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   11673篇
  免费   1373篇
  国内免费   3231篇
安全科学   1839篇
废物处理   280篇
环保管理   1763篇
综合类   7070篇
基础理论   1925篇
环境理论   1篇
污染及防治   1409篇
评价与监测   641篇
社会与环境   863篇
灾害及防治   486篇
  2024年   40篇
  2023年   243篇
  2022年   445篇
  2021年   520篇
  2020年   499篇
  2019年   452篇
  2018年   423篇
  2017年   561篇
  2016年   628篇
  2015年   639篇
  2014年   628篇
  2013年   841篇
  2012年   1023篇
  2011年   1111篇
  2010年   854篇
  2009年   1018篇
  2008年   668篇
  2007年   774篇
  2006年   759篇
  2005年   606篇
  2004年   444篇
  2003年   425篇
  2002年   394篇
  2001年   315篇
  2000年   314篇
  1999年   253篇
  1998年   221篇
  1997年   196篇
  1996年   168篇
  1995年   165篇
  1994年   122篇
  1993年   94篇
  1992年   89篇
  1991年   46篇
  1990年   35篇
  1989年   33篇
  1988年   30篇
  1987年   25篇
  1986年   21篇
  1985年   18篇
  1984年   20篇
  1983年   12篇
  1982年   13篇
  1981年   14篇
  1980年   19篇
  1979年   12篇
  1978年   12篇
  1977年   6篇
  1971年   9篇
  1970年   5篇
排序方式: 共有10000条查询结果,搜索用时 45 毫秒
991.
上海市危险废物处理处置及管理对策探讨   总被引:1,自引:0,他引:1  
刘海英 《上海环境科学》2010,29(1):41-43,46
简要介绍了国外危险废物管理制度及法律法规体系;表述了我国危险废物的管理法规.制度及控制标准;阐述了上海市危险废物处理处置及管理现状;分析了存在的主要问题;从6个方面提出了上海市危险废物的管理对策。  相似文献   
992.
应用生态动力学模型评价上海淀山湖富营养化控制方案   总被引:9,自引:0,他引:9  
近年来,由于淀山湖入湖河流和环湖污水排放,淀山湖水质严重富营养化,夏季高温季节蓝藻水华时有发生。基于最近开展的比较系统的大规模水文、水质、生物同步监测和底质氮磷营养盐释放通量实验,进行入湖氮磷营养盐通量计算分析。通过建立淀山湖水动力一生态动力学耦合模型,利用同步实测和历史资料进行水动力模型和生态动力学模型的率定验证,模拟典型风场作用下的淀山湖三维流场特征;利用生态动力学模型系统研究淀山湖氮磷营养盐和藻类的时空变化和演替规律,初步掌握淀山湖的富营养化过程;综合评价了污染负荷削减、水力调度(水体停留时间)等措施对控制淀山湖富营养化的作用,明确磷是淀山湖藻类生长的关键营养盐限制因子。模型预测结果表明,磷负荷削减50%以上才能使淀山湖夏季蓝藻生物量开始下降;削减90%以上的营养盐负荷才能有效抑制蓝藻水华;水体停留时间的长短是藻类是否过度繁殖的重要条件,加大引水流量,减少淀山湖水体停留时间是有效控制蓝藻水华的重要途径;目前阶段,与控制营养盐负荷(50%)相比,增大引水流量可以更有效地降低蓝藻暴发时的生物量。  相似文献   
993.
Water quality models are important tools to support the optimization of aquatic ecosystem rehabilitation programs and assess their efficiency. Basing on the flow conditions of the Daqinghe River Mouth of the Dianchi Lake, China, two-dimensional water quality model was developed in the research. The hydrodynamics module was numerically solved by the alternating direction iteration (ADI) method. The parameters of the water quality module were obtained through the in situ experiments and the lab analyses that were conducted from 2006 to 2007. The model was calibrated and verified by the observation data in 2007. Among the four modelled key variables that were water level, CODcr, NH3-N and PO4-P, the minimum value of the coefficient of determination (CoD) was 0.69, which mean the model performed reasonably well. The developed model was then applied to simulate the water quality changes at the downstream cross-section assuming that the designed restoration programs were implemented. According to the simulated results, the restoration programs could cut down the loads of CODcr and PO4-P about 15%, however, they would have very little effect on the NH3-N removal. Besides, the water quality at the outlet cross-section would be still in class V (3838-02), indicating more measures should be taken to further reduce the loads. The study demonstrated the capability of water quality models to support aquatic ecosystem restorations.  相似文献   
994.
