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   10293篇
  免费   401篇
  国内免费   5篇
  2023年   51篇
  2021年   83篇
  2020年   149篇
  2019年   184篇
  2018年   238篇
  2017年   258篇
  2016年   276篇
  2015年   214篇
  2014年   278篇
  2013年   1230篇
  2012年   440篇
  2011年   446篇
  2010年   268篇
  2009年   280篇
  2008年   414篇
  2007年   433篇
  2006年   387篇
  2005年   404篇
  2004年   378篇
  2003年   356篇
  2002年   337篇
  2001年   156篇
  2000年   146篇
  1999年   158篇
  1998年   183篇
  1997年   140篇
  1996年   118篇
  1995年   120篇
  1994年   123篇
  1993年   109篇
  1992年   107篇
  1991年   97篇
  1990年   78篇
  1989年   95篇
  1988年   95篇
  1987年   76篇
  1986年   72篇
  1985年   100篇
  1984年   111篇
  1983年   108篇
  1982年   99篇
  1981年   89篇
  1980年   86篇
  1979年   69篇
  1978年   102篇
  1977年   75篇
  1976年   93篇
  1975年   77篇
  1974年   77篇
  1973年   63篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
The primary care setting is seen by many to be at the forefront of the attempt to encourage people to follow healthier diets. Conducted in a single practice, the present study firstly considered the effectiveness of three ‘healthy eating’ clinics for patients found to have elevated cholesterol levels at screening. Through the use of a randomised trial, these patients received either basic dietay information or were invited back more frequently and requested to complete food diaries, half of which were then analysed through a computer program. At one year follow up the three programmes were found to have produced a 6.7% reduction in cholesterol levels. However, no differences were found between the three programmes. The study secondly examined a range of health belieji, based on the health belief model, as predictors of reductions in cholesterol levels. These were generally found to be poor predictors, with only the belief that one's diet is related to the chances of developing a number of major conditions and the perception of bam'ers dealing with confidence predicting these reductions. Finally, the case for incorporating self-efficacy beliefs into the healh belief model is outlined and the need for health counsellors to tailor their messages to the pre-existing beliefi and behaviours of patients is highlighted.  相似文献   
62.
Neural networks can be used as a tool in the explanation of neuropsychological data. Using the Hebbian Learning Rule and other such principles as competition and modifiable interlevel feedback, researchers have successfully modeled a widely used neuropsychological test, the Wisconsin Card Sorting Test. One of these models is reviewed here and extended to a qualitative analysis of how verbal fluency might be modeled, which demonstrates the importance of accounting for the attentional components of both tests. Difficulties remain in programming sequential cognitive processes within a parallel distributed processing (PDP) framework and integrating exceedingly complex neuropsychological tests such as Proverbs. PDP neural network methodology offers neuropsychologists co-validation procedures within narrowly defined areas of reliability and validity.  相似文献   
63.
A study that involved parents as reading tutors was carried out at home during the summer with four elementary children, three with learning disabilities. One purpose was to determine the effects of tutoring in the basal reader on reading rates at home. Another purpose was to determine potential generalization effects as a result of parent tutoring on different academic tasks at home and, later at school, on different and similar tasks. A combination multiple-baseline and reversal design tested for replication and generalization effects. Increases in correct rates were noted for the targeted variables across conditions. The results indicated that parents tutoring with school basal texts during the summer produced marked increases in reading rates that generalized at home to different academic tasks and at school to different and similar tasks. This suggests that parents, when using specific tutoring procedures, can increase their children's academic skills.  相似文献   
64.
Retrospective and prospective reports of the onset of disruptive child behaviors were analyzed in a sample of clinic-referred boys. The younger boys (ages 7–9 years), compared with the older boys (ages 10–12 years), showed the highest level of disruptive behavior and, judging from mothers' reports, had the fastest progression of onsets from less serious to more serious problem behaviors. Despite some overlap, developmental sequences in problem behavior within the domains of hyperactivity/inattention, oppositional behavior, and conduct problems were similar across the two age groups. This was also the case for developmental sequences of overt or confrontive problem behaviors and covert or concealing conduct problems. Sequences of the onset of oppositional behavior and conduct problems were validated through prospective data, based on the information from mothers, teachers, and boys themselves. The implications of the findings are discussed for the formulation of developmental pathways of behavior and the analysis of causal factors.  相似文献   
65.
