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   17615篇
  免费   717篇
  国内免费   8篇
  18340篇
  2019年   255篇
  2018年   324篇
  2017年   285篇
  2016年   327篇
  2015年   209篇
  2014年   303篇
  2013年   1458篇
  2012年   518篇
  2011年   538篇
  2010年   349篇
  2009年   357篇
  2008年   463篇
  2007年   504篇
  2006年   478篇
  2005年   382篇
  2004年   420篇
  2003年   386篇
  2002年   371篇
  2001年   479篇
  2000年   539篇
  1999年   368篇
  1998年   228篇
  1997年   172篇
  1996年   179篇
  1995年   177篇
  1992年   291篇
  1991年   293篇
  1990年   305篇
  1989年   286篇
  1988年   278篇
  1987年   245篇
  1986年   250篇
  1985年   269篇
  1984年   201篇
  1983年   215篇
  1982年   167篇
  1981年   159篇
  1980年   163篇
  1979年   256篇
  1978年   223篇
  1975年   224篇
  1974年   247篇
  1973年   278篇
  1972年   232篇
  1971年   218篇
  1970年   172篇
  1969年   200篇
  1968年   255篇
  1967年   248篇
  1966年   213篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
951.
The influence of a genetic risk factor, apolipoprotein E (apoE) epsilon4 variant, was assessed in older adults aged 70 to 94 on 3 occasions over 7 years. The results of latent growth curve analyses are reported for individuals genotyped for apoE at the 2nd measurement occasion (n = 601) and for a subsample of individuals without probable or definite dementia during the 1st or 2nd occasion (n = 434). ApoE-epsilon4 status was a significant predictor of level and change in memory performance and change in speed performance in the full sample, and of initial level and change in memory performance in the nondemented subsample. These results support previous findings that apoE-epsilon4 is associated with accelerated memory deterioration in individuals without clinical dementia.  相似文献   
952.
The present analyses examined age-related measurement bias in responses to items on the revised Beck Depression Inventory (BDI) in depressed late-life patients versus midlife patients. Item response theory (IRT) models were used to equate the scale and to differentiate true-group differences from bias in measurement in the 2 samples. Baseline BDI data (218 late life and 613 midlife) were used for the present analysis. IRT results indicated that late-life patients tended to report fewer cognitive symptoms, especially at low to average levels of depression. Conversely, they tended to report more somatic symptoms, especially at higher levels of depression. Adjusted cutoff scores in the late-life group are provided, and possible reasons for age-related differences in the performance of the BDI are discussed.  相似文献   
953.
The authors investigated the effect of aging on flashbulb (FB) memories. In 1996, elderly Turks recalled how they had heard about 2 remote events--the death of the first president of Turkey (in 1938) and another event involving a change in the national borders of the country (in 1939)--and both elderly and younger adults recalled how they heard about the recent death of the 8th president of Turkey (in 1993). Seventy percent of the elderly had FB memories for the 1938 death; critical variables for the formation of FB memories were personal importance attached to the event and rehearsal. Ninety percent of younger Turks and 72% of elderly Turks had FB memories for the 1993 death; the only variable that differed between the 2 groups was rehearsal.  相似文献   
954.
Women with disabilities have low employment rates and about one-third live in poverty. They represent half of the population using either services of the vocational rehabilitation (VR) system or the welfare system, and many use both. Although both systems have made gains in improving their employment status, neither comprehensively addresses the needs of this population. Welfare policy has encouraged state level innovation and moved large numbers of people into employment in as little as five years. State welfare agencies offer a range of services specifically addressing the needs of families with children. VR agencies have decades of specific experience assisting people with disabilities gain employment. Welfare reform has been the cruise ship moving large numbers of people across an ocean. VR agencies have been the kayak builders designing specialized small craft to move specific people along tributaries. What can they learn from each other? Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
955.
