全文获取类型
收费全文 | 55657篇 |
免费 | 2087篇 |
国内免费 | 18篇 |
出版年
2019年 | 646篇 |
2018年 | 828篇 |
2017年 | 888篇 |
2016年 | 915篇 |
2015年 | 685篇 |
2014年 | 831篇 |
2013年 | 4082篇 |
2012年 | 1535篇 |
2011年 | 1595篇 |
2010年 | 981篇 |
2009年 | 985篇 |
2008年 | 1443篇 |
2007年 | 1362篇 |
2006年 | 1263篇 |
2005年 | 1184篇 |
2004年 | 1131篇 |
2003年 | 1069篇 |
2002年 | 1114篇 |
2001年 | 1610篇 |
2000年 | 1514篇 |
1999年 | 1118篇 |
1998年 | 604篇 |
1997年 | 517篇 |
1992年 | 939篇 |
1991年 | 950篇 |
1990年 | 937篇 |
1989年 | 933篇 |
1988年 | 898篇 |
1987年 | 860篇 |
1986年 | 920篇 |
1985年 | 993篇 |
1984年 | 811篇 |
1983年 | 771篇 |
1982年 | 600篇 |
1981年 | 624篇 |
1980年 | 510篇 |
1979年 | 903篇 |
1978年 | 661篇 |
1977年 | 575篇 |
1976年 | 608篇 |
1975年 | 803篇 |
1974年 | 909篇 |
1973年 | 937篇 |
1972年 | 774篇 |
1971年 | 731篇 |
1970年 | 712篇 |
1969年 | 760篇 |
1968年 | 910篇 |
1967年 | 835篇 |
1966年 | 818篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
931.
Frits E. Zegers 《Psychometrika》1986,51(4):559-562
A chance-corrected version of the family of association coefficients for metric scales proposed by Zegers and ten Berge is
presented. It is shown that a matrix with chance-corrected coefficients between a number of variables is Gramian. The members
of the chance-corrected family are shown to be partially ordered.
The author is obliged to Jos ten Berge for helpful comments. 相似文献
932.
933.
Four experiments investigated the relation between the development of binocular vision and infant spatial perception. Experiments 1 and 2 compared monocular and binocular depth perception in 4- and 5-month-old infants. Infants in both age groups reached more consistently for the nearer of two objects under binocular viewing conditions than under monocular viewing conditions. Experiments 3 and 4 investigated whether the superiority of binocular depth perception in 4-month-olds is related to the development of sensitivity to binocular disparity. Under binocular viewing conditions in Experiment 3, infants identified as disparity-sensitive reached more consistently for the nearer object than did infants identified as disparity-insensitive. The two groups' performances did not differ under monocular viewing conditions. These results suggest that, binocularly, the disparity-sensitive infants perceived the objects' distances more accurately than did the disparity-insensitive infants. In Experiment 4, infants were habituated to an object, then presented with the same object and a novel object that differed only in size. Disparity-sensitive infants showed size constancy by recovering from habituation when viewing the novel object. Disparity-insensitive infants did not show clear evidence of size constancy. These findings suggest that the development of sensitivity to binocular disparity is accompanied by a substantial increase in the accuracy of infant spatial perception. 相似文献
934.
H Wallach F J Marshall 《Journal of experimental psychology. Human perception and performance》1986,12(3):338-342
The distortion of polar perspective depends on the depth of the tridimensional shape and on the observation distance. In four experiments using 54 undergraduates as subjects, we found that a compensation process which takes depth and observation distance into account corrects for such distortions. Compensation was demonstrated in experiments in which deceptive information on depth and on observation distance was provided. The result was distortions of the perceived shapes that would be expected if compensation were based on the deceptive information. 相似文献
935.
A homogeneous sample of normal adults living in a religious order in a study of age effects on reference as a cohesive device in discourse production and comprehension. Narrative and procedural discourse were examined across various levels of complexity and stimulus/response requirements. Results indicate that significant ambiguity of reference emerges in the younger elderly group (age 64-76) in comparison to the middle-aged group (age 27 to 55), and increases markedly in the older elderly group (age 77-92). Related impairments of comprehension and cognition were also observed. These findings are interpreted to be general features of linguistic variation with advancing age. Communicative consequences of ambiguous reference are discussed. 相似文献
936.
Participants completed the Rotter internal/external (IE) instrument using three different response formats before and after completion of the Outward Bound program, and were evaluated by external observers at the end of the intervention. Multitrait-multimethod analyses indicated that five specific IE facets identified in previous research were consistently distinguished with each of the response formats. While responses were substantially more internal after the intervention, effect sizes varied with the IE facet and with the response format. Observer responses were significantly correlated with self-responses, and provided additional support for the construct validity of responses to the Rotter instrument and the interpretation of the intervention effect. Nevertheless, problems with the Rotter instrument were identified, and the implications for further research were discussed. 相似文献
937.
