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   694篇
  免费   112篇
  国内免费   35篇
  841篇
  2023年   10篇
  2022年   14篇
  2021年   31篇
  2020年   36篇
  2019年   31篇
  2018年   38篇
  2017年   39篇
  2016年   42篇
  2015年   29篇
  2014年   33篇
  2013年   181篇
  2012年   27篇
  2011年   36篇
  2010年   21篇
  2009年   26篇
  2008年   47篇
  2007年   30篇
  2006年   27篇
  2005年   10篇
  2004年   14篇
  2003年   10篇
  2002年   3篇
  2001年   12篇
  2000年   3篇
  1999年   10篇
  1998年   8篇
  1997年   2篇
  1995年   4篇
  1994年   4篇
  1993年   5篇
  1992年   2篇
  1991年   3篇
  1990年   2篇
  1989年   1篇
  1988年   3篇
  1987年   6篇
  1986年   2篇
  1985年   1篇
  1984年   2篇
  1983年   4篇
  1982年   2篇
  1981年   1篇
  1980年   3篇
  1979年   4篇
  1978年   7篇
  1977年   5篇
  1976年   7篇
  1975年   3篇
排序方式: 共有841条查询结果,搜索用时 15 毫秒
751.
752.
This paper aims at analysing decisions which are actually made by watch officers onboard ferries in the Dover Strait. More precisely, it aims at characterizing the generic situations in which several courses of actions are available and identifying the strategy underlying an action choice. Relying on the RPD model of Klein [Klein, G. (1997). The recognition-primed decision (RPD) model: Looking back, looking forward. In C. E. Zsambok & G. Klein (Eds.), Naturalistic decision making (pp. 285–292). Mahwah: Lawrence Erlbaum Associates], it points out the critical cues, the goals of actors and the rules they use.Two sets of data were processed: motions of vessels observed from the vessel traffic system and verbal protocols recorded onboard a ferry with three watch officers.Logistic regression models show that different types of ships do not act in the same way: the slowest vessels tend to keep their course and speed, even if they have to move. The faster cargo ships such as ferries alter their course in compliance with the regulations. In some situations, a ferry may nevertheless follow informal rules. Onboard a ‘give way’ ferry, a watch officer may – in some conditions – alter his course to port rather than to starboard to reduce the course alteration and the loss of time. On board the ‘stand on’ vessel, he may perform an action in order to master the situation, even if the rule requires him to keep his course and speed.  相似文献   
753.
The ability to recognise kin has been demonstrated in several animal species. However, the mechanisms of kin recognition often remain unknown. The most frequently discussed sensory modalities to recognise kin are visual, olfactory and acoustical cues. Three-spined sticklebacks (Gasterosteus aculeatus) are able to differentiate between kin and non-kin when presented visual and olfactory cues combined. To elucidate, which cues they use to recognise kin female sticklebacks were given the choice between two identical computer animations of courting stickleback males. Next to one animation, water conditioned by a brother was added, while near the other, water from an unrelated male was added. In half of the experiments, the brother was familiar while in the other half he was unfamiliar to the female. Both scenarios were carried out with both outbred and inbred fish. The results showed that the females adjusted their choice behaviour according to relatedness. Furthermore, they were able to recognise both familiar as well as unfamiliar brothers. Inbreeding did not affect this ability. Hence, three-spined sticklebacks are able to recognise their relatives using olfactory cues alone. The cognitive mechanisms underlying this ability were independent from familiarity and not impaired by inbreeding.  相似文献   
754.
Attention deactivates the inferior medial prefrontal cortex (IMPC), but it is uncertain if emotions can attenuate this deactivation. To test the extent to which common emotions interfere with attention, we measured changes of a blood flow index of brain activity in key areas of the IMPC with positron emission tomography (PET) of labeled water (H(15)2O) uptake in brain of 14 healthy subjects. The subjects performed either a less demanding or a more demanding task of attention while they watched neutral and emotive images of people in realistic indoor or outdoor situations. In the less demanding task, subjects used the index finger to press any key when a new image appeared. In the more demanding task, subjects chose the index or middle finger to press separate keys for outdoor and indoor scenes. Compared to the less demanding task, in a global search of all gray matter, the more demanding significantly lowered blood flow (rCBF) in left IMPC, left and right insula, and right amygdala, and significantly raised blood flow in motor cortex and right precuneus. Restricted searches of rCBF changes by emotion, at coordinates of significant effect in previous studies of the medial prefrontal and temporal cortices, revealed significant activation in the fusiform gyrus, independently of the task. In contrast, we found no effect of emotional content in the IMPC, where emotions failed to override the effect of the task. The results are consistent with a role of the IMPC in the selection among competitive inputs from multiple brain regions, as predicted by the theory of a default mode of brain function. The absent emotional interference with the deactivation of the default state suggests that the inferior prefrontal cortex continued to serve the attention rather than submit to the distraction.  相似文献   
755.
