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   1907篇
  免费   74篇
  国内免费   186篇
安全科学   105篇
废物处理   19篇
环保管理   281篇
综合类   804篇
基础理论   241篇
污染及防治   281篇
评价与监测   392篇
社会与环境   39篇
灾害及防治   5篇
  2024年   4篇
  2023年   42篇
  2022年   25篇
  2021年   46篇
  2020年   52篇
  2019年   38篇
  2018年   36篇
  2017年   54篇
  2016年   75篇
  2015年   65篇
  2014年   63篇
  2013年   90篇
  2012年   69篇
  2011年   108篇
  2010年   68篇
  2009年   126篇
  2008年   109篇
  2007年   107篇
  2006年   100篇
  2005年   65篇
  2004年   49篇
  2003年   67篇
  2002年   71篇
  2001年   65篇
  2000年   71篇
  1999年   67篇
  1998年   53篇
  1997年   44篇
  1996年   32篇
  1995年   36篇
  1994年   48篇
  1993年   29篇
  1992年   30篇
  1991年   27篇
  1990年   14篇
  1989年   18篇
  1988年   25篇
  1987年   20篇
  1986年   10篇
  1985年   7篇
  1984年   7篇
  1983年   9篇
  1982年   9篇
  1980年   4篇
  1979年   2篇
  1978年   2篇
  1977年   4篇
  1975年   1篇
  1974年   2篇
  1968年   1篇
排序方式: 共有2167条查询结果,搜索用时 15 毫秒
991.
To determine background values of the 252 chemical compounds listed in Dutch legislation, a survey was designed with the aim of estimating percentiles of the cumulative frequency distributions and areal fractions exceeding the former, legislative reference values. Sampling locations were selected by probability sampling, so that in estimating the target quantities no model assumptions on the spatial variation were required, and valid estimates could be obtained by design-based inference. Strata in random sampling were formed by overlaying an aggregated soil map and land use map. For most of the heavy metals the areal fraction with concentrations in the topsoil (0-10 cm) exceeding the reference value was smaller than the allowable maximum of 5%. For these compounds a background value was determined smaller than the reference value. Exceptions were V, Co, Ba and Cu, for which a background value was defined (slightly) larger than the reference value.  相似文献   
992.
The development and use of critical loads of air pollutant deposition in the U.S. is gaining momentum, and recent research efforts in the U.S. have produced valuable data for calculating critical loads. Critical loads are used to quantify the levels of air pollutants that are expected to impact forest health, soil fertility, aquatic biota condition, and other ecosystem responses. In addition, model refinements for improving critical loads estimates, and maps for illustrating critical loads for acidification and nitrogen saturation and eutrophication resulting from excess nutrient nitrogen, have been developed at various scales. However, prior to the effort described here, no cohesive process existed to provide a national-scale critical loads database and maps as a unified product representing all U.S. ecosystems. The FOCUS (Focal Center Utility Study) Project was initiated to coordinate the development and implementation of a clear, consistent, repeatable process for calculating and mapping critical loads within the U.S. In the FOCUS Phase I Pilot Study, empirical and calculated critical loads data for the U.S. were synthesized from dozens of regional and national-scale monitoring networks, research projects and publically available databases following an approach similar to that used in Europe. The United Nations Economic Commission for Europe (UNECE), through its International Cooperative Programme on Modelling and Mapping of Critical Levels & Loads and Air Pollution Effects, Risks and Trends (ICP-M&M) collects, analyzes and maps critical loads data. Countries participating in the Convention on Long-range Transboundary Air Pollution (CLRTAP) use a Critical Loads “Focal Center” in each country to serve as the point of contact for submitting regional and national-scale critical loads data to the ICP-M&M. One of the purposes of this study was to develop a foundation for interacting with other Focal Centers by assembling critical loads data, creating a database, establishing modeling protocols, and developing infrastructure within the U.S to report and update critical loads on a national scale. Because the U.S. does not currently have an officially designated Focal Center, critical loads data were provided as an informal, unofficial submission to the Coordination Center for Effects (CCE) of the ICP-M&M in March 2011, in the interest of international cooperation and exchange of information on the effects of atmospheric deposition of pollutants on ecosystems. We envision that these data will enable U.S. scientists, land managers, and environmental policymakers to enter into a productive and meaningful dialogue within the US, and also with the international scientific community on methods for estimating, calculating, mapping, interpreting, and refining critical loads for the effects of acidification and excess nutrient nitrogen on terrestrial and aquatic ecosystems. This paper describes the process used to develop national-scale critical loads in the U.S., summarizes the FOCUS Phase I approach and database development effort, and presents some initial national-scale critical loads mapping products.  相似文献   
993.