W H Warren D S Young D N Lee 《Journal of experimental psychology. Human perception and performance》1986,12(3):259-266
Running over uneven ground requires visually regulating step length to secure proper footing. To examine how this is achieved, we studied subjects running on a treadmill on a series of irregularly spaced targets. The movements of their lower limbs and coccyx relative to the targets were monitored opto-electronically by a Selspot system. The results indicated that step length was adjusted to strike the targets primarily by varying the vertical component of impulse applied to the ground during the stance phase. In contrast, horizontal impulse was not varied significantly, and changing the reach forward of the foot on landing contributed little to variation in step length. Changing the vertical impulse simply altered the step time proportionately. Thus the data are consistent with a time-based model in which vertical impulse is modulated by the optic variable delta tau (Lee, 1976) specifying the time gap that has to be bridged by the runner between two targets. 相似文献
938.
Disturbances in exploratory behavior and functional recovery in the Y and radial mazes following dopamine depletion of the lateral septum 总被引:1,自引:0,他引:1
The effects of 6-hydroxydopamine (6-OHDA) injected into the lateral septum in rats were investigated for spontaneous alternation behavior in a Y maze and for spatially oriented behavior in an 8-arm radial maze. The performance of the animals in these tests was assessed under two physiological states, food-satiated and food-deprived. The selective depletion of septal dopaminergic concentrations leads to behavioral disturbances in both the Y and the radial mazes. These deficits disappeared when the animals with 6-OHDA lesions were food-deprived. These results confirm other studies from our laboratory and support two conclusions. First, lesions of dopaminergic neurons lead to behavioral impairments which resemble those found after the total lesion of the structure they innervate. Second, these behavioral impairments are responsive to therapeutic treatments, manipulations of the internal or external environment, or the level of arousal, since under certain conditions a recovery of function can occur in the absence of dopaminergic neurons. These two points provide additional support for a nonspecific role for the dopaminergic neurons originating in the ventral tegmental area. These neurons could have a permissive role in the functioning of the forebrain structures they innervate. 相似文献
939.
Recent findings indicate that post-training glucose injections can modulate memory storage for inhibitory (passive) avoidance training. Experiment I extended these findings to determine whether glucose, like other memory modulating treatments, enhances memory storage when administered after training with low footshock and impairs memory storage after high footshock training. In Experiment I, male Sprague-Dawley rats were trained in a one-trial inhibitory avoidance task using either a brief footshock (0.5 mA, 0.7 s) or slightly more intense footshock kept on until escape (0.7 mA, mean escape latency = 3.4 s). Immediately after training, each rat received a subcutaneous injection of glucose (100 mg/kg). When tested for retention performance 24 h later, the glucose-injected animals exhibited enhanced retention performance for low footshock training and impaired retention for high footshock training. Experiment II determined whether pretreatment with adrenergic antagonists blocked the effects of glucose on memory. Pretreatment with the alpha- or beta-adrenergic receptor antagonists, phenoxybenzamine, or propranolol, respectively, had no effect on acquisition or retention in animals trained with the brief footshock and did not affect glucose facilitation of that memory. In animals trained to escape footshock, phenoxybenzamine did not attenuate the amnesia produced by glucose. Propranolol-pretreated animals had impaired retention whether or not they received post-training amnestic injections of glucose; glucose had no effect on retention in these amnestic animals. These findings add further support to the view that glucose release after training and treatment may represent a physiological response subsequent to epinephrine release in modulating memory storage processing. 相似文献
940.
The 2-deoxyglucose (2-DG) autoradiographic method was used to map metabolic activity in the brain of socially deprivated rats during an active avoidance test. The method investigated the effects of razobazam during this learning test. The animals were socially deprivated for 5 weeks. On the first experimental day the animals were trained to avoid a footshock by jumping onto a platform. During training and testing, the total number of avoidance responses was scored. On the second day during one 2-DG session of 40 min, razobazam increased the avoidance score by 18% as compared to controls. Autoradiographs were analyzed using a two-dimensional densitometric method. The analysis of the brain structures showed a 22% reduction of optical density in the nucleus habenularis lateralis, a 25% increase in the caudal part of the nucleus accumbens, and a 13% increase in the frontal cortex in rats treated with razobazam, but no change in the amygdala. These results provide a preliminary concept to explain how the new compound razobazam produced a better learning performance in socially deprivated rats. 相似文献