全文获取类型
收费全文 | 2169篇 |
免费 | 468篇 |
国内免费 | 35篇 |
专业分类
2672篇 |
出版年
2023年 | 14篇 |
2022年 | 12篇 |
2021年 | 48篇 |
2020年 | 29篇 |
2019年 | 140篇 |
2018年 | 152篇 |
2017年 | 165篇 |
2016年 | 131篇 |
2015年 | 94篇 |
2014年 | 59篇 |
2013年 | 97篇 |
2012年 | 40篇 |
2011年 | 29篇 |
2010年 | 17篇 |
2009年 | 57篇 |
2008年 | 87篇 |
2007年 | 85篇 |
2006年 | 72篇 |
2005年 | 80篇 |
2004年 | 74篇 |
2003年 | 64篇 |
2002年 | 73篇 |
2001年 | 48篇 |
2000年 | 70篇 |
1999年 | 47篇 |
1998年 | 38篇 |
1997年 | 40篇 |
1996年 | 27篇 |
1995年 | 24篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1985年 | 51篇 |
1984年 | 71篇 |
1983年 | 49篇 |
1982年 | 72篇 |
1981年 | 70篇 |
1980年 | 104篇 |
1979年 | 60篇 |
1978年 | 61篇 |
1977年 | 58篇 |
1976年 | 36篇 |
1975年 | 22篇 |
1974年 | 39篇 |
1973年 | 19篇 |
排序方式: 共有2672条查询结果,搜索用时 15 毫秒
21.
Barbara A. Morrongiello Rick C. Robson Catherine T. Best Rachel K. Clifton 《Journal of experimental child psychology》1984,37(2):231-250
Five-year-old children were tested for perceptual trading relations between a temporal cue (silence duration) and a spectral cue (F1 onset frequency) for the “say-stay” distinction. Identification functions were obtained for two synthetic “say-stay” continua, each containing systematic variations in the amount of silence following the /s/ noise. In one continuum, the vocalic portion had a lower F1 onset than in the other continuum. Children showed a smaller trading relation than has been found with adults. They did not differ from adults, however, in their perception of an “ay-day” continuum formed by varying F1 onset frequency only. The results of a discrimination task in which the two acoustic cues were made to “cooperate” or “conflict” phonetically supported the notion of perceptual equivalence of the temporal and spectral cues along a single phonetic dimension. The results indicate that young children, like adults, perceptually integrate multiple cues to a speech contrast in a phonetically relevant manner, but that they may not give the same perceptual weights to the various cues as do adults. 相似文献
22.
This research had two aims. The first was to test three explanations of performance on N-term series tasks by young children: the labeling model of B.DeBoysson-Bardies and K. O'Regan (1973), Nature (London), 246, 531–534, the sequential-contiguity model of L. Breslow (1981, Psychological Bulletin, 89, 325–351), and the ordered array or image model of C. A. Riley and T. Trabasso (1974, Journal of Experimental Child Psychology, 17, 187–202). In the first experiment, 5-year-old children were taught additional premises which would interfere with labeling and sequential-contiguity processes, but not with forming an ordered array. Reasoning performance was essentially comparable to previous results with the paradigm, thus supporting the ordered array model. The second aim was to reexamine children's ability to learn sets of premises which can be assembled into an ordered array, since there was reason to believe that previous studies had created false positives. In the second experiment, 3- to 7-year-old children were taught either overlapping (a > b, b > c, …) or nonoverlapping (a > b, c > d, …) premises. Overlapping premises can be integrated into an ordered array (a, b, c, d, e), but nonoverlapping premises cannot. However, the overlapping condition proved more difficult, and the success rate for preschoolers () was of zero order. This raises doubts about their ability to learn a set of premises of the kind required for transitive inference. These doubts were strengthened by the third experiment which showed that when premises were not presented in serial order, preschool () children could not learn the premises of an N-term series task. 相似文献
23.
LGBTQI2S+ (lesbian, gay, bisexual, transgender, questioning, intersex, and two-spirit, etc.) individuals face unique challenges to physical activity participation, such as discrimination and exclusion. Square dance is a form of collaborative group dancing and while traditionally a heteronormative form of dance, gay square dance is typically open to everyone, regardless of sexual orientation. Square dancing offers opportunities to belong to a community of others engaged in the same activity, which older adults often find satisfying. The aim of this research was to understand how older adults who identify as women experience social support in the context of participating in gay square dance and the role previous experiences of social exclusion play in influencing these experiences. Fourteen self-identified women (age range 55–79 years; n = 11 White, n = 1 Black, n = 2 Jewish) belonging to a gay square dance club participated. Participants self-identified as heterosexual (n = 7), lesbian (n = 3), pansexual (n = 1), bisexual (n = 1), or did not identify with existing terminology (n = 2). Interviews were conducted during a gay square-dancing festival and thematically analyzed. Findings highlighted that participants experienced acceptance which affirmed their sense of self and enabled their authentic selves. To foster a sense of belonging and close relationships, specific actions (e.g., demonstrative welcoming of newcomers, mutual support) were taken by other participants in the group. Physical touch is an inherent part of square dancing, which took on different meanings for participants and was overall perceived as safe. Inclusive groups like gay square dance clubs are an important and consistent means where older adult women can experience meaningful social relationships and interactions. 相似文献
24.
Combinators and structurally free logic 总被引:2,自引:0,他引:2
25.
Relation algebras from cylindric and polyadic algebras 总被引:1,自引:0,他引:1
26.
27.
28.
29.
This paper investigates partitions of lattices of modal logics based on superintuitionistic logics which are defined by forming, for each superintuitionistic logic L and classical modal logic , the set L[] of L-companions of . Here L[] consists of those modal logics whose non-modal fragments coincide with L and which axiomatize if the law of excluded middle p V p is added. Questions addressed are, for instance, whether there exist logics with the disjunction property in L[], whether L[] contains a smallest element, and whether L[] contains lower covers of . Positive solutions as concerns the last question show that there are (uncountably many) superclean modal logics based on intuitionistic logic in the sense of Vakarelov [28]. Thus a number of problems stated in [28] are solved. As a technical tool the paper develops the splitting technique for lattices of modal logics based on superintuitionistic logics and ap plies duality theory from [34]. 相似文献
30.
Given a 1-ary sentence operator , we describe L - another 1-ary operator - as as a left inverse of in a given logic if in that logic every formula is provably equivalent to L. Similarly R is a right inverse of if is always provably equivalent to R. We investigate the behaviour of left and right inverses for taken as the operator of various normal modal logics, paying particular attention to the conditions under which these logics are conservatively extended by the addition of such inverses, as well as to the question of when, in such extensions, the inverses behave as normal modal operators in their own right. 相似文献