全文获取类型
收费全文 | 903篇 |
免费 | 34篇 |
国内免费 | 254篇 |
专业分类
安全科学 | 45篇 |
废物处理 | 68篇 |
环保管理 | 67篇 |
综合类 | 481篇 |
基础理论 | 166篇 |
污染及防治 | 269篇 |
评价与监测 | 34篇 |
社会与环境 | 28篇 |
灾害及防治 | 33篇 |
出版年
2023年 | 6篇 |
2022年 | 32篇 |
2021年 | 22篇 |
2020年 | 24篇 |
2019年 | 18篇 |
2018年 | 28篇 |
2017年 | 36篇 |
2016年 | 28篇 |
2015年 | 42篇 |
2014年 | 61篇 |
2013年 | 66篇 |
2012年 | 47篇 |
2011年 | 64篇 |
2010年 | 56篇 |
2009年 | 44篇 |
2008年 | 63篇 |
2007年 | 47篇 |
2006年 | 52篇 |
2005年 | 43篇 |
2004年 | 26篇 |
2003年 | 37篇 |
2002年 | 36篇 |
2001年 | 42篇 |
2000年 | 36篇 |
1999年 | 41篇 |
1998年 | 37篇 |
1997年 | 23篇 |
1996年 | 23篇 |
1995年 | 25篇 |
1994年 | 19篇 |
1993年 | 19篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1973年 | 1篇 |
排序方式: 共有1191条查询结果,搜索用时 31 毫秒
641.
642.
超声波处理剩余活性污泥促进厌氧消化 总被引:9,自引:1,他引:8
用超声波处理剩余活性污泥(简称污泥),考察了污泥絮体结构、污泥中溶解性化学需氧量(SCOD)的变化规律及超声波处理对污泥厌氧消化的影响。实验结果表明,声强大于1 040W/m2时,用超声波处理污泥30m in以上,污泥絮体被打碎,污泥絮体结构遭到严重破坏,污泥中SCOD迅速增加,加速了污泥中有机质的水解反应;声强为2 000W/m2时,用超声波处理污泥60m in,中温((37±1)℃)厌氧消化10d,COD去除率为41%;厌氧消化25d的总产气量比未经超声波处理的污泥总产气量提高了53%;将发酵罐容积放大10倍,经超声波处理的污泥25d累积的总产气量比未经超声波处理的污泥总产气量提高了约25%。 相似文献
643.
644.
645.
Xiaodong Yu Yang Li Xiaofeng Gu Jiming Bao Huizhong Yang Li Sun 《Environmental monitoring and assessment》2014,186(12):8969-8980
Water quality monitoring is a critical part of environmental management and protection, and to be able to qualitatively and quantitatively determine contamination and impurity levels in water is especially important. Compared to the currently available water quality monitoring methods and techniques, laser-induced breakdown spectroscopy (LIBS) has several advantages, including no need for sample pre-preparation, fast and easy operation, and chemical free during the process. Therefore, it is of great importance to understand the fundamentals of aqueous LIBS analysis and effectively apply this technique to environmental monitoring. This article reviews the research conducted on LIBS analysis for liquid samples, and the article content includes LIBS theory, history and applications, quantitative analysis of metallic species in liquids, LIBS signal enhancement methods and data processing, characteristics of plasma generated by laser in water, and the factors affecting accuracy of analysis results. Although there have been many research works focusing on aqueous LIBS analysis, detection limit and stability of this technique still need to be improved to satisfy the requirements of environmental monitoring standard. In addition, determination of nonmetallic species in liquid by LIBS is equally important and needs immediate attention from the community. This comprehensive review will assist the readers to better understand the aqueous LIBS technique and help to identify current research needs for environmental monitoring of water quality. 相似文献
646.
You-Ya Zhou Ji-Fang Yu Zeng-Guang Yan Chao-Yan Zhang Ya-Bo Xie Li-Qiang Ma Qing-Bao Gu Fa-Sheng Li 《Environmental monitoring and assessment》2013,185(4):3037-3048
A method based on headspace (HS) sampling coupling with portable gas chromatography (GC) with photo ionization detector (PID) was developed for rapid determination of benzene, toluene, ethylbenzene, and xylenes (BTEX) in soils. Optimal conditions for HS gas sampling procedure were determined, and the influence of soil organic matter on the recovery of BTEX from soil was investigated using five representative Chinese soils. The results showed that the HS-portable-GC-PID method could be effectively operated at ambient temperature, and the addition of 15 ml of saturated NaCl solution in a 40-ml sampling vial and 60 s of shaking time for sample solution were optimum for the HS gas sampling procedure. The recoveries of each BTEX in soils ranged from 87.2 to 105.1 %, with relative standard deviations varying from 5.3 to 7.8 %. Good linearity was obtained for all BTEX compounds, and the detection limits were in the 0.1 to 0.8 μg kg?1 range. Soil organic matter was identified as one of the principal elements that affect the HS gas sampling of BTEX in soils. The HS-portable-GC-PID method was successfully applied for field determination of benzene and toluene in soils of a former chemical plant in Jilin City, northeast China. Considering its satisfactory repeatability and reproducibility and particular suitability to be operated in ambient environment, HS sampling coupling with portable GC-PID is, therefore, recommended to be a suitable screening tool for rapid on-site determination of BTEX in soils. 相似文献
647.
