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   1913篇
  免费   89篇
各国政治   96篇
工人农民   111篇
世界政治   172篇
外交国际关系   158篇
法律   986篇
中国政治   15篇
政治理论   447篇
综合类   17篇
  2023年   20篇
  2022年   23篇
  2021年   17篇
  2020年   63篇
  2019年   64篇
  2018年   70篇
  2017年   83篇
  2016年   81篇
  2015年   69篇
  2014年   77篇
  2013年   279篇
  2012年   73篇
  2011年   58篇
  2010年   67篇
  2009年   59篇
  2008年   64篇
  2007年   77篇
  2006年   66篇
  2005年   78篇
  2004年   59篇
  2003年   57篇
  2002年   57篇
  2001年   39篇
  2000年   48篇
  1999年   39篇
  1998年   28篇
  1997年   21篇
  1996年   15篇
  1995年   23篇
  1994年   18篇
  1993年   12篇
  1992年   26篇
  1991年   11篇
  1990年   13篇
  1989年   21篇
  1988年   17篇
  1987年   13篇
  1986年   12篇
  1985年   9篇
  1984年   10篇
  1983年   12篇
  1982年   6篇
  1981年   4篇
  1980年   6篇
  1979年   4篇
  1977年   3篇
  1975年   5篇
  1974年   3篇
  1969年   5篇
  1966年   3篇
排序方式: 共有2002条查询结果,搜索用时 93 毫秒
171.
Legislators claim that how they explain their votes matters as much as or more than the roll calls themselves. However, few studies have systematically examined legislators’ explanations and citizen attitudes in response to these explanations. We theorize that legislators strategically tailor explanations to constituents in order to compensate for policy choices that are incongruent with constituent preferences, and to reinforce policy choices that are congruent. We conduct a within‐subjects field experiment using U.S. senators as subjects to test this hypothesis. We then conduct a between‐subjects survey experiment of ordinary people to see how they react to the explanatory strategies used by senators in the field experiment. We find that most senators tailor their explanations to their audiences, and that these tailored explanations are effective at currying support—especially among people who disagree with the legislators’ roll‐call positions.  相似文献   
172.
Disasters such as flash flooding, mass shootings, and train and airplane accidents involving large numbers of victims produce significant opportunity for research in the biosciences. This opportunity exists in the extreme tails of life events, however, during which decisions about life and death, valuing and foregoing, speed and patience, trust and distrust, are tested simultaneously and abundantly. The press and urgency of these scenarios may also challenge the ability of researchers to comprehensively deliver information about the purposes of a study, risks, benefits, and alternatives. Under these circumstances, we argue that acquiring consent for the immediate use of data that are not time sensitive represents a gap in the protection of human study participants. In response, we offer a two-tiered model of consent that allows for data collected in real-time to be held in escrow until the acute post-disaster window has closed. Such a model not only respects the fundamental tenet of consent in research, but also enables such research to take place in an ethically defensible manner.  相似文献   
173.
The extraction of DNA from human skeletal remains applied to forensic, and evolutionary studies do not exclude risks, which are to be evaluated when working with unique specimens that could be damaged or even destroyed. In the present study were evaluated several nondestructive methods for recovering DNA instead of the most currently used pulverization method. Three different procedures to access inside the dental pieces (occlusal perforation, cervical perforation, and cervical cut) have been compared with the aim of recovering as many cell remains as possible to carry out a DNA extraction. Given the DNA quantitation results, a method was proposed that consists of a cervical cut to facilitate the access to the pulp cavity and a subsequent filing of the root canals down to the apex of the dental root. This methodology allows the recovery of both mitochondrial and nuclear DNA, with the minimum deterioration for the dental pieces.  相似文献   
174.
175.
In forensics, bloodstains on dark fabrics might be invisible for the naked eye. Although several visualization, presumptive, and confirmatory blood tests have been developed, all have one or more disadvantages, especially on DNA analysis. We report here the use of a visualization assay that can visually detect blood drops up to 1/20 dilution. In this assay, the fabric is placed between two wet filter papers and covered by glass surfaces on both sides. Pressure is applied on the glass surfaces in which bloodstains transfer onto the filter papers through capillary forces. Detected stains can be tested with other more sensitive presumptive blood tests performed on the filter paper. Even more, DNA analysis can be performed on the transferred bloodstains. The presented visualization assay is easy to perform, extremely cheap, requires little hands on time, and does not affect bloodstain pattern analysis.  相似文献   
176.
177.
178.
179.
180.
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