全文获取类型
收费全文 | 62664篇 |
免费 | 2524篇 |
国内免费 | 38篇 |
专业分类
65226篇 |
出版年
2020年 | 696篇 |
2019年 | 847篇 |
2018年 | 1150篇 |
2017年 | 1129篇 |
2016年 | 1265篇 |
2015年 | 863篇 |
2014年 | 1082篇 |
2013年 | 5063篇 |
2012年 | 1956篇 |
2011年 | 1987篇 |
2010年 | 1312篇 |
2009年 | 1353篇 |
2008年 | 1862篇 |
2007年 | 1805篇 |
2006年 | 1652篇 |
2005年 | 1423篇 |
2004年 | 1464篇 |
2003年 | 1362篇 |
2002年 | 1384篇 |
2001年 | 1735篇 |
2000年 | 1735篇 |
1999年 | 1358篇 |
1998年 | 703篇 |
1997年 | 672篇 |
1995年 | 639篇 |
1992年 | 1141篇 |
1991年 | 1060篇 |
1990年 | 1025篇 |
1989年 | 984篇 |
1988年 | 990篇 |
1987年 | 906篇 |
1986年 | 943篇 |
1985年 | 973篇 |
1984年 | 863篇 |
1983年 | 771篇 |
1982年 | 626篇 |
1979年 | 917篇 |
1978年 | 719篇 |
1977年 | 637篇 |
1976年 | 660篇 |
1975年 | 716篇 |
1974年 | 876篇 |
1973年 | 923篇 |
1972年 | 728篇 |
1971年 | 691篇 |
1970年 | 615篇 |
1969年 | 659篇 |
1968年 | 814篇 |
1967年 | 735篇 |
1966年 | 718篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
931.
Hans P. W. Vermeeren 《Synthese》1986,69(3):273-290
Controversies, i.e., multiple theory confrontations, may have a strong impact on the development of science. By an analysis of the so-called “resonance controversy” in chemistry the view that controversies and their resolution differ considerably from the process of theory succession is defended. It is argued that controversies are symptomatic of foundational problems, produce theory-scattering or domain-splitting, and induce ontological shifts. An explication is given of the role of existence claims and the applicability of Ockham's Razor in the resolution of controversies. The requirement of a realistic interpretation of theories at all times, as defended by some philosophers, is criticised. 相似文献
932.
Truth and proof: The Platonism of mathematics 总被引:1,自引:0,他引:1
W. W. Tait 《Synthese》1986,69(3):341-370
933.
934.
935.
936.
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
937.
Temporal integration and vibrotactile backward masking 总被引:1,自引:0,他引:1
P M Evans J C Craig 《Journal of experimental psychology. Human perception and performance》1986,12(2):160-168
Subjects were presented with vibrotactile target patterns to their left index fingertips. The target patterns varied in the number of line segments that they contained and were presented in the presence or absence of a backward-masking stimulus. The stimulus onset asynchrony (SOA) between the target and masker was varied. In an identification task, subjects' errors indicated that the effect of the masker at brief SOAs was to increase the perceived number of line segments in the target. This effect diminished with increasing SOA, and at the longest SOAs subjects confused targets with patterns containing the same number of line segments but varying in how the line segments were related. In an estimation task, the effect of the masker was to increase the number of line segments estimated to be contained in the target pattern. The effect of the masker at brief SOAs is discussed in terms of an integration theory of vibrotactile backward masking. At longer SOAs, the results suggest that the masker may interfere with the extraction of relational information in the target pattern. 相似文献
938.
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
939.
Memory storage and retrieval processes in category learning 总被引:1,自引:0,他引:1
W K Estes 《Journal of experimental psychology. General》1986,115(2):155-174
The detailed course of learning is studied for categorization tasks defined by independent or contingent probability distributions over the features of category exemplars. College-age subjects viewed sequences of bar charts that simulated symptom patterns and responded to each chart with a recognition and a categorization judgment. Fuzzy, probabilistically defined categories were learned relatively rapidly when individual features were correlated with category assignment, more slowly when only patterns carried category information. Limits of performance were suboptimal, evidently because of capacity limitations on judgmental processes as well as limitations on memory. Categorization proved systematically related to feature and exemplar probabilities, under different circumstances, and to similarity among exemplars of categories. Unique retrieval cues for exemplar patterns facilitated recognition but entered into categorization only at retention intervals within the range of short-term memory. The findings are interpreted within the framework of a general array model that yields both exemplar-similarity and feature-frequency models as special cases and provides quantitative accounts of the course of learning in each of the categorization tasks studied. 相似文献
940.
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