全文获取类型
收费全文 | 523篇 |
免费 | 87篇 |
国内免费 | 388篇 |
专业分类
安全科学 | 31篇 |
废物处理 | 100篇 |
环保管理 | 54篇 |
综合类 | 531篇 |
基础理论 | 72篇 |
污染及防治 | 190篇 |
评价与监测 | 19篇 |
社会与环境 | 1篇 |
出版年
2024年 | 1篇 |
2023年 | 13篇 |
2022年 | 14篇 |
2021年 | 33篇 |
2020年 | 32篇 |
2019年 | 33篇 |
2018年 | 46篇 |
2017年 | 31篇 |
2016年 | 50篇 |
2015年 | 54篇 |
2014年 | 37篇 |
2013年 | 58篇 |
2012年 | 74篇 |
2011年 | 52篇 |
2010年 | 34篇 |
2009年 | 45篇 |
2008年 | 26篇 |
2007年 | 45篇 |
2006年 | 36篇 |
2005年 | 39篇 |
2004年 | 35篇 |
2003年 | 30篇 |
2002年 | 27篇 |
2001年 | 22篇 |
2000年 | 31篇 |
1999年 | 24篇 |
1998年 | 12篇 |
1997年 | 15篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1994年 | 2篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有998条查询结果,搜索用时 15 毫秒
831.
混凝法预处理糖精钠废水研究 总被引:8,自引:1,他引:8
无机混凝剂硫酸铝,硫酸铁分别与有机絮凝剂聚丙烯酰胺配合使用处理糖精钠废水,并进行处理效果比较,结果表明,硫酸铝和聚丙烯酰胺配合使用的处理效果好,当硫酸铝投加量为3.2g/L,聚丙烯酰胺投加量为8mg/L,pH为6时,废水CODcr可从41300mg/L减小到16800mg/L,去除率达61%;Cu^2+浓度从32.73mg/L降至3.17mg/L,去除率达90.3%,且提高了BOD5/CODcr值 相似文献
832.
高效复合絮凝剂的研制与性能研究 总被引:9,自引:0,他引:9
以酸洗废液和硅酸钠为原料,氯酸钾为氧化剂,加入少量的添加剂,制得高效玩机高分子复合絮凝剂-聚合硫酸铁/聚硅酸复合絮凝剂,研究了其絮凝性能,考察了添加剂、聚铁与聚硅酸的混合比对其絮凝效果的影响以及该絮凝剂适用的pH范围,结果表明,使用该絮凝剂处理城市废水和长江水,絮体密实粗大,沉降速度快,余浊低。 相似文献
833.
834.
Fabian P Kohlpaintner M Rollenbeck R 《Environmental science and pollution research international》2005,12(5):290-296
Background Biomass burning is a source of carbon, sulfur and nitrogen compounds which, along with their photochemically generated reaction
products, can be transported over very long distances, even traversing oceans. Chemical analyses of rain and fogwater samples
collected in the mountaineous rain forest of south Ecuador show frequent episodes of high sulfate and nitrate concentration,
from which annual deposition rates are derived comparable to those found in polluted central Europe. As significant anthropogenic
sources are lacking at the research site it is suspected that biomass burning upwind in the Amazon basin is the major source
of the enhanced sulfate and nitrate imput.
Methods Regular rain and fogwater sampling along an altitude profile between 1800 and 3185 m has been carried out in the Podocarpus
National Park close to the Rio SanFrancisco (3°58'S, 79°5'W) in southern Ecuador. pH values, electrical conductivity and chemical
ion composition were measured at the TUM-WZW using standard methods.
Results and Discussion Results reported cover over one year from March 2002 until May 2003. Annual deposition rates of sulfate were calculated ranging
between 4 and 13 kg S/ha year, almost as high as in polluted central Europe. Nitrogen deposition via ammonia (1.5–4.4 kg N/ha
year) and nitrate (0.5–0.8 kg N/ha year) was found to be lower but still much higher than to be expected in such pristine
natural forest environment. By means of back trajectory analyses it can be shown that most of the enhanced sulfur and nitrogen
deposition is most likely due to forest fires far upwind of the Ecuadorian sampling site, showing a seasonal variation, with
sources predominantly found in the East/NorthEast during January–March (Colombia, Venezuela, Northern Brazil) and East/SouthEast
during July–September (Peru, Brazil).
Conclusion Our results show that biomass burning in the Amazon basin is the predominant source of sulfur and nitrogen compounds that
fertilize the mountaineous rain forest in south Ecuador.
Recommendation and Outlook The mountaineous rain forest in south Ecuador has developed on poor and acid soils, with low nutrient availability. The additional
fertilization resulting from anthropogenic biomass burning constitutes a significant disturbance of this ecosystem, its functioning
and biodiversity. Thus it is planned to employ isotope analyses for quantifying the pathways of nitrate and sulfate deposition
in these natural forests. 相似文献
835.
