全文获取类型
收费全文 | 15423篇 |
免费 | 311篇 |
国内免费 | 192篇 |
专业分类
15926篇 |
出版年
2012年 | 1528篇 |
2011年 | 1691篇 |
2010年 | 381篇 |
2009年 | 193篇 |
2008年 | 1323篇 |
2007年 | 1251篇 |
2006年 | 1181篇 |
2005年 | 959篇 |
2004年 | 864篇 |
2003年 | 783篇 |
2002年 | 742篇 |
2001年 | 454篇 |
2000年 | 548篇 |
1999年 | 240篇 |
1998年 | 85篇 |
1997年 | 42篇 |
1996年 | 63篇 |
1995年 | 37篇 |
1994年 | 86篇 |
1993年 | 100篇 |
1992年 | 105篇 |
1991年 | 112篇 |
1990年 | 104篇 |
1989年 | 106篇 |
1988年 | 127篇 |
1987年 | 132篇 |
1986年 | 102篇 |
1985年 | 130篇 |
1984年 | 117篇 |
1983年 | 141篇 |
1982年 | 102篇 |
1981年 | 98篇 |
1980年 | 83篇 |
1979年 | 89篇 |
1978年 | 84篇 |
1966年 | 48篇 |
1965年 | 133篇 |
1964年 | 104篇 |
1963年 | 126篇 |
1962年 | 55篇 |
1958年 | 151篇 |
1957年 | 130篇 |
1956年 | 143篇 |
1955年 | 84篇 |
1954年 | 81篇 |
1953年 | 75篇 |
1952年 | 71篇 |
1951年 | 72篇 |
1950年 | 44篇 |
1949年 | 51篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
In the current study, we explored observers' use of two distinct analyses for determining their direction of motion, or heading: a scene-based analysis and a motion-based analysis. In two experiments, subjects viewed sequentially presented, paired digitized images of real-world scenes and judged the direction of heading; the pairs were presented with various interstimulus intervals (ISIs). In Experiment 1, subjects could determine heading when the two frames were separated with a 1,000-ms ISI, long enough to eliminate apparent motion. In Experiment 2, subjects performed two tasks, a path-of-motion task and a memory-load task, under three different ISIs, 50 ms, 500 ms, and 1,000 ms. Heading accuracy decreased with an increase in ISI. Increasing memory load influenced heading judgments only for the longer ISI when motion-based information was not available. These results are consistent with the hypothesis that the scene-based analysis has a coarse spatial representation, is a sustained temporal process, and is capacity limited, whereas the motion-based analysis has a fine spatial resolution, is a transient temporal process, and is capacity unlimited. 相似文献
972.
Two studies on political hindsight bias were conducted on the occasions of the German parliament election in 1998 and the Nordrhein-Westfalen state parliament election in 2000. In both studies, participants predicted the percentage of votes for several political parties and recalled these predictions after the election. The observed hindsight effects were stronger than those found in any prior study on political elections (using percentage of votes as the dependent variable). We argue that the length of the retention interval between original judgement and recollection is mainly responsible for this difference. In our second study, we investigated possible artifacts in political hindsight biases using a control-group design where half of the participants recalled their predictions shortly before or after the election. Hindsight bias was preserved, reinforcing the results of earlier studies with non-control-group designs. Finally, we discuss the possibility that the hindsight experience (in political judgement and in general) actually consists of three different, partly independent components. 相似文献
973.
Sit-and-wait strategies in dynamic visual search 总被引:1,自引:0,他引:1
The role of memory in visual search has lately become a controversial issue. Horowitz and Wolfe (1998) observed that performance in a visual search task was little affected by whether the stimuli were static or randomly relocated every 111 ms. Because a memory-based mechanism, such as inhibition of return, would be of no use in the dynamic condition, Horowitz and Wolfe concluded that memory is likewise not involved in the static condition. However, Horowitz and Wolfe could not effectively rule out the possibility that observers adopted a different strategy in the dynamic condition than in the static condition. That is, in the dynamic condition observers may have attended to a subregion of the display and waited for the target to appear there (sit-and-wait strategy). This hypothesis is supported by experimental data showing that performance in their dynamic condition does not differ from performance in another dynamic condition in which observers are forced to adopt a sit-and-wait strategy by being presented with a limited region of the display only. 相似文献
974.
Semantic categorization in the human brain: spatiotemporal dynamics revealed by magnetoencephalography 总被引:2,自引:0,他引:2
Löw A Bentin S Rockstroh B Silberman Y Gomolla A Cohen R Elbert T 《Psychological science》2003,14(4):367-372
We examined the cortical representation of semantic categorization using magnetic source imaging in a task that revealed both dissociations among superordinate categories and associations among different base-level concepts within these categories. Around 200 ms after stimulus onset, the spatiotemporal correlation of brain activity elicited by base-level concepts was greater within than across superordinate categories in the right temporal lobe. Unsupervised clustering of data showed similar categorization between 210 and 450 ms mainly in the left hemisphere. This pattern suggests that well-defined semantic categories are represented in spatially distinct, macroscopically separable neural networks, independent of physical stimulus properties. In contrast, a broader, task-required categorization (natural/man-made) was not evident in our data. The perceptual dynamics of the categorization process is initially evident in the extrastriate areas of the right hemisphere; this activation is followed by higher-level activity along the ventral processing stream, implicating primarily the left temporal lobe. 相似文献
975.
