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   16158篇
  免费   618篇
  国内免费   4篇
  2019年   213篇
  2018年   258篇
  2017年   219篇
  2016年   257篇
  2015年   169篇
  2014年   262篇
  2013年   1273篇
  2012年   435篇
  2011年   487篇
  2010年   292篇
  2009年   314篇
  2008年   416篇
  2007年   442篇
  2006年   422篇
  2005年   344篇
  2004年   373篇
  2003年   335篇
  2002年   331篇
  2001年   451篇
  2000年   510篇
  1999年   343篇
  1998年   208篇
  1997年   158篇
  1996年   167篇
  1995年   168篇
  1992年   277篇
  1991年   285篇
  1990年   297篇
  1989年   280篇
  1988年   268篇
  1987年   234篇
  1986年   247篇
  1985年   260篇
  1984年   192篇
  1983年   208篇
  1982年   158篇
  1980年   160篇
  1979年   250篇
  1978年   217篇
  1977年   152篇
  1975年   215篇
  1974年   243篇
  1973年   268篇
  1972年   225篇
  1971年   210篇
  1970年   163篇
  1969年   195篇
  1968年   249篇
  1967年   239篇
  1966年   209篇
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
281.
Contrast effects were obtained in rats in the consumption of saccharin solutions in three different paradigms. Degree of negative contrast varied as a function of concentration disparity, but not equally in the three procedures. Successive negative contrast occurred following shifts from 0.15% to either 0.075% or 0.05% saccharin but did not occur following shifts to 0.10% or 0.125% saccharin. Some degree of simultaneous contrast was obtained with all four concentration disparities. Anticipatory contrast, where the intake of the first substance is suppressed by a more preferred second substance, occurred only in the case of the 0.05%-0.15% difference in concentrations. It was suggested that the several contrast paradigms engage somewhat different psychological processes differentially involving emotional, sensory, and associative mechanisms, but all lead to behavior based on relative value. A modification of Toates's (1981) incentive model of ingestive behavior was suggested to incorporate relativity effects based on both associative and nonassociative factors in the consumption of both nutritive and nonnutritive substances.  相似文献   
282.
The 2-deoxyglucose (2-DG) autoradiographic method was used to map metabolic activity in the brain of socially deprivated rats during an active avoidance test. The method investigated the effects of razobazam during this learning test. The animals were socially deprivated for 5 weeks. On the first experimental day the animals were trained to avoid a footshock by jumping onto a platform. During training and testing, the total number of avoidance responses was scored. On the second day during one 2-DG session of 40 min, razobazam increased the avoidance score by 18% as compared to controls. Autoradiographs were analyzed using a two-dimensional densitometric method. The analysis of the brain structures showed a 22% reduction of optical density in the nucleus habenularis lateralis, a 25% increase in the caudal part of the nucleus accumbens, and a 13% increase in the frontal cortex in rats treated with razobazam, but no change in the amygdala. These results provide a preliminary concept to explain how the new compound razobazam produced a better learning performance in socially deprivated rats.  相似文献   
283.
Children receiving 1 year or 1/2 year of a preventive social problem solving program in elementary school were compared with each other and with a no-treatment group upon entry into middle school. One year of training was significantly related to reductions in the severity of a variety of middle-school stressors. Most importantly, a clear mediating role for social problem solving (SPS) skills was found. Children lacking in SPS skills were more likely to experience intense stressors; however, possessing the skills was not necessarily predictive of adjustment to stressors. The results are discussed in terms of the implications of this asymmetry and the strong support given to the value of social problem solving as a preventive intervention for children.  相似文献   
284.
The ability to think of a previously studied item has often been shown to be impaired when, in one way or another, the extraitem context is changed from study to test. In a series of five experiments, such impairment is induced in a somewhat different way. A fragment (e.g. r-i--rop) of a just-studied word (raindrop) is shown to be less readily completed if it is presented bit by bit (r------p, r----r-p, r-i--r-p, r-i--rop) rather than all at once (Experiments 1, 3, 4, and 5). No such effect is found if the word has not been studied beforehand (Experiments 2, 3, 4, and 5). This pattern of results occurs even when fragments of studied and nonstudied words occur in the same test and under conditions in which subjects cannot tell whether a given fragment is of a studied or nonstudied word (Experiments 4 and 5). In addition, for words that have been studied beforehand, the impairment is shown to increase systematically with the number of steps involved in the presentation of the word fragment (Experiment 3) and also to persist when the time allowed for completion of the final version of the fragment is increased from 4 s to a full minute (Experiment 5).  相似文献   
285.
