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   165篇
  免费   10篇
  国内免费   31篇
安全科学   13篇
废物处理   21篇
环保管理   43篇
综合类   64篇
基础理论   10篇
污染及防治   23篇
评价与监测   13篇
社会与环境   8篇
灾害及防治   11篇
  2024年   1篇
  2023年   3篇
  2022年   4篇
  2021年   2篇
  2020年   5篇
  2019年   2篇
  2018年   2篇
  2017年   3篇
  2016年   3篇
  2015年   6篇
  2014年   4篇
  2013年   17篇
  2012年   10篇
  2011年   14篇
  2010年   14篇
  2009年   14篇
  2008年   11篇
  2007年   12篇
  2006年   7篇
  2005年   7篇
  2004年   7篇
  2003年   6篇
  2002年   5篇
  2001年   18篇
  2000年   5篇
  1999年   3篇
  1998年   1篇
  1997年   1篇
  1995年   1篇
  1993年   4篇
  1992年   1篇
  1991年   2篇
  1990年   1篇
  1989年   1篇
  1987年   1篇
  1986年   1篇
  1984年   2篇
  1982年   1篇
  1981年   1篇
  1979年   1篇
  1977年   1篇
  1972年   1篇
排序方式: 共有206条查询结果,搜索用时 46 毫秒
111.
火灾荷载的选取是设计火灾的重要环节,同时也是保证火灾风险评估科学可靠的关键因素。火灾荷载的实地调查和统计分析是火灾荷载研究工作的重要手段。通过对全国各地23家KTV娱乐场所的349个包间进行调查,统计出KTV包间可燃物种类、质量情况以及不同可燃物所占质量比。并且,通过调查得出KTV包间的面积情况。对所调查的349个包间的火灾荷载分布情况进行研究,利用数理统计的方法得到了该类场所火灾荷载密度、均值、最大值、最小值等数据,为火灾风险评估中火灾场景的设计提供了数据基础。  相似文献   
112.
首先通过3个墙片的水平低周反复伪动力试验,对比研究了混凝土板墙加固后墙片与剪力墙的承载力、耗能能力等各项抗震性能.由于试验条件的限制,试验仅对比研究了120 mm混凝土剪力墙与双面60 mm混凝土板墙加固后墙片的抗震性能.在试验基础上,利用有限元软件建立合理的计算模型,将计算结果与试验结果进行了对比分析;利用该计算模型...  相似文献   
113.
Curtis  C. J.  Barbieri  A.  Camarero  L.  Gabathuler  M.  Galas  J.  Hanselmann  K.  Kopaček  J.  Mosello  R.  Nickus  U.  Rose  N.  Stuchlik  E.  Thies  H.  Ventura  M.  Wright  R. 《Water, Air, & Soil Pollution: Focus》2002,2(2):115-126
Critical load models for acidityprovide a measure of the sensitivity of surfacewaters to acid deposition, and can be used todetermine critical load exceedance and potentiallong-term harmful effects. Three static models,the Steady-State Water Chemistry model, diatommodel and First-order Acidity Balance model, arehere applied to 11 high mountain lakes in Norway,Scotland, the Alps, the Pyrenees and the Tatras.Between five and seven of the lakes show criticalload exceedance, depending on the model used.Nitrogen as well as sulphur deposition isimportant in causing exceedance. Since soil andvegetation cover are generally sparse, geologyand lake retention time appear to be key factorsin the determination of critical load. Retentionof nitrogen is observed, but it is unclearwhether this occurs within the lake or theterrestrial part of the catchment.  相似文献   
114.
Critical Loads and levels have played a centralrole in the successful development of effect-based emissionreduction strategies for Europe in the fields of acidification,eutrophication and ground-level ozone. The aim of theInternational Programme on Mapping Critical Loads and Levelsled by Germany, with participation of 24 countries, is todetermine critical loads and levels for forest, crops, naturalvegetation, soils, water and materials. The exceedances ofcritical loads and critical levels are used to quantify the riskfor environmental damage by air pollution and tosupport the development of optimised abatement strategies.  相似文献   
115.
1950年以来鄱阳湖流域水沙变化规律及影响因素分析   总被引:1,自引:0,他引:1  
运用Mann-Kendall趋势检验法和回归分析等方法,对鄱阳湖流域赣江外洲站、抚河李家渡站、信江梅港站、饶河虎山站和修水万家埠站1950~2012年径流量和1956~2012年输沙量的变化进行了系统分析,并探讨了水沙变化的原因。研究结果表明:(1)鄱阳湖流域五大河流水沙的趋势变化特征相异,除李家渡站径流无明显趋势变化外,其余各站均呈不显著的增加趋势(未超过α=0.05显著性检验临界值);外洲站、梅港站和李家渡站输沙量呈减少的趋势变化,且1985年以后呈显著的减少趋势,而虎山站和万家埠站输沙量在1965~1999年呈不显著的增加趋势,1999年以后才开始减少;(2)入湖总水量呈不显著的增加趋势,发生突变的年份为1992年;入湖总沙量呈显著的减少趋势,发生突变的年份为1996年,入湖总沙量突变滞后于入湖总水量;(3)流域径流量变化主要受降雨量的影响,而输沙量变化主要受水土保持和水库建设等人类活动的影响,且水库拦沙是鄱阳湖流域输沙量减少的主要原因。  相似文献   
116.
