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   700篇
  免费   5篇
  国内免费   32篇
安全科学   4篇
废物处理   1篇
环保管理   207篇
综合类   170篇
基础理论   143篇
环境理论   1篇
污染及防治   148篇
评价与监测   39篇
社会与环境   24篇
  2023年   1篇
  2022年   11篇
  2021年   20篇
  2020年   8篇
  2019年   10篇
  2018年   7篇
  2017年   22篇
  2016年   40篇
  2015年   18篇
  2014年   20篇
  2013年   26篇
  2012年   16篇
  2011年   65篇
  2010年   45篇
  2009年   64篇
  2008年   58篇
  2007年   40篇
  2006年   29篇
  2005年   13篇
  2004年   16篇
  2003年   24篇
  2002年   20篇
  2001年   19篇
  2000年   17篇
  1999年   20篇
  1998年   14篇
  1997年   14篇
  1996年   13篇
  1995年   9篇
  1994年   6篇
  1993年   5篇
  1992年   9篇
  1991年   5篇
  1990年   7篇
  1989年   1篇
  1988年   3篇
  1987年   5篇
  1986年   4篇
  1985年   3篇
  1984年   2篇
  1982年   2篇
  1981年   2篇
  1980年   1篇
  1978年   1篇
  1977年   1篇
  1967年   1篇
排序方式: 共有737条查询结果,搜索用时 0 毫秒
161.
滇池的污染及其控制对策   总被引:10,自引:0,他引:10  
滇池是昆明市的主要水源,是昆明市国民生产发展的经济命脉。由于人类活动的影响,导致滇池湖泊生态系统发生了一系列变迁.汇水区域森林覆盖率降低;水土流失严重,湖泊水域缩小,水体有机污染及富营养化日趋严重;水体质量下降;湖泊老化等环境问题、针对问题,采取综合治理措施。  相似文献   
162.
王勇  董亮 《环境科技》2005,18(Z1):73-75
随着工业污染源的有效控制,非点源污染已经成为我国重要污染类型之一,如何科学地认识并有效控制非点源污染已成为研究课题.在此介绍了非点源的基础工具--非点源模型的主要类型、结构和特点,并对目前主要的非点源模型进行了比较分析,探讨了非点源模型发展的趋势.  相似文献   
163.
We describe conceptual and simulation models of land use within the intertidal zone of the Guayas River estuary to quantify the contribution of mangrove wetlands to maintaining environmental quality of a tropical estuary. The goal of this exercise is to demonstrate the important consideration of ecological constraints in determining economic and management decisions; and how modeling can be used to quantify impacts of land use such as loss of mangrove wetlands on environmental quality. Our conceptual model treats solar energy, river flow, and tides as forcing functions that control the properties of estuarine ecosystems, but also describes market forces and cultural policies as constraints on properties of socioeconomic systems. The controversy of coastal resource management in Ecuador centers around the relative impacts of shrimp pond construction and management as negative feedbacks to the environmental quality of the Guayas River estuary. Unique oceanographic processes and land use changes contribute to complex issues of water and habitat quality in this tropical estuary, the largest estuarine complex on the Pacific coast of South America. A dynamic box model was developed for the estuary and calibrated with data collected from a 14 month survey of water quality parameters throughout the estuary. Scenarios included conversion of mangroves to shrimp ponds in three regions of the estuary, and the construction of a dam by varying three different rates of river discharge at 100, 50 and 10% of 1989 base flow. Good water quality is maintained by the low residence time of water in the estuary (11 d) because of seasonally high river flow and tidal exchange. With a 90% reduction of mangrove forests in the estuary caused by shrimp pond construction, total nitrogen concentrations increased 5 fold. However, as river discharge decreased to 10%, the same construction caused a 60 fold increase in nitrogen concentrations to 250 μM. Increases in nitrogen concentrations were higher in the upper estuary region, with much less change in the lower estuary. Thus the sensitivity of environmental quality to changes in land use in the intertidal and upland zone are linked to the hydrography of the estuary and is site specific. In the future, the combinations of these ecological models together with economic analyses of the goods and services of mangroves may provide better techniques to evaluate the economic impacts of specific coastal zone management decisions.  相似文献   
164.
The activity of fish monooxygenases has been extensively used as a monitoring tool to detect contamination of water bodies by cytochrome P450-inducing agents. In this study we evaluated the activities of ethoxy- (EROD), methoxy- (MROD) and pentoxy- (PROD) resorufin-O-dealkylases in the liver of Nile tilapias (Oreochromis niloticus) collected at the Guandu river, at a reference clean site (Lake 1) and at two other sampling sites (Lakes 2 and 3) in Rio de Janeiro state, Brazil. Alkoxyresorufin-O-dealkylases were measured fluorimetrically in the hepatic S9 fraction. EROD (17.7-fold), MROD (14.2-fold) as well as PROD activities were considerably higher in tilapias from Guandu river. A moderate increase of EROD (5.0-fold) and MROD (5.4-fold) was also found in tilapias from Lake 3. These findings suggest that Guandu river watershed, the main source of urban drinking water supply in Rio de Janeiro, is polluted with CYP1A-inducing xenobiotics. Furthermore, we also found a good linear relationship between EROD and MROD, a finding that agrees with the hypothesis that the two reactions are catalysed by the same CYP1A isoform in O. niloticus.  相似文献   
165.
