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   9311篇
  免费   741篇
  国内免费   369篇
  2024年   23篇
  2023年   161篇
  2022年   129篇
  2021年   244篇
  2020年   387篇
  2019年   413篇
  2018年   408篇
  2017年   455篇
  2016年   413篇
  2015年   277篇
  2014年   405篇
  2013年   1233篇
  2012年   196篇
  2011年   394篇
  2010年   305篇
  2009年   450篇
  2008年   485篇
  2007年   510篇
  2006年   446篇
  2005年   387篇
  2004年   338篇
  2003年   283篇
  2002年   222篇
  2001年   139篇
  2000年   112篇
  1999年   122篇
  1998年   101篇
  1997年   82篇
  1996年   59篇
  1995年   63篇
  1994年   49篇
  1993年   43篇
  1992年   38篇
  1990年   22篇
  1989年   28篇
  1988年   17篇
  1987年   17篇
  1985年   128篇
  1984年   129篇
  1983年   108篇
  1982年   91篇
  1981年   69篇
  1980年   73篇
  1979年   69篇
  1978年   95篇
  1977年   57篇
  1976年   42篇
  1975年   31篇
  1974年   24篇
  1973年   29篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
We examined age differences in attributions to internal (controllable and uncontrollable), external (uncontrollable), and unstable factors for performance on a free recall memory task in 149 young, middle-aged, and older adults. Attributions varied by age and by level of memory performance. Middle-aged and older adults rated internal, uncontrollable factors (ability and genes) as more influential for high performance than for low performance, and they were less likely than young adults to attribute low performance to these factors. Within age groups, only the older adults rated memory ability as more influential than strategy use, even though they were as likely as the other age groups to use a categorization strategy. Attributions to both internal controllable (strategy use) and uncontrollable (ability) factors as well as to health were associated with better memory performance. These attributions partially mediated the relationship between age and memory performance. Thus, attributions may provide some insight into sources of age differences in memory performance.  相似文献   
992.
The aim of this study was to investigate the accuracy of the Portuguese version of Addenbrooke’s Cognitive Examination–Revised (ACE-R) in detecting and differentiating early stage subcortical vascular dementia (SVD) from early stage Alzheimer’s disease (AD). Ninety-two subjects (18 SVD patients, 36 AD patients, and 38 healthy controls) were assessed using the ACE-R. Between-group’s differences were evaluated using the Quade’s rank analysis of covariance. The diagnostic accuracy and discriminatory ability of the ACE-R were examined via receiver operating characteristic (ROC) analysis. The ACE-R was able to successfully discriminate between patients and healthy subjects. The mean ACE-R total scores differed between SVD and AD patients; there were also significant differences in attention and orientation and in memory measures between the groups. An optimal cut-off of 72/73 was found for the detection of AD (sensitivity: 97%; specificity: 92%) and SVD (sensitivity: 100%; specificity: 92%).  相似文献   
993.
994.
ABSTRACT

The Informant Questionnaire on Cognitive Decline (IQCODE) is a formal informant report instrument, originally developed by Jorm and Jacomb (1989 Jorm, A. F. and Jacomb, P. A. 1989. The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): Socio-demographic correlates, reliability, validity and some norms. Psychological Medicine, 19(4): 10151022. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]; Psychological Medicine, 19(4), 1015). The goal of the present study was to evaluate the range of cognitive decline in which the IQCODE is most sensitive, using item response theory (IRT). Existing data (N = 740) from a sample of community-dwelling older adults was used for this purpose. A 2-parameter model estimating item difficulty and discrimination fit the data best. Additionally, the IQCODE provided the most psychometric information in the range of ?0.5 < θ < 1.5, with peak information obtained at approximately θ = 0.4. Based on individuals' latent score (θ) estimates, items on the IQCODE are adequate for use as a screening tool for dementia. Results of the item calibration may be useful for targeted assessment needs, such as the development of short forms.  相似文献   
995.
ABSTRACT

Participants in the Healthy Old People in Edinburgh (HOPE) study (N = 398) were assessed on Raven's Progressive Matrices and Logical Memory on up to three occasions. Covariates included education, social class, disease and medication status, blood pressure and study outcome. Raven's score declined linearly with age, whereas decline in Logical Memory was accelerating. There was significant variation in individuals' rates of decline for Ravens but not Logical Memory. Slope–intercept covariances were not significant. Those who later developed dementia already exhibited lower scores, more so for Logical Memory than Raven's. Death and study attrition were related to performance, again greater for Logical Memory. Conclusions: The HOPE approach of progressive screening is a feasible and practical method for studying healthy cognitive ageing. As predicted for an initially healthy sample, rates of decline were relatively homogeneous. The hypothesis of differential decline was not supported, nor was a strict interpretation of the hypothesis that cognitive ageing is entirely pathology driven.  相似文献   
996.
ABSTRACT

