全文获取类型
收费全文 | 80785篇 |
免费 | 3327篇 |
国内免费 | 37篇 |
出版年
2020年 | 910篇 |
2019年 | 1108篇 |
2018年 | 1582篇 |
2017年 | 1639篇 |
2016年 | 1658篇 |
2015年 | 1209篇 |
2014年 | 1419篇 |
2013年 | 6844篇 |
2012年 | 2609篇 |
2011年 | 2704篇 |
2010年 | 1672篇 |
2009年 | 1686篇 |
2008年 | 2379篇 |
2007年 | 2288篇 |
2006年 | 2116篇 |
2005年 | 1776篇 |
2004年 | 1759篇 |
2003年 | 1735篇 |
2002年 | 1624篇 |
2001年 | 2748篇 |
2000年 | 2613篇 |
1999年 | 1932篇 |
1998年 | 925篇 |
1997年 | 770篇 |
1996年 | 846篇 |
1995年 | 762篇 |
1994年 | 764篇 |
1993年 | 745篇 |
1992年 | 1617篇 |
1991年 | 1511篇 |
1990年 | 1485篇 |
1989年 | 1406篇 |
1988年 | 1377篇 |
1987年 | 1301篇 |
1986年 | 1264篇 |
1985年 | 1366篇 |
1984年 | 1097篇 |
1983年 | 920篇 |
1979年 | 1119篇 |
1978年 | 840篇 |
1977年 | 733篇 |
1975年 | 946篇 |
1974年 | 1026篇 |
1973年 | 1096篇 |
1972年 | 911篇 |
1971年 | 817篇 |
1969年 | 739篇 |
1968年 | 937篇 |
1967年 | 803篇 |
1966年 | 833篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
Visually guided catching and tracking skills in pigeons: A preliminary analysis 总被引:2,自引:1,他引:1 下载免费PDF全文
Research on reaching, tracking, and catching in the pigeon has been hampered by limitations of technology. A new system was developed in which the target was a small rectangle presented on a video display terminal and the pecking response was detected with touch technology. The target moved up and down vertically with sinusoidal velocity. A coincidence between the location of the pigeon's beak and the cursor produced reinforcement. The pigeon pecked ahead and behind the target, but most pecks occurred behind the target so the dominant tracking strategy was lagging. The pigeon was adept at “catching” the target at many locations throughout the trajectory. Transfer of motor learning was tested on probe trials during which the trajectory changed from vertical to horizontal. On transfer trials the pigeons' dominant pattern of pecking immediately shifted from vertical to horizontal. The motor skill displayed by the pigeons was flexible and adaptive, suggesting that the pigeons had learned to track the cursor. 相似文献
912.
Sidman M Wynne CK Maguire RW Barnes T 《Journal of the experimental analysis of behavior》1989,52(3):261-274
Three adult subjects were taught a set of two-choice simultaneous discriminations, with three positive and three negative stimuli; all possible combinations of positive and negative stimuli yielded nine different pairs. The discriminations were repeatedly reversed and rereversed, the former positive stimuli becoming negative and the former negative stimuli becoming positive. With all subjects, a reversal of the contingencies for one pair of stimuli became sufficient to change their responses to all of the other pairs. The reversals had produced functional stimulus classes. Then, all subjects showed conditional discriminations emerging between members of a functional class; given a sample from one class and comparisons from both classes, they selected the comparison that was in the same class as the sample. Next, 2 of the subjects showed that the within-class conditional relations possessed the symmetric and transitive properties of equivalence relations; after having been taught to relate new stimuli to existing class members, the subjects then matched other class members to the new stimuli. Subsequent tests of two-choice discriminations showed that the conditional discriminations had transferred functional class membership to the new stimuli. The 3rd subject, who did not show equivalence relations among functional class members, was also found to have lost the within-class conditional relations after the equivalence tests. 相似文献
913.
Inferring Emotions From Multiple Cues: Revealing Age-Related Differences in "How" Without Differences in "Can" 总被引:1,自引:0,他引:1
This study examined differences in children's use of social cues to make emotional inferences. Children ages 4, 5, and 8 years were presented with stimuli that depicted another child in affectively congruous and affectively incongruous expression/situation combinations. The intensity of positive and negative facial expressions was varied across situations. Subjects judged the target's feelings and selected among the alternative facial expressions or situations the one they had just seen. No significant age-related differences were found in the extent to which children registered and used both the expressive and situational information when making emotional inferences. The main experimental measure asked children to explain their judgments. In explaining their judgments, subjects' rationales indicated that they: (a) used both the situational and expressive cues; and (b) were sensitive to congruous versus incongruous cues, and even to mild versus strong incongruous cues. Children's rationales also reflected a sensitivity to expressive and situational negativity. For each age group, the rationales were more elaborate when the cues were problematic. Characteristic strategies, however, were also found for each age group. These distinct strategies may reflect social-life changes in children's social "theories" of emotion. 相似文献
914.