Working in the fragment of Martin-Löfs extensional type theory [12] which has products (but not sums) of dependent types, we consider two additional assumptions: firstly, that there are (strong) equality types; and secondly, that there is a type which is universal in the sense that terms of that type name all types, up to isomorphism. For such a type theory, we give a version of Russell's paradox showing that each type possesses a closed term and (hence) that all terms of each type are provably equal. We consider the kind of category theoretic structure which corresponds to this kind of type theory and obtain a categorical version of the paradox. A special case of this result is the degeneracy of a locally cartesian closed category with a morphism which is generic in the sense that every other morphism in the category can be obtained from it via pullback.The financial support of the Royal Society in London is gratefully acknowledged.  相似文献   
66.
Two experiments were conducted to examine the hypothesized differential effectiveness of two attentional focusing strategies in pain perception. In the first experiment, subjects (72 male college students) rated their levels of pain after being exposed to either low- or high-intensity pressure stimulation for 75 s. Subjects were instructed to use either an external or internal focus of attention during the pain induction. Results revealed that external focusing was more effective for coping than internal focusing across both levels of stimulus intensity. The second experiment was a replication of the first, and featured bolstered internal focusing and stimulus intensity manipulations. Results showed that high-intensity stimulation produced higher pain ratings than did low-intensity stimulation for subjects in the internal focusing conditions, but not for those in the external focusing conditions. The findings support the power of distraction strategies for dealing with short-term pain with a rapid onset. Theoretical implications are discussed.The authors thank Darwyn E. Linder and Daniel M. Landers for their help in development of this research. The authors are also indebted to Sarah Colley, Jona Davis, Nanci Neuberger, and Rebecca Roberts for their assistance in data collection.  相似文献   
67.
Established results on latent variable models are applied to the study of the validity of a psychological test. When the test predicts a criterion by measuring a unidimensional latent construct, not only must the total score predict the criterion, but the joint distribution of criterion scores and item responses must exhibit a certain pattern. The presence of this population pattern may be tested with sample data using the stratified Wilcoxon rank sum test. Often, criterion information is available only for selected examinees, for instance, those who are admitted or hired. Three cases are discussed: (i) selection at random, (ii) selection based on the current test, and (iii) selection based on other measures of the latent construct. Discriminant validity is also discussed.This work was supported in part by Grant SES-87-01890 from the Measurement Methods and Data Improvement Program of the U.S. National Science Foundation.  相似文献   
68.
Steven French 《Synthese》1989,78(2):141-166
Faced with strong arguments to the effect that Leibniz'sPrinciple of the Identity of Indiscernibles (PII) is not a necessary truth, many supporters of the Principle have staged a strategic retreat to the claim that it is contingently true in this, the actual, world. The purpose of this paper is to examine the status of the various forms of PII in both classical and quantum physics, and it is concluded that this latter view is at best doubtful, at worst, simply wrong.I would like to thank Michael Redhead and an anonymous referee for several useful suggestions and criticisms relating to the earlier version of this paper. I must also acknowledge the support given by the Centre of Logic, Epistemology and History of Science of the University of Campinas and the Brazilian National Council for Scientific and Technological Development in the later stages of the preparation of this work.  相似文献   
69.
Three experiments were designed to investigate the influence of initial recall on memory by assessing delayed recall after different immediate cued-recall tests. In all experiments, subjects performed semantic and phonemic encoding tasks on a word list. The subjects then received a cued-recall test that cued the target using the same word as the context word in the encoding task, a test that cued the target with a word from the same level at which the target was encoded, a test that cued the target with a cue from a different level at which the target was encoded, or no immediate-recall test. One day later, the subjects performed a final cued-recall test in which the type of cue (semantic or phonemic) was varied. Consistently, delayed recall was facilitated primarily when the cue on the immediate test was from the same level as the cue on the delayed test. This pattern of facilitation suggests that immediate cued-recall produces an elaboration of an existing memory representation that is closely tied to the type of cue used on the immediate test.  相似文献   
70.
Research conducted primarily in the United States suggests that the combination of Type A behaviour, high instrumentality, and low expressiveness may place individuals at relatively high risk for coronary-artery and heart disease. The present research investigates the trans-societal generalizability of the structure, reliability, relationships among, and distributional characteristics of these measures for 117 college students in Athens, Greece. As hypothesized, the Greek students were significantly less instrumental and less expressive than the American students, and scored significantly higher on the measure of Type A. Although there were significant mean differences between these samples, the results suggest that many of the interscale relationships are comparable, supporting an etic (universal) interpretation of the findings. Nevertheless, the results suggested several emic (unique) characteristics of these measures and their interrelationships.  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