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   7186篇
  免费   312篇
  国内免费   3篇
  2021年   86篇
  2020年   129篇
  2019年   110篇
  2018年   175篇
  2017年   166篇
  2016年   209篇
  2015年   157篇
  2014年   197篇
  2013年   678篇
  2012年   340篇
  2011年   344篇
  2010年   224篇
  2009年   211篇
  2008年   295篇
  2007年   306篇
  2006年   256篇
  2005年   273篇
  2004年   261篇
  2003年   246篇
  2002年   250篇
  2001年   129篇
  2000年   85篇
  1999年   120篇
  1998年   110篇
  1997年   106篇
  1996年   87篇
  1995年   79篇
  1994年   76篇
  1993年   80篇
  1992年   92篇
  1991年   83篇
  1990年   69篇
  1989年   50篇
  1988年   49篇
  1987年   60篇
  1986年   62篇
  1985年   73篇
  1984年   67篇
  1983年   72篇
  1982年   65篇
  1981年   80篇
  1980年   69篇
  1979年   66篇
  1978年   74篇
  1977年   74篇
  1976年   67篇
  1975年   58篇
  1974年   63篇
  1968年   42篇
  1966年   41篇
排序方式: 共有7501条查询结果,搜索用时 15 毫秒
881.
882.
The apparent contrast of backward- and forward-masked spatial sinusoids was measured by a brightness-matching technique suggested by Davidson (1966), designed to be free of artifacts associated with earlier matching methods. Data variability was relatively large due predominantly to (1) fluctuations in masking-interval duration, and (2) changes in the O’s criteria produced by the salient temporal and spatial differences between test and comparison fields. Several other potential sources of data variability were found to be negligible.  相似文献   
883.
Performance maintained under single variable-interval avoidance schedules, single variable-interval schedules of positive reinforcement, and concurrent schedules consisting of a variable-interval avoidance component and a variable-interval positive reinforcement component, was studied in three human subjects, using points exchangeable for money as the reinforcer. Response rate in the single variable-interval avoidance schedules was an increasing function of the frequency of monetary loss avoidance. Response rate in the single variable-interval positive reinforcement schedules was an increasing function of the frequency of obtained monetary reinforcement. In the concurrent avoidance/reinforcement schedules, the rate of responding in the avoidance component increased, and the rate of responding in the positive reinforcement schedule decreased (with one exception) as a function of the frequency of loss avoidance in the avoidance component. The logarithms of the ratios of the response rates in the two components, and the logarithms of the ratios of the times spent in the two components, were linearly related to the logarithms of the ratios of the frequency of loss avoidance in the avoidance component to the frequency of reinforcement in the positive reinforcement component. All three subjects exhibited marked undermatching of response rate ratios to reinforcement frequency ratios. The results are discussed in the context of Herrnstein's quantitative model of operant performance.  相似文献   
884.
885.
886.
The pro‐life paradox, as I call it, begins with a single claim endorsed by many American Christians: infants and young children are innocent in the sight of God because they cannot yet take responsibility for their spiritual well‐being. With this in mind, I argue that pro‐life believers have unwittingly fallen victim to a theological paradox in which their attempts to save the earthly lives of unborn children make it theoretically possible for said children to die an eternal death. On the one hand, many Christians trust in an eventual spiritual reckoning where God will separate the “sheep” from the “goats” (see Matthew 25:31–46), ushering the former into heaven while damning the latter to hell. However, those who cannot yet repent and seek salvation are not blamed for their spiritual failings. If they die, they go to heaven because they are too young and intellectually immature to know any better. But if dead children are spiritually blameless, then abortion practitioners have perversely and paradoxically saved millions of unborn souls by removing human volition (and thus damnation itself) from the equation and by making it possible for the unborn to experience the joys of heaven without the temptations of earth.  相似文献   
887.
888.
889.
890.
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