全文获取类型
收费全文 | 59024篇 |
免费 | 2386篇 |
国内免费 | 18篇 |
出版年
2020年 | 547篇 |
2019年 | 734篇 |
2018年 | 978篇 |
2017年 | 1007篇 |
2016年 | 1070篇 |
2015年 | 781篇 |
2014年 | 919篇 |
2013年 | 4300篇 |
2012年 | 1724篇 |
2011年 | 1886篇 |
2010年 | 1165篇 |
2009年 | 1155篇 |
2008年 | 1671篇 |
2007年 | 1687篇 |
2006年 | 1540篇 |
2005年 | 1357篇 |
2004年 | 1254篇 |
2003年 | 1178篇 |
2002年 | 1291篇 |
2001年 | 1959篇 |
2000年 | 1936篇 |
1999年 | 1463篇 |
1998年 | 681篇 |
1997年 | 605篇 |
1996年 | 605篇 |
1993年 | 546篇 |
1992年 | 1236篇 |
1991年 | 1135篇 |
1990年 | 1123篇 |
1989年 | 1024篇 |
1988年 | 1008篇 |
1987年 | 963篇 |
1986年 | 1039篇 |
1985年 | 1046篇 |
1984年 | 875篇 |
1983年 | 797篇 |
1982年 | 559篇 |
1981年 | 557篇 |
1979年 | 933篇 |
1978年 | 665篇 |
1975年 | 760篇 |
1974年 | 814篇 |
1973年 | 907篇 |
1972年 | 766篇 |
1971年 | 722篇 |
1970年 | 642篇 |
1969年 | 668篇 |
1968年 | 855篇 |
1967年 | 775篇 |
1966年 | 651篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
221.
The possibility that rats can navigate in the Morris water maze by reducing the difference between the memorized platform scene and the current sensory input was tested in nine blind rats. A computerized videosystem monitored the rats' movements in the pool and converted the rat-target distance into tones the frequency of which increased in 64 equal steps from 120 Hz at 128 cm to 7680 Hz at 0 cm. During 15 days of training to find a fixed platform position from different starting points (12 trials per day) average escape latencies decreased from 39.0 to 25.4 s. The performance significantly deteriorated when the acoustic distance signalization was omitted and/or when the target position was changed form trial to trial. It is concluded that blind rats solved the task by simultaneously employing search strategy based on position responses, mapping using acoustic background beacons, and distance reduction navigation. It is argued that the various strategies are additive and that their relative significance depends of the conditions of the experiment. 相似文献
222.
J L Díaz 《Behavioral and neural biology》1988,50(2):164-183
Fifty 8-week-old Balb/c mice were individually identified and housed together in a large and enriched environment for 5 months. Maze and open field exploration, response to an aversive noise, swimming, and induced grooming tests were applied to each mouse in an initial search for possible relationships between brain morphology and spontaneous behavior in isogenic individuals living in a complex social and physical environment. The tasks generated 39 quantitative behavioral indices which include locomotion, rearing, still, and grooming bout frequencies, latencies, total, and mean bout durations. At the end of the tests, the 7-month-old mice were sacrificed and the fresh weights of their whole brain, cerebellum, brain stem, diencephalon, telencephalon, and prosencephalon were rapidly obtained. Behavioral data have wide variations and do not adjust to normal population distributions. Means of the same parameter differ between tests. A Spearman correlation matrix of all data yielded many significant correlations between indices of the same task which can be interpreted in terms of time budget and sequence probability. Significant correlations between indices of different tests suggest diverse emotionalities, exploratory strategies, and motor skills. The correlations between body and brain weights and among separate brain regions were not significant. There were several low but significant correlations between brain weights and behavioral indices. Such correlations, the resulting factors, and significant behavioral differences between mice with large and small brains suggest that mice displaying low motor activity in novel environments have larger brains and forebrain/hindbrain ratios than mice with high activity, and that animals with high scores of some specific behaviors have larger brain areas physiologically related to such behaviors.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
223.
