全文获取类型
收费全文 | 188061篇 |
免费 | 8360篇 |
国内免费 | 155篇 |
出版年
2020年 | 2778篇 |
2019年 | 3443篇 |
2018年 | 3662篇 |
2017年 | 4105篇 |
2016年 | 4707篇 |
2015年 | 3933篇 |
2014年 | 4803篇 |
2013年 | 23450篇 |
2012年 | 4978篇 |
2011年 | 4285篇 |
2010年 | 4093篇 |
2009年 | 4859篇 |
2008年 | 4410篇 |
2007年 | 4045篇 |
2006年 | 4495篇 |
2005年 | 4401篇 |
2004年 | 3879篇 |
2003年 | 3476篇 |
2002年 | 3333篇 |
2001年 | 4041篇 |
2000年 | 3910篇 |
1999年 | 3653篇 |
1998年 | 2889篇 |
1997年 | 2730篇 |
1996年 | 2641篇 |
1995年 | 2452篇 |
1994年 | 2414篇 |
1993年 | 2386篇 |
1992年 | 3038篇 |
1991年 | 2843篇 |
1990年 | 2689篇 |
1989年 | 2546篇 |
1988年 | 2533篇 |
1987年 | 2521篇 |
1986年 | 2560篇 |
1985年 | 2756篇 |
1984年 | 2747篇 |
1983年 | 2497篇 |
1982年 | 2445篇 |
1981年 | 2420篇 |
1980年 | 2246篇 |
1979年 | 2525篇 |
1978年 | 2328篇 |
1977年 | 2243篇 |
1976年 | 2050篇 |
1975年 | 2234篇 |
1974年 | 2312篇 |
1973年 | 2245篇 |
1972年 | 1830篇 |
1971年 | 1724篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
761.
Jos M. F. ten Berge 《Psychometrika》1988,53(4):487-494
Van de Geer has reviewed various criteria for transforming two or more matrices to maximal agreement, subject to orthogonality constraints. The criteria have applications in the context of matching factor or configuration matrices and in the context of canonical correlation analysis for two or more matrices. The present paper summarizes and gives a unified treatment of fully general computational solutions for two of these criteria, Maxbet and Maxdiff. These solutions will be shown to encompass various well-known methods as special cases. It will be argued that the Maxdiff solution should be preferred to the Maxbet solution whenever the two criteria coincide. Horst's Maxcor method will be shown to lack the property of monotone convergence. Finally, simultaneous and successive versions of the Maxbet and Maxdiff solutions will be treated as special cases of a fully flexible approach where the columns of the rotation matrices are obtained in successive blocks.The author is obliged to Henk Kiers for computational assistance and helpful comments. 相似文献
762.
763.
764.
Renato A. Lewin 《Studia Logica》1988,47(4):387-389
We prove that there are two involutions defined by monadic terms that characterize Monadic Algebras. We further prove that the variety of Monadic Algebras is the smallest variety of Interior Algebras where these involutions give rise to an interpretation from the variety of Bounded Distributive Lattices into it.Research funded by Fondecyt, project N 764-1987. 相似文献
765.
M. W. Bunder 《Studia Logica》1988,47(2):129-143
In the early thirties, Church developed predicate calculus within a system based on lambda calculus. Rosser and Kleene developed Arithmetic within this system, but using a Godelization technique showed the system to be inconsistent.Alternative systems to that of Church have been developed, but so far more complex definitions of the natural numbers have had to be used. The present paper based on a system of illative combinatory logic developed previously by the author, does allow the use of the Church numerals. Given a new definition of equality all the Peano-type axioms of Mendelson except one can be derived. A rather weak extra axiom allows the proof of the remaining Peano axiom. Note. The illative combinatory logic used in this paper is similar to the logic employed in computer languages such as ML.The author wishes to thank Dr. Roger Hindley for proofreading this paper and for making some useful suggestions. This paper was presented at the 1986 Annual Conference of the Australasian Association of Logic in Auckland, 9–12 July, 1986. 相似文献
766.
We obtain in this paper a representation of the formulae of extensions ofL
by generalized quantifiers through functors between categories of first-order structures and partial isomorphisms. The main tool in the proofs is the back-and-forth technique. As a corollary we obtain the Caicedo's version of Fraïssés theorem characterizing elementary equivalence for such languages. We also discuss informally some geometrical interpretations of our results. 相似文献
767.
Gy. Fuhrmann 《Synthese》1988,75(3):349-372
It has been a vexing question in recent years whether concepts are fuzzy. In this paper several views on the fuzziness of concepts are pointed out to have stemmed from dubious concepts of fuzziness. The underlying notions of the roles feasibly played byprototype, set, andprobability in modeling concepts strongly suggest that the controversy originates from a vague relation between intuitive and mathematical ideas in the cognitive sciences. It is argued that the application of fuzzy sets cannot resolve this vagueness since they are one sided,viz., defined on sets. An alternative definition based on classes (in the sense of axiomatic set theory) is proposed. 相似文献
768.
769.
770.
Carolyn P. Atkins 《Journal of Fluency Disorders》1988,13(6):429-436
One hundred and thirty-three college students responded to percentage definitions of “good,” “minimal,” and “no” eye contact. They also judged their perceptions of a speaker with “little or no eye contact” on a semantic differential scale containing 60 polarized adjective pairs regarding personality traits. The majority of the student respondents defined an individual with “good” eye contact as looking at his/her audience/listener 90–100% of the time. This is a more stringent definition than other literature has indicated. Furthermore, speakers with little or no eye contact were judged less favorably on 70% of the items, which indicates that low eye contact adversely affects perceptions of a speaker's personality. Therefore, stutterers need to be made aware of the importance of and determinants of effective eye contact in communication. Also, the development of effective eye contact needs to be incorporated as a major goal in stuttering therapy. 相似文献