Fixation point digits have been widely used in tachistoscopic laterality studies as a simple and convenient means of ensuring unihemispheric projection of stimulus materials to the hemispheres. Previous findings demonstrate that fixation digits do not influence asymmetries in recognition accuracy studies with adult Ss. Present results, comparing four conditions differing in their use of fixation digits, show that in the naming latency paradigm the requirement to remember and report fixation control digits significantly augments RVF superiority. Implications for other latency tasks are discussed.  相似文献   
286.
Although single-subject research techniques are relevant and valuable to counselors, analyzing change by graphs alone is open to major sources of error. The author discusses these sources and explores the issues of serial dependency, unreliability of graphs, interjudge disagreement on graphed data, and the use of a more reliable statistical procedure (the time-series statistic) with relevance to the counselor in the field.  相似文献   
287.
The purpose of this study was to provide age-comparative evidence of social cognitive reasoning in adulthood, as mediated by the emotional saliency of tasks tapping postformal reasoning. Specifically, the tasks focused on the ability to resolve discrepant accounts of the same event sequence. It was assumed that less mature thinking may be more evident in reasoning contexts in which emotional factors play a major role. A postformal coding scheme was used to assess levels of reasoning in an interpersonal context. Tasks were administered to 60 subjects--adolescents and young and middle-aged adults. Measures of formal operations, ego level, and verbal ability were also administered. An interaction was found between age and degree of emotional saliency of the task for reasoning level. Specifically, adolescents performed less well on tasks higher in degree of emotional saliency. In addition, developmental differences in postformal reasoning as a function of age and ego level were found.  相似文献   
288.
Fluid intelligence belongs to that cluster of intellectual abilities evincing aging loss. To examine further the range of intellectual reserve available to aging individuals and the question of replicability in a new cultural and laboratory setting, 204 healthy older adults (mean age = 72 years; range = 60-86) participated in a short-term longitudinal training study. For experimental subjects, 10 sessions consisted of cognitive training involving two subability tests (Figural Relations, Induction) of fluid intelligence. The pattern of outcomes replicates and expands on earlier studies. Older adults have the reserve to evince substantial increases in levels of performance in fluid intelligence tests. Transfer of training, however, is narrow in scope. Training also increases accuracy of performance and the ability to solve more difficult test items. Difficulty level was estimated in a separate study, with a comparable sample of N = 112 elderly adults. Future research is suggested to examine whether intellectual reserve extends to near-maximum levels of performance.  相似文献   
289.
This study evaluated the relative efficacy of long (1 minute) and short (15 seconds) durations of negative practice for reducing self-stimulatory leg pounding of a traumatically brain-injured adult. In individual social skill training classes, long negative practice and short negative practice were administered concurrently in an alternating treatments design. Generalization of treatment effects outside of training sessions was assessed during the client's lunch period. The results revealed that both durations of negative practice were equally effective in reducing leg pounding during training sessions. However, the effects of training did not generalize to settings in which the practice contingency was not enforced. Pounding was more frequent and negative practice somewhat less effective during periods of high social stimulation.  相似文献   
290.
The present study examined some previously reported relationships between drug use by adolescents and perceived attitudes and behaviors of their parents. An anonymous questionnaire was administered to the student body of an inner-city secondary school for difficult students. Relationships between parental use of drugs and adolescent use of the same drugs were moderate and roughly equivalent across drugs. However, parental use of marijuana was strongly related to the adolescent's use of other, harder drugs such as opiates, cocaine, amphetamines, and barbiturates. This finding is explained within the framework of Kandel's postulated stages of drug initiation. It points to a need for further study of parental influences, which may be increasingly problematic as more individuals who have grown up in our marijuana-accepting society become parents of adolescents.  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