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   3010篇
  免费   35篇
  国内免费   155篇
安全科学   120篇
废物处理   198篇
环保管理   302篇
综合类   1125篇
基础理论   375篇
环境理论   2篇
污染及防治   769篇
评价与监测   186篇
社会与环境   81篇
灾害及防治   42篇
  2023年   26篇
  2022年   58篇
  2021年   47篇
  2020年   28篇
  2019年   36篇
  2018年   55篇
  2017年   73篇
  2016年   106篇
  2015年   62篇
  2014年   96篇
  2013年   219篇
  2012年   124篇
  2011年   155篇
  2010年   123篇
  2009年   125篇
  2008年   147篇
  2007年   146篇
  2006年   111篇
  2005年   102篇
  2004年   91篇
  2003年   83篇
  2002年   91篇
  2001年   63篇
  2000年   33篇
  1999年   21篇
  1998年   27篇
  1997年   12篇
  1996年   15篇
  1995年   61篇
  1994年   59篇
  1993年   48篇
  1992年   32篇
  1991年   33篇
  1990年   36篇
  1989年   29篇
  1988年   37篇
  1987年   34篇
  1986年   22篇
  1985年   14篇
  1984年   13篇
  1983年   18篇
  1982年   13篇
  1973年   10篇
  1919年   47篇
  1918年   44篇
  1917年   36篇
  1916年   53篇
  1915年   37篇
  1914年   71篇
  1913年   106篇
排序方式: 共有3200条查询结果,搜索用时 15 毫秒
1.
2.
气象卫星遥感在干旱监测中的应用   总被引:23,自引:1,他引:23  
居为民  孙涵 《灾害学》1996,11(4):25-29
本文根据NOAA极轨气象卫星AVHRR资料计算生成植被指数相对距平图用于旱情监测,并在江苏省1994年特大干旱中进行了应用服务  相似文献   
3.
Environmental Science and Pollution Research - Dissolved air flotation (DAF) is a widely used treatment process in drinking water and wastewater treatment plants despite high energy cost associated...  相似文献   
4.
Traditional ecological knowledge (TEK) can play an important role in the understanding of ecological systems. Although TEK has complemented scientific and managerial programs in a variety of contexts, its formal incorporation into remote sensing exercises has to date been limited. Here, we show that the vegetation classifications of the Ache, an indigenous hunter-gatherer tribe of the Mbaracayu Forest Reserve in Paraguay, are reflected in a supervised classification of satellite imagery of the reserve. Accuracy of classification was toward the low end of the range of published values, but was reasonable given the difficult nature of separating forest classes from satellite images. Comparison of the resultant map with a more traditionally elaborated vegetation map highlights differences between the two approaches and the gain in information obtained by considering TEK classifications. We suggest that integration of TEK and remote sensing may provide alternative insights into the ecology of vegetation communities and land cover, particularly in remote and densely forested areas where ecological field research is often limited by roads and/or trail systems.  相似文献   
5.
6.
7.
Environmental Science and Pollution Research - We investigated the distribution of nitrogen compounds in Han River as well as two tributaries of Tancheon and Jungrangcheon. Particularly, we...  相似文献   
8.
Printed circuit boards incorporated in most electrical and electronic equipment contain valuable metals such as Cu, Ni, Au, Ag, Pd, Fe, Sn, and Pb. In order to employ a hydrometallurgical route for the recycling of valuable metals from printed circuit boards, a mechanical pre-treatment step is needed. In this study, the metallic components from waste printed circuit boards have been enriched using a mechanical separation process. Waste printed circuit boards shredded to <10mm were milled using a stamp mill to liberate the various metallic components, and then the milled printed circuit boards were classified into fractions of <0.6, 0.6-1.2, 1.2-2.5, 2.5-5.0, and >5.0mm. The fractions of milled printed circuit boards of size <5.0mm were separated into a light fraction of mostly non-metallic components and a heavy fraction of the metallic components by gravity separation using a zig-zag classifier. The >5.0mm fraction and the heavy fraction were subjected to two-step magnetic separation. Through the first magnetic separation at 700 Gauss, 83% of the nickel and iron, based on the whole printed circuit boards, was recovered in the magnetic fraction, and 92% of the copper was recovered in the non-magnetic fraction. The cumulative recovery of nickel-iron concentrate was increased by a second magnetic separation at 3000 Gauss, but the grade of the concentrate decreased remarkably from 76% to 56%. The cumulative recovery of copper concentrate decreased, but the grade increased slightly from 71.6% to 75.4%. This study has demonstrated the feasibility of the mechanical separation process consisting of milling/size classification/gravity separation/two-step magnetic separation for enriching metallic components such as Cu, Ni, Al, and Fe from waste printed circuit boards.  相似文献   
9.
10.
The practice of contaminant transport and remediation has shown significant progress in recent years. However, despite the significant progress made, remediation efforts are often delayed by extremely long breakthrough curve tails that render efforts to bring the level of contaminants below the regulatory standards inefficient. One hypothesis is that these long tails are due to the reservoir-like slow diffusive processes in soil micropore zones. This study compares the effects of micropores at macroscopic and microscopic levels and establishes a link between these approaches for validation and calibration purposes. The link between macroscopic and microscopic levels is established through comparisons and testing of the two models while incorporating appropriate scale and boundary effects. Despite the differences in conceptual approaches and simulation time, the two approaches rendered meaningful results. The link helps forecast the effects of micropore zone transport processes in the subsurface efficiently and thus allows development of numerical tools that could contribute towards more efficient remediation design.  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