High-resolution modeling approach is increasingly being considered as a necessary step for improving the monitoring and predictions of regional air quality. This is especially true for highly urbanized region with complex terrain and land-use. This study uses Community Multiscale Air Quality (CMAQ) model coupled with MM5 mesoscale model for a comprehensive analysis to assess the suitability of such high-resolution modeling system in predicting ozone air quality in the complex terrains of Osaka, Japan. The 1-km and 3-km grid domains were nested inside a 9-km domain and the domain with 1-km grid covered the Osaka region. High-resolution Grid Point Value-Mesoscale Model (GPV-MSM) data were used after suitable validation. The simulated ozone concentrations were validated and evaluated using statistical metrics using performance criteria set for ozone. Daily maxima of ozone were found better simulated by the 1-km grid domain than the coarser 9-km and 3-km domains, with the maximum improvement in the mean absolute gross error about 3 ppbv. In addition, 1-km grid results fared better than other grids at most of the observation stations that showed noticeable di erences in gross error as well as correlation. These results amply justify the use of the integrated high-resolution MM5-CMAQ modeling system in the highly urbanized region, such as the Osaka region, which has complex terrain and land-use.  相似文献   
995.
构建了环境经济投入产出模型,针对淘汰落后产能对经济发展的影响进行了实证研究,定量计算了2006~2007年问淘汰落后产能对于经济社会发展的贡献度和影响.研究表明,虽然淘汰落后产能对于传统的国民经济发展指标有一定负面影响,但对于优化经济增长方式确实起到了积极作用.一是优化了产业结构,第一、二、三产业结构由2005年的12.4%,48.6%,39.0%调整为2006年的12.5%,48.2%和39.3%,2007年调整为12.6%,47.8%和39.6%,第二产业所占比重逐步下降,第三产业所占比重逐步上升;在第二产业内部.造纸、食品、电力、炼焦、金属冶炼、非金属矿物制品业等重污染行业的增加值所占比重持续下降,产业结构逐步得到优化.二是提高了经济效率,从涉及到的造纸、食品、电力、炼焦、金属冶炼、非金属矿物制品业6个产业部门2006年和2007年的COD和SO_2的产污系数看,都比2005年有所降低.2006年和2007年,食品制造业的单位增加值COD排放量比2005年分别下降了6.6%和25.0%;金属冶炼及压延加工业的单位增加值SO_2排放量比2005年分别下降3.5%和6.9%.  相似文献   
996.
Sesbania rostrata is renowned for its stem nodulation, but the role of stem nodulation in the root nodulation and adaptation of S.rostrata to Pb/Zn-enriched tailings environment has been poorly understood.We investigated the effects of inoculating (with stem nodule treatment) and non-inoculating (without stem nodule treatment) Azorhizobium caulinodans on the growth, root nodulation, and N fixation of S.rostrata grown on three different types of soil substrata: Pb/Zn tailings, garden soil amended tailings, and garden soil.The results showed that plant height, stem basal diameter, biomass, chlorophyll content, nitrogen content and N-accumulation per plant were 2.3%-4.9%, 2.2%-7.7%, 27.8%-72.2%, 17.1%-23.5%, 12.3%-34.2%, and 43.1%-131.2% higher in treatments with stem nodule than those without stem nodule for the same soil substrate, respectively.With respect to soil substrata, all the measurements had consistently higher values in tailings than in amended tailings and garden soil, indicating that the poorer the soil condition, the greater the contribution of stem nodule.In contrast, the number and fresh weight of root nodules on plants without stem nodule were 6.9-11.6 times and 5.8-29.0 times higher than those with stem nodule, respectively, especially with respect to the plants grew on Pb/Zn tailings.In general, stem nodulation favored plant growth and nitrogen fixation of S.rostrata, but suppressed root nodulation.With the ability of stem and root nodulation, S.rostrata can be used as a pioneer plant species for remediation of Pb/Zn tailings.  相似文献   
997.
