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   10677篇
  免费   332篇
各国政治   587篇
工人农民   290篇
世界政治   795篇
外交国际关系   536篇
法律   5979篇
中国共产党   3篇
中国政治   54篇
政治理论   2632篇
综合类   133篇
  2020年   103篇
  2019年   152篇
  2018年   223篇
  2017年   242篇
  2016年   261篇
  2015年   184篇
  2014年   215篇
  2013年   1363篇
  2012年   274篇
  2011年   291篇
  2010年   247篇
  2009年   265篇
  2008年   292篇
  2007年   261篇
  2006年   285篇
  2005年   257篇
  2004年   247篇
  2003年   247篇
  2002年   270篇
  2001年   374篇
  2000年   351篇
  1999年   281篇
  1998年   137篇
  1997年   159篇
  1996年   115篇
  1995年   126篇
  1994年   143篇
  1993年   131篇
  1992年   194篇
  1991年   227篇
  1990年   189篇
  1989年   218篇
  1988年   175篇
  1987年   177篇
  1986年   203篇
  1985年   167篇
  1984年   155篇
  1983年   171篇
  1982年   116篇
  1981年   124篇
  1980年   89篇
  1979年   149篇
  1978年   97篇
  1977年   79篇
  1976年   87篇
  1975年   82篇
  1974年   99篇
  1973年   96篇
  1972年   79篇
  1971年   72篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
951.
952.
953.
954.
Observational research involving access to personally identifiable data in medical records has often been conducted without informed consent, owing to practical barriers to soliciting consent and concerns about selection bias. Nevertheless, medical records research without informed consent appears to conflict with basic ethical norms relating to clinical research and personal privacy. This article analyzes the scope of these norms and provides an ethical justification for research using personally identifiable medical information without consent.  相似文献   
955.
956.
957.
A method is described to identify an unknown sample of plant material of forensic interest as Cannabis sativa L. The method consists in comparing the sequence of the nuclear ribosomal DNA Internal Transcribed Spacer I (ITS1) of the unknown sample with a Cannabis sequence. Our preliminary results show that the ITS1 is an ideal molecule for the identification of a sample suspected to be marijuana.  相似文献   
958.
We examined whether eyewitness identification latencies for sequential line‐up decisions indicate an optimum time boundary that reliably discriminates accurate from inaccurate decisions. Participants (N = 381) observed a crime simulation and attempted two separate identifications from target‐present or target‐absent sequential line‐ups. As has previously been found with simultaneous line‐ups, the optimum time boundary identified did not reliably discriminate accurate from inaccurate identifications for both line‐up targets. Diagnosticity for choosers was, however, much higher at very high confidence levels than at lower levels. Possible reasons for why one index of signal strength (confidence), but not another (latency), might postdict accuracy within the sequential framework were presented.  相似文献   
959.
Among the known causes of aircraft disasters, sabotage is perhaps the most terrifying and difficult to comprehend. Bombs have been exploded in at least 34 commercial aircraft, with the resultant loss of more than 300 lives. Motives for these acts include profit, the deaths of certain persons, and politics. On November 1, 1955, United Airlines Flight 629, bound to Denver-Portland, exploded and burned in flight near Longmont, Colorado, a few minutes after takeoff, with the loss of all 44 on board. Investigation revealed that the plane had been destroyed by the explosion of a bomb that had been placed in the rear luggage hold in Denver. Twelve days after the disaster, John Gilbert Graham, the son of one of the female passengers, was arrested and charged with murder. He reportedly admitted placing a time bomb on board the aircraft, apparently in order to collect $37,500.00 in life insurance that he had taken on his mother's life. Though he soon recanted, he was convicted of murder and was executed. The potential for additional such crimes remains.  相似文献   
960.
Public-goods dilemmas are characterized by conflicts between self-interest and the welfare of a group or society at large. Research has identified several factors that enhance cooperation in such dilemmas. However, less is known about how concern for distributive justice affects willingness to contribute in asymmetric public-goods dilemmas. To test the hypothesis that contributions to a common resource is related to perceived fairness, experiments were performed to investigate willingness to pay to the social service of child care in hypothetical societies. Experiment 1 aimed at replicating a previous survey study (Biel et al., 1997). Experiments 2 and 3 were extensions. In all three experiments subjects were asked to indicate how fair they considered different distributions of the quality of child care provided by their municipality. These distributions corresponded to the principles of equality, equity, and need. University students (32, 48, and 32 in the three experiments, respectively) served as subjects. Ratings of perceived fairness were positively related to willingness to pay. Other factors also positively related to willingness to pay included ability to pay, personal need, expected payment from others, and the number of households who had to contribute in order to maintain the quality. Furthermore, decreasing municipality size increased willingness to pay.  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