全文获取类型
收费全文 | 6204篇 |
免费 | 88篇 |
国内免费 | 1篇 |
专业分类
6293篇 |
出版年
2024年 | 56篇 |
2023年 | 69篇 |
2022年 | 90篇 |
2021年 | 114篇 |
2020年 | 149篇 |
2019年 | 146篇 |
2018年 | 284篇 |
2017年 | 268篇 |
2016年 | 249篇 |
2015年 | 159篇 |
2014年 | 187篇 |
2013年 | 793篇 |
2012年 | 435篇 |
2011年 | 438篇 |
2010年 | 272篇 |
2009年 | 191篇 |
2008年 | 333篇 |
2007年 | 281篇 |
2006年 | 250篇 |
2005年 | 239篇 |
2004年 | 141篇 |
2003年 | 149篇 |
2002年 | 151篇 |
2001年 | 66篇 |
2000年 | 91篇 |
1999年 | 50篇 |
1998年 | 34篇 |
1997年 | 31篇 |
1996年 | 28篇 |
1995年 | 21篇 |
1994年 | 18篇 |
1993年 | 31篇 |
1992年 | 36篇 |
1991年 | 33篇 |
1990年 | 29篇 |
1989年 | 27篇 |
1988年 | 35篇 |
1987年 | 25篇 |
1986年 | 18篇 |
1985年 | 18篇 |
1984年 | 20篇 |
1983年 | 14篇 |
1981年 | 12篇 |
1979年 | 20篇 |
1978年 | 17篇 |
1977年 | 12篇 |
1976年 | 15篇 |
1974年 | 12篇 |
1970年 | 11篇 |
1968年 | 11篇 |
排序方式: 共有6293条查询结果,搜索用时 15 毫秒
961.
Sébastien Allain Frédéric Danoix Mohamed Goune Khalid Hoummada Dominique Mangelinck 《Philosophical Magazine Letters》2013,93(2):68-76
The work-hardening behaviour of virgin martensitic steel has been investigated in a strictly un-aged state and after various ageing conditions. At room temperature (RT), the un-aged alloy shows astonishing tensile performances (ultimate tensile stress?=?1600?MPa/uniform elongation?=?15%) but unexpected serrations. These serrations can be suppressed by static ageing (at RT or higher) while maintaining the initial work-hardening rate (ageing at RT). Parallel investigations using atom probe tomography reveal that the distribution of carbon at the atomic scale evolves from purely homogeneous for virgin martensite to partly segregated at a very fine scale (5–10?nm) after static ageing. This particular mechanical behaviour can therefore be associated with a very local decrease in available carbon in solid solution due to redistribution and segregations on defects (nanotwins) that occurs rapidly, even after few days at RT. 相似文献
962.
AbstractWe examined the role of experience in affordance perception for low crawling with altered body dimensions under barriers of different heights. Adults decided which of five backpacks (10–30?cm thick) they would be able to wear while low crawling under barriers. Participants were assigned to one of three experience conditions. Participants in the Pre/Post-choice experience condition crawled under the barrier before and after picking a backpack, participants in the Feedback condition crawled under the barrier after picking a backpack, but participants in the No Experience condition received no low-crawling experience. Past research suggests that pre-choice experience with low crawling under the barrier would lead to more accurate responses. Overall, participants in all three conditions scaled the height of the backpack to the barrier height. Pre-choice low-crawling experience strongly influenced backpack choices such that participants in the Pre/Post condition picked significantly smaller backpacks and produced fewer failures than participants in the other conditions. The results provide evidence that brief practice, in an unfamiliar posture, can lead to improvements in affordance perception. 相似文献
963.
Sarah M. Tower‐Richardi Tad T. Brunyé Stephanie A. Gagnon Caroline R. Mahoney Holly A. Taylor 《Journal of applied social psychology》2014,44(9):611-621
Social status is associated with the vertical spatial dimension, with people conceptualizing higher social status with higher vertical positions. Two experiments tested whether this association influences relatively real‐world decisions about others by asking participants to act as real estate agents, aiding in the relocation of clients who explicitly or implicitly varied in social status. Across experiments, higher status clients were placed into higher elevation housing options. This influence of social status persisted when strategy‐aware participants were removed from analysis, and was not influenced by individual differences in social dominance or locus of control. Abstract concepts of social status are understood through associations with vertical space, and these mapping of abstract concepts to concrete percepts prove influential in guiding daily decisions. 相似文献
964.
