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   5953篇
  免费   175篇
  国内免费   3篇
  6131篇
  2019年   54篇
  2018年   110篇
  2017年   88篇
  2016年   85篇
  2015年   66篇
  2014年   74篇
  2013年   455篇
  2012年   172篇
  2011年   163篇
  2010年   82篇
  2009年   98篇
  2008年   139篇
  2007年   154篇
  2006年   131篇
  2005年   126篇
  2004年   123篇
  2003年   103篇
  2002年   117篇
  2001年   214篇
  2000年   205篇
  1999年   142篇
  1998年   56篇
  1997年   54篇
  1996年   60篇
  1993年   54篇
  1992年   119篇
  1991年   120篇
  1990年   117篇
  1989年   99篇
  1988年   89篇
  1987年   97篇
  1986年   108篇
  1985年   105篇
  1984年   95篇
  1983年   82篇
  1979年   95篇
  1978年   70篇
  1977年   62篇
  1976年   54篇
  1975年   67篇
  1974年   92篇
  1973年   100篇
  1972年   72篇
  1971年   69篇
  1970年   80篇
  1969年   75篇
  1968年   106篇
  1967年   82篇
  1966年   93篇
  1958年   62篇
排序方式: 共有6131条查询结果,搜索用时 0 毫秒
101.
The goal of the reported experiment was to study how adults judge the meaning of different kinds of smiling and laughing by preschool children, and the role played by other facial movements in determining this meaning. Videotapes and photographs of spontaneous facial expressions of children in a play situation served as stimuli. The results show that different kinds of smiling were judged by the adult subjects as being significantly different from each other. In order to find subgroups within the stimuli, cluster analyses were performed, and the resulting clusters indicated different mixtures of positive and negative emotions contained within the pictures. Regression analyses showed that the adults' judgements were dependent on the number of indicators for positive and negative emotions which could be seen in the pictures. The most important indicator movement for the judged strength of the positive emotion expressed in the smile was the raising of the cheeks and, for negative emotions, the lowering of the lip corners. The significance of the components of the expressions as well as the strength of the expressed emotion were, however, dependent on the mode of presentation (video/photo).  相似文献   
102.
This case study concerns an 18-year-old bilingual girl who suffered a radiation lesion in the left (dominant) thalamic and temporal region when she was 4 years old. Language and memory assessment revealed deficits in auditory short-term memory, auditory word comprehension, nonword repetition, syntactic processing, word fluency, and confrontation naming tasks. Both languages (English and Dutch) were found to be affected in a similar manner, despite the fact that one language (English) was acquired before and the other (Dutch) after the period of lesion onset. Most of the deficits appear to be related to verbal (short-term) memory dysfunction. Several hypotheses of subcortical involvement in memory processes are discussed with reference to existing theories in this area.  相似文献   
103.
The short- and long-range apparent motion processes are discussed in terms of the statistical properties of images. It is argued that the short-range process, exemplified by the random-dot kinematogram, is primarily sensitive to the dipole statistics, whereas the long-range process, exemplified by illusory occlusion, is treated by the visual system primarily in terms of the tripole and higher statistical correlation functions. The studies incorporate the balanced dot, which is a unique stimulus element that permits high pass filtering while preserving detailed positional information. Low spatial frequencies are shown to be critical for texture segregation in random-dot kinematograms, independent of the grain size or number density of texture elements. Illusory path perception in the long-range process is shown not to require low spatial frequencies, but is sensitive rather to global temporal phase coherency. These results are interpreted in terms of the respective roles of the power and phase spectra in perceptual organization. The construction of balanced dots is discussed in detail.  相似文献   
104.
