全文获取类型
收费全文 | 2199篇 |
免费 | 347篇 |
国内免费 | 1111篇 |
专业分类
安全科学 | 109篇 |
废物处理 | 119篇 |
环保管理 | 185篇 |
综合类 | 2298篇 |
基础理论 | 236篇 |
污染及防治 | 400篇 |
评价与监测 | 298篇 |
社会与环境 | 10篇 |
灾害及防治 | 2篇 |
出版年
2024年 | 39篇 |
2023年 | 132篇 |
2022年 | 181篇 |
2021年 | 228篇 |
2020年 | 211篇 |
2019年 | 176篇 |
2018年 | 124篇 |
2017年 | 106篇 |
2016年 | 140篇 |
2015年 | 143篇 |
2014年 | 200篇 |
2013年 | 175篇 |
2012年 | 158篇 |
2011年 | 191篇 |
2010年 | 127篇 |
2009年 | 133篇 |
2008年 | 152篇 |
2007年 | 166篇 |
2006年 | 131篇 |
2005年 | 111篇 |
2004年 | 94篇 |
2003年 | 97篇 |
2002年 | 77篇 |
2001年 | 71篇 |
2000年 | 43篇 |
1999年 | 48篇 |
1998年 | 37篇 |
1997年 | 26篇 |
1996年 | 24篇 |
1995年 | 20篇 |
1994年 | 22篇 |
1993年 | 14篇 |
1992年 | 12篇 |
1991年 | 15篇 |
1990年 | 11篇 |
1989年 | 21篇 |
1988年 | 1篇 |
排序方式: 共有3657条查询结果,搜索用时 31 毫秒
61.
62.
有机污染物对地表水的危害主要表现在自身氧化过程对水中溶解氧的消耗,化学需氧量(COD)是评定水中耗氧有机物含量的指标之一,本文主要研究讨论了化学需氧量指标并具体阐述了几种检测方法。 相似文献
63.
64.
聚糖原菌富集实验及其内源过程探究 总被引:1,自引:1,他引:0
细胞衰减是微生物内源过程的一个重要组成部分,可分为由细胞死亡引起的数量衰减和由细胞活性降低引起的活性衰减两部分.通过挥发性脂肪酸(VFA)吸收速率(VFAUR)测定、荧光原位杂交技术(FISH)以及LIVE/DEAD细胞染色技术,研究了富集聚糖原菌(GAOs)在序批式反应器(SBR)系统中好氧环境下的衰减特征.结果表明,当T=30℃、进料中m(COD)∶m(P)=100时,SBR系统中GAOs富集比例达94%.测定和计算表明,SBR富集系统中GAOs衰减速率和死亡速率分别为0.132 d-1和0.034 d-1,其数量衰减和活性衰减占其细胞总衰减比例分别为26%和74%.可见,GAOs数量衰减只占其细胞总衰减中很小一部分,而绝大部分衰减由活性衰减所引起. 相似文献
65.
66.
67.
Surfactant-enhanced remediation (SER) is an effective method for the removal of volatile organic compounds (VOCs) from contaminated soils and groundwater. To reuse the surfactant the VOCs must be separated from the surfactant solutions. The water solubility of VOCs can be enhanced using reversible surfactants with a redox-acive group, (ferrocenylmethyl)dodecyldimethylammonium bromide (Fcl2) and (ferrocenylmethyl)tetradecanedimethylammonium bromide (Fcl4), above and below their critical micelle concentrations (CMC) under reducing (I+) and oxidative (I2+) conditions. The CMC values of Fcl2 and Fcl4 in I+ are 0.94 and 0.56 mmol/L and the solubilization of toluene by Fcl2 and Fcl4 in I+ for toluene is higher than the solubilization achieved with sodium dodecyl sulfate, cetyltrimethylammonium bromide and Trition X-114. The solubilization capacity of the ferrocenyl surfactants for each tested VOCs ranked as follows: ethylbenzene > toluene > benzene. The solubilities of VOCs by reversible surfactant in I+ were 30% higher than those in I2+ at comparable surfactant concentrations. The effects of Fcl4 concentrations on VOCs removal efficiency were as follows: benzene > toluene > ethylbenzene. However, an improved removal efficiency was achieved at low ferrocenyl surfactant concentrations. Furthermore, the reversible surfactant could be recycled through chemical approaches to remove organic pollutants, which could significantly reduce the operating costs of SER technology. 相似文献
68.
Seepage from Hg mine wastes and calcines contains high concentrations of mercury (Hg). Hg pollution is a major environmental
problem in areas with abandoned mercury mines and retorting units. This study evaluates factors, especially the hydrological and
sedimentary variables, governing temporal and spatial variation in levels and state of mercury in streams impacted by Hg contaminated
runo . Samples were taken during di erent flow regimes in theWanshan Hg mining area in Guizhou Province, China. In its headwaters
the sampled streams/rivers pass by several mine wastes and calcines with high concentration of Hg. Seepage causes serious Hg
contamination to the downstream area. Concentrations of Hg in water samples showed significant seasonal variations. Periods of
higher flow showed high concentrations of total Hg (THg) in water due to more particles being re-suspended and transported. The
concentrations of major anions (e.g., Cl??, F??, NO3?? and SO4
2??) were lower during higher flow due to dilution. Due to both sedimentation
of particles and dilution from tributaries the concentration of THg decreased from 2100 ng/L to background levels (< 50 ng/L) within
10 km distance downstream. Sedimentation is the main reason for the fast decrease of the concentration, it accounts for 69% and 60%
for higher flow and lower flow regimes respectively in the upper part of the stream. Speciation calculation of the dissolved Hg fraction
(DHg) (using Visual MINTEQ) showed that Hg(OH)2 associated with dissolved organic matter is the main form of Hg in dissolved
phase in surface waters in Wanshan (over 95%). 相似文献
69.
70.