In recent years, evaluating the robustness of environmental models results has become essential in order to effectively support decision makers to define suitable emission control strategies. This evaluation is performed in literature through uncertainty and sensitivity analyses. Therefore, the application of such methodologies to air quality Integrated Assessment Models (IAMs) is extremely challenging. In fact, in this case uncertainty and sensitivity analyses should be assessed not only for each single component of the system, but also for the overall IAM. In the paper, an attempt is made to extend and systematize the information available on uncertainty/sensitivity analysis, at first considering environmental models in general, and then focusing on air quality IAMs. The study aims to offer a tentative framework addressed to modelers and decision makers in the implementation of IAM and evaluation of its results. The framework has been tested on Lombardy region (Northern Italy). The results show how the uncertainty on Drivers of emissions propagates on the whole modelling chain characterizing an integrated assessment study.  相似文献   
994.
995.
通过对海林市"十五"期间环境监测资料的统计、分析,系统地阐述了海林市的环境质量状况,解析了环境质量变化趋势和原因,并据此提出了环境对策,为环境管理和决策提供一定的科学依据和技术支持。  相似文献   
996.
997.
空气中PAHs的优化采样及分析方法研究   总被引:4,自引:0,他引:4       下载免费PDF全文
改装了HVS-1000型大流量采样器,实际工作中用滤膜"XAD-2加PUF"同时采集空气颗粒物和气相中的PAHs,有效地提高了采样效率,并初步定量评价了PAHs在颗粒物和气相中的分配;用添加替代物的方法评价了预处理过程的回收率;用乙腈和水梯度洗脱、PAHs专用色谱柱分离、紫外检测的方法对USEPA规定的16种PAHs类优先污染物进行了定性和定量分析.   相似文献   
998.
室内空气污染对人体健康的危害及预防   总被引:3,自引:0,他引:3  
论述了室内空气污染的主要指标,列出了沈阳市2003年的室内空气检测结果。阐明室内污染对人体尤其是对孕妇和儿童产生的危害性;并根据国家公布的室内环境标准,提出了消费者在进行室内装修时应采取的预防措施。  相似文献   
999.
室内空气采样及几种重要污染物的监测分析方法探讨   总被引:2,自引:0,他引:2  
程希  羌宁  季学李 《四川环境》2001,20(4):23-25,29
随着人们对室内空气质量重视程度的提高,室内空气监测技术近年来也不断得到发展。采样是监测中最重要的环节,采样时间、位置选择的正确与否直接影响测定的成功与否。采样目的是确定采样方案过程中的指导原则,一个成功的采样应用具备明确的目的性。氡、气溶胶、VOCs、甲醛是重要的室内污染物,其采样和测定技术逐步走向成熟。  相似文献   
1000.
C. Niessen  K. Eyferth 《Safety Science》2001,37(2-3):187-202
This paper reviews the development of a model of the air traffic controller's mental image, ‘picture’, or situation awareness, used for controlling air traffic. The computerised model's development, origins and theoretical basis are outlined, and the model is described in some detail in the context of current air traffic operations. The model can be utilised to explore the potential impacts of future automation on the cognitive performance of the air traffic controller. The general potential contributions of the area of cognitive modelling to system design and training in accelerating industries such as air traffic control, are also discussed.  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