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   67524篇
  免费   2793篇
  国内免费   48篇
  70365篇
  2020年   796篇
  2019年   966篇
  2018年   1395篇
  2017年   1412篇
  2016年   1492篇
  2015年   1022篇
  2014年   1214篇
  2013年   5852篇
  2012年   2199篇
  2011年   2409篇
  2010年   1453篇
  2009年   1407篇
  2008年   2096篇
  2007年   2056篇
  2006年   1807篇
  2005年   1641篇
  2004年   1599篇
  2003年   1476篇
  2002年   1496篇
  2001年   2278篇
  2000年   2176篇
  1999年   1606篇
  1998年   829篇
  1997年   717篇
  1996年   653篇
  1995年   636篇
  1994年   602篇
  1993年   631篇
  1992年   1292篇
  1991年   1219篇
  1990年   1220篇
  1989年   1107篇
  1988年   1083篇
  1987年   1045篇
  1986年   1063篇
  1985年   1100篇
  1984年   873篇
  1983年   748篇
  1982年   580篇
  1979年   816篇
  1978年   628篇
  1975年   747篇
  1974年   824篇
  1973年   763篇
  1972年   716篇
  1971年   630篇
  1969年   616篇
  1968年   722篇
  1967年   683篇
  1966年   627篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Self-report measures of Type A personality receive wide research usage despite mounting evidence that they are poor predictors of coronary heart disease. It was proposed that the limited prediction results in part from the failure to restrict measurement to only those Type A characteristics that are demonstrably related to excessive stress. The first study in this article reports a factor analysis of all items on the Jenkins Activity Survey (JAS), the most popular Type A questionnaire, along with 25 stress symptoms. Self-ratings were obtained from both male and female college students. Only one stress-related factor emerged including 12 JAS items out of 44. These were relevant to (a) hard-driving and competitive, (b) time-urgent, and (c) hostile/irritated characteristics. Study 2 reports correlations of +.50 and +.43 between the stress-relevant JAS items and stress for new samples of female and male college students. Study 3 considers the broader personality correlates of scores on the stress-relevant Type A items and reports markedly different patterns for male and female college students. Predicted correlations were found on new samples between these personality correlates, considered as scales, and stress-relevant Type A scores and stress.  相似文献   
952.
One of the most necessarily sensitive areas of pastoral care is dealing with perinatal death. This case study grows from a need for care providers to understand better the feelings of a mother in the loss of her baby. This particular exploration evolved from a taped interview with the writer's aunt (now in her seventies) and her dealings with the multiple losses she experienced over fifty years ago. Her conversation in the interview gives credibility to many coping skills that we endeavor to teach today and that she developed for herself out of a need to survive....it was as if the birds would never sing again.-Aunt Grace  相似文献   
953.
In this study, we investigated the factorial structure of the Manifest Anxiety Scale (MAS) among American, counseling graduate students (N = 227). The MAS was administered across transsituational and transtemporal conditions. The following four factors were yielded following orthogonal rotation: General Worries, Physiological Correlates of Anxiety, Distractibility, and Embarrassment. These four factors, however, explained less than one quarter of the common variance extracted. Following a comparison with previous factor analytic studies of the MAS, we discuss factors possibly contributing to the discrepant findings, with particular attention to the MAS's item content and psychometric properties and the nature of the population used.  相似文献   
954.
The equilibrium control hypothesis (lambda model) is considered with special reference to the following concepts: (a) the length-force invariant characteristic (IC) of the muscle together with central and reflex systems subserving its activity; (b) the tonic stretch reflex threshold (lambda) as an independent measure of central commands descending to alpha and gamma motoneurons; (c) the equilibrium point, defined in terms of lambda, IC and static load characteristics, which is associated with the notion that posture and movement are controlled by a single mechanism; and (d) the muscle activation area (a reformulation of the "size principle")--the area of kinematic and command variables in which a rank-ordered recruitment of motor units takes place. The model is used for the interpretation of various motor phenomena, particularly electromyographic patterns. The stretch reflex in the lambda model has no mechanism to follow-up a certain muscle length prescribed by central commands. Rather, its task is to bring the system to an equilibrium, load-dependent position. Another currently popular version defines the equilibrium point concept in terms of alpha motoneuron activity alone (the alpha model). Although the model imitates (as does the lambda model) spring-like properties of motor performance, it nevertheless is inconsistent with a substantial data base on intact motor control. An analysis of alpha models, including their treatment of motor performance in deafferented animals, reveals that they suffer from grave shortcomings. It is concluded that parameterization of the stretch reflex is a basis for intact motor control. Muscle deafferentation impairs this graceful mechanism though it does not remove the possibility of movement.  相似文献   
955.
