全文获取类型
收费全文 | 25719篇 |
免费 | 322篇 |
国内免费 | 3篇 |
专业分类
26044篇 |
出版年
2023年 | 63篇 |
2022年 | 44篇 |
2021年 | 90篇 |
2020年 | 165篇 |
2019年 | 180篇 |
2018年 | 3695篇 |
2017年 | 3010篇 |
2016年 | 2487篇 |
2015年 | 337篇 |
2014年 | 244篇 |
2013年 | 655篇 |
2012年 | 837篇 |
2011年 | 2690篇 |
2010年 | 2698篇 |
2009年 | 1636篇 |
2008年 | 1935篇 |
2007年 | 2429篇 |
2006年 | 210篇 |
2005年 | 364篇 |
2004年 | 318篇 |
2003年 | 234篇 |
2002年 | 173篇 |
2001年 | 191篇 |
2000年 | 204篇 |
1999年 | 126篇 |
1998年 | 66篇 |
1997年 | 69篇 |
1996年 | 47篇 |
1995年 | 23篇 |
1994年 | 31篇 |
1993年 | 27篇 |
1992年 | 57篇 |
1991年 | 60篇 |
1990年 | 55篇 |
1989年 | 47篇 |
1988年 | 45篇 |
1987年 | 36篇 |
1986年 | 30篇 |
1985年 | 26篇 |
1984年 | 30篇 |
1983年 | 25篇 |
1982年 | 20篇 |
1981年 | 22篇 |
1980年 | 21篇 |
1979年 | 27篇 |
1977年 | 18篇 |
1976年 | 22篇 |
1974年 | 19篇 |
1973年 | 18篇 |
1971年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
122.
The separate effects of group size, room size, and density (space per person) were investigated for subjects responding interactively or coactively to perceptual and cognitive tasks. The major findings are that crowding has greater effects on "feelings" and "interpersonal perceptions" than on task performance. Where crowding did have effects, they appeared to be mediated more by group size and, to some degree, room size than by density, especially for males. Female subjects appeared somewhat more density oriented than male subjects. 相似文献
123.
The relative effect of each informational dimension in an information integration task is a joint function of its weight and the range of values over which it is varied. A method is developed for separating these two factors. Weights obtained by this method were compared across variations of stimulus range. Subjects rated the performance of students on the basis of midterm exam scores and final exam scores. For some subjects, the range of scores on the final exam was twice that on the midterm and the reverse was true for other subjects. An averaging model was shown to describe the results, and weights did not differ for different stimulus ranges. This was true for each of two instructional conditions: one in which a particular weighting strategy was prescribed and one in which there was no prescribed weighting. Students who were instructed to use a 2∶1 weighting were found to assign more than twice as much weight to the final as to the midterm. 相似文献
124.
We have established a procedure for behavioral assessment of periodicity pitch perception in the cat. This procedure requires the training of cats to make a differential response to two different pure tones, and then testing for the transfer of learning when complex stimuli known to produce periodicity pitch sensations in humans are substituted for the pure tones. Complex stimuli consisted of three to five harmonically related frequencies of the same amplitude and phase. Eight cats were the subjects of these experiments. Two of them were controls. It is demonstrated here that cats do perceive periodicity pitch. We also used this procedure to measure the upper frequency limit of periodicity pitch perception for two cats. The frequencies tested were 100, 200, 300, 400, 600, 800, 900, and 1,200 Hz. The data indicate that the upper frequency limit of periodicity pitch perception in the cat is on the order of 600 to 800 Hz. There is a trend of decreasing prominence of the perception of periodicity pitch as the component frequencies are increased. These results are parallel to the human psychophysical data. 相似文献
125.
The present study investigated effects of age and instructions on temporal regulations of behavior in children. In the first experiment 4 1/2-year-old and 7-year-old subjects were trained with a DRL (differential reinforcement of low rates) 5-s and a DRL 10-s schedule. Results demonstrate that age and timing performance are related. Seven-year-olds are more efficient than the 4 1/2-year-olds. A striking decline in the 4 1/2-year-old children's capacity to space responses was observed in the DRL 10-s schedule as compared to the DRL 5-s schedule. Analysis of individual performances suggests that the evolution of DRL performance between 4 and 7 years of age depends not only on the development of the capacity to delay responding but also on the acquisition of the ability to represent the reinforcement contingencies, that is, the temporal parameters of the task to oneself. In order to test this hypothesis a second experiment was conducted where instructions to wait between operant responses were given to a group of 4 1/2-year-old subjects at the beginning of a DRL 5-s and a DRL 10-s schedule. The results show that these instructions enhance DRL performance. By directing the 4 1/2-year-old subjects' attention to the temporal requirements of the task, instructions led to efficient performance and accurate timing of responses to the DRL schedule. 相似文献
126.
127.
128.
129.
130.