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   2352篇
  免费   120篇
  国内免费   1篇
  2023年   10篇
  2022年   17篇
  2021年   22篇
  2020年   44篇
  2019年   59篇
  2018年   71篇
  2017年   72篇
  2016年   83篇
  2015年   61篇
  2014年   59篇
  2013年   306篇
  2012年   134篇
  2011年   101篇
  2010年   54篇
  2009年   89篇
  2008年   116篇
  2007年   103篇
  2006年   87篇
  2005年   92篇
  2004年   84篇
  2003年   72篇
  2002年   76篇
  2001年   37篇
  2000年   36篇
  1999年   35篇
  1998年   32篇
  1997年   27篇
  1996年   21篇
  1995年   22篇
  1994年   14篇
  1993年   27篇
  1992年   24篇
  1991年   21篇
  1990年   19篇
  1989年   20篇
  1988年   22篇
  1987年   21篇
  1986年   21篇
  1985年   23篇
  1984年   16篇
  1983年   23篇
  1982年   21篇
  1981年   15篇
  1980年   13篇
  1979年   16篇
  1978年   13篇
  1977年   19篇
  1976年   11篇
  1975年   14篇
  1973年   11篇
排序方式: 共有2473条查询结果,搜索用时 15 毫秒
171.
We hypothesized that semantic memory for object concepts involves both representations of visual feature knowledge in modality-specific association cortex and heteromodal regions that are important for integrating and organizing this semantic knowledge so that it can be used in a flexible, contextually appropriate manner. We examined this hypothesis in an fMRI study of mild Alzheimer’s disease (AD). Participants were presented with pairs of printed words and asked whether the words matched on a given visual–perceptual feature (e.g., guitar, violin: SHAPE). The stimuli probed natural kinds and manufactured objects, and the judgments involved shape or color. We found activation of bilateral ventral temporal cortex and left dorsolateral prefrontal cortex during semantic judgments, with AD patients showing less activation of these regions than healthy seniors. Moreover, AD patients showed less ventral temporal activation than did healthy seniors for manufactured objects, but not for natural kinds. We also used diffusion-weighted MRI of white matter to examine fractional anisotropy (FA). Patients with AD showed significantly reduced FA in the superior longitudinal fasciculus and inferior frontal-occipital fasciculus, which carry projections linking temporal and frontal regions of this semantic network. Our results are consistent with the hypothesis that semantic memory is supported in part by a large-scale neural network involving modality-specific association cortex, heteromodal association cortex, and projections between these regions. The semantic deficit in AD thus arises from gray matter disease that affects the representation of feature knowledge and processing its content, as well as white matter disease that interrupts the integrated functioning of this large-scale network.  相似文献   
172.
To increase our understanding of relationships between well-being and social/physical functioning and self-management abilities (SMAs) among chronically ill patients. The cross-sectional questionnaire-based study included 1,254 patients with cardiovascular diseases, 725 with chronic obstructive pulmonary disease, and 253 with diabetes (total, 2232/4200; 53 % response rate). Social and physical functioning correlated significantly with SMAs and well-being (all p?≤?0.001). After controlling for background characteristics, multiple regression showed that social and physical functioning were still related to SMAs (β?=?0.32–0.12; both p?≤?0.001) and well-being (β?=?0.39–0.14; both p?≤?0.001). The strengths of relationships between well-being and social (β?=?0.39 vs. 0.20) and physical (β?=?0.14 vs. 0.07) functioning declined significantly (both p?≤?0.001) when the SMA mediator was included in the equation. SMAs of chronically ill are related to their social and physical functioning. We found indications that chronically ill patients reporting lower levels of social and physical functioning are worse self-managers than are those with higher levels of functioning. Furthermore, SMAs may mediate the relationships between social and physical functioning and well-being. Self-management interventions aiming to enhance SMAs more broadly than traditional interventions aiming only to prevent functional decline are expected to improve SMAs and enhance well-being among chronically ill patients.  相似文献   
173.
Healthy parenting may be protective against the development of emotional psychopathology, particularly for children reared in stressful environments. Little is known, however, about the brain and behavioral mechanisms underlying this association, particularly during childhood and adolescence, when emotional disorders frequently emerge. Here, we demonstrate that psychological control, a parenting strategy known to limit socioemotional development in children, is associated with altered brain and behavioral responses to emotional conflict in 27 at‐risk (urban, lower income) youth, ages 9–16. In particular, youth reporting higher parental psychological control demonstrated lower activity in the left anterior insula, a brain area involved in emotion conflict processing, and submitted faster but less accurate behavioral responses—possibly reflecting an avoidant pattern. Effects were not replicated for parental care, and did not generalize to an analogous nonemotional conflict task. We also find evidence that behavioral responses to emotional conflict bridge the previously reported link between parental overcontrol and anxiety in children. Effects of psychological control may reflect a parenting style that limits opportunities to practice self‐regulation when faced with emotionally charged situations. Results support the notion that parenting strategies that facilitate appropriate amounts of socioemotional competence and autonomy in children may be protective against social and emotional difficulties.  相似文献   
174.
