全文获取类型
收费全文 | 60384篇 |
免费 | 2364篇 |
国内免费 | 25篇 |
出版年
2019年 | 804篇 |
2018年 | 1050篇 |
2017年 | 1128篇 |
2016年 | 1101篇 |
2015年 | 792篇 |
2014年 | 950篇 |
2013年 | 4596篇 |
2012年 | 1725篇 |
2011年 | 1858篇 |
2010年 | 1175篇 |
2009年 | 1160篇 |
2008年 | 1665篇 |
2007年 | 1588篇 |
2006年 | 1499篇 |
2005年 | 1321篇 |
2004年 | 1243篇 |
2003年 | 1213篇 |
2002年 | 1212篇 |
2001年 | 2004篇 |
2000年 | 1878篇 |
1999年 | 1406篇 |
1998年 | 704篇 |
1997年 | 580篇 |
1996年 | 571篇 |
1992年 | 1171篇 |
1991年 | 1137篇 |
1990年 | 1089篇 |
1989年 | 1051篇 |
1988年 | 1030篇 |
1987年 | 988篇 |
1986年 | 995篇 |
1985年 | 1075篇 |
1984年 | 870篇 |
1983年 | 755篇 |
1982年 | 613篇 |
1981年 | 596篇 |
1979年 | 921篇 |
1978年 | 690篇 |
1977年 | 608篇 |
1976年 | 623篇 |
1975年 | 799篇 |
1974年 | 849篇 |
1973年 | 925篇 |
1972年 | 742篇 |
1971年 | 655篇 |
1970年 | 644篇 |
1969年 | 683篇 |
1968年 | 820篇 |
1967年 | 710篇 |
1966年 | 757篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
901.
This study examines the effect of different behavioral conditions on patterns of correlation between regional cerebral metabolic rates for glucose. Cerebral glucose metabolism was determined with positron emission tomography and (11C)-deoxyglucose in 29 normal subjects between the ages of 23 and 55. Seventeen subjects were studied in an unstimulated (resting) condition and 12 subjects during a phoneme monitoring language stimulation. Partial correlation coefficients, controlling for whole brain glucose metabolism, were calculated for pairs of metabolic rates in 14 cortical and 2 subcortical regions. Both stimulated and unstimulated subjects showed statistically significant correlations between left and right hemisphere homologs. The stimulated subjects also showed significant within-hemisphere correlations between left but not right hemisphere regions. These included left perisylvian regions classically associated with language functions (left inferior frontal, left superior temporal and left transverse temporal cortical regions) as well as other regions. Significant correlations between left regions and a right superior temporal region were also found. In general, these findings show a pattern of cross-hemisphere symmetry at rest and of hemisphere asymmetry during stimulation. Moreover, the asymmetry observed during stimulation appears to be superimposed upon a pattern of cross-hemisphere symmetry similar to that observed in the unstimulated state. 相似文献
902.
903.
Roger P. Weissberg Emory L. Cowen Bohdan S. Lotyczewski Mary F. Boike N. Ahvay Orara Peter Stalonas Sharon Sterling Ellis L. Gesten 《American journal of community psychology》1987,15(4):387-401
Teacher-rated adjustment differences among young elementary school children from (a) a recent sample and a 1974 cohort, and (b) urban/suburban, male/female, and grade-level subgroups were examined. A problem behavior checklist (Classroom Adjustment Rating Scale) and a school competence measure (Health Resources Inventory) for 974 children from 5 urban and 5 suburban schools were completed by 101 first- to fourth-grade teachers. Children from the more current cohort were rated as significantly more maladjusted than those from the earlier sample on 8 of 10 adjustment variables. In the recent sample, girls and suburban children evidenced a greater number of school competencies and fewer problem behaviors than boys and urban children, respectively. The implications of these findings for the future use of the teacher rating scales are discussed. 相似文献
904.
905.
Processing of lexical ambiguities in aphasia 总被引:2,自引:2,他引:0
Wernicke's and Broca's aphasics performed a lexical decision task wherein they had to decide whether the third word of an auditorily presented triplet series of words was "real" or not. The first and third words of each triplet were related to one, both, or neither meaning of the second word which was semantically ambiguous. The performance pattern of the Wernicke's aphasics was similar to that of normals. They showed selective access to different meanings of the ambiguous words, as demonstrated by the fact that the context provided by the first word affected semantic facilitation on the third word. In contrast, Broca's aphasics showed no semantic facilitation in any priming condition. These results are consistent with previous findings, suggesting that semantic representations may be largely spared in Wernicke's aphasics. The failure of the Broca's aphasics to demonstrate facilitation is consistent with the view that they have a processing deficit in automatically accessing the lexical representation of words. 相似文献
906.
907.
Lexical contribution to nonword-repetition effects: Evidence from event-related potentials 总被引:1,自引:0,他引:1
Two experiments investigated the modulation of event-related potentials (ERPs) by the repetition of orthographically legal and illegal nonwords. In Experiment 1, subjects silently counted occasional words against a background of nonwords, a proportion of which were repetitions of an immediately preceding legal or illegal item. ERPs to repeated legal items showed a sustained, topographically diffuse, positive-going shift. In contrast, repeated illegal nonwords gave rise to ERPs showing a smaller and temporally more restricted positive-going modulation. In an attempt to equalize depth of processing across legal and illegal nonwords, subjects in Experiment 2 were required to count items containing a nonalphabetic character against the same background of nonword items. ERPs to repeated legal items showed a modulation similar to, although smaller than, that found in Experiment I, but no effects of repetition were observed in the ERPs to the illegal nonwords. It was concluded that the effects of repeating nonwords, at least as manifested in concurrently recorded ERPs, differ as a consequence of whether items can access lexical memory, and that this is inconsistent with the attribution of such effects solely to the operation of episodic memory processes. 相似文献
908.
To be pertinent to democratic practice, collective choice functions need not apply to all possible constellations of individual preference, but only to those that are humanly possible in an appropriate sense. The present paper develops a theory of humanly possible preference within the context of the mathematical theory of learning. The theory of preference is then exploited in an attempt to resolve Arrow's voting paradox through restriction of the domain of majoritarian choice functions. 相似文献
909.
Michael E. Brady 《Synthese》1987,71(1):37-59
The conclusions derived by Keynes in his Treatise on Probability (1921) concerning induction, analogical reasoning, expectations formation and decision making, mirror and foreshadow the main conclusions of cognitive science and psychology.The problem of weight is studied within an economic context by examining the role it played in Keynes' applied philosophy work, The General Theory (1936). Keynes' approach is then reformulated as an optimal control approach to dealing with changes in information evaluation over time. Based on this analysis the problem of inductive justification, from a societal perspective, is not, What can we rationally believe will occur in the economic future, given our past experiences? but Can we make the future so as to attain specific economic goals with practical certainty? An answer requires that restrictions be placed on the methodological individualist approach and the acceptance of a restricted holistic approach. 相似文献
910.
Separate verbal memory and naming deficits in attention deficit disorder and reading disability 总被引:4,自引:0,他引:4
In this study, verbal memory and naming abilities were investigated in reading disabled (RD) and control children who were characterized according to the presence or absence of attention deficit disorder (ADD). Results indicate that deficits in learning and memory for recently acquired information occur as a function of ADD rather than RD while deficits in naming are specific to RD rather than ADD. We conclude that ADD is a major source of additional and separate cognitive morbidity in RD children. 相似文献