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   37784篇
  免费   1471篇
  国内免费   15篇
  2020年   435篇
  2019年   555篇
  2018年   734篇
  2017年   807篇
  2016年   820篇
  2015年   565篇
  2014年   697篇
  2013年   2957篇
  2012年   1275篇
  2011年   1255篇
  2010年   822篇
  2009年   779篇
  2008年   1127篇
  2007年   1139篇
  2006年   1019篇
  2005年   908篇
  2004年   845篇
  2003年   801篇
  2002年   817篇
  2001年   1171篇
  2000年   1124篇
  1999年   879篇
  1998年   377篇
  1997年   379篇
  1996年   350篇
  1995年   353篇
  1994年   343篇
  1992年   737篇
  1991年   645篇
  1990年   700篇
  1989年   610篇
  1988年   640篇
  1987年   601篇
  1986年   604篇
  1985年   545篇
  1984年   505篇
  1983年   483篇
  1982年   348篇
  1979年   572篇
  1978年   398篇
  1975年   453篇
  1974年   493篇
  1973年   531篇
  1972年   400篇
  1971年   391篇
  1970年   351篇
  1969年   406篇
  1968年   471篇
  1967年   429篇
  1966年   359篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
Practice in front of a mirror is a common procedure for activities such as dance, gymnastics, and other sports. The purpose of this study was to examine the effect that performing with concurrent visual feedback from a mirror had on the acquisition of the power clean movement. 18 college-age males who had no prior experience with the power clean movement served as subjects who were assigned to one of two groups. One group had use of a mirror during the practice trials and the other practiced without the mirror. All subjects viewed an instructional videotape and had practice trials. All subjects were evaluated for proper technique on a pretest, a posttest without the mirror, and a posttest with the mirror. Analysis showed a significant difference between pre- and posttest performances for both groups and a significant difference between groups on the posttest performances with the mirror. Evidently the videotaped instruction was sufficient to allow both groups to improve in performance of the power clean. Differences in posttest performances with the mirror reflected the type of feedback (with or without the mirror) available during training.  相似文献   
172.
Previous research has suggested that women with a negative emotional orientation toward sexuality (i.e., erotophobia) have difficulty learning and retaining sexually relevant material such as contraceptive information. It has been hypothesized that these women become aroused by this material and that this arousal interferes with their ability to learn it. The importance of this issue led us to conduct the current study. Erotophobic and erotophilic women viewed presentations about contraception while their physiological responses were being monitored. In addition, they were tested on the information contained in the presentation before, immediately after, and again 4-6 weeks after the presentation. The results indicated that the erotophobic women knew less contraceptive information before the presentation and were more aroused by the presentation. This arousal, however, did not interfere with retention of the material. These results are discussed in terms of individual differences in reactions to sexual material and the ability to learn, retain, and use contraceptive information.  相似文献   
173.
174.
175.
A study was conducted with 104 hospital employees to assess the relationship between pay-for-performance perceptions and pay satisfaction. Unlike previous research examining this relationship, a multi-item measure of pay-for-performance perceptions and a multidimensional measure of pay satisfaction were used. As hypothesized, the results indicated a positive relationship between pay-for-performance perceptions and pay-raise satisfaction, pay-level satisfaction, and overall pay satisfaction even after the effects of salary level, salary increases, performance ratings, job tenure, job satisfaction, and promotions were controlled. The importance of gathering perceptual data on characteristics of the pay system believed to have differential relationships with the subdimensions of pay satisfaction are discussed.  相似文献   
176.
The IES Arrow-Dot was administered to 41 cocaine detoxification patients. This group's scores indicated lower ego functioning and higher impulsivity and superego functioning than other clinical samples. No significant differences were noted between the Arrow-Dot scores of patients who successfully completed the program and those who did not.  相似文献   
177.
This paper discusses least squares methods for fitting a reformulation of the general Euclidean model for the external analysis of preference data. The reformulated subject weights refer to a common set of reference vectors for all subjects and hence are comparable across subjects. If the rotation of the stimulus space is fixed, the subject weight estimates in the model are uniquely determined. Weight estimates can be guaranteed nonnegative. While the reformulation is a metric model for single stimulus data, the paper briefly discusses extensions to nonmetric, pairwise, and logistic models. The reformulated model is less general than Carroll's earlier formulation.The author is grateful to Christopher J. Nachtsheim for his helpful suggestions.  相似文献   
178.
179.
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   
180.
This article is concerned with the use of base-rate information that is derived from experience in classifying examples of a category. The basic task involved simulated medical decision making in which participants learned to diagnose hypothetical diseases on the basis of symptom information. Alternative diseases differed in their relative frequency or base rates of occurrence. In five experiments initial learning was followed by a series of transfer tests designed to index the use of base-rate information. On these tests, patterns of symptoms were presented that suggested more than one disease and were therefore ambiguous. The alternative or candidate diseases on such tests could differ in their relative frequency of occurrence during learning. For example, a symptom might be presented that had appeared with both a relatively common and a relatively rare disease. If participants are using base-rate information appropriately (according to Bayes' theorem), then they should be more likely to predict that the common disease is present than that the rare disease is present on such ambiguous tests. Current classification models differ in their predictions concerning the use of base-rate information. For example, most prototype models imply an insensitivity to base-rate information, whereas many exemplar-based classification models predict appropriate use of base-rate information. The results reveal a consistent but complex pattern. Depending on the category structure and the nature of the ambiguous tests, participants use base-rate information appropriately, ignore base-rate information, or use base-rate information inappropriately (predict that the rare disease is more likely to be present). To our knowledge, no current categorization model predicts this pattern of results. To account for these results, a new model is described incorporating the ideas of property or symptom competition and context-sensitive retrieval.  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