全文获取类型
收费全文 | 55652篇 |
免费 | 2087篇 |
国内免费 | 18篇 |
出版年
2020年 | 511篇 |
2019年 | 644篇 |
2018年 | 828篇 |
2017年 | 889篇 |
2016年 | 914篇 |
2015年 | 683篇 |
2014年 | 830篇 |
2013年 | 4080篇 |
2012年 | 1535篇 |
2011年 | 1593篇 |
2010年 | 981篇 |
2009年 | 985篇 |
2008年 | 1442篇 |
2007年 | 1364篇 |
2006年 | 1265篇 |
2005年 | 1185篇 |
2004年 | 1136篇 |
2003年 | 1068篇 |
2002年 | 1115篇 |
2001年 | 1611篇 |
2000年 | 1515篇 |
1999年 | 1119篇 |
1998年 | 602篇 |
1997年 | 516篇 |
1992年 | 939篇 |
1991年 | 952篇 |
1990年 | 938篇 |
1989年 | 934篇 |
1988年 | 898篇 |
1987年 | 860篇 |
1986年 | 920篇 |
1985年 | 994篇 |
1984年 | 812篇 |
1983年 | 771篇 |
1982年 | 600篇 |
1981年 | 624篇 |
1979年 | 901篇 |
1978年 | 661篇 |
1977年 | 575篇 |
1976年 | 608篇 |
1975年 | 803篇 |
1974年 | 909篇 |
1973年 | 938篇 |
1972年 | 775篇 |
1971年 | 733篇 |
1970年 | 712篇 |
1969年 | 760篇 |
1968年 | 911篇 |
1967年 | 835篇 |
1966年 | 819篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
951.
In some recent papers, the authors and Peter Gärdenfors have defined and studied two different kinds of formal operation, conceived as possible representations of the intuitive process of contracting a theory to eliminate a proposition. These are partial meet contraction (including as limiting cases full meet contraction and maxichoice contraction) and safe contraction. It is known, via the representation theorem for the former, that every safe contraction operation over a theory is a partial meet contraction over that theory. The purpose of the present paper is to study the relationship more finely, by seeking an explicit map between the component orderings involved in each of the two kinds of contraction. It is shown that at least in the finite case a suitable map exists, with the consequence that the relational, transitively relational, and antisymmetrically relational partial meet contraction functions form identifiable subclasses of the safe contraction functions, over any theory finite modulo logical equivalence. In the process of constructing the map, as the composition of four simple transformations, mediating notions of bottom and top contraction are introduced. The study of the infinite case remains open. 相似文献
952.
This paper discusses thecompatibility of the polychotomous Rasch model with dichotomization of the response continuum. It is argued that in the case of graded responses, the response categories presented to the subject are essentially an arbitrary polychotomization of the response continuum, ranging for example from total rejection or disagreement to total acceptance or agreement of an item or statement. Because of this arbitrariness, the measurement outcome should be independent of the specific polychotomization applied, for example, presenting a specific multicategory response format should not affect the measurement outcome. When such is the case, the original polychotomous model is called compatible with dichotomization.A distinction is made between polychotomization or dichotomization before the fact, that is, in constructing the response format, and polycho- or dichotomization after the fact, for example in dichotomizing existing graded response data.It is shown that, at least in case of dichotomization after-the-fact, the polychotomous Rasch model is not compatible with dichotomization, unless a rather special condition of the model parameters is met. Insofar as it may be argued that dichotomization before the fact is not essentially different from dichotomization after the fact, the value of the unidimensional polychotomous Rasch model is consequently questionable. The impact of our conclusion on related models is also discussed. 相似文献
953.
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
954.
955.
Michael Schluroff Thomas E. Zimmermann R. B. Freeman Jr. Klaus Hofmeister Thomas Lorscheid Arno Weber 《Brain and language》1986,27(2):322-344
Pupillary responses have proven to be reliable physiological correlates of cognitive effort in a variety of tasks, including language processing. To investigate the relation between psychological and syntactic complexity 20 syntactically ambiguous sentences, balanced for bias, were presented to 16 subjects, while their pupil size was continuously measured. These sentences could be read as verb oriented (syntactically more complex) or object oriented (syntactically less complex). Principal components analysis of pupillary movements revealed that verb-oriented readings, resulted in greater pupillary dilations than object-oriented readings, indicating that syntactically more complex sentences, as determined via a formal grammar, require greater cognitive effort in processing. This is viewed as further evidence for the notion that syntactic and psychological complexity are related. High- and low-bias sentences did not induce comparable differences in pupillary movements, indicating that the "multiple meaning theory" may have to be modified. 相似文献
956.
957.
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
958.
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
959.
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
960.