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   788篇
  免费   99篇
  国内免费   377篇
安全科学   102篇
废物处理   46篇
环保管理   143篇
综合类   633篇
基础理论   151篇
环境理论   1篇
污染及防治   120篇
评价与监测   25篇
社会与环境   31篇
灾害及防治   12篇
  2024年   4篇
  2023年   10篇
  2022年   26篇
  2021年   33篇
  2020年   37篇
  2019年   42篇
  2018年   50篇
  2017年   56篇
  2016年   65篇
  2015年   59篇
  2014年   82篇
  2013年   89篇
  2012年   90篇
  2011年   82篇
  2010年   68篇
  2009年   62篇
  2008年   50篇
  2007年   51篇
  2006年   64篇
  2005年   43篇
  2004年   25篇
  2003年   35篇
  2002年   18篇
  2001年   19篇
  2000年   17篇
  1999年   17篇
  1998年   11篇
  1997年   7篇
  1996年   13篇
  1995年   4篇
  1994年   6篇
  1993年   4篇
  1992年   8篇
  1991年   3篇
  1989年   1篇
  1988年   2篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1979年   1篇
  1978年   2篇
  1977年   1篇
排序方式: 共有1264条查询结果,搜索用时 93 毫秒
931.
研究了厌氧流化床微生物燃料电池(AFB-MFC)除碳脱氮产电性能的影响因素。结果表明:(1)AFB-MFC对NH4+-N的去除不起作用。电压下降主要是由于进水有机基质浓度下降造成。(2)不添加NO3--N时,在满足AFB-MFC脱氮所需的电子供体条件下增加进水COD/TN有利于AFB-MFC产电。(3)3种无机氮共存下,AFB-MFC在进水有机碳与无机氮质量比(C/N)不低于1.37时,对COD、NO2--N和NO3--N具有理想的去除效果。AFB-MFB在一定进水C/N范围内(1.37~2.50),能得到稳定的输出电压及功率密度。(4)固定进水C/N时,AFB-MFC在高碳氮负荷下仍能得到较理想的NO2--N、NO3--N、COD去除效果,AFB-MFC对NH4+-N去除效果不明显;增加碳氮负荷,AFB-MFC输出电压及功率密度没有明显的改变。(5)有机基质浓度不变下,AFB-MFC中充足的电子供体可保证较高的NO3--N、COD去除率。AFB-MFC输出电压及功率密度随着时间延长而先增加至稳定值后下降。  相似文献   
932.
MBR污泥混合液特性变化及膜污染关系研究   总被引:4,自引:1,他引:3  
考察了长期运行不排泥情况下膜生物反应器(MBR)中的污泥混合液特性变化,并结合Darcy公式探讨污泥性质与膜污染的关系.研究表明,在130 d的运行期间,随着污泥龄(SRT)的增加,污泥浓度增大,混合液粘度增大,污泥的平均粒径从51.56 μm增加到92.57μm后略有减小;对比上清液和出水的分子量分布特征发现,膜组件...  相似文献   
933.
以模拟含油废水为处理对象,用辣根过氧化物酶(HRP)去除水中的油,研究了HRP催化氧化柴油反应的工艺条件。实验结果表明,当柴油质量浓度为120mg/L时,在H2O2质量浓度为250mg/L、HRP的酶活性浓度为0.8U/mL、废水pH为7.4、温度为27℃、反应时间为3h的最佳工艺条件下,除油率可达60.89%。实验还考察了壳聚糖和聚乙二醇(PEG)对HRP催化过程的影响。实验结果显示,壳聚糖对HRP催化过程的影响很小,PEG则有很好的强化作用,在PEG质量浓度为160mg/L时,除油率可达79.31%。  相似文献   
934.
邢英 《化工环保》2007,27(1):46-49
介绍了生物柴油的特性、能耗及生物柴油的制备方法(直接混合法、微乳液法、高温热裂解法、酯交换法、超临界甲醇法)和生物柴油在工业应用巾存在的主要问题,阐述了国内外生物柴油的产业发展现状,展望了该产业在我田的发展前景。  相似文献   
935.
杉木拟赤杨混交林土壤肥力的研究   总被引:3,自引:0,他引:3  
通过对杉木拟赤杨混交林及杉木纯林土壤团聚体结构、土壤养分状况及酶活性的研究表明,与杉木纯林相比,混交林土壤结构性能得到改善,供肥和保肥能力加强,各种土壤酶活性提高,土壤肥力较好。表明杉木拟赤杨混交林具有良好的培肥土壤功能,对杉木人工林的地力维持和提高有重要意义。  相似文献   
936.
