全文获取类型
收费全文 | 22451篇 |
免费 | 943篇 |
国内免费 | 13篇 |
专业分类
23407篇 |
出版年
2020年 | 272篇 |
2019年 | 276篇 |
2018年 | 452篇 |
2017年 | 392篇 |
2016年 | 410篇 |
2015年 | 278篇 |
2014年 | 380篇 |
2013年 | 1635篇 |
2012年 | 669篇 |
2011年 | 719篇 |
2010年 | 393篇 |
2009年 | 461篇 |
2008年 | 614篇 |
2007年 | 630篇 |
2006年 | 570篇 |
2005年 | 496篇 |
2004年 | 483篇 |
2003年 | 470篇 |
2002年 | 427篇 |
2001年 | 801篇 |
2000年 | 802篇 |
1999年 | 605篇 |
1998年 | 257篇 |
1997年 | 220篇 |
1996年 | 205篇 |
1992年 | 492篇 |
1991年 | 431篇 |
1990年 | 491篇 |
1989年 | 413篇 |
1988年 | 392篇 |
1987年 | 371篇 |
1986年 | 395篇 |
1985年 | 444篇 |
1984年 | 346篇 |
1983年 | 287篇 |
1982年 | 227篇 |
1979年 | 328篇 |
1978年 | 259篇 |
1977年 | 207篇 |
1976年 | 201篇 |
1975年 | 301篇 |
1974年 | 347篇 |
1973年 | 353篇 |
1972年 | 275篇 |
1971年 | 242篇 |
1970年 | 208篇 |
1969年 | 228篇 |
1968年 | 288篇 |
1967年 | 251篇 |
1966年 | 272篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
971.
Ingmar Pörn 《Studia Logica》1983,42(2-3):293-298
In the paper I investigate aspects of adverbial modification as an operation applying an adverb or adverbial phrase to a predicate and thereby creating a new predicate. The logic of adverbial modification, on this view, belongs to the logic of predicate modifiers. The theory I present is intended to cover not only adverbial modification but also attributive modification, but problems concerning the latter will not be given any special attention. 相似文献
972.
Nondeterministic programs occurring in recently developed programming languages define nondeterminate partial functions. Formulas (Boolean expressions) of such nondeterministic languages are interpreted by a nonempty subset of {T (“true”), F (“false”), U (“undefined)}. As a semantic basis for the propositional part of a corresponding nondeterministic three-valued logic we study the notion of a truth-function over {T, F, U} which is computable by a nondeterministic evaluation procedure. The main result is that these truth-functions are precisely the functions satisfying four basic properties, called \( \subseteq \) -isotonic, \( \subseteq \) ?-isotonic, hereditarily guarded, and hereditarily guard-using, and that a function satisfies these properties iff it is explicitly definable (in a certain normal form) from “if..then..else..fi”, binary choice, and constants. 相似文献
973.
Interpretations regarding the effects of exogenous and endogenous variables on endogenous variables in linear structural equation systems depend upon the convergence of a matrix power series. Convergence depends upon the eigenvalues of the structural coefficient matrix. The test for convergence developed by Jöreskog and Sörbom is shown to be only sufficient, not necessary and sufficient. 相似文献
974.
975.
976.
Two kinds of causal inference rules which are widely used by social scientists are investigated. Two conceptions of causation also widely used are explicated — the INUS and probabilistic conceptions of causation. It is shown that the causal inference rules which link correlation, a kind of partial correlation, and a conception of causation areinvalid. It is concluded anew methodology is required for causal inference. 相似文献
977.
P Pohl 《Brain and language》1983,20(1):44-53
Four baboons (Papio cynocephalus) were tested using food as reward for ear advantages in the monaural discrimination of pure tones, three-tone musical chords, synthetically constructed consonant-vowels, and vowels. All four animals showed highly significant and reproducible ear advantages for each class of acoustic stimulus with marked individual differences in the direction of their ear asymmetry. The results obtained in these experiments represent the first evidence of ear asymmetries for different classes of acoustic stimuli in a nonhuman species. Further, the ear advantages found in these animals under monaural conditions resemble those obtained with dichotic presentation in human subjects and thus suggest that the baboon may be a valuable model of central auditory processing of various types of acoustic stimuli in man. 相似文献
978.
P D Duda 《Brain and language》1983,20(1):65-78
This study examined the effects of different concurrent verbal memory loads on a recognition accuracy task using bilaterally presented nouns. Four different memory load conditions were examined. They varied along a size dimension of either three or six words and along a complexity dimension of either easy concrete nouns or difficult highly abstract nouns. In each of the above conditions and in one control group, order or word report was controlled and in a second control group subjects were free to report the lateralized words in any order they wished. There were 20 subjects in each of the six groups. As expected, a significant right visual field superiority for verbal processing was obtained. there were no main effects of size of memory load nor complexity of m emory load on the laterality patterns. More subtle fluctuations in the patterns were found in the form of significant interactions between memory load, order of word report, and visual field. These interaction effects suggest that words reported second in the bilateral task, are more susceptible to the interfering effects of either larger or more complex memory loads. This is particularly true for right visual field words. While these data generally support a structural model of hemispheric organization, the interaction effects suggest that modifications must be made to the basic model to account for such factors as hemispheric capacity limits and order of report in the bilateral task. 相似文献
979.
Most dichotic listening experiments permit subjects to deploy attention in any way they choose. We argue that this adds uncontrolled variance to the observed right-ear advantage. In the first experiment, more robust laterality effects were obtained in an identification task with focused than with divided attention. Such differences were not found in the second experiment, when a detection procedure was used. Virtually all the laterality effect observed in the second study could be attributed to subjects who were biased attenders, in the sense that they exhibited more intrusions from the right ear to the left than vice versa. However, rather than indicating that laterality effects are simply attentional bias, this effect can be attributed to an asymmetry of perceptual discrimination. 相似文献
980.
The capacity to selectively attend to only one of multiple, spatially separated, simultaneous sound sources—the “cocktail party” effect—was evaluated in normal subjects and in those with anterior temporal lobectomy using common environmental sounds. A significant deficit in this capacity was observed for those stimuli located on the side of space contralateral to the lobectomy, a finding consistent with the hypothesis that within each anterior temporal lobe is a mechanism that is normally capable of enhancing the perceptual salience of one acoustic stimulus on the opposite side of space, when other sound sources are present on that side. Damage to this mechanism also appears to be associated with a deficit of spatial localization for sounds contralateral to the lesion. 相似文献