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   66674篇
  免费   1807篇
  国内免费   13篇
  2019年   528篇
  2018年   4048篇
  2017年   3379篇
  2016年   2929篇
  2015年   778篇
  2014年   802篇
  2013年   4778篇
  2012年   1797篇
  2011年   3583篇
  2010年   3224篇
  2009年   2235篇
  2008年   2875篇
  2007年   3237篇
  2006年   1125篇
  2005年   1186篇
  2004年   1135篇
  2003年   1085篇
  2002年   1043篇
  2001年   1394篇
  2000年   1333篇
  1999年   1053篇
  1998年   583篇
  1997年   545篇
  1996年   640篇
  1995年   622篇
  1994年   588篇
  1993年   577篇
  1992年   1039篇
  1991年   913篇
  1990年   937篇
  1989年   813篇
  1988年   810篇
  1987年   805篇
  1986年   793篇
  1985年   804篇
  1984年   761篇
  1983年   666篇
  1982年   547篇
  1981年   556篇
  1980年   512篇
  1979年   685篇
  1978年   583篇
  1976年   528篇
  1975年   648篇
  1974年   662篇
  1973年   674篇
  1972年   624篇
  1971年   556篇
  1970年   497篇
  1968年   596篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
It is widely assumed that reinforcers are biologically relevant stimuli, or stimuli that have been associated with biologically relevant stimuli. However, brief, arbitrary stimuli have also been reported to have reinforcement-like effects, despite being unrelated to biologically relevant stimuli like food. The present study explored the potential reinforcement-like effects of brief stimuli across 5 experiments. In Experiments 1 through 4, pigeon subjects responded for food reinforcement and brief stimulus presentations in a 2-component multiple schedule. Neither baseline response rates nor resistance to change during disruption tests were systematically greater in a component with versus without brief stimulus presentations. Increasing the rate and duration of brief stimulus presentations in Experiment 4 did not reveal reinforcement-like effects when compared directly with food. In Experiment 5, pigeons chose between independent terminal links in a concurrent-chains procedure. Across conditions, varying the location, duration, and rate of brief stimulus presentations in the terminal links had no systematic effects on preference. In contrast, varying rates of food reinforcers resulted in large and reliable shifts in preference. Therefore, the present study found no systematic evidence that brief stimuli unrelated to food reliably increase response rates, resistance to change, or preference. These data demonstrate the value of systematic replication, and a behavioral momentum approach to assessing potential reinforcement-like effects.  相似文献   
52.
53.
54.
55.
In two experiments, hungry rats were given instrumental lever-press training for an appetitive reinforcer and, in addition, were exposed to another type of food which was not contingent on lever pressing. In the first experiment, exposure to each type of food was on separate days, whereas in the second experiment rats were exposed to each type of food in strict alternation within each session. Subsequently, a food aversion was conditioned to the reinforcer for the experimental group and to the non-contingent food for the control group. In both experiments, animals with an aversion to the reinforcer responded less in an extinction test than animals with an aversion to the non-contingent food. Subsequent reacquisition tests confirmed that the aversion to the non-contingent food in the control group was of comparable strength with that to the reinforcer in the experimental group. The results were discussed in terms of whether the reinforcer is encoded in the associative structure set up by exposure to an instrumental contingency.  相似文献   
56.
57.
Gay marriages (as such) are not as yet allowed anywhere but the demand for them is increasing. Most countries take a liberal attitude towards marriage: few obstacles are put in its way. But objections to gay marriages continue to be raised. These objections are refuted and the case for gay marriage is assessed through the prism of various forms of liberalism. The normative argument for allowing gay marriage is shown to be both strong and consistent with many of the values upheld by the opponents of such unions.  相似文献   
58.
59.
60.
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