The acute effects of commercial formulation of chlorpyrifos-ethyl (Dursban(r)) and the secondary treated industrial/urban effluent (STIUE) exposure on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities in hepatopancreas and gills of Mediterranean crab Carcinus maenas were investigated. After 2 d of exposure to chlorpyriphos-ethyl, the AChE activity was inhibited in both organs at concentrations of 3.12 and 7.82 μg/L, whereas the BuChE was inhibited only at higher concentration 7.82 μg/L of commercial preparation Dursban(r). The exposure of crabs to Dursban(r) (3.12 μg/L) showed a significant decrement of AChE activity at 24 and 48 h, whereas the BuChE was inhibited only after 24 h and no inhibition for both enzymes was observed after 72 h. Moreover, a significant repression of AChE activity was observed in both organs of C. maenas exposed to 5% of STIUE. Our experiments indicated that the measurement of AChE activity in gills and hepatopancreas of C. meanas would be useful biomarker of organophosphorous (OP) and of neurotoxic effects of STIUE in Tunisia.  相似文献   
998.
High-resolution modeling approach is increasingly being considered as a necessary step for improving the monitoring and predictions of regional air quality.This is especially true for highly urbanized region with complex terrain and land-use.This study uses Community Multiscale Air Quality (CMAQ) model coupled with MM5 mesoscale model for a comprehensive analysis to assess the suitability of such high-resolution modeling system in predicting ozone air quality in the complex terrains of Osaka,Japan.The 1-km and 3-km grid domains were nested inside a 9-km domain and the domain with 1-km grid covered the Osaka region.High-resolution Grid Point Value-Mesoscale Model μgPV-MSM) data were used after suitable validation.The simulated ozone concentrations were validated and evaluated using statistical metrics using performance criteria set for ozone.Daily maxima of ozone were found better simulated by the 1-km grid domain than the coarser 9-km and 3-km domains,with the maximum improvement in the mean absolute gross error about 3 ppbv.In addition,1-km grid results fared better than other grids at most of the observation stations that showed noticeable differences in gross error as well as correlation.These results amply justify the use of the integrated high-resolution MM5-CMAQ modeling system in the highly urbanized region,such as the Osaka region,which has complex terrain and land-use.  相似文献   
999.
A Gram-negative, chromium(VI) tolerant and reductive strain CTS-325, isolated from a Chinese chromate plant, was identified as Ochrobactrum anthropi based on its biochemical properties and 16S rDNA sequence analysis. It was able to tolerate up to 10 mmol/L Cr(VI) and completely reduce 1 mmol/L Cr(VI) to Cr(III) within 48 h. When the strain CTS-325 was induced with Cr(VI), a protein increased significantly in the whole cell proteins. Liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis revealed that this protein was a superoxide dismutase (SOD) homology. The measured superoxide dismutase activity was 2694 U/mg after three steps of purification. The SOD catalyzes the dismutation of the superoxide anion (O2·−) into hydrogen peroxide and molecular oxygen. This protein is considered to be one of the most important anti-oxidative enzymes for O. anthropi as it allows the bacterium to survive high oxygen stress environments, such as the environment produced during the reduction process of Cr(VI).  相似文献   
1000.
In this study, chlorine decay experiments were conducted for the raw water from Nakdong River that is treated by Chilseo Water Treatment Plant (CWTP) situated in Haman, Korea as well as the e uents from sand and granular activated carbon (GAC) filters of CWTP and fitted using a chlorine decay model. The model estimated the fast and slow reacting nitrogenous as well as organic/inorganic compounds that were present in the water. It was found that the chlorine demand due to fast and slow reacting (FRA and SRA) organic/inorganic substances was not reduced significantly by sand as well as GAC filters. However, the treated e uents from those filters contained FRA and SRA that are less reactive and had small reaction rate constants. For the e uents from microfiltration, ultrafiltration, and nanofiltration the chlorine demand because FRA and SRA were further reduced but the reaction rate constants were larger compared to those of sand and GAC filter e uents. This has implications in the formation of disinfection by products (DBPs). If DBPs are assumed to form due to the interactions between chlorine and SRA, then it is possible that the DBP formation potential in the e uents from membrane filtrations could be higher than that in the e uents from granular media filters.  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