Recent research on Problematic Internet Use and Problematic Facebook Use (PIU and PFU) has focused on the idea that people who engage in PIU or PFU are more likely to present with mental health problems. The goal of the present study was to examine the contribution of positive mental health (PMH) to PIU and PFU among adolescents and young adults. A total of 1927 Italian adolescents and young adults participated in the study. Structural equation modeling showed that PMH is negatively linked to both PIU and PFU, indicating that PMH may be an important antecedent for both PIU and PFU among adolescents and young adults. In conclusion, dimensions of PMH may be taken into account by researchers and educational practitioners in preventing both PIU and PFU.  相似文献   
175.
Excessive alcohol consumption has a vast, negative impact on society. Rodent models have been successful in furthering our understanding of the biological underpinnings that drive alcohol consumption. Rodents emit ultrasonic vocalizations (USVs) that are each composed of several acoustic characteristics (e.g., frequency, duration, bandwidth, power). USVs reflect neurotransmitter activity in the ascending limb of the mesolimbic dopaminergic and cholinergic neurotransmitter systems and serve as noninvasive, real-time biomarkers of dopaminergic and cholinergic neurotransmission in the limbic system. In the present study, we recorded spontaneously emitted USVs from alcohol-naïve Long-Evans (LE) rats and then measured their alcohol intake. We compared the USV acoustic characteristics and alcohol consumption data from these LE rats with previously published data from selectively bred high-alcohol (P and HAD-1) and low-alcohol (NP and LAD-1) drinking lines from studies with the same experimental method. Predictive analytic techniques were applied simultaneously to this combined data set and revealed that (a) USVs emitted by alcohol-naïve rats accurately discriminated among high-alcohol consuming, LE, and low-alcohol consuming rat lines, and (b) future alcohol consumption in these same rat lines was reliably predicted from the USV data collected in an alcohol-naïve state. To our knowledge, this is the first study to show that alcohol consumption is predicted directly from USV profiles of alcohol-naïve rats. Because USV acoustic characteristics are sensitive to underlying neural activity, these findings suggest that baseline differences in mesolimbic cholinergic and dopaminergic tone could determine the propensity for future alcohol consumption in rodents.  相似文献   
176.
177.
178.
Within-group differences amongst gamers must be considered when studying the psychological correlates of gameplay. A conceptual framework, whereby gaming may be treated as a means to other ends—such as coping with boredom or bonding with friends—or as an end in itself, was the basis upon which the Gaming Styles Questionnaire was developed. Factor analysis and criterion-group validity, based on data obtained from a heterogeneous sample of gamers, offered support to a continuum of gamers, ranging from those for whom gaming is a means to other ends to those for whom gaming is an end in itself. Although age did not correlate with gaming style, men’s endorsement of gaming as an end in itself was stronger than women’s.  相似文献   
179.
In Alzheimer's disease (AD), it is now well established that recollection is impaired from the beginning of the disease, whereas findings are less clear concerning familiarity. One of the most important mechanisms underlying familiarity is the sense of familiarity driven by processing fluency. In this study, we attempted to attenuate recognition memory deficits in AD by maximizing the salience of fluency cues in two conditions of a recognition memory task. In one condition, targets and foils have been created from the same pool of letters (Overlap condition). In a second condition, targets and foils have been derived from two separate pools of letters (No‐Overlap condition), promoting the use of letter‐driven visual and phonetic fluency. Targets and foils were low‐frequency words. The memory tasks were performed by 15 patients with AD and 16 healthy controls. Both groups improved their memory performance in the No‐Overlap condition compared to the Overlap condition. Patients with AD were able to use fluency cues during recognition memory as older adults did, but this did not allow to compensate for dysfunction of recognition memory processes.  相似文献   
180.
To keep track of dynamically changing objects in one’s environment, it is necessary to individuate them from other objects, both temporally and spatially. Spatially, objects can be selected from nearby distractors using selective attention. Temporally, object updating processes incorporate new information into existing representations over time. Both of these processes have been implicated in a type of visual masking called object-substitution masking (OSM). Previous studies have found that the number of distractors (impacting selective attention) interacts with the strength of OSM. However, it has been suggested that this interaction is an artifact of ceiling performance at low set sizes, rather than necessitating a failure of attention during masking. Using event-related potentials (ERPs), we examined whether set size and masking interact as measured by markers of selective attention (N2pc) and visual working memory consolidation/maintenance (SPCN). Set size was found to affect the N2pc (200–350 ms) and late SPCN (500–650 ms), reflecting increased demands on selective attention and unnecessary storage respectively. An early window of the SPCN (350–500 ms) was affected by masking, suggesting that OSM influences object consolidation processes in this window, independent of the number of distractors. Overall, it was found that selective attention and visual awareness are dissociable neural processes in OSM, and that they are independently affected by set size and masking manipulations. Moreover, we found that the early SPCN may reflect disruptions to object consolidation, potentially revealing a neural mechanism supporting an object individuation-through-updating account of OSM.  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