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   252篇
  免费   12篇
  2020年   3篇
  2015年   4篇
  2014年   10篇
  2013年   10篇
  2012年   11篇
  2011年   18篇
  2010年   14篇
  2009年   5篇
  2008年   4篇
  2007年   8篇
  2006年   7篇
  2005年   8篇
  2004年   2篇
  2003年   3篇
  2002年   2篇
  2001年   5篇
  2000年   4篇
  1999年   4篇
  1998年   5篇
  1997年   2篇
  1996年   3篇
  1995年   2篇
  1993年   2篇
  1991年   3篇
  1990年   3篇
  1989年   3篇
  1988年   4篇
  1987年   4篇
  1986年   4篇
  1985年   6篇
  1984年   3篇
  1983年   5篇
  1982年   3篇
  1980年   4篇
  1979年   4篇
  1978年   4篇
  1977年   5篇
  1976年   5篇
  1975年   2篇
  1974年   3篇
  1973年   6篇
  1972年   4篇
  1971年   3篇
  1970年   4篇
  1969年   9篇
  1968年   5篇
  1967年   3篇
  1966年   4篇
  1965年   2篇
  1892年   3篇
排序方式: 共有264条查询结果,搜索用时 15 毫秒
41.
In recent years, industrial ecology (IE) has become increasingly integrated into formal education as a distinct body of work. The aim of this article is to describe the state of IE in postsecondary education across the world by providing an inventory of programs and courses offered from a search conducted during the summer of 2012. Although some interpretation of the results is conducted, the aim of this article is to provide a snapshot of the state of IE in higher education in 2012 and serve as a starting point for future work. Data were collected on IE courses and programs across the world by Internet search in order to determine the prevalence of IE in postsecondary curricula. Subsequently, 190 universities and colleges from 46 countries were identified as offering courses and/or programs in IE. From this research, a total of 409 courses and 78 programs were inventoried and course content was analyzed (where available). The results indicate that IE is mainly studied at the graduate level within engineering and environmental disciplines, although undergraduate‐level curricula are emerging. In terms of disciplinary departments offering said curricula, IE is presented as a topic of instruction in varied fields of study, such as business and administration, and the arts. From the course syllabi analyzed, the main subjects being taught within IE education are introductory principles and general tools. Advanced or specialized aspects of the field are also covered, however, less frequently.  相似文献   
42.
43.
Germinated maize (Zea mays L.) seedlings were enclosed in modified triaxial cells in an artificial substrate and exposed to oxygen deficiency stress (4% oxygen, hypoxia) or to mechanical resistance to elongation growth (mechanical impedance) achieved by external pressure on the artificial substrate, or to both hypoxia and impedance simultaneously. Compared with controls, seedlings that received either hypoxia or mechanical impedance exhibited increased rates of ethylene evolution, greater activities of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase, ACC oxidase, and cellulase, and more cell death and aerenchyma formation in the root cortex. Effects of hypoxia plus mechanical impedance were strongly synergistic on ethylene evolution and ACC synthase activity; cellulase activity, ACC oxidase activity, or aerenchyma formation did not exhibit this synergism. In addition, the lag between the onset of stress and increases in both ACC synthase activity and ethylene production was shortened by 2 to 3 h when mechanical impedance or impedance plus hypoxia was applied compared with hypoxia alone. The synergistic effects of hypoxia and mechanical impedance and the earlier responses to mechanical impedance than to hypoxia suggest that different mechanisms are involved in the promotive effects of these stresses on maize root ethylene biosynthesis.  相似文献   
44.
The major urinary protein (MUP) complex of normal inbred laboratory mice (Mus musculus musculus) is a family of three electrophoretically distinguishable components, designated 1, 2, and 3 in order of increasing anodal mobility at pH 5.5. Components 1 and 2 are under the control of a single genetic locus; the MUP complex of a given inbred strain consists of component 1 or 2 plus component 3. In this study, the urinary protein of two subspecies of Asian wild mice, Mus musculus molossinus (originally trapped in Japan) and Mus musculus castaneus (originally trapped in Thailand), was examined electrophoretically and ultracentrifugally. The MUP complex of male M. m. molossinus and M. m. castaneus sedimented at approximately the same rate as that of M. m. musculus (s 20 =2.0?2.2S). It consisted of a “fast” (i.e., more anodal than component 3) and an “intermediate” component plus one or more “origin” (i.e., less anodal than component 1) components. The “fast” and “origin” components were isolated chromatographically, and NH2-terminal sequences spanning the first 36 residues were determined. Comparison with the NH2-terminal sequences determined for components 1, 2, and 3 isolated from the urine of BALB/c or C57BL/6 mice revealed, except for a single replacement at position 6 in the “origin” component of M. m. molossinus, no differences among the 1, 2, “origin”, and “fast” components. Component 3 was highly homologous but differed from component 1 at nine positions; its residue at position 6 was the same as that of the M. m. molossinus “origin” component.  相似文献   
45.
46.
The amount of treatment received by 380 patients with backache was found to have been influenced more by their distress and illness behaviour than by the actual physical disease. Patients showing a large amount of inappropriate illness behaviour had received significantly more treatment (p less than 0.001). The symptoms and signs of illness behaviour need to be clearly distinguished from those of physical disease, and better assessment of illness behaviour is essential if everyday clinical practice is to fulfil the ideal of treating patients as well as diseases.  相似文献   
47.
48.
49.
50.
In a retrospective study of the incidence of mesothelioma in Scotland for 1950-67 80 cases were traced from pathological reports and biopsy material of malignant tumours invading the pleura and peritoneum. These cases were matched with two sets of controls. Detailed histories of residence, occupation, and degree of exposure to asbestos confirmed that the incidence of mesothelioma in Scotland is similar to that in other parts of Britain.  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