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   3441篇
  免费   73篇
各国政治   186篇
工人农民   80篇
世界政治   218篇
外交国际关系   151篇
法律   2287篇
中国政治   29篇
政治理论   525篇
综合类   38篇
  2020年   33篇
  2019年   26篇
  2018年   31篇
  2017年   55篇
  2016年   65篇
  2015年   39篇
  2014年   50篇
  2013年   325篇
  2012年   76篇
  2011年   97篇
  2010年   55篇
  2009年   56篇
  2008年   82篇
  2007年   97篇
  2006年   107篇
  2005年   113篇
  2004年   111篇
  2003年   113篇
  2002年   103篇
  2001年   168篇
  2000年   140篇
  1999年   97篇
  1998年   38篇
  1997年   36篇
  1996年   33篇
  1995年   30篇
  1994年   33篇
  1993年   35篇
  1992年   74篇
  1991年   79篇
  1990年   70篇
  1989年   93篇
  1988年   93篇
  1987年   82篇
  1986年   93篇
  1985年   72篇
  1984年   42篇
  1983年   51篇
  1982年   26篇
  1981年   38篇
  1979年   35篇
  1978年   27篇
  1977年   32篇
  1975年   37篇
  1974年   36篇
  1973年   33篇
  1972年   33篇
  1971年   28篇
  1969年   27篇
  1968年   23篇
排序方式: 共有3514条查询结果,搜索用时 15 毫秒
11.
12.
A new solid-phase extraction procedure for the determination of cocaine and benzoylecgonine in amniotic fluid, using high flow co-polymeric sorbents is reported. The recoveries of cocaine and benzoylecgonine within the range 0.1-1 mg/l were 95.7% and 50.3%, respectively. The use of high-flow sorbents allowed the easy extraction of amniotic fluid regardless of sample viscosity or physical nature. The use of these solid-phase columns provided many advantages over the more commonly used solvent extraction, including an increase in extraction speed and efficiency, reduced operator time, reduced solvent use and disposal volumes and exceptional extract quality. Further, the determination of amniotic fluid obtained from pregnant cocaine users may provide important information about handling of cocaine by the fetus at various gestational ages. The procedure was successfully applied to amniotic fluid from suspected cocaine abusers.  相似文献   
13.
An improved method has been developed for the reliable classification of different C1R genetic variant forms from human serum or plasma. The method combines the use of neuraminidase-digested samples followed by monodimensional isoelectric focusing in the pH range 5 to 8 followed by immunoblotting. The method yields a simple pattern, with one major band in homozygote and two major bands in heterozygote cases.  相似文献   
14.
15.
This article examines the relationship between conservatism and environmentalism, including the viability of an eco-conservative ideology. The discussion emphasizes two major points. First, that there is much greater shared ground between greens and conservatives than is often recognized. Yet second, that there are nonetheless significant obstacles to any harmonious alliance between the two. However, what is also shown is that these obstacles are not necessarily those most commonly cited.  相似文献   
16.
17.
Federal transportation officials assert that labor protections in the Urban Mass Transportation Act inhibit the propensity of local transit agencies to contract with private firms for services. The authors present results from a survey of a large sample of transit managers and econometric analysis to support their conclusion that labor protections do not appear to reduce the incidence of contracting. The labor protections, however, may be costly to transit management in other ways. The authors recommend actions, aside from repeal of labor protections, to increase contracting by local transit agencies.  相似文献   
18.
Compared to the practice in other professional schools and academic fields at universities, law professors are hired at a young age based primarily upon their academic merit determined through grades, class rank, and school rank. This emphasis upon narrowly defined academic merit—apart from achievement demonstrated through original scholarship or experience in professional practice—first emerged during "the professionalization of the American law professor" between 1870 and 1900 at Harvard Law School (HLS). Though normative today, this outcome was neither necessary nor uncontested. In the late nineteenth century the new standard of hiring faculty according to their academic merit was energetically opposed by those favoring the antecedent standard of professional experience and reputation. Only when financial considerations counterbalanced that traditional standard did hiring decisions tip in favor of the new principle. Not until the early 1900s, when the second generation of academic meritocrats dominated the HLS faculty, did the new hiring standard become unequivocally established as policy in the school and, by extension, in legal education.  相似文献   
19.
Some features of early child care are more prominent in Norway than in other countries, such as emphasis on the outdoor environment. Of general relevance and interest is the form of day care provided by forest day-care centers. Three ideas form the development of these centers placed in wild areas. First, throughout history, Norwegians have had a close attachment to nature and some parents want to provide their children with outdoor experiences at an early age. Second, urging children to play outdoors characterizes the image many parents have of a happy, healthy childhood. Third, provision of day care for children has always been restricted in western countries, forcing parents to invent types of service that can become part of an ecological system that promotes healthy development.The forest day-care centers developed recently represent a supplement to the wide typology of child care in the 21st century. The article outlines the connections between these ideas in general European and western history and Norwegian history and presents debate and decisions about a question dating from the last half of the 1980s. It concludes that the forest day-care centers are perhaps only a modern form of the original kindergarten concept, which started in Europe and America as gardens for children not gardens of children.  相似文献   
20.
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