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   84766篇
  免费   3444篇
  国内免费   44篇
  88254篇
  2020年   909篇
  2019年   1114篇
  2018年   1558篇
  2017年   1568篇
  2016年   1680篇
  2015年   1175篇
  2014年   1408篇
  2013年   6832篇
  2012年   2576篇
  2011年   2690篇
  2010年   1656篇
  2009年   1623篇
  2008年   2459篇
  2007年   2430篇
  2006年   2122篇
  2005年   1965篇
  2004年   1888篇
  2003年   1721篇
  2002年   1782篇
  2001年   2695篇
  2000年   2547篇
  1999年   1953篇
  1998年   1001篇
  1997年   870篇
  1996年   814篇
  1995年   780篇
  1993年   788篇
  1992年   1699篇
  1991年   1572篇
  1990年   1583篇
  1989年   1395篇
  1988年   1361篇
  1987年   1331篇
  1986年   1378篇
  1985年   1478篇
  1984年   1159篇
  1983年   1039篇
  1979年   1204篇
  1978年   857篇
  1976年   815篇
  1975年   1076篇
  1974年   1165篇
  1973年   1197篇
  1972年   1068篇
  1971年   969篇
  1970年   923篇
  1969年   904篇
  1968年   1177篇
  1967年   1096篇
  1966年   980篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
952.
Lewis Henry Morgan never used the term evolution in any of his major sociological works. If he may be labeled an evolutionist, the specificity of his views must be taken into account. The main "evolutionist" issue that concerned him was that of the unity or diversity of the human species. This was an urgent political and theological issue in the America of his day, and it impinged also on research on the American Indians. Morgan's first major study was designed to demonstrate the unity of origin of the American aborigines and their "Asian" origins. His methods were derived from the tradition of Indo-European philology. It was virtually as an afterthought that he added a social evolutionary component to what he conceived of as an exercise in philology. Later he came under the direct influence of the English evolutionists, and this was crucial for the conception of Ancient Society.  相似文献   
953.
Distributions of reinforcers between two components of multiple variable-interval schedules were varied over a number of conditions. Sensitivity to reinforcement, measured by the exponent of the power function relating ratios of responses in the two components to ratios of reinforcers obtained in the components, did not differ between conditions with 15-s or 60-s component durations. The failure to demonstrate the “short-component effect,” where sensitivity is high for short components, was consistent with reanalysis of previous data. With 60-s components, sensitivity to reinforcement decreased systematically with time since component alternation, and was higher in the first 15-s subinterval of the 60-s component than for the component whose total duration was 15 s. Varying component duration and sampling behavior at different times since component transition may not be equivalent ways of examining the effects of average temporal distance between components.  相似文献   
954.
This essay presents the findings from a study of the effect of divorce on spiritual growth among Protestants. Looking at movement in the areas of love of God, self, and others, it shows that the divorce experience can have varying levels of impact which relate at least partially to the traumatic intensity of the experience itself.Excerpted from The Effect of Divorce on Spiritual Growth: A Study in Protestant Spirituality (unpublished thesis), (c) 1984 Jean M. Blomquist. All rights reserved.  相似文献   
955.
The present experiments studied a three-event delayed sequence-discrimination (DSD) task: one arrangement (order) of two stimuli (red and yellow overhead lights) taken three in succession (e.g., red, yellow, red) was the positive sequence and the remaining seven arrangements were the negative sequences for responding and reward during the subsequent test stimulus. In Experiment 1, the final stimulus (recency) and the order of stimuli in the positive sequence controlled acquisition of discrimination. In Experiment 2, increasing the duration of memory intervals between stimuli reduced the discriminability of those negative sequences identical to the positive sequence after the delay. Three-event DSD performance in Experiments 1 and 2 was similar to two-event DSD performance in comparable published experiments. Models developed to explain pigeon performance in two-event DSD were extended to the three-event task. Results from both two- and three-event versions of the DSD task falsified a noncumulative model and several cumulative integration models (i.e., adding, averging, and some multiplying models), but corroborated one cumulative, multiplying model.  相似文献   
956.
957.
Scores on the Beck Depression Inventory (BDI) were periodically obtained from the roommates of college students who exhibited a persistent mild depression over a 3-month period. For comparative purposes, BDI scores were also obtained from roommates of individuals who were transiently depressed and from subjects with nondepressed roommates. In comparison with control subjects, the roommates of persistently depressed persons displayed a progressive increase in BDI score over the course of the study.  相似文献   
958.
959.
960.
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