Insight into one's own cognitive abilities, or metacognition, has been widely studied in developmental psychology. Relevance to the clinician is high, as memory complaints in older adults show an association with impending dementia, even after controlling for likely confounds. Another candidate marker of impending dementia under study is inconsistency in cognitive performance over short time intervals. Although there has been a recent proliferation of studies of cognitive inconsistency in older adults, to date, no one has examined adults' self-perceptions of cognitive inconsistency. Ninety-four community-dwelling older adults (aged 70–91) were randomly selected from a parent longitudinal study of short-term inconsistency and long-term cognitive change in aging. Participants completed a novel 40-item self-report measure of everyday cognitive inconsistency, including parallel scales indexing perceived inconsistency 5 years ago and at present, yielding measures of past, present, and 5-year change in inconsistency. The questionnaire showed acceptable psychometric characteristics. The sample reported an increase in perceived inconsistency over time. Higher reported present inconsistency and greater 5-year increase in inconsistency were associated with noncognitive (e.g., older age, poorer ADLs, poorer health, higher depression), metacognitive (e.g., poorer self-rated memory) and neuropsychological (e.g., poorer performance and greater 5-year decline in global cognitive status, vocabulary, and memory) measures. Correlations between self-reported inconsistency and neuropsychological performance were attenuated, but largely persisted when self-rated memory and age were controlled. Observed relationships between self-reported inconsistency and measures of neuropsychological (including memory) status and decline suggest that self-perceived inconsistency may be an area of relevance in evaluating older adults for memory disorders.  相似文献   
997.
ABSTRACT

In this study we addressed the subjective benefits of activity interventions that were designed to improve cognitive fitness in old age. Two hundred and fifty-nine women (aged 70–93 years) were randomized to participate in an exercise or a computer course or a control condition for 6 months. Subjective ratings of the perceived change of cognitive and physical fitness components were captured before, during, after the intervention interval, and at a 10-month follow-up. Positive and negative affect levels and objective cognitive fitness parameters served as possible covariates. Multilevel modeling revealed that the computer group rated memory and concentration as having improved at 4 months and again at 6 months. The exercise group, in contrast, perceived physical capacities as maintained or improved. The characteristics of the activity experience seem to determine the perceived fitness changes. We conclude that actual learning experiences improve one's self-concept of abilities.  相似文献   
998.
ABSTRACT

This study examines age-associated changes in retrieval on a picture-naming task, phonemic and semantic fluency tasks, and the Homophone Meaning Generation Test (HMGT). The sample included 152 Hebrew-speaking adults, half young (mean age 22.75) and half old (mean age 76.05). Groups differed on the picture-naming task and on both verbal fluency tasks, but not on the HMGT. Age explained a greater share of the variance than did education level on these three tests, whereas the opposite pattern of results was seen on the HMGT. We suggest that age-related word finding difficulties are attenuated when performance allows for semantic rather than phonological access.  相似文献   
999.
ABSTRACT

The process of adaptation to the physical and psychosocial consequences after stroke is a major challenge for many individuals affected. The aim of this study was to examine if stroke patients within 1 month of admission (n?=?153) and followed up at 1 year (n?=?107) engage in selection, optimization, and compensation (SOC) adaptive strategies and the relationship of these strategies with functional ability, health-related quality of life (HRQOL) and depression 1 year later. Adaptive strategies were measured using a 15-item SOC questionnaire. Internal and external resources were assessed including recovery locus of control, stroke severity, and socio-demographics. Outcome measures were the Stroke Specific Quality of Life Questionnaire (SS-QoL), the Nottingham Extended Activities of Daily Living Scale and the Depression Subscale of the Hospital Anxiety and Depression Scale. Findings indicated that stroke patients engaged in the use of SOC strategies but the use of these strategies were not predictive of HRQOL, functional ability or depression 1 year after stroke. The use of SOC strategies were not age specific and were consistent over time, with the exception of the compensation subscale. Results indicate that SOC strategies may potentially be used in response to loss regulation after stroke and that an individual's initial HRQOL functional ability, levels of depression and socio-economic status that are important factors in determining outcome 1 year after stroke. A stroke-specific measure of SOC may be warranted in order to detect significant differences in determining outcomes for a stroke population.  相似文献   
1000.
This study reports on my fieldwork experiences applying qualitative research strategies to study child sexual abuse in South Africa. It considers the challenges associated with, at three stages of data collection: ethical clearance, recruitment and data collection, followed by possible solutions. The study also considers the challenges from ethical and epistemological perspectives. I used a reflective self-study to analyse my experiences. My experiences revealed the following challenges: ethical process due to reasons not linked to the content of the research process would cause delays to the field-work. In addition, the use of [formal institutions] welfare institutions as sole research sites would result in a homogenous sample that does not permit comparison of experiences among the abuse cases. The costs to the researcher in terms of emotional and physical investment can be significant.  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