Bacterial contamination accounts for more than 60% of the impairments included on the 2008 Texas 303(d) List. Many of these bacterial impairments are along the Texas Gulf Coast because coastal waters often are regulated for oyster harvesting, which have strict water quality standards. Under the Clean Water Act, each one of these impaired waterbodies requires a total maximum daily load (TMDL) study to be performed. A recent, statewide study recommended the development and application of simple modeling approaches to address the majority of Texas's bacteria TMDLs, including “… simple load duration curve, GIS [geographic information systems], and/or mass balance models.” We developed the TMDL Balance model in response to this recommendation. TMDL Balance is a steady state, mass balance, GIS‐based model for simulating pollutant loads and concentrations in coastal systems. The model uses plug‐flow reactor and continuously‐stirred tank reactor equations to route spatially distributed point and nonpoint source loads through a watershed via overland flow, non‐tidal flow, and tidal flow, decaying the loads via first‐order kinetics. In this paper, we explain the development of the watershed loading portion of the TMDL Balance model, demonstrating the methodology through a case study: computing bacterial loads in the Copano Bay watershed of southeast Texas. The application highlights an example of distributing bacterial sources spatially based on land use data.  相似文献   
117.
A computer driven technique to analyze lifting forces, in non-homogeneous load situations, is described and tested. Analysis is based on a dynamic algorithm aimed to evaluate unconstrained lifting posture and non-homogeneous content of loads. For inputs we use actual geometrical body postures in the form of 3-dimensional co-ordinates obtained from pictures taken at a work site. The outputs show a good match between the findings and pre-study assumptions for balanced and non-balanced load lifting practice. The results of the experiments show a good degree of correlation with results reported by researchers for symmetrical lifting tasks and with National Institute for Occupational Health (NIOSH) lifting guidelines. It is believed that the technique can serve as the proper choice for industrial and safety analysts of lifting activities.  相似文献   
118.
ABSTRACT: Rainfall is a significant source of some constituents, particularly nitrogen species, in storm runoff from urban catchments. Median contributions of rainfall to storm runoff loads of 12 constituents from 31 urban catchments, representing eight geographic locations within the United States, ranged from 2 percent for suspended solids to 74 percent for total nitrite plus nitrate nitrogen. The median contribution of total nitrogen in rainfall to runoff loads was 41 percent. Median contributions of total-recoverable lead in rainfall to runoff loads varied by as much as an order of magnitude between catchments in the same geographic location. This indicates that average estimates of rainfall contributions to constituent loading in storm runoff may not be suitable in studies requiring accurate constituent mass-balance computations.  相似文献   
119.
Critical loads of cadmium, lead and mercury were computed by 18 countries of the LRTAP Convention. These national data were collated into a single database for the purpose of identifying sensitive areas in Europe. Computing exceedances, i.e. comparing the critical loads to atmospheric deposition, shows that cadmium was not a widespread risk in 2000, that the risk from lead deposition has decreased since 1990 but was still widespread in 2000, and that the risk from mercury remains high without much change from 1990 to 2000 in most of the countries.  相似文献   
120.
Critical loads have been used to develop international agreements on acidifying air pollution abatement, and within the UK and other countries, to develop national policies for pollution abatement. The Environment Agency (England and Wales) has regulatory obligations to protect sites of high conservation value from the threat of acidification, and hence requires a practical methodology for acidification assessments at the site-specific scale. The Environment Agency has therefore posed the question: Are the national critical load exceedance models sufficiently robust to form the basis for methods to assess harm to individual sites or are they only useful for national policy development? In order to provide one measure of the appropriateness of applying the models at the site-specific scale we incorporated estimates of uncertainty in both national and site-specific data into the calculation of critical load exceedance for individual sites. The exceedance calculations use data from a wide range of sources and the accuracy of the exceedance will be influenced by the accuracy of the input data sets. Using Monte Carlo methods to incorporate the uncertainty in the input data sets into the calculation a distribution of critical load exceedance values is generated rather than a single point estimate. This paper compares uncertainty analyses for coniferous forested sites in England and Wales using both national scale and site-specific data sets and uncertainty ranges.  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