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   3643篇
  免费   132篇
  国内免费   1篇
  3776篇
  2021年   35篇
  2020年   31篇
  2019年   47篇
  2018年   94篇
  2017年   71篇
  2016年   104篇
  2015年   68篇
  2014年   71篇
  2013年   344篇
  2012年   122篇
  2011年   151篇
  2010年   93篇
  2009年   99篇
  2008年   132篇
  2007年   136篇
  2006年   119篇
  2005年   118篇
  2004年   128篇
  2003年   119篇
  2002年   123篇
  2001年   89篇
  2000年   78篇
  1999年   69篇
  1998年   56篇
  1997年   48篇
  1996年   45篇
  1995年   48篇
  1994年   51篇
  1993年   52篇
  1992年   53篇
  1991年   44篇
  1990年   57篇
  1989年   50篇
  1988年   47篇
  1987年   41篇
  1986年   43篇
  1985年   53篇
  1984年   50篇
  1983年   40篇
  1982年   50篇
  1981年   43篇
  1980年   36篇
  1979年   38篇
  1978年   42篇
  1976年   31篇
  1975年   32篇
  1974年   30篇
  1973年   37篇
  1972年   28篇
  1971年   29篇
排序方式: 共有3776条查询结果,搜索用时 15 毫秒
921.
The experiences of mothers of adult offspring with Angelman, Cornelia de Lange, or Cri du Chat syndrome have not been previously explored in research. The current study focuses on experiences with social and medical services and the impact the rareness of an adult offspring’s syndrome has on the experiences of mothers. Eight mothers of adults with Angelman, Cornelia de Lange, or Cri du Chat syndrome were interviewed. Thematic Content Analysis was used to interpret the interviews. Four themes emerged from the analysis: (i) The rarity of their offspring’s syndrome, (ii) Uneven medical and social care service provision, (iii) The inertia of social care services, and (iv) Mothers as advocates. Mothers felt that the rareness of their offspring’s syndrome did not affect experiences with social care services, but did affect access to medical services and some aspects of day-to-day living. Accessing appropriate social care services was reported to be a lengthy and complex process. These data may help inform care service providers about how best to support adults with rare genetic syndromes and their families.  相似文献   
922.
The present study investigated whether memory for extinction in an appetitive task (the sand maze) could be attenuated by administration of cycloheximide (protein synthesis inhibitor) or propranolol (β-adrenergic receptor antagonist). Ninety-day-old male Long-Evans rats were trained to retrieve a sweet cereal reinforcer from an open container in the sand maze. One day following this non-spatial training, rats received three extinction trials in which they were placed in the maze with the reinforcer present, but unattainable. Thirty minutes prior to the first extinction trial, rats received an intraperitoneal injection of cycloheximide (1mg/kg), propranolol (25mg/kg), or vehicle (1mg/kg distilled water). Twenty-four hours later, rats were tested in the sand maze with the reinforcer again available. Results from the test trial showed that both cycloheximide and propranolol groups found the reinforcer more quickly than controls. Two weeks later, rats were trained on a spatial version of the sand maze in which they had to search for a buried reinforcer using extramaze cues. Cycloheximide and propranolol groups learned this task significantly faster than the control group, demonstrating the long-lasting effect of cycloheximide and propranolol on the blocking of memory for extinction.  相似文献   
923.
924.
To assist road safety professionals in developing effective strategies to combat the risk associated with driving while fatigued, a survey was administered to 1000 Australian drivers. Participants reported their past behaviours in regards to driving while sleepy and their perceptions of risk associated with driving fatigued as compared to speeding and driving under the influence of alcohol. Although participants appeared to be aware of the substantial risk associated with driving while sleepy, many drivers reported that they frequently drive when sleepy. Age and gender comparisons, revealed that risk taking behaviour in regards to driving while sleepy is occurring across all age groups and in both male and female drivers. Overall young to middle age drivers and male drivers reported the highest frequency of driving while sleepy and reported the lowest perceived personal risk in regards to driving while sleepy.  相似文献   
925.
Individuals diagnosed with major depressive disorder (MDD) often ruminate about their depression and their life situations, impairing their concentration and performance on daily tasks. We examined whether rumination might be due to a deficit in the ability to expel negative information from short-term memory (STM), and fMRI was used to examine the neural structures involved in this ability. MDD and healthy control (HC) participants were tested using a directed-forgetting procedure in a short-term item recognition task. As predicted, MDD participants had more difficulty than did HCs in expelling negative, but not positive, words from STM. Overall, the neural networks involved in directed forgetting were similar for both groups, but the MDDs exhibited more spatial variability in activation in the left inferior frontal gyrus (a region critical for inhibiting irrelevant information), which may contribute to their relative inability to inhibit negative information.  相似文献   
926.
Converging behavioural and neuropsychological evidence indicates that age-related changes in working memory contribute substantially to cognitive decline in older adults. Important questions remain about the relationship between working memory storage and executive components and how they are affected by the normal ageing process. In several studies using positron emission tomography (PET), we find age differences in the patterns of frontal activation during working memory tasks. We find that separable age differences can be linked to different cognitive operations underlying short-term information storage, and interference resolution. Some operations are associated with age-related increases in activation, with older adults displaying bilateral activations and recruiting prefrontal areas more than younger adults. Other operations are associated with age-related decreases in activation. We consider the implications of these results for understanding the working memory system and potential compensatory processes in the ageing brain.  相似文献   
927.
The most prominent models of numerical representation posit that numerical symbols are converted into a single internal, abstract representation prior to estimation and comparison processing. Here, we (1) provide a mathematical analysis of the predictions of the abstract-representation hypothesis, assuming the validity of the analog-representation hypothesis, (2) run a simulation to assess the patterns of data that result from our mathematical analysis, and (3) conduct two experiments to test the predictions of our model, using relative frequencies as inputs. We assess relative frequencies in a typical numerical distance task, whereby participants are presented with two relative frequencies and asked to identify the one that represents the larger quantity. Our data reveal that relative frequencies’ numerical representations (1) are analog and (2) are scale-specific (i.e., nonabstract).  相似文献   
928.
929.
930.
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