Transparent layer constancy   总被引:1,自引:0,他引:1  
Perceived transparency was studied as a constancy problem. In the episcotister (E-) model of scission, luminances are partitioned into layer and background components; four luminances determine values of two layer parameters that specify constancy of a transparent layer on different backgrounds. The E-model was tested in an experiment in which 12 Ss matched 24 pairs of four-luminance patterns by adjusting two luminances of the comparison pattern. Both the standard and the comparison were perceived as a transparent layer on a checkerboard. The E-model predicts matches when layer values are identical in the two patterns. One parameter was constant, constraining the adjustment along the second dimension. Obtained values corresponded well with E-predictions. Alternative models based on local luminance or average contrast ratios accounted for less variability. Results indicate that transparency models should utilize luminance, not reflectance, as the independent variable.  相似文献   
105.
In rats, pretraining ip administration of the central benzodiazepine receptor antagonist, flumazenil (5.0 mg/kg), or of the inverse agonist, n-butyl-beta-carboline-3-carboxylate (BCCB) (0.2 or 0.5 mg/kg), facilitated retention of a step-down inhibitory avoidance task; the central agonists, clonazepam and diazepam (0.4 or 1.0 mg/kg), had an opposite effect, and the peripheral agonist, 4'-chlordiazepam (1.25 or 6.25 mg/kg), was without effect. Pre- but not post-training flumazenil (2.0 mg/kg) blocked the effect of BCCB (0.5 mg/kg), clonazepam (1.0 mg/kg), or diazepam (1.0 mg/kg) given also pretraining. The post-training administration of all of these drugs had no effect on retention of the avoidance task. Flumazenil (5.0 mg/kg) and BCCB (0.5 mg/kg), given before training, enhanced retention test performance of habituation to a buzzer but not of habituation to an open field. In the three tasks studied, none of the drugs used had any appreciable effect on training session parameters. These results suggest that there is an endogenous mechanism mediated by benzodiazepine agonists, sensitive to inverse agonists, that normally down-regulates acquisition of certain behaviors; this mechanism becomes activated only when the tasks involve or occur with a certain degree of stress or anxiety (i.e., inhibitory avoidance or habituation to the buzzer) and not in less stressful or anxiogenic tasks (i.e., habituation to an open field).  相似文献   
106.
The relationship between sex role flexibility and prosocial behavior among preschool children was investigated. Subjects included 16 boys and 18 girls, ranging in age from 36 to 60 months, from intact families of the upper middle class. A nonhierarchical multiple regression analysis was undertaken to determine the contributions of the predictor variables of sex, age, IQ, and sex role flexibility, as well as their interactions with prosocial behavior (criterion variable). Results indicated that while the overall regression model was not significant, the variable of Sex × Sex Role Flexibility did contribute significantly to the model. Inspection of the correlation coefficients associated with this variable revealed that while sex role flexibility and prosocial behavior among boys were significantly and positively related, among girls no significant relationship was found.  相似文献   
107.
It was hypothesized that older widows (N=309) who had been care givers to their husbands would have undertaken a greater number of household responsibilities than had women who had not been care givers. Findings indicated that, prior to the husband's death, more traditionally male and more traditionally female tasks were performed by the care-giving wives (n=158). This was particularly true in the case of Alzheimer's care givers (n=21). More importantly, widows' present feelings of competence were related to undertaking household responsibilities, with those who had been care givers expressing significantly higher levels of competence.  相似文献   
108.
Prime Minister Yitzhak Rabin's assassination has less of a lasting impact on the Israeli public's political values, beliefs and attitudes than might have been anticipated from the magnitude of the event and intensity of the immediate responses. Why did the assassination have such a short-lived effect? This article considers the puzzle as a specific case of the broader phenomenon of collective political trauma and its consequences for values, beliefs and attitudes held by the mass public toward issues that it associates with the traumatic event. The article offers six deductively inferred hypotheses that describe, explain and link affective, cognitive and behavioral aspects of collectively experienced trauma. These hypotheses form a pre-theory explaining the perseverence of core political cognitions, even in the face of a considerable challenge to their validity and relevance.  相似文献   
109.
110.
Strong representability of fork algebras, a set theoretic foundation   总被引:1,自引:0,他引:1  
  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