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   689篇
  免费   17篇
  国内免费   12篇
安全科学   26篇
废物处理   38篇
环保管理   157篇
综合类   68篇
基础理论   150篇
环境理论   3篇
污染及防治   178篇
评价与监测   59篇
社会与环境   29篇
灾害及防治   10篇
  2023年   4篇
  2022年   4篇
  2021年   9篇
  2020年   8篇
  2019年   10篇
  2018年   11篇
  2017年   16篇
  2016年   24篇
  2015年   12篇
  2014年   24篇
  2013年   103篇
  2012年   17篇
  2011年   32篇
  2010年   27篇
  2009年   27篇
  2008年   26篇
  2007年   39篇
  2006年   26篇
  2005年   22篇
  2004年   20篇
  2003年   30篇
  2002年   24篇
  2001年   8篇
  2000年   17篇
  1999年   9篇
  1998年   5篇
  1997年   4篇
  1996年   9篇
  1995年   9篇
  1994年   15篇
  1993年   5篇
  1992年   9篇
  1991年   6篇
  1990年   4篇
  1989年   3篇
  1988年   6篇
  1987年   6篇
  1986年   5篇
  1985年   7篇
  1984年   12篇
  1983年   5篇
  1982年   7篇
  1981年   10篇
  1980年   7篇
  1979年   5篇
  1978年   5篇
  1977年   4篇
  1976年   3篇
  1975年   4篇
  1974年   3篇
排序方式: 共有718条查询结果,搜索用时 15 毫秒
711.
The paper presents a new sampling method for studying in-body radioactive contamination by bone-seeking radionuclides such as 90Sr, 239+240Pu, 238Pu, 241Am and selected gamma-emitters, in human bones. The presented results were obtained for samples retrieved from routine surgeries, namely knee or hip joints replacements with implants, performed on individuals from Southern Poland. This allowed to collect representative sets of general public samples. The applied analytical radiochemical procedure for bone matrix is described in details. Due to low concentrations of 238Pu the ratio of Pu isotopes which might be used for Pu source identification is obtained only as upper limits other then global fallout (for example Chernobyl) origin of Pu. Calculated concentrations of radioisotopes are comparable to the existing data from post-mortem studies on human bones retrieved from autopsy or exhumations. Human bones removed during knee or hip joint surgery provide a simple and ethical way for obtaining samples for plutonium, americium and 90Sr in-body contamination studies in general public.  相似文献   
712.
The value of research on the accuracy of job analysis is questioned. It is argued that the traditional criteria employed to evaluate job analysis accuracy (i.e., interrater agreement and deviations from proxy true scores) provide information of little practical value. Alternative criteria focusing on the consequences of job analysis data are suggested. Consequence‐oriented criteria are clarified through a review of the various inferential leaps or decision points that job analysis supports. In addition, the consequences of job analysis are also thought to be a function of the rules governing the making of job‐analysis‐based inferences which, unfortunately, are sometimes unspecified in even the most molecular job analysis methodologies. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   
713.
714.
Carbon dioxide capture and storage (CCS) involves the capture of CO2 at a large industrial facility, such as a power plant, and its transport to a geological (or other) storage site where CO2 is sequestered. Previous work has identified pipeline transport of liquid CO2 as the most economical method of transport for large volumes of CO2. However, there is little published work on the economics of CO2 pipeline transport. The objective of this paper is to estimate total cost and the cost per tonne of transporting varying amounts of CO2 over a range of distances for different regions of the continental United States. An engineering-economic model of pipeline CO2 transport is developed for this purpose. The model incorporates a probabilistic analysis capability that can be used to quantify the sensitivity of transport cost to variability and uncertainty in the model input parameters. The results of a case study show a pipeline cost of US$ 1.16 per tonne of CO2 transported for a 100 km pipeline constructed in the Midwest handling 5 million tonnes of CO2 per year (the approximate output of an 800 MW coal-fired power plant with carbon capture). For the same set of assumptions, the cost of transport is US$ 0.39 per tonne lower in the Central US and US$ 0.20 per tonne higher in the Northeast US. Costs are sensitive to the design capacity of the pipeline and the pipeline length. For example, decreasing the design capacity of the Midwest US pipeline to 2 million tonnes per year increases the cost to US$ 2.23 per tonne of CO2 for a 100 km pipeline, and US$ 4.06 per tonne CO2 for a 200 km pipeline. An illustrative probabilistic analysis assigns uncertainty distributions to the pipeline capacity factor, pipeline inlet pressure, capital recovery factor, annual O&M cost, and escalation factors for capital cost components. The result indicates a 90% probability that the cost per tonne of CO2 is between US$ 1.03 and US$ 2.63 per tonne of CO2 transported in the Midwest US. In this case, the transport cost is shown to be most sensitive to the pipeline capacity factor and the capital recovery factor. The analytical model elaborated in this paper can be used to estimate pipeline costs for a broad range of potential CCS projects. It can also be used in conjunction with models producing more detailed estimates for specific projects, which requires substantially more information on site-specific factors affecting pipeline routing.  相似文献   
715.
Arid zone rivers have highly variable flow rates, and flood control projects are needed to protect adjacent property from flood damage. On the other hand, riparian corridors provide important wildlife habitat, especially for birds, and riparian vegetation is adapted to the natural variability in flows on these rivers. While environmental and flood control goals might appear to be at odds, we show that both goals can be accommodated in the Limitrophe Region (the shared border between the United States and Mexico) on the Lower Colorado River. In 1999, the International Boundary and Water Commission proposed a routine maintenance project to clear vegetation and create a pilot channel within the Limitrophe Region to improve flow capacity and delineate the border. In 2000, however, Minute 306 to the international water treaty was adopted, which calls for consideration of environmental effects of IBWC actions. We conducted vegetation and bird surveys within the Limitrophe and found that this river segment is unusually rich in native cottonwood and willow trees, marsh habitat, and resident and migratory birds compared to flow-regulated segments of river. A flood-frequency analysis showed that the existing levee system can easily contain a 100 year flood even if vegetation is not removed, and the existing braided channel system has greater carrying capacity than the proposed pilot channel.  相似文献   
716.
2-Chlorophenol (2-CP), 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) at initial concentrations of 10, 20, 50 and 100mg l(-1) were degraded in aqueous media by direct UV photolysis using dielectric barrier discharge XeBr( *) excilamp (283nm) in a flow-through photoreactor. The pseudo-first order rate constants were highest and half-life times were lowest for 4-CP. The rates of photolysis under the experimental conditions increased in the order: 2-CP<2,4-DCP<4-CP. The intermediates of photolysis were identified by GC-MS and HPLC. The evolution of hydroquinone and p-benzoquinone as major intermediates of 4-CP photolysis was monitored.  相似文献   
717.
718.
Environment, Development and Sustainability - This study assesses the spatiotemporal development of land use systems and climate variability in Southwestern Ghana over the past five decades using...  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