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   43578篇
  免费   804篇
  国内免费   11篇
  2020年   229篇
  2018年   3708篇
  2017年   3076篇
  2016年   2552篇
  2015年   438篇
  2014年   402篇
  2013年   1863篇
  2012年   1195篇
  2011年   2992篇
  2010年   2858篇
  2009年   1819篇
  2008年   2227篇
  2007年   2697篇
  2006年   562篇
  2005年   698篇
  2004年   646篇
  2003年   546篇
  2002年   564篇
  2001年   781篇
  2000年   809篇
  1999年   587篇
  1998年   301篇
  1997年   260篇
  1996年   239篇
  1992年   473篇
  1991年   431篇
  1990年   473篇
  1989年   437篇
  1988年   414篇
  1987年   418篇
  1986年   424篇
  1985年   447篇
  1984年   367篇
  1983年   327篇
  1982年   269篇
  1981年   237篇
  1979年   415篇
  1978年   306篇
  1977年   285篇
  1976年   258篇
  1975年   362篇
  1974年   407篇
  1973年   377篇
  1972年   339篇
  1971年   295篇
  1970年   263篇
  1969年   336篇
  1968年   364篇
  1967年   334篇
  1966年   334篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
A cost-benefit analysis of demand for food.   总被引:20,自引:17,他引:3       下载免费PDF全文
Laboratory studies of consumer demand theory require assumptions regarding the definition of price in the absence of a medium of exchange (money). In this study we test the proposition that the fundamental dimension of price is a cost-benefit ratio expressed as the effort expended per unit of food value consumed. Using rats as subjects, we tested the generality of this "unit price" concept by varying four dimensions of price: fixed-ratio schedule, number of food pellets per fixed-ratio completion, probability of reinforcement, and response lever weight or effort. Two levels of the last three factors were combined in a 2 x 2 x 2 design giving eight groups. Each group was studied under a series of six FR schedules. Using the nominal values of all factors to determine unit price, we found that grams of food consumed plotted as a function of unit price followed a single demand curve. Similarly, total work output (responses x effort) conformed to a single function when plotted in terms of unit price. These observations provided a template for interpreting the effects of biological factors, such as brain lesions or drugs, that might alter the cost-benefit ratio.  相似文献   
132.
133.
Effects of visual aids on acquisition of selected tennis skills   总被引:1,自引:0,他引:1  
The study compared the effects of supplemental visual aids on the acquisition of selected tennis skills. The forehand and backhand drive placement tests of the Hewitt Tennis Achievement Test were used to pretest, midtest, and posttest 55 subjects who were assigned to one of three treatments: control (instructor's verbal feedback only), videotaped replay viewing (with instructor's feedback), and loop-film viewing (modeling, with instructor's feedback). Each received 1200 min. of instruction. There were no statistically significant differences among groups; however, empirical evidence suggested that the use of videotaped replay and loop-film technique has merit and might be given consideration for use in instructional settings.  相似文献   
134.
We hypothesized that in the decodification of connotative aspects of visual chromatic stimuli the periphery of the body plays an important role. In particular we hypothesized that the decodification process of so called "warm" and "cold" colours is related to a real modification of the temperature of the body which is the basis of the "subjective feeling" and of the attribution of the "emotional meaning" to the stimulus. So we have measured the temperature of the body of 36 female psychology students while they were looking at a luminous screen through spectacles in which filters (coloured lenses) of different colours were placed. Analysis indicated that during the perception of so called "warm" colours a statistically significant increase in the temperature of the body appeared. We observed an enhancement of temperature on the left side of the body during the perception with red and yellow filters and a small increase in temperature on the right side of the body with orange and yellow filters. In the discussion of the results we considered also the role of the cerebral dominance in decodification process of the connotative components of stimuli.  相似文献   
135.
The purpose of this study was to investigate differences in scores of 59 mentally retarded adults (mild, moderate, severe, or profound), 133 advantaged, and 130 disadvantaged (low income) children in Grades 1, 2, 3 on the Primary Measures of Music Audiation. Test-retest reliabilities for the Tonal and Rhythm subtests were .81 and .86, respectively, for the retarded group. Analysis of variance indicated that the mildly retarded children performed significantly better than other groups of retarded children on these two tests. 2 x 3 analyses of variance indicated that third graders from both advantaged and disadvantaged groups performed significantly better than the first or second graders on both subtests and that advantaged children performed significantly better than the disadvantaged. However, disadvantaged children made greater gains, especially for third graders, than the advantaged.  相似文献   
136.
137.
138.
The Rosenberg Self-esteem Scale was administered to 550 14- and 16-yr.-old (+/- 6 mo.) girls. Self-esteem scores were categorized by weight and weight by height. Scores on the Quetelet Index for obesity were correlated with self-esteem scores. Mean self-esteem of the low- and middle-weight by height group was significantly higher than the mean of the high-weight by height group. In analyzing weight alone, the self-esteem of the middle-weight group was significantly higher than the self-esteem of the high-weight group. The correlation of the obesity index and self-esteem indicated that as weight increased self-esteem decreased.  相似文献   
139.
140.
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