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   428篇
  免费   3篇
  国内免费   13篇
安全科学   15篇
废物处理   31篇
环保管理   26篇
综合类   108篇
基础理论   81篇
污染及防治   147篇
评价与监测   30篇
社会与环境   6篇
  2022年   3篇
  2021年   6篇
  2020年   4篇
  2019年   3篇
  2018年   13篇
  2017年   9篇
  2016年   22篇
  2015年   5篇
  2014年   15篇
  2013年   28篇
  2012年   21篇
  2011年   30篇
  2010年   16篇
  2009年   22篇
  2008年   22篇
  2007年   33篇
  2006年   23篇
  2005年   13篇
  2004年   13篇
  2003年   14篇
  2002年   10篇
  2001年   8篇
  2000年   7篇
  1999年   6篇
  1998年   6篇
  1997年   4篇
  1996年   2篇
  1995年   2篇
  1994年   6篇
  1993年   4篇
  1992年   2篇
  1988年   2篇
  1986年   3篇
  1976年   2篇
  1970年   3篇
  1966年   4篇
  1964年   3篇
  1962年   2篇
  1960年   4篇
  1959年   3篇
  1958年   2篇
  1957年   6篇
  1956年   4篇
  1955年   5篇
  1954年   4篇
  1939年   1篇
  1936年   1篇
  1930年   1篇
  1927年   1篇
  1925年   1篇
排序方式: 共有444条查询结果,搜索用时 250 毫秒
1.
Concentrations of platinum and lead were measured in common grass sampled near the Autobahn. Additionally, platinum was determined in spot checks of ash from seawage sludge incinerators to 1972. The increase in Pt levels since 1987 was traced back to releases from automobile catalytic converters. The emission rate of a car equipped with a catalytic converter has been estimated by comparison with Pb.  相似文献   
2.
Diadromous fish often enter freshwater directly from seawater via fish ladders or channels built in estuarine dams. The oxygen consumption rates (OCR) of glass eel, Anguilla japonica, were determined using an automatic intermittent flow respirometer under various salinity and temperature regimes to physiologically explain this direct movement. The endogenous rhythm of the OCR in wild glass eels, freshly collected from estuaries, was nearly synchronous with the tidal pattern at the estuarine collection site. When the salinity was changed from 20 psu (12°C) at a constant temperature to that of freshwater, the OCR of the glass eels decreased by 21.6±7.0% (mean ± SD) (P<0.05), showing a dampened rhythm for about 48 h. After this period of impediment, the glass eels resumed normal metabolic activity. Direct migration from seawater to freshwater under constant temperature would result in a severe physiological stress for these glass eels for about two days. When the glass eels were exposed to a cyclic change in water temperature of 2°C 26 h−1, as they encounter in estuaries, and then were introduced to freshwater abruptly, the OCR rhythm corresponded to the cyclic changes in water temperature after exposure to freshwater. Under these conditions, the mean OCR of the glass eels had a small difference before and after exposure to freshwater. These data explained how glass eels can directly move from sea water into the freshwater without any apparent metabolic stress in the estuaries showing cyclic change in water temperature (Δt=2°C).  相似文献   
3.
The article describes the use of Scots pine bark to identifynitrogen sources in eastern Germany, as well as background areas in Russia and Bulgaria, by using natural isotope ratios of total nitrogen (Nt) and individual N compoundssuch as ammonium (NH4 +), nitrate (NO3 -)and amid nitrogen (amide-N). The samples collected were analysed using an elemental analyser in connection with a gas isotope mass spectrometer (EA-IRMS). Natural 15N abundances in pine bark from impact areas suggest that the ammonium accumulated on the surface of the bark is releasedfrom livestock management. Bark of Scots pines growing near agricultural land had highly depleted 15Nt values (between –8 and –12), while bark from background areas (unpolluted areas) displayed slightly negative 15Nt values (mean 15Nt = –3.8). It is assumed that part of the N adsorbed on the bark surface is mainly derived from ammonia(mean 15Nt = –40.3) escaping from livestock housing and during the application of manure. This assumption is confirmed by experiments under controlled conditions in which manure samples were spread on soil. In addition, temporal and spatial variations of 15Nt abundances in pine bark from various locations in eastern Germany as wellas pine stands in Nature Park Dübener Heath are discussed.  相似文献   
4.
5.
6.
7.
重庆大气可吸入颗粒物中多环芳烃的分析测定   总被引:4,自引:0,他引:4  
本文报告了重庆大气可吸入颗粒物(IP)中多环芳烃(PAH)的分析测定方法和结果.用GC-MS定性和定量分析了重庆IP中的PAH;研究了IP中PAH的种类和分布情况;确认重庆IP中存在甲基多环芳烃(MePAH)、约占33%;颗粒大小分布表明,约有98%PAH存在于小于3μm的颗粒中.  相似文献   
8.
9.
The relationship between man-made CO2 emission and atmospheric CO2 concentration has been established. The factors that affect CO2 reduction allotment and the impacts on future energy demand and supply were discussed, in order to help energy policy makers both in developed countries and in developing countries for understanding the fundamental constraint on energy sector resulted from global warming related CO2 reduction, and hopefully in finding a common objective starting point to deal with global warming negotiation in energy sector, and to investigate the optimum stabilization goal and process acceptable to all sovereign countries that based on equity and applicability.  相似文献   
10.
Environmental Science and Pollution Research - Bioreduction of selenium oxyanions to elemental selenium is ubiquitous; elucidating the properties of this biogenic elemental selenium (BioSe) is thus...  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