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   1084篇
  免费   62篇
  国内免费   219篇
安全科学   27篇
废物处理   3篇
环保管理   276篇
综合类   599篇
基础理论   96篇
污染及防治   94篇
评价与监测   71篇
社会与环境   142篇
灾害及防治   57篇
  2024年   3篇
  2023年   22篇
  2022年   49篇
  2021年   36篇
  2020年   29篇
  2019年   21篇
  2018年   36篇
  2017年   44篇
  2016年   57篇
  2015年   62篇
  2014年   56篇
  2013年   64篇
  2012年   81篇
  2011年   80篇
  2010年   67篇
  2009年   77篇
  2008年   49篇
  2007年   53篇
  2006年   68篇
  2005年   45篇
  2004年   39篇
  2003年   44篇
  2002年   38篇
  2001年   21篇
  2000年   24篇
  1999年   18篇
  1998年   15篇
  1997年   10篇
  1996年   15篇
  1995年   9篇
  1994年   8篇
  1993年   14篇
  1992年   21篇
  1991年   7篇
  1990年   14篇
  1989年   4篇
  1988年   7篇
  1987年   6篇
  1986年   5篇
  1984年   2篇
  1982年   5篇
  1981年   6篇
  1980年   8篇
  1979年   5篇
  1977年   2篇
  1975年   2篇
  1973年   2篇
  1972年   7篇
  1971年   4篇
  1969年   1篇
排序方式: 共有1365条查询结果,搜索用时 31 毫秒
871.
垃圾渗滤液调节池工艺设计   总被引:3,自引:0,他引:3  
分析了影响垃圾填埋场渗滤液产生量多少的因素,比较了渗滤液产量的计算方法,并通过工程实例计算了渗滤液产量及调节池容积,在调节池设计上采用了浮盖技术,以满足渗滤液预处理功能和控制蚊蝇滋生及臭气外逸,目的是便于有关人员在使用《生活垃圾卫生填埋技术规范》(CJJ17—2004)标准时能正确理解调节池设计规定。  相似文献   
872.
The Alfeios River, the longest and highest flow-rate river in Peloponnisos, constitutes an important water resource and ecosystem in Greece. In the present study, human activities in the Alfeios River Basin are described, and their impacts on water quality and the ecosystem are analyzed; effects resulting from interventions on river geomorphology between Flokas Dam and the river delta are determined. These actions have caused significant adverse impacts on the infrastructure (the dam, railroad, and road bridges), the level of aquifer water table and area water uses, and the aquatic and riparian ecosystem. A general integrated management strategy is formulated and a master management plan is proposed for resolving management problems in river basins. The plan considers local conditions and national requirements and complies with the European Communities legislation; it would help prevent further basin deterioration, improve water quality, and protect water resources and ecosystems in the area in accordance to sustainable development. The Alfeios River Basin serves as a case study in the development of the plan.Published online Note: This version was published online in June 2005 with the cover date of August 2004.  相似文献   
873.
The Guanabara Bay basin, SE Brazil, is shown as an experimental site to evaluate development and sustainability in coastal areas. We developed a Driver–Pressure–State–Impact–Response (DPSIR) framework in a practical context to integrate natural and socio-economic indicators. Sustainability reflects public policies towards the utilization of natural resources. Cost-benefit analysis (CBA) included in DPSIR evaluates losses and benefits resulting from such policies. CBA has some limitations due to the difficulty of valuating environmental goods and services. Instead of valuating them we propose to combine sustainability indicators and defensive expenditures for the implementation of public policies. This approach agrees with the environmental conservation paradigm implicit in sustainable development. It allows an estimation of the physical natural capital depreciation (PNCD), by using it to correct the gross domestic product (GDP) of the study area, and demonstrating the present non-sustainable characteristics of the current policies applied to the area.  相似文献   
874.
