首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   531篇
  免费   74篇
  国内免费   215篇
安全科学   60篇
废物处理   78篇
环保管理   60篇
综合类   390篇
基础理论   89篇
污染及防治   81篇
评价与监测   31篇
社会与环境   10篇
灾害及防治   21篇
  2024年   2篇
  2023年   9篇
  2022年   21篇
  2021年   23篇
  2020年   17篇
  2019年   19篇
  2018年   19篇
  2017年   22篇
  2016年   26篇
  2015年   22篇
  2014年   33篇
  2013年   46篇
  2012年   43篇
  2011年   54篇
  2010年   31篇
  2009年   34篇
  2008年   35篇
  2007年   57篇
  2006年   34篇
  2005年   43篇
  2004年   26篇
  2003年   35篇
  2002年   33篇
  2001年   25篇
  2000年   20篇
  1999年   13篇
  1998年   22篇
  1997年   13篇
  1996年   4篇
  1995年   8篇
  1994年   12篇
  1993年   7篇
  1992年   3篇
  1991年   4篇
  1990年   1篇
  1989年   1篇
  1987年   1篇
  1978年   1篇
  1975年   1篇
排序方式: 共有820条查询结果,搜索用时 265 毫秒
711.
This risk assessment on 1,1,2-trichloroethane (T112) was carried out specifically for the marine environment, according to the methodology laid down in the EU risk assessment Regulation (1488/94) and the Guidance Document of the EU New and Existing Substances Regulation (TGD, 1997). The study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of the "predicted environmental concentrations" (PEC) and the "predicted no effect concentrations" (PNEC) for the marine aquatic environment. In total, 22 studies for fish, 45 studies for invertebrates and 9 studies for algae have been evaluated. Both acute and chronic toxicity studies have been taken into account and the appropriate assessment factors have been used to define a PNEC value of 300 µg/l. Most of the available monitoring data apply to rivers and estuaries and were used to calculate PECs. The most recent data (1991-1995) support a typical PEC of 0.01 µg T112/l water and a worst case PEC of 5 µg T112/l water. The calculated PEC/PNEC ratios give a safety margin of 60 to 30,000 between the predicted no effect concentration and the exposure concentration. Additional evaluation of environmental fate and bioaccumulation characteristics showed that no concern is expected for food chain accumulation.  相似文献   
712.
This risk assessment on 1,2-dichloroethane (EDC) was carried out specifically for the marine environment, according to the methodology laid down in the EU risk assessment Regulation (1488/94) and the Guidance Document of the EU New and Existing Substances Regulation (TGD, 1997). The study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of the "predicted environmental concentrations" (PEC) and the "predicted no effect concentrations" (PNEC) for the marine aquatic environment. In total, 21 studies for fish, 17 studies for invertebrates and 7 studies for algae have been evaluated. Both acute and chronic toxicity studies have been taken into account and the appropriate assessment factors have been used to define a PNEC value of 1100 µg/l. Most of the available monitoring data apply to rivers and estuaries and were used to calculate PECs. The most recent data (1991-1995) support a typical PEC of 0.5 µg EDC/l and a worst case PEC of 6.4 µg EDC/l. The calculated PEC/PNEC ratios give a safety margin of 170 to 2200 between the predicted no effect concentration and the exposure concentration. Additional evaluation of environmental fate and bioaccumulation characteristics showed that no concern is expected for food chain accumulation.  相似文献   
713.
This risk assessment on chloroform was carried out specifically for the marine environment, according to the methodology laid down in the EU risk assessment Regulation (1488/94) and the Guidance Document of the EU New and Existing Substances Regulation (TGD, 1997). The study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of the "predicted environmental concentrations" (PEC) and the "predicted no effect concentrations" (PNEC) for the marine aquatic environment. In total, 23 studies for fish, 17 studies for invertebrates and 10 studies for algae have been evaluated. Both acute and chronic toxicity studies have been taken into account and the appropriate assessment factors have been used to define a typical PNEC value of 72 µg/l. Due to limitations of the studies evaluated, a worst PNEC of 1 µg/l could also be used. Most of the available monitoring data apply to rivers and estuaries and were used to calculate PECs. The most recent data (1991-1995) support a typical PEC of 0.2 µg chloroform per litre of water and a worst case PEC of 5 to 11.5 µg chloroform per litre of water. The calculated PEC/PNEC ratios give a safety margin of 6 to 360 between the predicted no effect concentration and the exposure concentrations. A worst case ratio, however, points to a potential risk for sensitive species. Refinement of the assessment is necessary by looking for more data. Additional evaluation of environmental fate and bioaccumulation characteristics showed that no concern is expected for food chain accumulation.  相似文献   
714.
This risk assessment on tetrachloroethylene (PER) was carried out specifically for the marine environment, according to the methodology laid down in the EU risk assessment Regulation (1488/94) and the Guidance Document of the EU New and Existing Substances Regulation (TGD, 1997). The study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of the "predicted environmental concentrations" (PEC) and the "predicted no effect concentrations" (PNEC) for the marine aquatic environment. In total, 18 studies for fish, 13 studies for invertebrates and 8 studies for algae have been evaluated. Both acute and chronic toxicity studies have been taken into account and the appropriate assessment factors have been used to define a PNEC value of 51 µg/l. Most of the available monitoring data apply to rivers and estuary waters and were used to calculate PECs. The most recent data (1991-1995) support a typical PEC of 0.2 µg PER/l water and a worst case PEC of 2.5 µg PER/l water. The calculated PEC/PNEC ratios give a safety margin of 20 to 250 between the predicted no effect concentration and the exposure concentration. Additional evaluation of environmental fate and bioaccumulation characteristics showed that no concern is expected for food chain accumulation.  相似文献   
715.