Gu Y Yang Y Lin Q Li Q Wang Z Wang X 《Journal of environmental monitoring : JEM》2012,14(7):1943-1950
Heavy metals in sediments from Baisha Bay, Nan'ao Island, one of Guangdong Province's largest mariculture bases in Southern China, were investigated. The results display that the concentrations of 6 heavy metals from surface sediments were 0.040-0.220 (Cd), 24.22-39.61 (Pb), 25.30-42.66 (Cr), 10.83-19.54 (Ni), 15.06-39.24 (Cu) and 55.12-141.73 mg kg(-1) (Zn), respectively. The highest concentrations and the greatest increasing rates of heavy metals were found in a sediment core in a fish cage culture area due to receiving sewage discharge, uneaten fish bait, and boat gasoline combustion. Cd was preferentially associated with the acid-soluble fraction and Pb mainly with the reducible fraction in surface sediments. Meanwhile, Cd and Pb displayed greatest labile fractions, indicating anthropogenic origin. A principal component analysis (PCA) revealed three groupings (Cd; Cr, Ni and Cu; Pb and Zn) that mainly result from different distributions of the metals in the various fractions. The ecological risk of the polluted sediments stemmed mainly from Cd, and from Pb and Cu to a lesser degree. It is suggested that the density of fish-stocking be controlled, periodic movement of rafts (cages) be introduced, and the total numbers of net-cages and human activities in the mariculture zones be restricted. in order to facilitate the recovery of the polluted sediment. 相似文献
648.
Xiaomin Gu Yong Xiao Shiyang Yin Xingyao Pan Yong Niu Jingli Shao Yali Cui Qiulan Zhang Qichen Hao 《Environmental monitoring and assessment》2017,189(10):514
In this study, the hydrochemical characteristics of shallow groundwater were analyzed to get insight into the factors affecting groundwater quality in a typical agricultural dominated area of the North China Plain. Forty-four shallow groundwater samples were collected for chemical analysis. The water type changes from Ca·Na-HCO3 type in grass land to Ca·Na-Cl (+NO3) type and Na (Ca)-Cl (+NO3+SO4) type in construction and facility agricultural land, indicating the influence of human activities. The factor analysis and geostatistical analysis revealed that the two major factors contributing to the groundwater hydrochemical compositions were the water-rock interaction and contamination from sewage discharge and agricultural fertilizers. The major ions (F, HCO3) and trace element (As) in the shallow groundwater represented the natural origin, while the nitrate and sulfate concentrations were related to the application of fertilizer and sewage discharge in the facility agricultural area, which was mainly affected by the human activities. The values of pH, total dissolved solids, electric conductivity, and conventional component (K, Ca, Na, Mg, Cl) in shallow groundwater increased from grass land and cultivated land, to construction land and to facility agriculture which were originated from the combination sources of natural processes (e.g., water-rock interaction) and human activities (e.g., domestic effluents). The study indicated that both natural processes and human activities had influences on the groundwater hydrochemical compositions in shallow groundwater, while anthropogenic processes had more contribution, especially in the reclaimed water irrigation area. 相似文献
649.
壳聚糖接枝共聚物的合成及应用研究 总被引:2,自引:0,他引:2
在N2保护下,以浓度为0.8 mmol/L硝酸铈铵为引发剂,控制壳聚糖(CTS)和丙烯酰胺(AM)质量比为mCTS∶mAM=1∶6,于50℃下接枝共聚反应3 h,得改性的壳聚糖衍生物(CAM).用IR对产物进行表征.通过对废水的处理,研究了共聚产物在絮凝、COD去除、脱色上的应用.结果表明:CAM的絮凝效果好于聚丙烯酰胺和壳聚糖,CAM对COD的去除率达到84.7%,并有较好的脱色效果. 相似文献
650.