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   2683篇
  免费   167篇
  国内免费   155篇
安全科学   253篇
废物处理   30篇
环保管理   1013篇
综合类   752篇
基础理论   435篇
环境理论   2篇
污染及防治   188篇
评价与监测   197篇
社会与环境   95篇
灾害及防治   40篇
  2024年   5篇
  2023年   33篇
  2022年   34篇
  2021年   69篇
  2020年   104篇
  2019年   59篇
  2018年   41篇
  2017年   84篇
  2016年   99篇
  2015年   96篇
  2014年   116篇
  2013年   121篇
  2012年   104篇
  2011年   168篇
  2010年   99篇
  2009年   203篇
  2008年   133篇
  2007年   141篇
  2006年   124篇
  2005年   115篇
  2004年   94篇
  2003年   119篇
  2002年   109篇
  2001年   77篇
  2000年   102篇
  1999年   87篇
  1998年   65篇
  1997年   38篇
  1996年   50篇
  1995年   46篇
  1994年   27篇
  1993年   36篇
  1992年   26篇
  1991年   18篇
  1990年   16篇
  1989年   18篇
  1988年   14篇
  1987年   11篇
  1986年   9篇
  1985年   8篇
  1984年   5篇
  1983年   5篇
  1982年   11篇
  1981年   12篇
  1980年   13篇
  1979年   15篇
  1978年   11篇
  1977年   5篇
  1974年   2篇
  1970年   2篇
排序方式: 共有3005条查询结果,搜索用时 54 毫秒
861.
上海市2003年生态足迹计算与分析   总被引:15,自引:2,他引:13  
叶田  杨海真 《四川环境》2005,24(3):15-18
本文应用Wackernagel等提出的生态足迹概念和方法对上海区2003年的生态足迹和承载力进行计算和分析。结果表明,2003年上海市人均生态足迹为3.36hm^2,人均生态承载力为0.46hm^2。在此基础上提出了减缓上海市生态赤字的一系列措施,最后对模型的完善作出了展望。  相似文献   
862.
发展生态第三产业是生态城区建设的必然要求.本文以长沙市芙蓉区为例,在分析了芙蓉区第三产业现状的基础上,提出了建设生态第三产业的发展对策.  相似文献   
863.
生态补偿机制及其对相关利益主体的影响   总被引:7,自引:0,他引:7  
以建立和完善生态环境补偿机制的时代背景为出发点,在阐述生态补偿机制内涵的基础上,从政治生态学的角度分析生态补偿机制的运行对各相关利益主体的影响与作用,并对我国生态补偿机制的进一步完善提出对策建议。  相似文献   
864.
中国现有的生态环境建设的立法,缺乏对生态环境建设基本法律制度系统而明确的规定,无法满足生态环境建设的实际需要.针对现状,就中国生态环境建设的基本法律制度加以探讨,以期完善生态环境建设的立法规定.  相似文献   
865.
ABSTRACT: Several methods have been developed to interpolate point rainfall data and integrate areal rainfall data from any network of stations. From previous studies, it can be concluded that models for spatial analysis of rainfall are dependent on topography, area of analysis, type of rainfall, and density of gauging network. The purpose of this study is to evaluate a set of six appropriate models for point and areal rainfall estimations over a 4000 square mile area in South Florida. In this study, a case of developing spatial continuity model for monthly rainfall from a database that had various lengths of records and missing data is documented. The spatial correlation and variogram models for monthly rainfall were developed. Six methods of spatial interpolation were applied and the results validated with historical observations. The results of the study indicate that the multiquadric, kriging, and optimal interpolation schemes are the best three methods for interpolation of monthly rainfall within the study area. The optimal and kriging methods have the advantage of providing estimates of the error of interpolation. The optimal interpolation method uses the spatial correlation function and the kriging method uses the variogram function. The two spatial functions are related. Either of the two methods provide good estimates of monthly point and areal rainfall in the study area.  相似文献   
866.