Many researchers have hypothesized relationships between personality disorders and gender role (i.e., masculinity and femininity). However, research has not addressed if people who are masculine or feminine more often meet the criteria for personality disorders. The present study examined whether college students (N = 665, 60% women) higher in masculinity or femininity more often exhibited features of the 10 DSM-IV personality disorders. Feminine men exhibited more features of all the personality disorders except antisocial. Dependent traits were associated with higher femininity and lower masculinity. Antisocial traits were associated with masculinity. Both men and women who typically behaved consistent with their gender had more narcissistic and histrionic features, whereas participants who typically behaved unlike their gender had more features of the Cluster A personality disorders.  相似文献   
956.
The authors compare older adults' lexical-decision data with younger adults' data reported in P. Allen, A. F. Smith, et al. (2002). On the basis of their work, it was proposed that consistent-case wordswould be processed by the faster holistic (magnodominated) stream, but that mixed-case words would be processed by the slower analytic (interblob-dominated or blob-dominated) steams. Hue mixing was predicted to have no effect on consistent-case performance, but mixed-hue/mixed-case words were predicted to be recognized faster than monochrome/mixed-case words. Younger adults showed the predicted results, but older adults did not. These results suggest that holistic central processes are maintained, but that older adults exhibited an analytic decrement  相似文献   
957.
Neuroendocrine activation during stress is affected by many factors contributing to the variability of the stress response. The present study was aimed at evaluating long-term changes in hypothalamo-pituitary-adrenocortical (HPA) axis function and in hedonic behavior in adult offspring prenatally stressed by maternal food restriction, with attention on possible gender differences. Adult offspring were blood sampled via a tail artery cannula. Prenatally stressed females had significantly higher adrenal weights compared to males. Plasma ACTH levels, which rose in response to acute stress induced by handling, were significantly higher in females compared to those in males. A similar pattern was found in plasma corticosterone. The rise in ACTH levels was more pronounced in prenatally stressed rats though the rise in corticosterone failed to be modified. Corticotropin releasing hormone (CRH) and proopiomelanocortin mRNA levels in the hypothalamic paraventricular nucleus and anterior pituitary, respectively, were found to be unchanged. The present experiments failed to reveal a decrease in hedonic behavior in prenatally stressed rats. In contrast, in male offspring a tendency to a higher sucrose preference was observed. These data together with observed changes in hormone and CRH mRNA levels indicate that the gestational stress used did not result in a depression-like state in adult offspring.  相似文献   
958.
959.
To examine the role of perceptual object representations in the control of eye movements and attention, a pair of experiments adapted the object-cuing paradigm of Egly, Driver, and Rafal (1994) to require eye movements. Displays were pairs of adjacent rectangles, each containing two characters. Observers were asked to make a speeded judgment of a target character’s orientation, and a cue was provided prior to target/distractor onset to indicate the target’s likely location. Gaze-contingent presentation of target and distractors was used to demand overt scanning of displays. Eye movements during task performance evinced two forms of object-based effects. First, saccades following fixation on an invalidly cued item were more likely to be made within the cued rectangle than between rectangles. Second, saccades within the cued rectangle were preceded by shorter dwell times than saccades between rectangles. Extrafoveal processing of stimuli within the cued rectangle, however, was not facilitated, suggesting that covert attention was not allocated more densely within the cued than within the uncued object.  相似文献   
960.
Glucocorticoid modulation of emotional memory has repeatedly been shown in aversive learning paradigms, but has received little attention in appetitive tasks. It has also been suggested that it may be selective for contextual cues. In order to investigate if glucocorticoids can modulate memory in discrete-cue conditioning of both appetitive and aversive tasks, two experiments were carried out. Male Lister-Hooded rats received pairings of an auditory cue and either food-reward (experiment 1) or footshock (experiment 2), followed immediately by posttraining injections of the glucocorticoid receptor agonist dexamethasone (0.3, 0.6, and 1.2 mg/kg) or vehicle. Dexamethasone (1.2 mg/kg) led to significantly enhanced learning. These results give support to the notion that glucocorticoids play a role in the modulation of both appetitive and aversive emotional memories and show that their role in learning goes beyond the construction of context representations. The modulation of appetitive and aversive discrete-cue learning may be subserved by a common mechanism.  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