垃圾填埋气(LFG)用作车辆燃料资源化现状及发展前景   总被引:8,自引:0,他引:8  
介绍垃圾填埋气用作车辆燃料资源化的优点 ,应用中需解决的净化、贮存和发动机改造的关键技术问题及国外研究应用现状 ,指出在我国具有广阔的发展前景。  相似文献   
937.
采用聚丙烯酰胺溶胶-凝胶法制备了A位掺杂(Cu、Ce)LaSrCoO4复合氧化物催化剂,考察了它们对CO和C3H8的催化氧化活性,并运用XRD,TPR和TPD等手段对催化剂进行了表征。结果表明,不同稀土掺杂对LaSrCoO4复合氧化物的CO和C3H8氧化活性的影响不同,Cu掺杂能增加Co3+、化学吸附氧和晶格氧的数量,提高复合氧化物的活性,而Ce则相反。  相似文献   
938.
Chinese traditional medicine wastewater, rich in macromolecule and easy to foam in aerobic biodegradation such as Glycosides, was treated by two identical bench-scale aerobic submerged membrane bioreactors (SMBRs) operated in parallel under the same feed, equipped with the same electronic control backwashing device. One was used as the control SMBR (CSMBR) while the other was dosed with powdered activated carbon (PAC) (PAC-amended SMBR, PSMBR). The backwashing interval was 5 min. One suction period was about 90 min by adjusting preestablished backwashing vacuum and pump frequency. The average flux of CSMBR during a steady periodic state of 24 d (576 h) was 5.87 L/h with average hydraulic residence time (HRT) of 5.97 h and that of PSMBR during a steady periodic state of 30 d (720 h) was 5.85 L/h with average HRT of 5.99 h. The average total chemical oxygen demand (COD) removal efficiency of CSMBR was 89.29% with average organic loading rate (OLR) at 4.16 kg COD/(m^3.d) while that of PSMBR was 89.79% with average OLR at 5.50 kg COD/(m^3.d). COD concentration in the effluent of both SMBRs achieved the second level of the general wastewater effluent standard GB8978-1996 for the raw medicine material industry (300 mg/L). Hence, SMBR with electronic control backwashing was a viable process for medium-strength Chinese traditional medicine wastewater treatment. Moreover, the increasing rates of preestablished backwashing vacuum, pump frequency, and vacuum and flux loss caused by mixed liquor in PSMBR all lagged compared to those in CSMBR; thus the actual operating time of the PSMBR system without membrane cleaning was extended by up to 1.25 times in contrast with the CSMBR system, and the average total COD removal efficiency of PSMBR was enhanced with higher average OLR.  相似文献   
939.
The releasing characteristics of phosphorus,nitrogen compounds,organics,and some metal cations during thermal treatment of excess sludge were investigated.It was found that during heating not only phosphorus,but also nitrogen compounds,organics,and some metal cations could be released in abundance.The maximum orthophosphate (ortho-P) release of about 90 mg/L in concentration was observed at 50℃in 1 h.Except for volatile fatty acids (VFAs),comparatively little total nitrogen (TN),total organic carbon (TOC),and metal cations were released at the same time.Such results might favor further process of phosphorus recovery.VFAs were considerably released only at 50℃.Acetic,butyric,and propionic acid were the most abundant components in turn and their releasing profiles exhibited good linear relationship with time (R~2=0.9977,0.9624,and 0.8908,respectively).The concentrations of Mg~(2 ) and K~ increased with time and temperature during thermal treatment,but Ca~(2 ) decreased.The release of Mg~(2 ) and K~ agreed well with TP release (R~2=0.9892 and 0.9476,respectively).Temperature in the experimental range had very little impact on the linear relationships, especially of Mg~(2 ).Moreover,the parameter of mixed liquor suspended solids (MLSS) was found to be an important factor for thermal sludge treatment as the released ortho-P and total phosphorus (TP) at 50℃increased more than one-fold when MLSS was increased from 4000 to 8000 mg/L.  相似文献   
940.
The burning of kerosene in jet turbines is investigated for two reference flights with a Boeing 747-400 and an Airbus A320-200, representing the typical Lufthansa planes for long and middle distance. The ecological evaluation is performed by Life Cycle Assessment (LCA). Formation of condensation trails, which is a specific environmental impact caused by air traffic, has to be considered in addition to established LCA impact categories. Based on the ecological assessment, an improvement assessment is performed. Environmental performance of diesel fuel during the combustion in car engines is analysed based on available publications. The relevant parameters for the environmental impact of the combustion of diesel (aromatics content, reduction of sulphur content, the reduction of the density and raising of the cetane number) are discussed with regard to improvements of the exhaust qualities of kerosene. A reduction of the aromatics content promises to improve the emission of soot which should be further investigated.  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