 | 177篇 |
评价与监测 | 20篇 |
社会与环境 | 22篇 |
灾害及防治 | 34篇 |
出版年
2024年 | 1篇 |
2023年 | 15篇 |
2022年 | 25篇 |
2021年 | 28篇 |
2020年 | 31篇 |
2019年 | 31篇 |
2018年 | 30篇 |
2017年 | 47篇 |
2016年 | 49篇 |
2015年 | 61篇 |
2014年 | 55篇 |
2013年 | 54篇 |
2012年 | 119篇 |
2011年 | 73篇 |
2010年 | 54篇 |
2009年 | 69篇 |
2008年 | 60篇 |
2007年 | 79篇 |
2006年 | 85篇 |
2005年 | 52篇 |
2004年 | 37篇 |
2003年 | 35篇 |
2002年 | 32篇 |
2001年 | 36篇 |
2000年 | 21篇 |
1999年 | 18篇 |
1998年 | 17篇 |
1997年 | 16篇 |
1996年 | 12篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1987年 | 1篇 |
排序方式: 共有1272条查询结果,搜索用时 390 毫秒
41.
电催化氧化法处理阳离子染料废水的试验研究 总被引:2,自引:0,他引:2
以结晶紫作为阳离子染料,采用电催化氧化法对阳离子染料溶液进行了电解脱色处理试验,研究了电流密度、电解质种类、电解质浓度、pH值等对该溶液脱色率的影响,测定了电解时溶液中生成的余氯浓度和溶液的紫外-可见吸收光谱曲线,并对不同电解时间的溶液的吸光度进行了归一化计算。结果表明:随着电解时间的延长,水溶液中活性氯浓度不断上升,经一定时间后达到最大值;在电催化和活性氯的协同作用下,阳离子染料结晶紫分子中的大π共轭体系被破坏、苯环结构基本瓦解,溶液快速脱色;在电流密度为5.1mA/cm2、NaCl浓度为4g/L、pH值为9.41的条件下,初始浓度为100mg/L的结晶紫溶液经过20min的电解,其脱色率可高达98.31%。 相似文献
42.
海水淡化水在既有管网输配的铁释放控制研究 总被引:1,自引:0,他引:1
由于具有强腐蚀性,海水淡化水在既有市政管网输配过程中往往会产生严重的"红水"现象,主要是由于管网中铁的释放.为了研究控制既有管网中铁释放的有效措施,对管龄为30~40 a的钢管和灰口铸铁管内壁的腐蚀瘤进行分析,主要组成物质为Fe3O4和FeOOH;选择腐蚀较严重的钢管进行静态浸泡试验,重点分析了自来水和淡化水的掺混比、pH值、碱度、氯离子和硫酸根离子对铁释放的影响,并以铁浓度为控制量,初步给出了海水淡化水在既有管网中安全输配所需满足的水质条件:自来水和淡化水的掺混比≥2∶1,pH值在7.6以上,碱度>200 mg.L-1. 相似文献
43.
The objective of this study was to compare the effects of repeated field applications of three urban compost amendments and one farmyard manure amendment over a 9-year period on aggregate stability in a silty loam soil initially characterized by low clay and initial organic matter contents and poor aggregate stability. Three different aggregate stability tests with increasing disruptive intensities (fast wetting > mechanical breakdown > slow wetting tests) and different disaggregation mechanisms, were used. All of the amendments, which were applied at approximately 4 Mg C ha−1 every other year, increased the organic carbon content and improved the stability of the aggregates against the disruptive action of water, as determined by each of the stability tests. However, the year-to-year variations in the aggregate stability that related to factors other than the organic inputs were greater than the cumulative increase in aggregate stability relative to the control. The positive effects of the tested amendments on aggregate stability were linked to their contribution to soil organic C contents (r = 0.54 for the fast wetting test and r = 0.41-0.42 for the mechanical breakdown and slow wetting tests; p < 0.05). The addition of urban composts had a larger positive effect on aggregate stability than farmyard manure at the majority of sampling dates. The addition of biodegradable immature compost, such as municipal solid waste (MSW), improved the aggregate stability through an enhanced resistance to slaking. The addition of mature composts, such as the co-compost of sewage sludge and green wastes (GWS) or biowaste compost (BW), improved the aggregate stability by increasing interparticular cohesion. The MSW compost was the most efficient in improving aggregate stability during the first 6 years of the experiment (average improvements of +22%, +5% and +28% in the fast wetting, mechanical breakdown and slow wetting tests, respectively, compared to the control treatment); this result was likely due to the larger labile organic pool of the MSW compost that was highly effective at stimulating soil microbial activity. After the first 6 years, the two other composts, GWS and BW, became more efficient (average improvements of +25%, +61% and +33% in the fast wetting, mechanical breakdown and slow wetting tests, respectively, compared to the control treatment), which was probably linked to the greater increase in soil organic C contents. Therefore, the application of urban compost to silty soil that is susceptible to water erosion was effective at improving aggregate stability and thus could be used to enhance the resistance of soil to water erosion. 相似文献
44.
为了了解过氧化氢与三维电极的协同作用,以罗丹明B模拟废水进行了实验研究,探索了填料配比、外加电压、过氧化氢投加量、初始废水pH值、染料初始浓度等单因子对降解罗丹明B的影响,并通过正交试验研究各因素对该法处理罗丹明B模拟废水的效应.结果表明,过氧化氢与三维电极在处理罗丹明B模拟废水时具有明显的协同作用;外加电压=20v,... 相似文献
45.
46.
47.
试验采用氟化铵与石灰石粉、石灰乳反应制取氟化钙,研究了反应温度、物料浓度、物料过量系数等各主要参数变化对氟化钙结晶、过滤速度、氟收率及其含量的影响,摸索出最优反应条件。 相似文献
48.
49.
50.