Simulation and control strategy for the variational influent of WWTP   总被引:2,自引:0,他引:2  
With the development of activated sludge model, the simulation software for the design and operation of wastewater treatment plant (WWTP) was produced and has been widely used. The dynamic change of the quality and flow of influent are major factors causing the unstable operation of wastewater treatment process. As a basic model, ASMI model was used for the simulation of activated sludge process, and double exponential model was selected for the simulation of secondary sedimentation tank. The influences of influent change to the aeration tank and secondary sedimentation tank were investigated, and the relationship among influent change, the quality of effluent and the level of sludge blanket in secondary sedimentation tank was established. On the basis of the simulation results, the operation of the WWTP could be adjusted under the dynamic change of the influent. Furthermore, the controlling strategy combined the feed-forward on the influent flow and the feedback on the level of sludge blanket in the secondary sedimentation tank was studied.  相似文献   
867.
This study was undertaken to determine the importance of riparian buffers to stream ecology in agricultural areas. The original Maryland Biological Stream Survey (MBSS) data set was partitioned to represent agricultural sites in Maryland's Coastal Plain and Piedmont regions. ANOVA, multiple linear regression (MLR), and CART regression tree models were developed using riparian and site catchment landscape characteristics. MBSS data were both stratified by physiographic region and analyzed as a combined data set. All models indicated that land management at the site was not the controlling factor for fish IBIs (FIBI) at that site and, hence, using FIBI to evaluate site-scale factors would not be a prudent procedure. Measures of instream habitat and location in the stream network were the dominant explanatory factors for FIBI models. Both CART and MLR models indicated that forest buffers were influential on benthic IBIs (BIBI). Explanatory variables reflected instream conditions, adjacent landscape influence, and chemistry in the Coastal Plains sites, all of which are relatively site specific. However, for Piedmont sites, hydrologic factors were important, in addition to adjacent landscape influence, and chemistry. Both Coastal Plain and Piedmont CART models identified several hydrologic factors, emphasizing the dominant control of hydrology on the physical habitat index (PHI). Riparian buffers were a secondary influence on PHI in the Coastal Plain, but not in the Piedmont. Between 40% and 70% of the variation in FIBI, BIBI, and PHI was explained by the “easily obtainable” variables available from the MBSS data set. While these are empirical results specific to Maryland, the general findings are of use to other locations where the establishment of forest buffers is considered as an aquatic ecosystem restoration measure.  相似文献   
868.
城市垃圾填埋场生态恢复工程表面覆盖材料的研究   总被引:9,自引:2,他引:7  
以青岛市湖岛垃圾填埋场作为试验点,对城市垃圾填埋场生态恢复工程的表面覆盖处理技术中的材料选择进行了研究。对城市垃圾场生态恢复工程表面处理中覆盖材料的选择指标主要取决于其投入费用和生态恢复的产出效益,同时因恢复工程的设计方案和填埋地点而异。对以降低投入为优选因子或以获得植物产出效益为主要目的的设计方案,分别推荐已分解的垃圾土和砂土为覆盖材料。   相似文献   
869.
滇池生态动力学模型的改进   总被引:8,自引:0,他引:8       下载免费PDF全文
在分析滇池生态系统的基础上,从滇池浮游植物的优势种出发,根据各种藻大的生长特性.分别给予不同的温度限制因子,以此推求其增殖速率,并根据不同时期、不同地点优势藻种的构成比,加权出该时段浮游植物总的生长率。这一改进克服了以往模拟计算中把参数取为常数的缺陷.较好地模拟了浮游植物的生长过程和TN、TP等水质指标的年内变化情况。   相似文献   
870.
西子生态农场的综合开发利用研究   总被引:8,自引:0,他引:8  
介绍了西子生态农场建设的情况。农场采用德国引进的固液分离技术处理畜禽粪便,制取沼气,沼气发电用于整个农场。沼液,沼渣得到综合利用、整个农场实现污水循环使用,取得了良好的经济效益。,社会效益和生态效益,具有推广价值。  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