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   5209篇
  免费   106篇
  国内免费   78篇
安全科学   224篇
废物处理   257篇
环保管理   1335篇
综合类   461篇
基础理论   1231篇
环境理论   5篇
污染及防治   1271篇
评价与监测   370篇
社会与环境   189篇
灾害及防治   50篇
  2023年   27篇
  2022年   25篇
  2021年   53篇
  2020年   36篇
  2019年   65篇
  2018年   81篇
  2017年   108篇
  2016年   128篇
  2015年   125篇
  2014年   116篇
  2013年   595篇
  2012年   186篇
  2011年   265篇
  2010年   200篇
  2009年   208篇
  2008年   282篇
  2007年   286篇
  2006年   245篇
  2005年   180篇
  2004年   200篇
  2003年   198篇
  2002年   176篇
  2001年   96篇
  2000年   115篇
  1999年   104篇
  1998年   76篇
  1997年   70篇
  1996年   80篇
  1995年   81篇
  1994年   73篇
  1993年   73篇
  1992年   77篇
  1991年   46篇
  1990年   58篇
  1989年   47篇
  1988年   41篇
  1987年   45篇
  1986年   49篇
  1985年   44篇
  1984年   51篇
  1983年   52篇
  1982年   41篇
  1981年   55篇
  1980年   48篇
  1979年   27篇
  1978年   28篇
  1977年   20篇
  1976年   16篇
  1975年   14篇
  1971年   14篇
排序方式: 共有5393条查询结果,搜索用时 968 毫秒
381.
ABSTRACT: A water use model was developed to estimate water savings from installation of low-flow showerheads and toilet displacement devices in residential housing. The model measures household water use in per capita terms with adjustments for age of occupants, household income, if occupants responsible for direct payment of water bill, and type of water fixtures. Detailed data on 308 single family residences involved with a pilot retrofit program in the Seattle, Washington, area were analyzed. We estimated per capita indoor water use to decline by 6.4 and 2.1 percent from complete installation of low-flow showerheads and toilet displacement devices, respectively.  相似文献   
382.

News And Comments

Restoring a ravished Island  相似文献   
383.
384.
This research demonstrates the contribution of phenomenological inquiry within the realm of geographic and environmental planning. The contention is that a focus on the wide range of individual meanings and values ascribed to landscapes, a marginalized element in many planning assessments, can bring out data to more substantively inform decision making, A case study of user meanings imparted to residual waterfront land in Hoboken, New Jersey, USA, suggests that such property provides an array of amenities to residents. Most importantly, it expands the range of recreational activities, creates visual relief from the monotonous urban milieu, and provides scenic vistas to promote an awareness of the quality of life still possible in cities. The study concludes that planners can use phenomenology to generate data for more judicious decision making.  相似文献   
385.
Data are presented for a particular population on its perception of English and Welsh local authority areas in terms of desirability for residence. The method employed permits a distinction between positive and negative judgements as well as a measure of the differing degree to which areas figure in the mind at all. It is established that the areas are seen in terms of a sharply differentiated hierarchy of preference and that there is considerable variation in the extent to which areas are “visible”. In aggregate negative judgements predominate and the most frequently expressed attitude is strong dislike. Places in the south‐west are popular as are some places in the north. London Boroughs are unpopular although in varying degrees. The most favoured place is Cornwall and the least favoured is Wolverhampton. It is argued that perceptions studied in the “direct” way used here are important to complement those employing an “oblique” method in which criteria of choice are assumed or established by social survey and then used to create a profile of preference against which places can be measured and ranked.  相似文献   
386.
ABSTRACT: A method to evaluate the effect of hydropower development on downstream dissolved oxygen (DO) is presented for a low head dam. Water, previously aerated during release over spillways and under gates, is diverted through the hydropower facility without further aeration. The oxygen transfer that occurs as a result of air entrainment at the various release points of a dam is measured. Oxygen transfer efficiencies are calculated and incorporated into an oxygen transfer model to predict average release DO concentrations. This model is used to systematically determine the effect of hydropower operation on downstream DO. Operational alternatives are investigated and a simple operational guide is developed to mitigate the effects of hydropower operation. Combinations of reduced generation and optimal releases from the dam allow the hydropower facility to operate within DO standards.  相似文献   
387.
ABSTRACT: Irrigation development of the dolomite aquifer in eastera Kankakee and northern Iroquois Counties, Illinois, is extensive and increasing. Interruptions of domestic supplies have been reported with increasing frequency during the 1980's. To address this issue, a regional assessment of the ground-water resources of the region was conducted in 1987 and 1988. Options for managing the dolomite aquifer were also investigated. Hydrogeology of the dolomite aquifer was determined using five aquifer tests. Tranamissivity values of the dolomite aquifer ranged from 14,000 to 50,000 gpd/ft (168 to 600 m3/m/day). Storage coefficients were between 0.0001 and 0.0002, within the range of a confined (artesian) aquifer. Based on flow-net analyses, recharge of the dolomite aquifer ranged from 85,000 to 285,000 gpd/mi2 (124.4 to 417.0 m3/day/km2). Water levels of the dolomite aquifer were mapped during five periods in 1987 and 1988 by measuring up to 226 wells completed in the dolomite aquifer. Maximum regional water-level declines because of irrigation pumpage were 44 feet (13.4 m) in 1987 and 72 feet (21.9 m) during the drought of 1988. Based on ground-water use data, precipitation records, and hydrogeologic information, the magnitude of water-level declines can be attributed more to differing hydrogeologic conditions than to pumpage or climatic changes. Existing ground-water management methods for resolving conflicts over the ground-water resources of the study area are reviewed and alternative management options explored.  相似文献   
388.
ABSTRACT: This article, based on a review of the literature, examines several aspects of the rhizosphere ecology of submersed macrophytes. These include the role of the rhizosphere microflora in affecting plant growth through influences on nutrient availability and production of plant growth regulating compounds. Interactions between components of the sediment microflora and plant roots are considered in relation to plant nitrition and growth. Possible applications of this information to the management of submersed macrophytes are considered.  相似文献   
389.
390.
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