The aim of this study was to investigate the modulations of locomotion induced by a rhythmic cognitive task (counting one's steps). Subjects (6- and 8-year-olds and adults) were requested to walk freely, and then to walk while counting their steps. Here a decrease in cadence values was observed in children only, with quasi-total repercussions on velocity at the age of 6 only. The spatiotemporal structuring of locomotion described here is already present at 6 years of age and is not altered in the step-counting situation: strong links were observed between cadence and velocity, and between stride length and velocity, and weak links between cadence and stride length.  相似文献   
956.
Predictions of physical symptomatology by daily life events and by major life events were compared, replicating and expanding work reported by DeLongis, Coyne, Dakof, Folkman, & Lazarus (1982). Analyses of daily, prospective data collected on 79 married men for 90 days demonstrated that daily, undesirable events were better predictors of symptom frequencies than either past, major life events or daily, desirable events. These results, similar to those found by DeLongis et al. (1982), were further explored by examining "healthy" subjects versus subjects with prior medical conditions. Undesirable daily events were a much stronger predictor of physical symptoms in the healthy group than in the prior medical conditions group.  相似文献   
957.
Four groups of rats, one of which served as a normal, nonoperated group, were used. The other three groups were operated and fitted with an electrode carrier of eight electrodes of varying lengths arranged in a 7.5 mm X 5 mm rectangle. About 10 or 12 days after surgery, the following groups of animals underwent a 14-day regimen wherein each animal spent 15 min in a deep, metal, electrically insulated cylinder: Group A, normal, nonoperated group, with no intervention; Group B, stimulated each day with 45 trains of rectangular biphasic pulses (3 trains per min) at the rate of 20 pulses per second (pps); Group C, the same but at the rate of 100 pps; Group D, the same but 180 pps. After a 48-hr fast and without benefit of shaping, each animal was placed for 60 min in a lever-pressing device and was rewarded with a pellet after each three to four presses. The resulting performance curves showed no improvement in pressing rate for Group A; marginal improvement for Group B; definite improvement for Group C; and the greatest improvement for Group D, the terminal rate being almost twice that of Group C.  相似文献   
958.
Eye movements and the perceptual span in beginning and skilled readers   总被引:4,自引:0,他引:4  
Four experiments are reported which examined the size of the perceptual span in second-, fourth-, and sixth-grade children, as well as adult skilled readers. The results indicated that the perceptual span in beginning readers is slightly smaller than the perceptual span of skilled readers. Using a moving window technique, it was found that the perceptual span of beginning readers extends about 11 character spaces to the right of fixation; for skilled readers, the span extends 14-15 spaces to the right of fixation. Beginning readers apparently devote more of their processing to the foveally fixated word than more proficient readers, but their perceptual span appears to be asymmetric to the right of fixation as is the case for skilled readers. The results of the experiments also indicated that the size of the perceptual span is variable and can be influenced by the difficulty of the text. It is concluded that the size of the perceptual span does not cause beginning readers' slow reading rates.  相似文献   
959.
960.
Altruism and aggression: the heritability of individual differences   总被引:8,自引:0,他引:8  
Five questionnaires measuring altruistic and aggressive tendencies were completed by 573 adult twin pairs of both sexes from the University of London Institute of Psychiatry Volunteer Twin Register. The questionnaires measured altruism, empathy, nurturance, aggressiveness, and assertiveness. The intraclass correlations for the five scales, respectively, were .53, .54, .49, .40, and .52 for 296 monozygotic pairs, and .25, .20, .14, .04, and .20 for 179 same-sex dizygotic pairs, resulting in broad heritability estimates of 56%, 68%, 70%, 72%, and 64%. Additional analyses, using maximum-likelihood model-fitting, revealed approximately 50% of the variance on each scale to be associated with genetic effects, virtually 0% with the twins' common environment, and the remaining 50% with each twins' specific environment and/or error associated with the test. Correcting for the unreliability in the tests raised the maximum-likelihood heritabilities to approximately 60%. Age and sex differences were also found: altruism increased over the age span from 19 to 60, whereas aggressiveness decreased, and, at each age, women had higher scores than men on altruism and lower scores on aggressiveness.  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