Over the past 35 years, a trend of decreasing water clarity has been documented in Lake Tahoe, attributable in part to the delivery of fine grained sediment emanating from upland and channel erosion. A recent study showed that the Upper Truckee River is the single largest contributor of sediment to Lake Tahoe, with a large proportion of the sediment load emanating from streambanks. This study combines field data with numerical modeling to identify the critical conditions for bank stability along an unstable reach of the Upper Truckee River, California. Bank failures occur during winter and spring months, brought on by repeated basal melting of snow packs and rain‐on‐snow events. Field studies of young lodgepole pines and Lemmon's willow were used to quantify the mechanical, hydrologic, and net effects of riparian vegetation on streambank stability. Lemmon's willow provided an order of magnitude more root reinforcement (5.5 kPa) than the lodgepole pines (0.5 kPa); the hydrologic effects of the species varied spatially and temporally and generally were of a smaller magnitude than the mechanical effects. Overall, Lemmon's willow provided a significant increase in bank strength, reducing the frequency of bank failures and delivery of fine grained sediment to the study reach of the Upper Truckee River.  相似文献   
875.
ABSTRACT: This paper examines irrigation water supply deficit and associated risk indicators due to random climate events and potential effects on irrigated food production during the period 1996 to 2025 for seven river basins in the USA, China, and India. An integrated water and food model with global scope is applied for the analysis. The global climate regime during 1961 to 1990 is used to generate 30 climatic scenarios for the time period 1996 to 2025, and these scenarios are applied to the model in order to characterize the randomness of precipitation, runoff, and evapotranspiration, which affects both irrigation water supply and demand. The risk with random climate events is represented by reliability, variability, and vulnerability from different perspectives. Regarding irrigation water supply, Colorado will bear an increasingly unstable situation although the average water supply relative to the demand will maintain at a relatively high level; selected basins in China and India indicate that significantly lower levels of reliability and more deleterious affects from drought can be expected, but under a less variable condition due to assumed water storage increase. From 1996 to 2025, the effects of water deficits on irrigated food production are characterized with a nonlinear phenomenon and food production loss will be more sensitive to irrigation water supply deficit in the future. Future work following this paper needs to consider the impact of global climate change and the water quality of the irrigation return flow and result verification by local studies.  相似文献   
876.
目前在高职高专数学教育中存在着只注重数学知识、数学思维、数学思想的研究和教学的现象,而数学教学中应体现的人文精神却常常被忽视了。本文分析了数学教学中蕴涵的人文精神,并提出应坚持自觉性与渗透性的原则,加强数学教学中人文精神培养。  相似文献   
877.
苏南太湖地区乡镇工业水污染综合防治研究   总被引:1,自引:0,他引:1  
分析了苏南太湖地区迅猛发展的乡镇工业对水环境造成的污染,并提出了综合防治对策和意见:①利用水环境容量,合理布局乡镇工业;②合理调整行业结构;④积极开展生产全过程的排污控制;④认真进行废水治理,切实加强环境管理。  相似文献   
878.
詹兆渝  余勇 《灾害学》1992,7(1):1-5
本文通过建立气象灾害评定的模糊数学模式,对四川盆地农业气象灾害进行评定。使评定语言从定性跃入定量,评定对象从单类展向整体,而且评定时序从无序深入有序,得到了一致的历史序列。  相似文献   
879.
黑河流域退化生态系统恢复与重建问题探讨   总被引:4,自引:0,他引:4  
黑河流域是河西走廊主要的内陆流域之一。本文在简要分析流域生态退化现象以及生态恢复与重建实质的基础上 ,讨论和提出了黑河流域退化生态系统恢复重建的基本思路和不同生态类型区生态优化的方向 ,进一步提出了生态恢复重建的基本框架构想和基本对策  相似文献   
880.
猫跳河流域开发与环境质量变异   总被引:9,自引:0,他引:9  
猫跳河流域经过30多年以水能为先导的开发,已成为贵州经济最发达的区域,但是。由于区内工业集中、人口膨胀等多种因素的影响,也导致环境及生态系统发生变化,出现资源—经济—环境的较大矛盾。本文通过众多的调查研究资料,对猫跳河流域开发所引起的环境问题:人口变化、水利水电引起环境变异、水环境变异、大气环境质量变异、野生生物衰亡及生境变异、土地环境变异作了闸述,并对流域开发的综合效应进行了全面分析。  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