Dietrich A 《Consciousness and cognition》2003,12(2):231-256
It is the central hypothesis of this paper that the mental states commonly referred to as altered states of consciousness are principally due to transient prefrontal cortex deregulation. Supportive evidence from psychological and neuroscientific studies of dreaming, endurance running, meditation, daydreaming, hypnosis, and various drug-induced states is presented and integrated. It is proposed that transient hypofrontality is the unifying feature of all altered states and that the phenomenological uniqueness of each state is the result of the differential viability of various frontal circuits. Using an evolutionary approach, consciousness is conceptualized as hierarchically ordered cognitive function. Higher-order structures perform increasingly integrative functions and thus contribute more sophisticated content. Although this implies a holistic approach to consciousness, such a functional hierarchy localizes the most sophisticated layers of consciousness in the zenithal higher-order structure: the prefrontal cortex. The hallmark of altered states of consciousness is the subtle modification of behavioral and cognitive functions that are typically ascribed to the prefrontal cortex. The theoretical framework presented yields a number of testable hypotheses. 相似文献
976.
977.
Wilde NJ Strauss E Chelune GJ Hermann BP Hunter M Loring DW Martin RC Sherman EM 《心理评价》2003,15(1):56-63
Five competing models specifying the factor structure underlying the Wechsler Memory Scale-Third Edition (D. Wechsler, 1997b) primary subtest scores were evaluated in a sample of patients with intractable temporal lobe epilepsy (N = 254). Models specifying separate immediate and delayed constructs resulted in inadmissible parameter estimates and model specification error. There were negligible goodness-of-fit differences between a 3-factor model of working memory, auditory memory, and visual memory and a nested--more parsimonious--2-factor model of working memory and general memory. The results suggest that specifying a separate visual memory factor provides little advantage for this sample--an unexpected finding in a population with lateralized dysfunction, for which one might have predicted separate auditory and visual memory dimensions. 相似文献
978.
Bielajew C Konkle AT Kentner AC Baker SL Stewart A Hutchins AA Santa-Maria Barbagallo L Fouriezos G 《Stress (Amsterdam, Netherlands)》2003,6(4):269-280
The chronic mild stress (CMS) procedure was developed in rodents to target anhedonia, the core symptom of depressive melancholia. Stress exposure has been shown to induce a variety of physiological, biochemical and behavioral alterations associated with depression, although its anhedonic consequences as indexed by either sucrose intake and preference or thresholds for brain stimulation reward are less reliably observed. In the present study, we assessed the effects of six weeks of CMS on the latter measure in two strains of male and female rats subsequently challenged with an acute psychophysical stressor, forced swimming; their behavior in the swimming cylinder was evaluated on two consecutive days. While brain stimulation reward thresholds and response rates were unchanged by CMS exposure, significant differences in forced swim behaviors were observed between male control and CMS groups. In particular, male Long Evans rats with a history of CMS showed the largest decrease in the duration of active behaviors on the second test day, a pattern less evident in the Sprague-Dawley strain of rats, or in any of the female groups. The results suggest that the effects of depressogenic manipulations are strain and gender dependent, with male Long Evans rats most susceptible, as demonstrated by the selective reduction of struggling behaviors. Inclusion of multiple measures, including the forced swim test, would provide a better understanding of the psychopathological profile engendered by chronic exposure to mild stressors and its genetic specificity. 相似文献
979.
Two experiments tested competing predictions about the nature of the irrelevant speech effect that were derived from Neath's (2000) feature model and from Salamé and Baddeley's (1982) phonological loop model. The first experiment examined the combined effects of irrelevant speech and articulatory suppression when target items were presented auditorily. Contrary to the suggestions of Neath, but consistent with the phonological loop model, the effects of articulatory suppression and irrelevant speech were additive even when the irrelevant speech was presented during the retention interval The second experiment examined the combined effects of irrelevant speech and phonological similarity when target items were presented visually. Consistent with the phonological loop model, the effects of phonological similarity and irrelevant speech were additive when participants were specifically instructed to use articulatory/phonological rehearsal to remember the list items. The results therefore contradicted Neath's claim that irrelevant speech abolishes the phonological similarity effect when list items are presented visually. However, the effect of phonological similarity was abolished in the irrelevant speech conditions when no instructions were given concerning rehearsal. It is argued that the phonological similarity effect disappears in some experiments because participants sometimes employ a semantic rehearsal strategy, consistent with the views of Salamé and Baddeley (1986). 相似文献
980.
Raz A Landzberg KS Schweizer HR Zephrani ZR Shapiro T Fan J Posner MI 《Consciousness and cognition》2003,12(3):332-346
Recent data indicate that under a specific posthypnotic suggestion to circumvent reading, highly suggestible subjects successfully eliminated the Stroop interference effect. The present study examined whether an optical explanation (e.g., visual blurring or looking away) could account for this finding. Using cyclopentolate hydrochloride eye drops to pharmacologically prevent visual accommodation in all subjects, behavioral Stroop data were collected from six highly hypnotizables and six less suggestibles using an optical setup that guaranteed either sharply focused or blurred vision. The highly suggestibles performed the Stroop task when naturally vigilant, under posthypnotic suggestion not to read, and while visually blurred; the less suggestibles ran naturally vigilant, while looking away, and while visually blurred. Although visual accommodation was precluded for all subjects, posthypnotic suggestion effectively eliminated Stroop interference and was comparable to looking away in controls. These data strengthen the view that Stroop interference is neither robust nor inevitable and support the hypothesis that posthypnotic suggestion may exert a top-down influence on neural processing. 相似文献