采用紫外分光光度法、逐时络合比色法和红外图谱从不同角度对高浓度聚合硫酸铁硅和聚合硅酸铁的形态分布及转化规律进行了探讨。紫外吸收表明,聚铁硅絮凝剂中主要以Fe(OH)2^+、Fe2(OH)2^4+等二聚体为主,而且还有三聚体或其他聚合形态的存在;逐时络合分析显示,复合型聚铁硅体系中硅形态以Si(c)为主,铁形态以Fe(a)和Fe(c)为主;红外图谱证实高浓度聚铁硅是以羟桥为主结构连接的高分子复合物,在1100cm^-1附近M-OH-M的振动证明有铁羟基及其聚合态存在,且其形态区别于PFS。 相似文献
836.
高温下氧化焙烧细磨后的砷华生产废渣,利用软锰矿浆吸收产生的SO2气体,吸收液经净化除杂、浓缩结晶等工序可制备工业产品硫酸锰.适宜的焙烧条件如下:焙烧温度为650℃,焙烧时间为60 min,废渣粒度为-97μm.选择合适的吸收工艺,Mn的浸出率可达96.20%,此时SO2脱除率为87.20%. 相似文献
837.
838.
应用X射线衍射和化学分析等手段研究了中南地区几种地带性土壤中的氧化铁类型与钼吸附的关系,结果表明:供试土壤粘粒的氧化铁以晶质氧化铁为主,非晶质氧化铁含量低;砖红壤和赤红壤中的晶质氧化铁以赤铁矿为主.其次为针铁矿;红壤、棕红壤中针铁矿含量比赤铁矿含量稍高,黄棕壤中的晶质氧化铁全为针铁矿;针铁矿的平均晶粒大小(MCD)一般比赤铁矿的小,而比表面积却比赤铁矿的大;针铁矿型氧化铁的钼吸附量比针-赤混合型氧化铁的高,从砖红壤到黄棕壤.单位重量的晶质氧化铁的钼吸附量随G/(G+H)比值的升高而增大. 相似文献
839.
Karen Budwill Phillip M. Fedorak William J. Page 《Journal of Polymers and the Environment》1996,4(2):91-102
The microbial degradation of poly (3-hydroxyalkanoates) (PHAs) under anaerobic conditions with various terminal electron acceptors was examined. Nitrate-reducing consortia were established using activated sludge, and PHAs were shown to be biodegradable under these conditions. A positive correlation between carbon dioxide production and nitrate reduction was demonstrated. Nitrous oxide accumulated as the main N-containing product of nitrate reduction. The amount of PHAs in activated sludge cultures decreased approximately 20% within 40 days of incubation. Attempts were made to establish iron- and sulfate-reducing consortia from spring water, yet it could not be demonstrated that the mixed cultures were capable of degrading PHAs. Pure cultures of iron- and sulfate-reducing bacteria could not utilize PHAs as sole carbon sources. Methanogenic environments sampled included pond sediment and rumen fluid. PHAs were fermented to methane and carbon dioxide after 10 weeks by a sediment consortium, with 43 to 57% of the substrate carbon transformed to methane. Although it could not be demonstrated that PHAs were biodegraded by a rumen fluid consortium, a facultative anaerobic bacterium, identified as aStaphylococcus sp., that could grow on PHAs was isolated from rumen fluid. 相似文献
840.
针对高负荷餐厨垃圾和剩余污泥混合发酵系统在实际应用过程中存在的盐度抑制问题,通过批次试验探究了不同钠盐(CH3COONa、NaCl和Na2SO4)对中温混合发酵体系的影响,考察了添加不同浓度钠盐时混合发酵体系的甲烷累积产量、有机物去除率、挥发性脂肪酸(VFAs)累积量及水解、酸化、乙酸化和产甲烷速率的抑制作用.结果表明,随着CH3COONa浓度的增加,相应的甲烷产量逐渐增加,但在高浓度时理论甲烷产量降低,当Na+浓度为8 g·L-1时,对产甲烷抑制率为21%.此外,NaCl和Na2SO4对甲烷累积产量具有抑制作用,相同Na+浓度下,Na2SO4对混合发酵体系甲烷产量的抑制作用更大;当SO42-浓度为8.3 g·L-1时,相应甲烷抑制率为23%.相反,Cl-浓度为3.1~6.2 g·L-1时,对混合发酵过程中甲烷抑制率为4.6%~7.7%;但随着Cl-浓度增至9.3~12.3 g·L-1时,甲烷产量提升了14.5%~37.6%.分析认为,NaCl对混合发酵过程有机物去除率的抑制作用主要是Na+的影响,而Na2SO4的抑制作用主要来源于SO42-和Na+的协同作用.NaCl和Na2SO4对水解速率和产甲烷速率的抑制作用较大,而对酸化速率和乙酸化速率抑制作用较小. 相似文献