全文获取类型
收费全文 | 51687篇 |
免费 | 2138篇 |
国内免费 | 19篇 |
出版年
2020年 | 529篇 |
2019年 | 639篇 |
2018年 | 916篇 |
2017年 | 903篇 |
2016年 | 922篇 |
2015年 | 633篇 |
2014年 | 842篇 |
2013年 | 3786篇 |
2012年 | 1510篇 |
2011年 | 1635篇 |
2010年 | 930篇 |
2009年 | 1004篇 |
2008年 | 1422篇 |
2007年 | 1409篇 |
2006年 | 1325篇 |
2005年 | 1156篇 |
2004年 | 1141篇 |
2003年 | 1063篇 |
2002年 | 1068篇 |
2001年 | 1675篇 |
2000年 | 1588篇 |
1999年 | 1221篇 |
1998年 | 596篇 |
1997年 | 507篇 |
1992年 | 974篇 |
1991年 | 907篇 |
1990年 | 942篇 |
1989年 | 891篇 |
1988年 | 868篇 |
1987年 | 810篇 |
1986年 | 850篇 |
1985年 | 944篇 |
1984年 | 748篇 |
1983年 | 683篇 |
1982年 | 549篇 |
1981年 | 511篇 |
1979年 | 798篇 |
1978年 | 598篇 |
1977年 | 492篇 |
1976年 | 527篇 |
1975年 | 696篇 |
1974年 | 792篇 |
1973年 | 817篇 |
1972年 | 644篇 |
1971年 | 590篇 |
1970年 | 560篇 |
1969年 | 598篇 |
1968年 | 740篇 |
1967年 | 644篇 |
1966年 | 656篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
941.
Bandler and Grinder's hypothesis that eye-movements reflect sensory processing was examined. 28 volunteers first memorized and then recalled visual, auditory, and kinesthetic stimuli. Changes in eye-positions during recall were videotaped and categorized by two raters into positions hypothesized by Bandler and Grinder's model to represent visual, auditory, and kinesthetic recall. Planned contrast analyses suggested that visual stimulus items, when recalled, elicited significantly more upward eye-positions and stares than auditory and kinesthetic items. Auditory and kinesthetic items, however, did not elicit more changes in eye-position hypothesized by the model to represent auditory and kinesthetic recall, respectively. 相似文献
942.
For 40 males who smoked 20 cigarettes a day titratable acidity of the urine was significantly correlated with nicotine/cotinine excretion at several sample intervals, as was urinary pH, but not urinary acidity and daily cigarette consumption or serum COHB. 相似文献
943.
944.
When people are exposed to misleading details after a witnessed event, they often claim that they saw the misleading details as part of the event. We refer to this as themisinformation effect. In four experiments, involving 570 subjects, we explored the role that discrepancy detection plays in the misinformation effect. Experiment 1 showed that subjects who naturally read a post-event narrative more slowly were more resistant to the effects of misleading information contained in the narrative. In Experiment 2, subjects who naturally read more slowly were more likely to detect a discrepancy between what they were reading and what was stored in their memory. In Experiment 3, subjects who were instructed to read slowly were more likely to detect a discrepancy than were those who were instructed to read quickly. In Experiment 4, subjects who were instructed to read slowly were more resistant to misleading postevent information. Taken together, these results suggest that longer reading times are associated with a greater scrutiny of postevent information. This leads to an increased likelihood that discrepancies will be detected and that the misinformation will be resisted. 相似文献
945.
Intermediate prepositional logics we consider here describe the setI() of regular informational types introduced by Yu. T. Medvedev [7]. He showed thatI() is a Heyting algebra. This algebra gives rise to the logic of infinite problems from [13] denoted here asLM
1. Some other definitions of negation inI() lead to logicsLM
n
(n ). We study inclusions between these and other systems, proveLM
n
to be non-finitely axiomatizable (n ) and recursively axiomatizable (n < ). We also show that formulas in one variable do not separateLM
from Heyting's logicH, andLM
n
(n < ) from Scott's logic (H+S). 相似文献
946.
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
947.
Two different concepts of distinguishability are often mixed up in attempts to derive in quantum mechanics the (anti)symmetry of the wave function from indistinguishability of identical particles. Some of these attempts are analyzed and shown to be defective. It is argued that, although identical particles should be considered as observationally indistinguishable in (anti)symmetric states, they may be considered to be conceptually distinguishable. These two notions of (in)distinguishability have quite different physical origins, the former one being related to observations while the latter has to do with the preparation of the system. 相似文献
948.
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
949.
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
950.
Hans P. W. Vermeeren 《Synthese》1986,69(3):273-290
Controversies, i.e., multiple theory confrontations, may have a strong impact on the development of science. By an analysis of the so-called “resonance controversy” in chemistry the view that controversies and their resolution differ considerably from the process of theory succession is defended. It is argued that controversies are symptomatic of foundational problems, produce theory-scattering or domain-splitting, and induce ontological shifts. An explication is given of the role of existence claims and the applicability of Ockham's Razor in the resolution of controversies. The requirement of a realistic interpretation of theories at all times, as defended by some philosophers, is criticised. 相似文献