965.
Electrolytic lesions of the medial prefrontal cortex do not interfere with long-term memory of extinction of conditioned fear
下载免费PDF全文

Lesion studies indicate that rats without the medial prefrontal cortex (mPFC) have difficulty recalling fear extinction acquired the previous day. Several electrophysiological studies have also supported this observation by demonstrating that extinction-related increases in neuronal activity in the mPFC participate in expression of fear extinction. However, a more recent study has shown that fear extinction can be recalled, in certain circumstances, without mPFC potentiation, suggesting contribution of other circuits. Here, we examined this possibility in rats that were subjected to auditory fear conditioning, extinction training, and extinction retention test 7 d later. Electrolytic lesions were made in the mPFC, the motor cortex (MO), the dorsal septum (SEP), or the mediodorsal thalamus (MD), because of their potential participation in conditioned fear inhibition; combined lesions including the mPFC with the MO, SEP, or MD were also made. The lesions were made either 1 wk before conditioning or 1 d after extinction training. All rats normally extinguished their conditioned freezing behavior during extinction training and did not display any return of this behavior during the retention test. These data reveal that the mPFC is not required for the acquisition, the expression, or the retrieval of extinction memories but do not exclude the possibility that the mPFC normally participates in these processes. 相似文献
966.
Searching for icons, symbols, or signs is an integral part of tasks involving computer or radar displays, head-up displays in aircraft, or attending to road traffic signs. Icons therefore need to be designed to optimize search times, taking into account the factors likely to slow down visual search. Three factors likely to adversely affect visual search were examined: the time of day at which search was carried out, the visual complexity of the icons, and the extent to which information features in the icon were grouped together. The speed with which participants searched icon arrays for a target was slower early in the afternoon, when icons were visually complex and when information features in icons were not grouped together to form a single object. Theories of attention that account for both feature-based and object-based search best explain these findings and are used to form the basis for ways of improving icon design. 相似文献
967.
968.
969.
Verbruggen F Liefooghe B Vandierendonck A 《Quarterly journal of experimental psychology (2006)》2006,59(1):190-203
In the present study, the relation between interference at the early processing stages and response inhibition was investigated. In previous studies, response stopping appeared to be slowed down when irrelevant distracting information was presented. The purpose of the present study was to further explore the relationship between interference control and response inhibition. In Experiment 1, a stop signal paradigm was combined with a global/local task. The typical global-to-local interference effect is generally attributed to early processing stages, such as stimulus perception and identification. Results of this experiment demonstrated a congruency effect for both reaction time data and zstopping performance. In Experiment 2, these results were replicated with a flanker task that used stimulus-incongruent but response-congruent flankers. Results of both experiments suggest that response inhibition and interference at the early processing stages interact. 相似文献
970.
Performance in the McGeorge and Burton (1990) digit invariance task was originally thought to be mediated by unconscious abstraction of a “rule” that identified the invariant feature across all study items. Subsequent explanations have suggested explicit strategy use or similarity-to-exemplar matching rather than abstraction. This paper presents data that suggest that both similarity and abstraction can be used under different task demands. Delay between study and test afforded abstraction of the invariant knowledge whereas reducing the pool of study exemplars enhanced responding based on specific similarity. These results parallel effects found in the categorization literature. Rule abstraction in this sense may be due to statistical learning of feature frequency rather than abstraction of a central tendency or a complex/conceptual rule. Categorizing responses into subjective memory states (remember/know/guess) demonstrates that neither the similarity matching nor the abstraction mechanism uses information from episodic memory. Confidence measures show that participants are more confident of responses when the prototypical representation is used but not specific similarity. Taken together, these data suggest that abstracted knowledge is not held consciously but that participants have meta-awareness of when they are using the abstracted representation. 相似文献