Sundarban mangrove ecosystem in India is one of the largest detritus based ecosystem of the world and it supplies the detritus and nutrients to the adjacent Hooghly-Matla estuarine complex. In this estuary a group of fish completely detritivorous in nature, belonging to the genus Mugil spp. is present. This group of fish is expected to have important effects on the trophic dynamics of ecosystems, but exact nature of these effects is not known. In order to study the impact that detritivory by fish may have on the estuarine food chain, we developed mathematical formulations. We run two models, one with phytoplankton, zooplankton, carnivorous fish, detritus and nutrient and without this group of fish and a second one after including this fish in the system. In our model this group of fish has no major impact on primary productions of the estuarine system but has extensive role in total fish production. Coexistence of detritivorous fish and carnivorous fish occurs within reasonable parameter range. We have tested different growth rates of phytoplankton, grazing rates and predation rates of zooplankton, detritivorous fish and carnivorous fish for total system equilibrium. Carnivorous fish predation rate on detritivorous fish and detritivorous fish grazing rate on detritus are very important. Different foraging ratios are also tested in this study. Foraging preference of carnivorous fish on detritivorous fish appears significant for the system equilibrium.  相似文献   
166.
山地可持续人居环境初探   总被引:1,自引:0,他引:1  
传统的山地人居环境是建立在传统的农业社会经济、文化基础之上的对自然环境的被动式生态适应,缺少居安安全性、便捷性、舒适性等生活基本保证。现代山地人居环境将以现代生态学为指导,突破山地特殊生态特性对人类的制约,实现人与山地自然和谐共生,满足社区居民物质和精神双重层次的需求,从而真正成为可持续发展的人居环境。  相似文献   
167.
我国利用水生植物监测和净化污水的研究进展   总被引:1,自引:0,他引:1  
本文综述了我国利用水生植物监测和净化重金属废水、化工废水、生活污水、放射性核素废水以及抑制富营养化水体中藻类研究进展。并讨论了各种生态因子对水生植物净化效率的影响。为建立低投资、高效率、易管理的植物净化处理设施提供参考。  相似文献   
168.
辽北地区水生昆虫与水质监测试验   总被引:1,自引:0,他引:1  
辽北地区水生昆虫与水质监测的试验是采用美国昆虫学家莫尔斯.约翰提出的监测模式进行的。文中重点阐明了水生昆虫的采样方法、生境观察指标、污染指数值确定方法、评价标准,并进行了应用实例分析。研究结果表明,水生昆虫监测方法适用于快速监测和评价河流水质。  相似文献   
169.
生态文明下城市复合生态管理模式与对策   总被引:1,自引:1,他引:0  
党的"十八大"明确了以资源节约利用、生态环境保护为基础的生态文明建设的原则,该研究正是基于生态文明的理念下,从城市规划、产业结构、资源政策、环境承载力以及公众参与等5个方面对城市生态管理模式进行了多维性思考,指出只有坚持规划先行、优化升级产业结构、提高资源的政策调控、增强环保意识、探索多元化的公众参与模式,才是实现我国城市生态建设协调健康发展的基础,同时也指出城市复合生态管理才是我国未来城市生态建设的发展趋势,是我国城市生态管理模式发展的现实需求。该研究期望能够正确把握生态文明下城市生态管理的本质内涵,为日益市场化的城市提供高水平的城市生态管理范本,也为实现长久、稳定的可持续发展提供理论依据和指导思想。  相似文献   
170.
Owing to their widespread use in wooden products, industrial products, cosmetics, and personal care products, biocides are frequently detected in wastewater and surface water. In this study, I examined the acute toxicities of 10 commonly used biocides, namely methylisothiazolinone, benzisothiazolinone, octylisothiazolinone, dichlorooctylisothiazolinone, iodopropynyl butylcarbamate, triclosan, azoxystrobin, pyraclostrobin, climbazole, and clotrimazole, in the water flea (Daphnia similis), freshwater planarians (Dugesia japonica) and green neon shrimp (Neocaridina denticulata). Among the 10 tested biocides, dichlorooctylisothiazolinone was the most toxic to both D. similis and N. denticulata, whereas pracolstrobin was the most toxic to Du. japonica. By contrast, the least toxic biocides for D. similis, Du. japonica, and N. denticulata were climbazole, iodopropynyl butylcarbamate, and methylisothiazolinone, respectively. The 48-h nominal LC50 values of all the biocides, except for benzisothiazolinone and climbazole, in D. similis were mostly less than 1 mg/L. In addition, the 96-h nominal LC50 values of all the biocides, except for methylisothiazolinone and iodopropynyl butylcarbamate, in Du. japonica was less than 1 mg/L. These results indicate the biocides with low LC50 values are relatively toxic to freshwater organisms.  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