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   21769篇
  免费   542篇
各国政治   1162篇
工人农民   1508篇
世界政治   1427篇
外交国际关系   1035篇
法律   11737篇
中国共产党   2篇
中国政治   184篇
政治理论   5113篇
综合类   143篇
  2023年   73篇
  2021年   71篇
  2020年   204篇
  2019年   243篇
  2018年   1553篇
  2017年   1528篇
  2016年   1394篇
  2015年   376篇
  2014年   358篇
  2013年   1947篇
  2012年   574篇
  2011年   1329篇
  2010年   1320篇
  2009年   922篇
  2008年   1119篇
  2007年   1091篇
  2006年   426篇
  2005年   434篇
  2004年   555篇
  2003年   523篇
  2002年   341篇
  2001年   454篇
  2000年   424篇
  1999年   393篇
  1998年   235篇
  1997年   199篇
  1996年   197篇
  1995年   182篇
  1994年   195篇
  1993年   176篇
  1992年   222篇
  1991年   215篇
  1990年   202篇
  1989年   188篇
  1988年   216篇
  1987年   196篇
  1986年   207篇
  1985年   180篇
  1984年   190篇
  1983年   190篇
  1982年   124篇
  1981年   96篇
  1980年   97篇
  1979年   121篇
  1978年   105篇
  1977年   90篇
  1976年   81篇
  1975年   70篇
  1974年   78篇
  1969年   61篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
211.
212.
213.
Fifty-three clusters of blowfly eggs of the genus Calliphora vicina were observed in the laboratory up to the hatching stage under reproducible and virtually field-like conditions. Rearing the larvae was then continued up to pupation, the larval growth in length being recorded several times a day. As the object was to study the dependence of the larvae increase in length on the temperature conditions in vitro, the substratal humidity and food supply were kept unchanged during the entire study. The temperature ranged from 6.5 degrees C to 35 degrees C, with the temperature for the individual cluster kept constant during the entire developmental process. Data on about 5500 measured larvae were statistically evaluated. The basic result established was that in the case of the blowfly of the genus Calliphora vicina in vivo, all developmental stages relevant to the entomologic determination of the time of death depend on the temperature conditions: (1) the duration of the egg stage increases with decreasing temperature; (2) the speed of larval growth is slower at lower temperatures; (3) the maximal larval length is reached earlier at higher temperatures; (4) the mean value of maximal length decreases with increasing temperature; (5) larvae under all temperature conditions decrease in size after having reached their maximal length, the decrease in length being more rapid at higher temperatures; (6) constant temperatures over 30 degrees C lead to "stunted forms" which do not pupate and die; (7) constant temperatures under approximately 16 degrees C after the peak of growth has been reached inhibit the readiness to pupate, which causes the larvae to fall into a stationary state of rest, which will be interrupted only when the temperature is raised and resumption of the metamorphosis is thus induced. To allow rapid reconstruction of the larval age in general practice, the established growth data were set out in the form of a diagram designated isomegalendiagram, which permits temperature-fluctuation-related entomologic determination of the time of death with a maximum degree of accuracy.  相似文献   
214.
The events of January 6, 2021, when violent rioters attacked the Capitol building in Washington in order to disrupt validation of the 2020 presidential election, forced an unprecedented reckoning with the state of American politics. Members of Congress struggled to account for the rhetoric that gave rise to the event; law enforcement grappled with the challenge of holding accountable those who perpetrated the violence; and journalistic outlets wrestled with reporting a complex web of conspiracy theories and disinformation that gave rise to the insurrection. But for senior military leaders, the question was how to explain the troubling presence of active duty servicemembers and veterans in the first attack on the American seat of government in two centuries. The result is a profound and urgent discussion in U.S. civil-military relations.  相似文献   
215.
The purposes of this essay are to describe how federal research and development policy has altered authority relationships and to suggest a new concept of legitimacy in accord with the changed conditions. Research and development (R and D) creates an indeterminate future. Thus, the politics of research and development incorporates an apparent contradiction : political leadership demands that jobs be done which require creative and unpredictable actions on the part of private organizations, while it also demands that contractors be held responsible for fulfilling goals efficiently, avoiding deleterious secondary consequences, and refraining from abuses of power. The paradox can be resolved by creating norms of responsibility that allow for judgments on how a job is done rather than what is to be done. New institutions for technological assessment to check on unintended consequences of projects and citizen review boards to estimate the quality of life engendered by projects may provide such norms of responsibility.  相似文献   
216.
217.
218.
219.
220.
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