合成了一种用来吸附和去除水溶液中酚类化合物的 2 羧基苯甲酰基修饰的超高交联吸附树脂 (ZH 0 1) ,并从动力学和吸附容量角度比较了XAD 4、AM 1和ZH 0 1分别吸附浓度为 80 0mg/L苯酚的情况。实验结果表明 ,ZH 0 1吸附剂有利于吸附苯酚、对甲苯酚和对硝基苯酚之类的酚类化合物。动力学和热力学研究都得到了相同的结果 :ZH 0 1对苯酚和对甲苯酚吸附是化学吸附的过渡状态 ,而对对硝基苯酚的吸附是一种物理吸附过程 ,并且显示了ZH 0 1表面均孔特性。苯酚在ZH 0 1上的小柱吸附研究表明了吸附穿透容量和总吸附量分别为 2 .38mmol/g和 3.0 5mmol/g ,溶剂甲醇对吸附在ZH 0 1上苯酚的脱附效果较好。  相似文献   
716.
Volatilization and Biodegradation of VOCs in Membrane Bioreactors (MBR)   总被引:1,自引:0,他引:1  
Volatilization and biodegradation are major competitive volatile organic compound (VOC) removal mechanisms in biological wastewater treatment process, which depend on compound specific properties and system design/operational parameters. In this study, a mathematical model was used to determine major removal pathways at various organic loading rates (OLR), solids residence time (SRT) and dissolved oxygen (DO) concentrations in a biological process for vinyl acetate. Model results showed that biological treatment process should be designed with long SRT, high OLR and low DO concentrations to maximize biodegradation and minimize volatilization of VOCs. Unless a VOC is toxic to microorganisms under the given conditions, low VOC emission rates are an inherent advantage of MBRs, which operate at higher OLR and longer SRT compared to conventional activated sludge process. A lab scale membrane bioreactor (MBR) was operated at varying OLR to investigate the relative volatilization and biodegradation rates for acetaldehyde, butyraldehyde and vinyl acetate. Synthetic wastewater containing three VOCs was introduced to the MBR. The DO concentration and SRT was maintained at 2.0 mg L− 1 and 100 days, respectively. The overall VOC removal rate was more than 99.7% for three VOCs at all the OLR. For vinyl acetate, the biodegradation rate increased from 93.87 to 99.40% and the volatilization removal rate decreased from 6.09 to 0.59% as OLR was increased from 1.1 to 2.0 kg COD m− 3 d− 1. It was confirmed that a MBR can be a promising solution to reduce VOC emissions from wastewater.  相似文献   
717.
建筑火灾烟气运动数值模拟方法的回顾与评价   总被引:5,自引:0,他引:5  
系统地介绍了建筑火灾烟气运动的各种数值模拟方法。将收集到的59种建筑火灾模型分为4大类,包括9种网络模型、32种区域模型、15种场模型及3种复合模型;从理论角度阐述了各类模型的计算方法,着重介绍了其中有代表性的几个模型;提出复合模型是未来模型的发展方向。为初涉建筑火灾烟气运动数值模拟的研究人员提供了思路。  相似文献   
718.
海岸带风暴潮减水的统计分析   总被引:1,自引:0,他引:1  
在青岛大港观测站连续30年实测资料的基础上,按照年、季、月等时段分别抽样,对风暴潮减水进行了长期统计分析.考虑到海岸地区风暴潮减水的诱因不同,在一维复合极值分布的基础上,提出了"组合分布法".新方法探讨了假设所有数据源于同一分布而产生的重现值估计误差.与年极值法和阈值法的计算结果进行了比较,说明以往算法得到的重现值偏低,并给出了青岛地区受季节变化影响的风暴减水设计重现值.统计表明,青岛大港春、秋、冬季均有风暴减水发生.由于寒潮大风是其产生的主导因素,以冬季的极值减水序列为样本,所得重现值与考虑季节变化得到的重现值相当.说明在实际工程区域,选取主要天气形势产生的水文要素为样本,替代所有观测数据,使统计计算得以简化的做法是可行的.  相似文献   
719.
IntroductionChromeleatherscrapisthesolid wasteofleatherindustry .Itsmaincompositionisprotein(mainlycollagenprotein ,globulinandalbumin) ,someCrcompoundbondingwiththeprotein ,alittlecarbohydrate ,fatandsomeinorganics.Thechromeleatherscrapstackedwillputridgra…  相似文献   
720.
通过在3组日处理规模为5m^3/d的活性污泥法装置中进行连续进出水试验,考察了投加多功能复合微生物制剂(multifunctional compound micro—organisms preparation,MCMP)对污水处理过程中剩余污泥减量的影响。中试研究结果表明,曝气池中,每次MCMP菌剂加入量为日处理水量的0.02%~0.04%的条件下,运行2个月装置未排放剩余污泥,有效地实现剩余污泥源头减量的预期要求。该技术不增加或改变原有污水处理工艺和运行方式,不增加处理系统总的动力消耗,并且不会对出水水质产生不良影响。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号