Newell KM 《Journal of motor behavior》1989,21(1):92-96
One of the significant limitations of the motor control and skill acquisition domain is that the theories, models, and hypotheses are, in most cases, task specific. Many lines of theorizing fail to hold up under even small changes in task constraints, although clearly the field does have some robust phenomena. It is proposed that a broader consideration of the role of task constraints, which is grounded in the methodology of nonlinear dynamics, may help to formulate a more general action theory of coordination and control. 相似文献
915.
In comparative anatomical studies of the shoulder, the humeral retractors are often grouped together as propulsive muscles, which are important in the propulsive stroke of the forelimb during quadrupedal locomotion. Electromyographic (EMG) analyses of these muscles in opossums, cats, and dogs in general have confirmed such conclusions. An EMG study of chimpanzee shoulder muscles during knuckle-walking found, however, that the humeral retractors are either inactive or perform a function unrelated to propulsion (Larson & Stern, 1987). This contrast in muscle recruitment patterns between chimpanzees and more "typical" mammalian quadrupeds was attributed to the derived morphology of the chimpanzee shoulder. The present study examines the activity patterns of the humeral retractors in the vervet monkey, a primate more closely resembling nonprimate mammals in its shoulder morphology. The results of this EMG analysis show that despite the significant differences in anatomy between chimpanzees and vervets, the two species display very similar muscle recruitment patterns during quadrupedalism, and there is evidence for this same pattern in other species of primates. These differences in muscle activity patterns between primates and nonprimate mammals may be related to changes in the neurological control of locomotion in primates due to the evolutionary development of manipulative abilities in the primate forelimb. 相似文献
916.
D L Schacter J F Kihlstrom L C Kihlstrom M B Berren 《Journal of abnormal psychology》1989,98(4):508-514
Previous research on multiple personality disorder (MPD) has been concerned with between-personalities amnesia, and little attention has been paid to within-personality memory function. This study examined the autobiographical memory of a multiple personality patient, I.C., with cueing procedures that have proven useful in previous studies of normal and abnormal memory. Results indicated that I.C. was able to retrieve autobiographical episodes from the recent past, although her performance differed in several respects from that of matched controls. The study also revealed a striking deficit in I.C.'s autobiographical memory for childhood: She was unable to recall a single episode from prior to the age of 10 in response to various retrieval cues, whereas control subjects had no difficulty recalling numerous childhood episodes. This phenomenon of extended childhood amnesia has not been reported previously in studies of MPD. 相似文献
917.
Examined relapse rates in those individuals who have experienced an episode of unipolar depression as a function of the number of previous episodes, gender, age at onset of the episode (less than 40 vs. greater than 40), time since a previous episode, and depression level at time of interview. From of 6,742 participants, 2,046 were interviewed; of these, 1,130 had at least one, 513 reported a second and 173 reported a third episode. The probability for relapse was positively related to number of previous episodes, being female, depression level at time of interview, but not to age at onset (less than 40 vs. greater than 40). Women were also more likely to have more severe episodes. Participants with elevated depression symptoms reported a greater number of previous episodes. Following the first episode, there was a decline in hazard rate for men but not women; following the second episode, there was no change in vulnerability for men; for women, the results were ambiguous. 相似文献
918.
Painting Group Portraits: Studying Life Outcomes for Aggressive and Withdrawn Children 总被引:1,自引:0,他引:1
Aggression and social withdrawal have long been of interest to personality psychologists. The present article presents a longitudinal study of the development of children selected from a community sample who were high on aggression and withdrawal. The selection of outcome variables is discussed, and outcomes during adolescence are described. For both males and females, high aggressiveness was predictive of low intelligence, poor school achievement, and psychiatric problems. For females, high aggressiveness was also predictive of general health problems. High social withdrawal was predictive of poor school achievement. Females who were high on withdrawal also had an elevated rate of abortions. Individuals who were high on both aggression and withdrawal had relatively poor social competence, had general problems with behavior, had low intelligence, and were performing poorly in school. 相似文献
919.
Is dependence on phonological information in children's reading a product of instructional approach? 总被引:1,自引:0,他引:1
Eight-year-old British children were found to be less accurate at rejecting pseudohomophones than ordinary nonwords in a lexical decision task, but 8-year-old New Zealand children did not show this effect. A subsequent homophone decision task showed that this difference was not due to the New Zealand children being unable to distinguish pseudohomophones from other nonwords. The New Zealand children, however, were less accurate than the British children in pronouncing the pseudohomophones they had identified. It was argued that the British children tended to sound out the items before making a choice in the lexical decision task, which gave salience to phonological rather than visual information, resulting in increased errors to the pseudohomophones. It was concluded that where the British children showed this dependency on use of phonological information it was a product of the teaching approach they had experienced. 相似文献
920.