The self-appraisal model of Type A behavior holds that Type A's desire an accurate appraisal of abilities, and respond to uncertainty about abilities with exaggerated attempts to generate diagnostic information. The model also predicts that the major emotional response to uncertainty for Type A's is anxiety. In this study, Type A's and B's were induced to succeed or fail on a task where they were either very certain or very uncertain of their subsequent ability levels. Task failure produced greater depression, anger, and frustration for all subjects. Consistent with the self-appraisal model's prediction, uncertainty (regardless of success or failure) led to greater anxiety for Type A's than for Type B's. In fact, greater uncertainty produced lower anxiety for Type B's, indicating that Type A's and B's differ dramatically in their emotional responses to uncertainty about abilities. 相似文献
224.
Picture-pointing auditory and reading comprehension tests were administered to anomic and conduction aphasics. Subjects responded to active sentences of the present progressive form. The possible errors which a subject could make on these experimental tasks included failure to correctly interpret noun order, number, or lexical meaning. Both groups made significantly more correct responses than error responses. Of their error responses, noun-order errors significantly exceeded number and lexical errors for which no differences were observed. When compared with results previously obtained for agrammatic Broca's aphasics, no differences in the pattern of errors were identified. These results are discussed relative to current theories of syntactic processing and for the mechanisms which account for these syntactic comprehension deficits following aphasia. 相似文献
225.
The ability of right-brain-damaged (RBD) subjects to correctly insert a word into a well-formed stimulus sentence was tested. Subjects also performed three evaluative tasks designed to establish their degree of general cognitive impairment. The performance of RBD subjects on these tasks was compared to that of left-brain-damaged (LBD) and non-brain-damaged (NBD) subjects. Although RBD subjects outperformed LBD subjects on the language-related evaluative tasks, the RBD group was significantly more impaired on a subset of the insertion task. This subset included items which required reassignment of the syntactic status of elements in the stimulus sentence in order for the insertion to be carried out. The results of this study permit refinement of the common characterization of RBD individuals as rigid in their interpretation of meaning and indicate right-hemisphere involvement in aspects of the grammar previously thought to be inaccessible to it. 相似文献
226.
A pediatric auditory version of the Stroop procedure was developed and administered to 48 normal children from 3 to 6 years of age. Our purpose was to define the developmental course characterizing interaction between auditory and semantic speech dimensions in young children. The procedure was a reaction time (RT) task that required children to respond as quickly and as accurately as possible to words spoken by a male or a female voice. Children were instructed to ignore what was said and to push the "Mommy" button if Mommy was talking or the "Daddy" button if Daddy was talking. Performance was obtained for words with neutral, congruent, and conflicting semantic content. Preschool children manifested processing dependencies that were similar to those observed in adults on the visual Stroop procedure. Conflict between semantic and auditory dimensions significantly increased RT and congruence between the two dimensions significantly decreased RT relative to the neutral condition. The pattern of results indicated that the meaning of words was processed automatically in the normal children. The magnitude of the Stroop effect reflected developmental change with increasing age. 相似文献
227.
228.
M J Nissen J L Ross D B Willingham T B Mackenzie D L Schacter 《Brain and cognition》1988,8(1):117-134
We studied an individual with multiple personality disorder in whom each of several personalities claimed to have no direct awareness of the others and to be unable to consciously remember the experiences of other personalities. A broad selection of implicit and explicit memory tests was used to determine the extent to which one personality had access to knowledge acquired by another and the circumstances in which that knowledge would be expressed. The implicit assessment of memory was a necessary but not sufficient condition for demonstrating interpersonality access. The degree of compartmentalization of knowledge in this patient depended largely on whether the interpretation of presented information was likely to differ across personalities. 相似文献
229.
230.
The hypothesis that physical exercise provides benefits to individuals under periods of life stress has rarely been subject to empirical verification. This article presents the results of a longitudinal study of stress and well-being in adolescence in which the ability of exercise to buffer stress-induced deteriorations in physical health was examined. In accordance with predictions, prospective analyses revealed that the negative impact of stressful life events on health declined as exercise levels increased. These findings suggest that exercise may be a valuable resource for combating life stress. Discussion centers on possible mediating mechanisms and on the practical implications of the results. 相似文献