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   6363篇
  免费   105篇
  国内免费   444篇
安全科学   167篇
废物处理   333篇
环保管理   461篇
综合类   1452篇
基础理论   1494篇
环境理论   5篇
污染及防治   2142篇
评价与监测   472篇
社会与环境   330篇
灾害及防治   56篇
  2023年   67篇
  2022年   180篇
  2021年   186篇
  2020年   102篇
  2019年   129篇
  2018年   224篇
  2017年   249篇
  2016年   317篇
  2015年   260篇
  2014年   379篇
  2013年   536篇
  2012年   401篇
  2011年   432篇
  2010年   308篇
  2009年   261篇
  2008年   416篇
  2007年   366篇
  2006年   296篇
  2005年   237篇
  2004年   219篇
  2003年   190篇
  2002年   161篇
  2001年   109篇
  2000年   66篇
  1999年   74篇
  1998年   51篇
  1997年   42篇
  1996年   45篇
  1995年   49篇
  1994年   43篇
  1993年   24篇
  1992年   31篇
  1991年   30篇
  1990年   24篇
  1989年   18篇
  1988年   20篇
  1987年   12篇
  1986年   26篇
  1985年   14篇
  1984年   12篇
  1983年   17篇
  1982年   20篇
  1981年   11篇
  1980年   13篇
  1972年   10篇
  1966年   16篇
  1965年   10篇
  1957年   11篇
  1956年   13篇
  1954年   10篇
排序方式: 共有6912条查询结果,搜索用时 359 毫秒
91.
92.
93.
94.
95.
96.
LevelofcoordinateddevelopmentineconomyandenvironmentZhangQide,WangYuxiu,RenJinsongLiaoningInstituteofEnvironmentProtectionSci...  相似文献   
97.
A result that application of sodium selenite or fly ash to some of soilin loess plateau can increase Se content in wheat grain has been demonstrated by the pot and field experiments, and added Se in soil can last its availability for 3 years. So this is a good measure for improving the low Se soils and preventing the Kaschin-Beck disease.  相似文献   
98.
通过对顺城河北地区地表水环境现状特点及其污染状况的调查详细分析了各支流的纳污量,了解河北地区各支流对浑河主河道的“污染贡献”,运用科学的方法确定各功能水质目标,提出水污染总量、控制削减方案和治理方案。  相似文献   
99.
Activity development of key groups of enzymes involved in municipal refuse decomposition was measured in laboratory landfill bioreactors with and without leachate recycling and inoculation for about 210 days.The results showed that the enzymes(amylase,protease,cellulase,lipase and pectinase)were present in fresh refuse but at low values and positively affected by leachate recycling and refuse inoculation.The total average of cellulase activity in digesters D3 operated with leachate recycling but no inoculation,D4 and D5 operated with leachate recyling and inoculation was much higher than that in digesters D1 and D2 without leachate recycling and inoculation by 88%-127%,117%-162%and 64%-98%.The total average of protease activity was higher in digester D4 than that in digesters D1,D2,D3and D5 by 63%,39%,24%and 24%,respectively,and the positive effect of leachate recycling and inoculation on protease activity of landfilled refuse mainly was at the first two months.The total average of amylase activity was higher in digesters D3,D4 and D5 than that in digesters D1 and D2 by 83%-132%,96%-148%and 81%-129%.During the early phase of incubation,the stimulatory effect of inoculation on lipase activity was measured,but refuse moisture was the main factor affecting lipase activity of landfilled refuse.The inoculation,initial and continuous inoculation of microorganisms existing in leachate,was the mainly stimulatory factor affecting pectinase activity of landfilled refuse.  相似文献   
100.
Road transport produces significant amounts of emissions by using crude oil as the primary energy source. A reduction of emissions can be achieved by implementing alternative fuel chains. The objective of this study is to carry out an economic, environmental and energy (EEE) life cycle study on natural gas-based automotive fuels with conventional gasoline in an abundant region of China. A set of indices of four fuels/vehicle systems on the basis of life cycle are assessed in terms of impact of EEE, in which natural gas produces compressed natural gas (CNG), methanol, dimethylether (DME) and Fischer Tropsch diesel (FTD). The study included fuel production, vehicle production, vehicle operation, infrastructure and vehicle end of life as a system for each fuel/vehicle system. A generic gasoline fueled car is used as a baseline. Data have been reviewed and modified based on the best knowledge available to Chongqing local sources. Results indicated that when we could not change electric and hydrogen fuel cell vehicles into commercial vehicles on a large scale, direct use of CNG in a dedicated or bi-fuel vehicle is an economical choice for the region which is most energy efficient and more environmental friendly. The study can be used to support decisions on how natural gas resources can best be utilized as a fuel/energy resource for automobiles, and what issues need to be resolved in Chongqing. The models and approaches for this study can be applied to other regions of China as long as all the assumptions are well defined and modified to find a substitute automotive energy source and establish an energy policy in a specific region.  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