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   544篇
  免费   3篇
  国内免费   5篇
安全科学   1篇
废物处理   9篇
环保管理   25篇
综合类   299篇
基础理论   87篇
污染及防治   97篇
评价与监测   21篇
社会与环境   12篇
灾害及防治   1篇
  2018年   5篇
  2017年   8篇
  2016年   11篇
  2015年   8篇
  2013年   17篇
  2012年   8篇
  2011年   21篇
  2010年   13篇
  2009年   15篇
  2008年   20篇
  2007年   18篇
  2006年   6篇
  2005年   13篇
  2004年   14篇
  2003年   15篇
  2002年   12篇
  2001年   7篇
  1999年   12篇
  1998年   14篇
  1997年   7篇
  1996年   6篇
  1995年   8篇
  1994年   6篇
  1993年   5篇
  1975年   5篇
  1973年   6篇
  1972年   5篇
  1970年   8篇
  1967年   8篇
  1966年   4篇
  1965年   11篇
  1964年   4篇
  1963年   13篇
  1962年   10篇
  1961年   9篇
  1960年   10篇
  1959年   13篇
  1958年   9篇
  1957年   7篇
  1956年   9篇
  1955年   7篇
  1954年   5篇
  1953年   6篇
  1952年   5篇
  1951年   4篇
  1938年   4篇
  1930年   4篇
  1926年   6篇
  1914年   6篇
  1913年   10篇
排序方式: 共有552条查询结果,搜索用时 15 毫秒
551.
Kurt Lewin and others have showed that group discussion effectively changed attitudes and behaviors compared to individually targeted messages. This study examines the roles of normative and informational social influence in this effect. High school students heard a message about replacing toxic products with nontoxic alternatives; classes were randomly assigned to hear the message delivered as a lecture or via guided group discussion. For female students (N=250 in 26 classes), HLM mediation analyses suggested normative influence predominated: Discussion was more effective than lecture and this effect was fully mediated by students’ perceptions that other students endorsed nontoxics. Content analyses of students’ comments indicated that three kinds of remarks led female students to this perception: (1) sharing knowledge about nontoxics; (2) asking questions about nontoxics; and (3) little praise for toxic products. For male students in separate HLM analyses (N=107 in 19 of the same classes), informational influence was most apparent: Postmeeting attitudes were higher after discussion than lecture, and this effect was partially mediated by cognitive elaboration about the message (but not perceptions others endorsed the message). In addition, males’ quiz grades were higher after discussion, and students’ comments fully mediated the discussion to quiz grades relationship. Results support the importance of hearing others’ promessage comments for changing socially motivated behaviors, although the routes of influence appear to differ for these samples of male and female students.  相似文献   
552.
Biomineralization dependent on bacterial activity has been described for struvite which is formed in soils, guano, putrescent matter and sediments. A new biomineral containing nickel instead of magnesium, Ni(NH4)(PO4) . 6H2O, has been identified. It was formed by nickel resistant Streptomyces acidiscabies E13, and putatively named nickel struvite. The mineral formation is dependent on biological activity since non-viable bacterial cells are not capable to induce formation of Ni-struvite under identical conditions. Formation of Ni-struvite was observed on colony surfaces upon prolonged incubation of solid minimal or complex media containing elevated concentrations of 8-15mM NiCl2. The formation of magnesium containing crystals was not observed although Mg2+ is present in the medium. However, the process was not depending on desiccation since small crystals attached to the mycelial biomass of the bacteria were observed microscopically also in liquid cultures of nickel supplemented minimal and complex media after two weeks of incubation. The capacity to induce biomineralization of a nickel containing mineral is postulated to constitute a resistance factor, allowing the soil bacterium to withstand high nickel concentrations. The strain shows nickel resistance as an adaption to its habitat, since this bacterium was isolated from a former uranium mining site in Eastern Thuringia, Germany, where nickel concentrations of up to 2000ppm (translating to appr. 30mM) occur as a result of former mining activities.  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