全文获取类型
收费全文 | 4806篇 |
免费 | 587篇 |
国内免费 | 1650篇 |
专业分类
安全科学 | 557篇 |
废物处理 | 229篇 |
环保管理 | 864篇 |
综合类 | 3207篇 |
基础理论 | 623篇 |
污染及防治 | 844篇 |
评价与监测 | 365篇 |
社会与环境 | 254篇 |
灾害及防治 | 100篇 |
出版年
2024年 | 11篇 |
2023年 | 77篇 |
2022年 | 188篇 |
2021年 | 196篇 |
2020年 | 191篇 |
2019年 | 212篇 |
2018年 | 225篇 |
2017年 | 231篇 |
2016年 | 316篇 |
2015年 | 287篇 |
2014年 | 347篇 |
2013年 | 437篇 |
2012年 | 449篇 |
2011年 | 469篇 |
2010年 | 364篇 |
2009年 | 460篇 |
2008年 | 254篇 |
2007年 | 305篇 |
2006年 | 298篇 |
2005年 | 292篇 |
2004年 | 194篇 |
2003年 | 184篇 |
2002年 | 163篇 |
2001年 | 136篇 |
2000年 | 115篇 |
1999年 | 102篇 |
1998年 | 83篇 |
1997年 | 68篇 |
1996年 | 66篇 |
1995年 | 80篇 |
1994年 | 47篇 |
1993年 | 31篇 |
1992年 | 35篇 |
1991年 | 20篇 |
1990年 | 16篇 |
1989年 | 9篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 9篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1974年 | 3篇 |
1972年 | 4篇 |
排序方式: 共有7043条查询结果,搜索用时 62 毫秒
61.
《环境科学学报(英文版)》2023,35(4):29-39
Residual ammonium is a critical parameter affecting the stability of mainstream partial nitritation/anammox (PN/A), but the underlying mechanism remains unclear. In this study, mainstream PN/A was established and operated with progressively decreasing residual ammonium. PN/A deteriorated as the residual ammonium decreased to below 5 mg/L, and this was paralleled by a significant loss in anammox activity in situ and an increasing nitrite oxidation rate. Further analysis revealed that the low-ammonium condition directly decreased anammox activity in situ via two distinct mechanisms. First, anammox bacteria were located in the inner layer of the granular sludge, and thus were disadvantageous when competing for ammonium with ammonium-oxidizing bacteria (AOB) in the outer layer. Second, the complete ammonia oxidizer (comammox) was enriched at low residual ammonium concentrations because of its high ammonium affinity. Both AOB and comammox presented kinetic advantages over anammox bacteria. At high residual ammonium concentrations, nitrite-oxidizing bacteria (NOB) were effectively suppressed, even when their maximum activity was high due to competition for nitrite with anammox bacteria. At low residual ammonium concentrations, the decrease in anammox activity in situ led to an increase in nitrite availability for nitrite oxidation, facilitating the activation of NOB despite the dissolved oxygen limitation (0.15–0.35 mg/L) for NOB persisting throughout the operation. Therefore, the deterioration of mainstream PN/A at low residual ammonium was primarily triggered by a decline in anammox activity in situ. This study provides novel insights into the optimized design of mainstream PN/As in engineering applications. 相似文献
62.
63.
本文介绍了采用地理信息系统技术制作海洋环境质量评价图的基本内容,重点阐述了图件的表现形式、编制过程和具体的操作方法,为海洋环境质量评价图的制作提供了一种新的方法。 相似文献
64.
磺酰脲类除草剂的残留分析 总被引:8,自引:0,他引:8
磺酰脲类除草剂是一类新型超高效除草剂,大约包括2V化合物,已被广泛用于禾谷作物防除阔叶杂草以及某些禾本科杂草,该类除草剂在环境中的残留浓度〈1μg.kg^-1水平。常规的分析方法包括生物鉴定,酶免疫分析,气相色谱法和高效液相色谱法(HPLC)、HPLC/MS联用后,可以准确测定复杂环境样中磺酰脲类除草剂的痕量残留。 相似文献
65.
大气中挥发性苯系物的Carbotrap吸附气相色谱法 总被引:6,自引:0,他引:6
本文研究以Carbotrap作吸附剂,在常温采集大气中挥发性苯系物,直接采用热脱附气相色谱分析。对新型吸附剂Carbotrap的采样-脱附-分析精度,回收率,突破体积等作了试验。本法具有灵敏度高,操作简单,不需复杂的样品预处理,色谱峰好,吸附剂可反复使用等优点。可对大气中10-9级苯系物进行测定,RSD≤3.5%。 相似文献
66.
锅炉烟气脱硫技术发展综述 总被引:4,自引:0,他引:4
在调查研究的基础上,论述国内外烟道气脱硫技术的发展与前景,提出开发生产适合我国国情的烟气脱硫技术势在必行。还简要介绍了最为普遍的石灰/石灰石法脱硫基本原理。 相似文献
67.
68.
69.
70.
The sunlight photodegradation half-lives of 20 mg/L acetochlor were 151, 154 and 169 days in de-ionized water, river water and paddy water, respectively. When exposed to ultraviolet (UV) light, acetochlor in aqueous solution was rapidly degraded. The half-lives were7.1, 10.1, and 11.5 min in de-ionized water, river water and paddy water, respectively. Photopreduets of acetochlor were identified by gas chromatography/mass spectrometry(GC/MS) and found at least twelve photoproducts resulted from dechlorination with subsequent hydrtrxylation and cyclization processes. The chemical structures of ten photoproducts were presumed on the basis of mass spectrum interpretation and literature data. Photoproducts are identified as 2-ethyl-6-methylaniline; N, N-diethylaniline ; 4, 8-dimethyl-2-oxo- 1,2,3,4- tetrahydroquino-line; 2-oxo-N-(2-ethyl-6-methylphenyl)-N-(ethoxymethyl) acetamide; N-(ethoxymethyl)-2‘-ethyl-6‘-methylformanilide; 1-hydroxyaeetyl-2-ethoxyl-7-ethylind ole; 8-ethyl-l-ethoxymethyl-2-oxo-1, 2, 3, 4-tetrahydroquinoline; 4, 8-dimethyl-l-ethoxymethyl-2-oxo-1, 2, 3, 4-tetrahydroquinoline; 2-hydroxy-2‘-ethyl-6‘-methyl-N-(ethoxymethyl) acetanilide and a compound related to acetochlor. The other two photoproducts were detected by GC/MS although their chemical structure was unknown. 相似文献