首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   47053篇
  免费   1174篇
  国内免费   9篇
  48236篇
  2020年   294篇
  2019年   332篇
  2018年   3863篇
  2017年   3215篇
  2016年   2697篇
  2015年   579篇
  2014年   575篇
  2013年   2534篇
  2012年   1427篇
  2011年   3185篇
  2010年   3008篇
  2009年   1987篇
  2008年   2485篇
  2007年   2941篇
  2006年   796篇
  2005年   964篇
  2004年   881篇
  2003年   771篇
  2002年   770篇
  2001年   911篇
  2000年   888篇
  1999年   651篇
  1998年   385篇
  1997年   373篇
  1996年   312篇
  1995年   298篇
  1994年   284篇
  1993年   288篇
  1992年   518篇
  1991年   474篇
  1990年   499篇
  1989年   419篇
  1988年   397篇
  1987年   403篇
  1986年   367篇
  1985年   393篇
  1984年   409篇
  1983年   388篇
  1982年   333篇
  1981年   291篇
  1980年   259篇
  1979年   346篇
  1978年   341篇
  1977年   294篇
  1976年   286篇
  1975年   328篇
  1974年   379篇
  1973年   333篇
  1972年   255篇
  1968年   278篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
B. C. Patten  G. T. Auble 《Synthese》1980,43(1):155-181
Conclusion The systems approach to niche presented herein stands as an example of the unifying potential of mathematical system theory when applied to concepts and principles of ecology. Beginning with subjective concepts from the naturalistic tradition, the niche was framed in the formalism of general system theory. So modeled, it appeared as a restriction of a more general construct, the environ. Both niches and environs are implementable in the context of ecosystem models, and with the growing ability of ecologists to construct such models, system theoretic niches and environs both should serve in the future to clarify old problems of ecology, and make it possible to raise new classes of problems. The nature of niches, always difficult conceptually for the ecologist, may now give way to further development, both theoretical and empirical.  相似文献   
962.
In two interview studies subjects were asked what memory aids they used and how often. In particular, the reported frequencies of use of external aids such as shopping lists and memos were compared with those of internal aids that have been investigated by psychologists, such as the method of loci. Subjects in the first study were 15 male and 15 female university students, and in the second, a group of 30 adult women, most of whom were housewives. In both studies the aids reported to be used most were external ones. However, it is pointed out that the most commonly used methods of remembering must be internal, although these are not usually considered to be aids. Some difficulties that arise in the assessment of memory in interview and questionnaire studies are discussed.  相似文献   
963.
964.
Relationships between gender choices and both movement patterns and social behavior were studied in first- and second-grade boys. Three-child, structured play groups were each composed of a boy whose mother saw him as high masculine in play preference on the Games Inventory, one seen as average, and one low masculine. Behaviors rated from videotapes included gender presentation variables, (e.g., leg separation), indicators of dominance and personal comfort (e.g.,range of movements), and indicators of social skill and peer response (e.g., interaction initiations). The low masculine boys were found to be the most feminine in their gender presentation, least dominant and aggressive, and the least socially successful of the boys. The greatest difference was between the low and the high masculine boys. The average masculine boys' scores were generally intermediate,but more similar to the low masculine boys on some variables and more similar to the high masculine boys on others. These conclusions apply to a group interaction play task, but not to an initial noninteractive play task. A secondary study in which girls played with low and average masculine boys is also reported. Here it was found that low masculine boys were generally intermediate between average boys and girls on gender presentation and dominance variables, but lowest of the groups on social interaction variables. The authors appreciate the comments of Peter Bentler and Spencer Thompson on a draft of this paper, the assistance of Laura McCain in running subjects and scoring tapes, and the expertise of Shu-Yeng Wong for computer programming.  相似文献   
965.
966.
The lexical representation of Serbo-Croatian nouns was investigated in a lexical decision task. Because Serbo-Croatian nouns are declined, a noun may appear in one of several grammatical cases distinguished by the inflectional morpheme affixed to the base form. The grammatical cases occur with different frequencies, although some are visually and phonetically identical. When the frequencies of identical forms are compounded, the ordering of frequencies is not the same for masculine and feminine genders. These two genders are distinguished further by the fact that the base form for masculine nouns is an actual grammatical case, the nominative singular, whereas the base form for feminine nouns is an abstraction in that it cannot stand alone as an independent word. Exploiting these characteristics of the Serbo-Croatian language, we contrasted three views of how a noun is represented: (1) the independent-entries hypothesis, which assumes an independent representation for each grammatical case, reflecting its frequency of occurrence; (2) the derivational hypothesis, which assumes that only the base morpheme is stored, with the individual cases derived from separately stored inflectional morphemes and rules for combination; and (3) the satellite-entries hypothesis, which assumes that all cases are individually represented, with the nominative singular functioning as the nucleus and the embodiment of the noun’s frequency and around which the other cases cluster uniformly. The evidence strongly favors the satellite-entries hypothesis.  相似文献   
967.
Two methods of language instruction administered to mentally retarded subjects at the two-word stage of language development were investigated. Subjects of the mimicry training group imitated Agent-Action-Object (AAO) constructions immediately after presentation, while subjects of the imitative modeling group first heard the AAO presentation and later produced the AAO construction in response to a verb question. Imitative modeling subjects achieved as many correct AAO responses during training and more correct responses on a generalization task and in a free play setting. They also displayed more novel response behavior (selective imitations) and spontaneously corrected productions. The results support the use of modeling procedures for inducing language production in the retarded.  相似文献   
968.
969.
Subsequent to success or failure experience, 48 subjects attempted a psychomotor task in order to escape or avoid an aversive stimulus (tone). Their attempts at solving the task over 24 trials were made in the presence of subject-experimenters each of whom had expectancies instilled regarding the solution to the task. The job of the subject-experimenters was to “offer information” on every third trials as the subjects attempted to solve the task. It was hypothesized that the expectancies of the subject-experimenters would be communicated to the subjects via periodic comments, that these expectancies would differentially affect the subjects' performance on the task, and that prior experience on a similar task would differentially affect subjects' performances on the task. The results demonstrated that the expectancies instilled in the subject-experimenters were communicated and influenced the performances of subjects as predicted. It appears that consistency with respect to the expectancies communicated played a major role in producing significant effects. Prior experience failed to produce significant differences on task performance, a finding conflicting with that of D.S. Hiroto (Journal of Experimental Psychology, 1974, 102, 187–193). The results are discussed from the perspective of using the overt, explicit communication of expectancies as a means for exploring the illusive phenomenon of the experimenter expectancy effect.  相似文献   
970.
While left-hemisphere language dominance is more general than dextrality, and reversed dominance is less frequent than sinistrality, there are disputes in both the clinical and the experimental literature on a number of related issues which pertain to a possible language contribution from the minor hemisphere. These issues include the nature and extent of bilaterality in sinistrals, whether this is more pronounced in the strongly or weakly sinistral, and in those with or without other sinistral close relatives, whether sinistrality is largely or at all a consequence of birth stress, whether sinistrals differ from dextrals in visuospatial or even verbal skills, Levy's (1978) hypothesis that a knowledge of the hand position employed in writing (hooked or noninverted) may accurately predict language lateralization in sinistrals, and the possible extent of a minor hemisphere contribution to the recognition of high frequency, concrete, or imageable nouns. Findings relating to the above issues are reviewed, and it is concluded that much of the current confusion stems from poor control of subject factors such as sex, strength and family history of handedness, and nature of stimuli and their mode of presentation.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号