全文获取类型
收费全文 | 58010篇 |
免费 | 2313篇 |
国内免费 | 32篇 |
专业分类
60355篇 |
出版年
2020年 | 672篇 |
2019年 | 836篇 |
2018年 | 1185篇 |
2017年 | 1188篇 |
2016年 | 1259篇 |
2015年 | 854篇 |
2014年 | 1059篇 |
2013年 | 5220篇 |
2012年 | 1879篇 |
2011年 | 2033篇 |
2010年 | 1198篇 |
2009年 | 1242篇 |
2008年 | 1868篇 |
2007年 | 1842篇 |
2006年 | 1639篇 |
2005年 | 1504篇 |
2004年 | 1472篇 |
2003年 | 1339篇 |
2002年 | 1381篇 |
2001年 | 1842篇 |
2000年 | 1738篇 |
1999年 | 1361篇 |
1998年 | 766篇 |
1997年 | 639篇 |
1996年 | 587篇 |
1995年 | 602篇 |
1994年 | 560篇 |
1993年 | 576篇 |
1992年 | 1068篇 |
1991年 | 1011篇 |
1990年 | 990篇 |
1989年 | 897篇 |
1988年 | 867篇 |
1987年 | 843篇 |
1986年 | 847篇 |
1985年 | 914篇 |
1984年 | 728篇 |
1983年 | 634篇 |
1982年 | 523篇 |
1979年 | 687篇 |
1978年 | 541篇 |
1976年 | 499篇 |
1975年 | 635篇 |
1974年 | 671篇 |
1973年 | 632篇 |
1972年 | 573篇 |
1971年 | 501篇 |
1968年 | 563篇 |
1967年 | 569篇 |
1966年 | 506篇 |
排序方式: 共有10000条查询结果,搜索用时 6 毫秒
201.
202.
A E Puente 《Perceptual and motor skills》1988,66(2):639-642
MMPI profiles of 22 chronic arthritic patients were compared to 22 control pain (nonorganic) patients. While elevations were noted in the HS, D, and Hy scales for the rheumatoid patients, the over-all profiles differed from controls on the PA scale. 相似文献
203.
Under simple- and choice-RT conditions, the biceps brachii muscle was examined in 8 healthy male subjects to determine how the temporal and spatial characteristics of elbow flexion and forearm supination differed at the initial phase of EMG activity and whether preparation or the presence of response uncertainty influenced the EMG outputs of the two movements. In the simple-RT condition, RT of supination was significantly faster than that of flexion but EMG activity of supination was less than that of flexion. In contrast, in the choice-RT condition, RT of flexion was significantly faster than that of supination but EMG activity of flexion was significantly reduced compared to supination. These findings indicate that advanced preparation or motor set facilitates the differentiation of RTs and EMG activities of the response movements and that response uncertainty causes a significant change in the temporal and spatial specificity of both elbow flexion and forearm supination. 相似文献
204.
This paper gives a method for determining a sample size that will achieve a prespecified bound on confidence interval width for the interrater agreement measure,. The same results can be used when a prespecified power is desired for testing hypotheses about the value of kappa. An example from the literature is used to illustrate the methods proposed here. 相似文献
205.
Hierarchical classes: Model and data analysis 总被引:1,自引:0,他引:1
A discrete, categorical model and a corresponding data-analysis method are presented for two-way two-mode (objects × attributes) data arrays with 0, 1 entries. The model contains the following two basic components: a set-theoretical formulation of the relations among objects and attributes; a Boolean decomposition of the matrix. The set-theoretical formulation defines a subset of the possible decompositions as consistent with it. A general method for graphically representing the set-theoretical decomposition is described. The data-analysis algorithm, dubbed HICLAS, aims at recovering the underlying structure in a data matrix by minimizing the discrepancies between the data and the recovered structure. HICLAS is evaluated with a simulation study and two empirical applications.This research was supported in part by a grant from the Belgian NSF (NFWO) to Paul De Boeck and in part by NSF Grant BNS-83-01027 to Seymour Rosenberg. We thank Iven Van Mechelen for clarifying several aspects of the Boolean algebraic formulation of the model and Phipps Arabie for his comments on an earlier draft. 相似文献
206.
207.
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
208.
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
209.
210.
It has been proposed that a principal cause of the agrammatism of some Broca's aphasics is that such patients, unlike normal subjects, are unable to make use of a special retrieval mechanism for closed-class ("function") words (D. C. Bradley, 1978, Computational distinctions of vocabulary type, Unpublished Ph.D. thesis; D. C. Bradley, M. F. Garrett, & E. B. Zurif, 1980. In D. Caplan (Ed.), Biological studies of mental processes). The main evidence for the existence of such a mechanism consisted of two observations: (1) the recognition of open-class words was observed to be frequency-sensitive, but that of closed-class words was not; and (2) lexical decisions for nonwords which began with open-class words were delayed, whereas there was no such interference for nonwords which began with closed-class words. However, the first of these observations has proved nonreplicable (e.g., B. Gordon & A. Caramazza, 1982, Brain and Language, 15, 143-160, 1983, Brain and Language, 19, 335-345; J. Segui, J. Mehler, W. Frauenfelder, & J. Morton, 1982, Neuropsychologia, 20, 615-627), and in the present paper, three lexical decision experiments are reported in which it is found that, when certain confounding variables are controlled, nonwords which begin with closed-class words are subject to interference. Moreover, contrary to a suggestion of Kolk and Blomert (1985, Brain and Language, 26, 94-105) the interference is independent of the presence of closed-class items in the lexical decision word list. It seems, then, that closed-class words are not qualitatively different from open-class words with respect either to frequency sensitivity or to nonword interference, and in consequence, the above proposed explanation of agrammatism is left without major empirical support. 相似文献