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   52319篇
  免费   1959篇
  国内免费   28篇
  2019年   638篇
  2018年   917篇
  2017年   972篇
  2016年   1019篇
  2015年   742篇
  2014年   801篇
  2013年   4011篇
  2012年   1430篇
  2011年   1625篇
  2010年   984篇
  2009年   957篇
  2008年   1328篇
  2007年   1315篇
  2006年   1196篇
  2005年   1639篇
  2004年   1304篇
  2003年   1249篇
  2002年   1056篇
  2001年   1800篇
  2000年   1745篇
  1999年   1272篇
  1998年   562篇
  1997年   476篇
  1996年   488篇
  1992年   1077篇
  1991年   1044篇
  1990年   996篇
  1989年   939篇
  1988年   930篇
  1987年   892篇
  1986年   871篇
  1985年   939篇
  1984年   742篇
  1983年   615篇
  1982年   473篇
  1981年   478篇
  1979年   769篇
  1978年   563篇
  1977年   508篇
  1976年   486篇
  1975年   652篇
  1974年   737篇
  1973年   794篇
  1972年   637篇
  1971年   577篇
  1970年   553篇
  1969年   548篇
  1968年   689篇
  1967年   610篇
  1966年   636篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
Ten untreated patients with recently diagnosed Parkinson's disease (PD), 9 treated patients with more advanced pathology, and 17 matched normal controls were investigated with three reaction tasks with increasing cognitive load but identical motor requirements: simple reaction, choice reaction with indicative stimuli, and choice reaction with ambiguous stimuli. Times required until a home key was released (= reaction time) and from then until a response key was pressed (= movement time) were recorded. Estimates of pure decision time (overall response time minus movement time in a simple reaction time task) revealed a difference between advanced and early PD patients. Advanced PD patients showed an overall slowing of decision time in the reaction time tasks, but the effect of the cognitive load of the tasks on the decision time was comparable to a control group. The untreated early PD patients performed quite normally in the more simple decision tasks but showed a disproportionate slowing of decision time in tasks with higher cognitive load.  相似文献   
12.
Several previous studies have shown that memory span is greater for short words than for long words. This effect is claimed to occur even when the short and long words are matched for the number of syllables and phonemes and so to provide evidence for subvocal articulation as being one mechanism that underlies memory span (Baddeley, Thomson, & Buchanan, 1975). The three experiments reported in this paper further investigate the articulatory determinants of word length effects on span tasks. Experiment 1 replicated Baddeley et al.'s finding of an effect of word length on auditory and visual span when the stimuli consist of words that differ in terms of the number of syllables. Experiments 2 and 3 showed that the effects of word length are eliminated when the words in the span task are matched for the number of syllables and phonemes but differ with respect to the duration and/or complexity of their articulatory gestures. These results indicate that it is the phonological structure of a word and not features of its actual articulation that determines the magnitude of the word length effect in span tasks.  相似文献   
13.
14.
15.
16.
17.
Adult age differences in the consistency effect were examined in 3 experiments. The consistency effect refers to items inconsistent with expectations being better remembered than items consistent with expectations. Younger and older adults walked into an office room and viewed objects that varied in their consistency with expectation. Immediate and delayed recognition tests on item information (i.e., distractors were defined by their semantic identity) revealed that both age groups recognized unexpected items better than expected items. However, when recognition of token information was requested (i.e., distractors were defined by their physical appearance), younger adults, in contrast to older adults, exhibited consistency effects. Also, under divided attention, young adults revealed the same pattern of data as did elderly adults under full attention. The results are discussed in terms of capacity-related differences in distinctive encoding.  相似文献   
18.
We investigated motivational and cognitive processes of behavior change with respect to mammography screening. One hundred forty-two women (ages 40 and older) recruited from three worksites answered a 41-item questionnaire consisting of statements based on constructs from the transtheoretical model of behavior change. Principal-components analysis identified two factors: a six-item component representing positive perceptions of mammography (Pros) and a six-item component representing avoidance of mammography (Cons). Analysis of variance showed that Pros, Cons, and a derived Decisional Balance measure (Pros minus Cons) were associated with stage of mammography adoption. Results are consistent with applications of the model to smoking cessation. The model is also discussed as it relates to other theories of behavior change and as a general strategy for analyzing perceptual data pertinent to health-related actions and intentions for behavioral change.  相似文献   
19.
Range of electric vehicles (EVs) has long been considered a major barrier in acceptance of electric mobility. We examined the nature of how range is experienced in an EV and whether variables from other adaptation contexts, notably stress, have explanatory power for inter‐individual differences in what we term comfortable range. Forty EVs were leased to a sample of users for a 6‐month field study. Qualitative and quantitative analyses of range experiences were performed, including regression analyses to examine the role of stress‐buffering personality traits and coping skills in comfortable range. Users appraised range as a resource to which they could successfully adapt and that satisfied most of their daily mobility needs. However, indicators were found that suggested suboptimal range utilisation. Stress‐buffering personality traits (control beliefs, ambiguity tolerance) and coping skills (subjective range competence, daily range practice) were found to play a substantial role in comfortable range. Hence, it may be possible to overcome perceived range barriers with the assistance of psychological interventions such as information, training, and interface design. Providing drivers with a reliable usable range may be more important than enhancing maximal range in an electric mobility system.  相似文献   
20.
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