We investigated the relative involvement of cortical regions supporting attentional control in older and younger adults during performance on a modified version of the Stroop task. Participants were exposed to two different types of incongruent trials. One of these, an incongruent-ineligible condition, produces conflict at the non-response level, while the second, an incongruent-eligible condition, produces conflict at both non-response and response levels of information processing. Greater attentional control is needed to perform the incongruent-eligible condition compared to other conditions. We examined the cortical recruitment associated with this task in an event-related functional magnetic resonance imaging paradigm in 25 older and 25 younger adults. Our results indicated that while younger adults demonstrated an increase in the activation of cortical regions responsible for maintaining attentional control in response to increased levels of conflict, such sensitivity and flexibility of the cortical regions to increased attentional control demands was absent in older adults. These results suggest a limitation in older adults’ capabilities for flexibly recruiting the attentional network in response to increasing attentional demands.  相似文献   
756.
The behavioral tasks aiming to evaluate learning and memory mechanisms currently available to zebrafish (Danio rerio) involve long training sessions frequently along multiple days and are based on shuttle box or active-avoidance protocols, preventing a detailed analysis of cellular and molecular time-dependent processes involved in memory acquisition and consolidation. In order to explore zebrafish’s potential contribution to the characterization of the molecular machinery underlying learning and memory rapidly acquired and reliable paradigms are necessary. In this study we present a rapid and effective learning protocol in a single-trial inhibitory avoidance in zebrafish. In a simple apparatus, adult animals learned to refrain from swimming from a white into a dark compartment in order to avoid an electric shock during a single-trial training session that lasted less than 2 min. The resulting memory is robust, long-lasting and sensitive to NMDA-receptor antagonist MK-801 given in the tank water immediately after training. Experiments aiming to further characterize the events underlying memory formation, retrieval or extinction or those looking for cognitive profiling of mutants, neurotoxicological studies and disease models may benefit from this task, and together with complementary strategies available for zebrafish may significantly improve our current knowledge on learning and memory mechanisms.  相似文献   
757.
Several theories have been proposed to account for the apparent non-responsiveness to punishment cues or aversive events demonstrated by members of some disinhibited groups. Included among these theories are those that emphasize individual differences in temperament, temperament-related biases associated with the allocation of attentional resources, and impairments in executive functions. This study examined the relative contribution of each of these variables to the prediction of passive avoidance errors (PAEs, or failures to inhibit responding to punishment cues) during a computerized go/no-go task. Variations in temperament, attentional allocation to punishment feedback, and executive functions were found to independently and additively contribute to the prediction of PAEs in a mixed sample of men and women recruited at a university campus (n=145). Results from this study, therefore, support multiple theoretical perspectives on PAEs as assessed by the go/no-go experimental paradigm.  相似文献   
758.
Two studies examined the relationships among trait negative affectivity, dispositional thought suppression, and intrusions in non-clinical samples. In Study 1 (N=87), participants were presented with a series of emotionally evocative images and intrusions were examined 48 h after presentation via self-report. In Study 2 (N=118), intrusions were examined using a behavioral Key-press and self-report at two time points (5 and 20 min) following exposure to a series of emotionally evocative images. In each study, participants were assessed for trait negative affectivity and the tendency to engage in thought suppression in response to unpleasant cognitions. Results from both studies support a model in which chronic thought suppression fully mediates the relationship between negative affectivity and the frequency of intrusions.  相似文献   
759.
In Experiment 1, participants high (n=15) or low in avoidance (n=14), as measured by the Acceptance and Action Questionnaire, completed a simple matching task that required them to choose whether or not to look at an aversive visual image. Only the high-avoidance participants took longer to emit a correct response that produced an aversive rather than a neutral picture. Additionally, the high-avoiders reported greater levels of anxiety following the experiment even though they rated the aversive images as less unpleasant and less emotionally arousing than their low-avoidant counterparts. In Experiment 2, three groups, representing high-, mid- and low-avoidance (n=6 in each) repeated the matching task with the additional recording of event-related potentials (ERPs). The findings of Experiment 1 were replicated in terms of reaction times and subjective ratings. The ERPs confirmed that the participants attended to the content of the images and differentiated between the aversive and neutral image types. The ERPs also showed significantly greater negativity for electrodes over the left hemisphere relative to the midline for only the high-experiential avoidance (EA) group. Given the left hemisphere dominance for language, the data suggest that the high-EA group engaged in verbal strategies to regulate their emotional responses.  相似文献   
760.
Oroxylin A is a flavonoid and was originally isolated from the root of Scutellaria baicalensis Georgi., one of the most important medicinal herbs in traditional Chinese medicine. The aim of this study was to investigate the ameliorating effects of oroxylin A on memory impairment using the passive avoidance test, the Y-maze test, and the Morris water maze test in mice. Drug-induced amnesia was induced by administering scopolamine (1 mg/kg, i.p.) or diazepam (1 mg/kg, i.p.). Oroxylin A (5 mg/kg) significantly reversed cognitive impairments in mice by passive avoidance and the Y-maze testing (P<.05). Oroxylin A also improved escape latencies in training trials and increased swimming times and distances within the target zone of the Morris water maze (P<.05). Moreover, the ameliorating effects of oroxylin A were antagonized by both muscimol and diazepam (0.25 mg/kg, i.p., respectively), which are GABA(A) receptor agonists. Furthermore, oroxylin A (100 microM) was found to inhibit GABA-induced inward Cl(-) current in a single cortical neuron. These results suggest that oroxylin A may be useful for the treatment of cognitive impairments induced by cholinergic dysfunction via the GABAergic nervous system.  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