全文获取类型
收费全文 | 2704篇 |
免费 | 668篇 |
国内免费 | 267篇 |
专业分类
安全科学 | 176篇 |
废物处理 | 154篇 |
环保管理 | 203篇 |
综合类 | 1421篇 |
基础理论 | 492篇 |
污染及防治 | 855篇 |
评价与监测 | 90篇 |
社会与环境 | 71篇 |
灾害及防治 | 177篇 |
出版年
2025年 | 2篇 |
2024年 | 24篇 |
2023年 | 71篇 |
2022年 | 152篇 |
2021年 | 121篇 |
2020年 | 73篇 |
2019年 | 77篇 |
2018年 | 93篇 |
2017年 | 122篇 |
2016年 | 156篇 |
2015年 | 196篇 |
2014年 | 189篇 |
2013年 | 261篇 |
2012年 | 215篇 |
2011年 | 210篇 |
2010年 | 168篇 |
2009年 | 155篇 |
2008年 | 164篇 |
2007年 | 136篇 |
2006年 | 126篇 |
2005年 | 84篇 |
2004年 | 70篇 |
2003年 | 83篇 |
2002年 | 74篇 |
2001年 | 63篇 |
2000年 | 67篇 |
1999年 | 86篇 |
1998年 | 65篇 |
1997年 | 60篇 |
1996年 | 57篇 |
1995年 | 50篇 |
1994年 | 30篇 |
1993年 | 40篇 |
1992年 | 31篇 |
1991年 | 27篇 |
1990年 | 15篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1958年 | 1篇 |
排序方式: 共有3639条查询结果,搜索用时 0 毫秒
11.
12.
13.
14.
15.
16.
Bromine-contained disinfectants and biocides are widely used in swimming pools, recreational waters and cooling towers. The objective of this study was to evaluate the formation of thrihalomethanes (THMs) and haloacetonitriles (HANs) and their cytotoxicity in algae solutions during free bromine disinfection. Disinfection by-products formation potential experiments were conducted using model solutions containing 7 mg/L (as total organic carbon) Microcystis aeruginosa cells. Effects of free bromine dosage, pH and ammonia were investigated. The results showed that brominated disinfection by-products were the major products when free bromine was applied. The total THMs formed during bromination was much as that formed during chlorination, whereas HANs were elevated by using bromination instead of chlorination. Dibromoacetonitrice (C2H2NBr2 ) and bromoform (CHBr3 ) were the only detected species during free bromine disinfection. The production of C2H2NBr2 and CHBr 3 increased with disinfectant dosage but decreased with dosing ammonia. CHBr3 increased with the pH changing from 5 to 9. However, C2H2NBr2 achieved the highest production at neutral pH, which was due to a joint effect of variation in hydrolysis rate and free bromine reactivity. The hydrolysis of C2H2NBr2 was base-catalytic and nearly unaffected by disinfectant. Finally, estimation of cytotoxicity of the disinfected algae solutions showed that HANs formation was responsible for the majority of toxicity. Considering its highest toxicity among the measured disinfection by-products, the elevated C2H2NBr2 should be considered when using bromine-related algaecide. 相似文献
17.
Chang Liu Jianlin Luo Xiaona Li Qiang Gao Jianzhang Li 《Journal of Polymers and the Environment》2018,26(1):158-165
The effects of three compounded curing agents on the properties and performance of the urea-formaldehyde (UF) resin were investigated in this study. The compounded curing agents were prepared by mixing ammonium chloride with hexamethylenetetramine, citric acid, and oxalic acid respectively at a ratio of 1:1, named N-H, N–CA, and N–OA, respectively. The curing process, crystallinity, and physical properties were measured, and the three-ply plywood was fabricated to measure its prepress strength, wet shear strength, and formaldehyde emission. Results showed that the compounded curing agents N–CA and N–OA enhanced the initial viscosity, crosslinking density and thermal stability of UF resin. Additionally, the prepress strength of the plywood bonded by UF resin with N–CA and N–OA increased by 82 and 111% respectively compared to the UF resin with NH4Cl, and the wet shear strength increased by 14 and 16%, the formaldehyde emission decreased by 19 and 42% respectively. However, owing to the short pot-life of these curing agent limited their storage time, the curing agents N–CA and N–OA should be applied to fabricate plywood in winter for obtaining a better bond strength and a lower formaldehyde emission. While the UF resin with N–HT showed a suitable pot-life, so it could be applied to fabricate plywood in summer for long time storage and avoiding procuring problem. 相似文献
18.
19.
文章以闲置12个月的厌氧氨氧化生物膜填料重新启动厌氧氨氧化反应器,并对反应器的活性恢复情况、脱氮效果和微生物菌群结构开展研究。实验结果表明:在启动的200 d逐渐将进水氨氮、亚硝态氮浓度从50 mg/L提高到70 mg/L,水力停留时间从12 h缩短到4 h,后期氨氮去除率达80%以上,亚硝酸盐去除率达95%。170~200 d的稳定期中,平均去除负荷0.71±0.15 kg/(m~3·d)。另外,通过高通量测序技术对反应器中微生物群落变化情况进行了系统分析。启动过程中填料中污泥微生物浮霉菌门Planctomyctes的相对丰度从13.7%增长到了36.0%,成为优势菌群。 相似文献
20.