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   90106篇
  免费   3577篇
  国内免费   35篇
  2020年   927篇
  2019年   1210篇
  2018年   1606篇
  2017年   1690篇
  2016年   1777篇
  2015年   1276篇
  2014年   1519篇
  2013年   6916篇
  2012年   2815篇
  2011年   2960篇
  2010年   1858篇
  2009年   1847篇
  2008年   2603篇
  2007年   2660篇
  2006年   2425篇
  2005年   2145篇
  2004年   1987篇
  2003年   1891篇
  2002年   1983篇
  2001年   2795篇
  2000年   2707篇
  1999年   2077篇
  1998年   1042篇
  1997年   917篇
  1996年   911篇
  1995年   838篇
  1992年   1781篇
  1991年   1634篇
  1990年   1643篇
  1989年   1478篇
  1988年   1486篇
  1987年   1426篇
  1986年   1491篇
  1985年   1468篇
  1984年   1286篇
  1983年   1179篇
  1982年   866篇
  1981年   850篇
  1979年   1386篇
  1978年   999篇
  1975年   1109篇
  1974年   1207篇
  1973年   1328篇
  1972年   1097篇
  1971年   1026篇
  1970年   912篇
  1969年   993篇
  1968年   1225篇
  1967年   1121篇
  1966年   928篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
881.
Task-unrelated-thought frequency as a function of age: a laboratory study   总被引:4,自引:0,他引:4  
Using retrospective reports, Giambra (1977-1978, 1979-1980) found an inverse relation between age and daydreaming/mind wandering. To deal with an alternate explanation of these results based on age-dependent memorial deficiencies and attitudes toward daydreaming/mind wandering and to provide independent convergent validity, five experiments were carried out. Task-unrelated thoughts (TUTs) were taken as the operational definition of daydreams/mind wanderings and their frequency recorded in vigilance tasks. All five experiments found an inverse relation between age (17-92 years, N = 471) and TUTs, confirming the reliability and validity of the earlier studies. The age-dependent reduction in TUTs was considered as evidence of reduced nonconscious information processing with increased age. The results of this study were incompatible with a recent theory that predicts for older individuals an increased input of irrelevant thoughts into working memory due to the older individual's reduced inhibitory control.  相似文献   
882.
Age differences in the acculturation process   总被引:1,自引:0,他引:1  
Age differences were assessed in a conceptual model that seeks to explain how acculturation affects psychological well-being among Mexican Americans. The data were from a national probability sample of 859 persons of Mexican decent. It was hypothesized that low acculturation creates financial stress. Moreover, low acculturation and financial stress were in turn predicted to erode feelings of personal control and self-esteem. Finally, diminished feelings of control and low self-esteem were hypothesized to exert a negative impact on psychological well-being. When data from respondents of all ages was assessed, empirical support was found for all of the hypotheses except the linkage between acculturation and financial stress. However, few age differences emerged in the model. The authors conclude that older Mexican Americans may not be more vulnerable to the stressors associated with acculturation.  相似文献   
883.
Age, exercise, and coding performance   总被引:1,自引:0,他引:1  
We investigated the effects of exercise on the coding performance of young and older subjects. Hypotheses were tested that exercise either facilitates spatial localization or reduces susceptibility to distraction in older subjects. In a balanced design, we administered Digit Symbol and Symbol Digit coding tasks to exercisers and nonexercisers at two age levels under conditions of low or high within-task interference. The findings showed higher performance by the exercisers than by the nonexercisers only at the older age level and only with the Symbol Digit task. These findings support the hypothesis that exercise compensates for a loss of spatial localization skills with age. We found no evidence that susceptibility to distraction either increased with age or was affected by chronic exercise.  相似文献   
884.
This study compared the temporal organization of graphic movements executed either actually or mentally. Six subjects had to perform two tasks, writing a sentence and drawing a cube, either as a real performance or as an imagined one, with either the right or the left hand, and with either a small or a large tracing amplitude. In the same subject, for the same hand, mental and actual movement times were both very stable and very close from trial to trial regardless of the tracing amplitude. Thus, mental movements mimic closely real movements in their temporal organization and are likely to involve the same planning program.  相似文献   
885.
Guideline sentencing systems, including the new federal guidelines, have not settled on a clear conception of when and how a trial judge should explain sentences. Indeterminate sentencing systems did not have a tradition of written sentencing decisions and recent sentencing reforms do not focus on the trial judge's role. This article suggests the many advantages of written sentencing opinions. Initial experience under the federal sentencing guidelines bolsters the conclusion that written sentencing opinions in appropriate cases—including both sentences “within” guidelines and guideline “departures”—are the next step in the evolving law of sentencing and the best way to recognize trial judges as an essential engine of principled change.  相似文献   
886.
As the incidence of acquired immunodeficiency syndrome (AIDS) becomes more widespread, individuals with AIDS will present themselves for counseling in both public and private settings, and counselors will need to become familiar with the psychological manifestations of the AIDS virus. This article provides case material that demonstrates the emotional responses of gay men to AIDS. Specifically, denial, anger, rage, guilt, and shame are discussed with an emphasis on the human dimensions of AIDS.  相似文献   
887.
888.
Prior to assuming the upright crouching posture over their pups during nursing bouts, lactating rats typically engage in several oral behaviors, including nuzzling, licking and rearranging pups. By acutely depriving dams of various aspects of perioral stimulation from pups (with anesthesia of the mystacial pads or of the tongue, with mouth suturing, or with muzzling), we found the following: (1) Distal stimulation from pups maintains proximity-seeking behavior, but is insufficient to stimulate nursing behavior. (2) Lack of tongue feedback decreases pup licking and hastens the onset of crouching. (3) Snout, but not tongue, contact with pups is required for hovering over them. (4) The position of the dam while hovering over her litter enables the pups to gain access to her ventrum, thereby provoking her upright, crouching posture. (5) Older pups are capable of bypassing the dam's perioral attentions and stimulating crouching directly by burrowing under the dam's ventrum.  相似文献   
889.
The physiological effects of racism, as a stressor, were examined as they related to blood pressure (BP) and anger experiences in Black college students. Current research has failed to consider the stressful effects of racism as a factor contributing to the higher incidence of essential hypertension among Blacks. Twenty-seven Black college students viewed three excerpts showing racist situations involving Blacks; anger-provoking, nonracist situations; and neutral situations. After each scene, BP was taken, and a mood checklist was administered. The Framingham Anger Scale and the Anger Expression Scale were administered. Analyses revealed that BP significantly increased during the presentation of racist stimuli but not of anger-provoking or neutral stimuli. Self-reports of state anger, as measured by the mood checklist, were significant for both the anger-provoking and racist stimuli. BP scores were significantly correlated to the two trait anger measures. Exposure to racist stimuli was associated with BP increases among Blacks. Such cumulative exposure to racism may have important implications for the etiology of essential hypertension.  相似文献   
890.
A cross-sex difference on one variable is often hypothesized to be related to a gender difference on a second variable. However, caution should be exercised in making such comparative hypotheses. We gathered the expected and actual examination grades for 168 female and 163 male college students. As in prior research, males had higher expectancies than females (p<.05). But analysis of the intrasex regression equations indicated that the relationship of expectancies to performance was different for women than it was for men. Thus, a cross-sex difference in expectancies did not correspond to a parallel difference in grades. This finding highlights the potential hazards of making certain cross-sex comparisons, and we argue for more caution in their application.  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