全文获取类型
收费全文 | 20770篇 |
免费 | 38篇 |
专业分类
20808篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 5篇 |
2021年 | 16篇 |
2020年 | 20篇 |
2019年 | 10篇 |
2018年 | 3500篇 |
2017年 | 2830篇 |
2016年 | 2261篇 |
2015年 | 208篇 |
2014年 | 92篇 |
2013年 | 122篇 |
2012年 | 616篇 |
2011年 | 2411篇 |
2010年 | 2527篇 |
2009年 | 1487篇 |
2008年 | 1718篇 |
2007年 | 2185篇 |
2006年 | 35篇 |
2005年 | 219篇 |
2004年 | 166篇 |
2003年 | 120篇 |
2002年 | 70篇 |
2001年 | 31篇 |
2000年 | 54篇 |
1999年 | 18篇 |
1998年 | 21篇 |
1997年 | 17篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 7篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1969年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
251.
The Bengalese finch (Lonchura striata var. domestica) is a species of songbird. Males sing courtship songs with complex note-to-note transition rules, while females discriminate
these songs when choosing their mate. The present study uses serial reaction time (RT) to examine the characteristics of the
Bengalese finches’ sequential behaviours beyond song production. The birds were trained to produce the sequence with an “A–B–A”
structure. After the RT to each key position was determined to be stable, we tested the acquisition of the trained sequential
response by presenting novel and random three-term sequences (random test). We also examined whether they could abstract the
embedded rule in the trained sequence and apply it to the novel test sequence (abstract test). Additionally, we examined rule
abstraction through example training by increasing the number of examples in baseline training from 1 to 5. When considered
as (gender) groups, training with 5 examples resulted in no statistically significant differences in the abstract tests, while
statistically significant differences were observed in the random tests, suggesting that the male birds learned the trained
sequences and transferred the abstract structure they had learned during the training trials. Individual data indicated that
males, as opposed to females, were likely to learn the motor pattern of the sequence. The results are consistent with observations
that males learn to produce songs with complex sequential rules, whereas females do not. 相似文献
252.
Non-human primates possess species-specific repertoires of acoustically distinct call types that can be found in adults in
predictable ways. Evidence for vocal flexibility is generally rare and typically restricted to acoustic variants within the
main call types or sequential production of multiple calls. So far, evidence for context-specific call sequences has been
mainly in relation to external disturbances, particularly predation. In this study, we investigated extensively the vocal
behaviour of free-ranging and individually identified Diana monkeys in non-predatory contexts. We found that adult females
produced four vocal structures alone (‘H’, ‘L’, ‘R’ and ‘A’ calls, the latter consisting of two subtypes) or combined in non-random
ways (‘HA’, ‘LA’ and ‘RA’ call combinations) in relation to ongoing behaviour or external events. Specifically, the concatenation
of an introductory call with the most frequently emitted and contextually neutral ‘A’ call seems to function as a contextual
refiner of this potential individual identifier. Our results demonstrate that some non-human primates are able to increase
the effective size of their small vocal repertoire not only by varying the acoustic structure of basic call types but also
by combining them into more complex structures. We have demonstrated this phenomenon for a category of vocalisations with
a purely social function and discuss the implications of these findings for evolutionary theories of primate vocal communication. 相似文献
253.
Although rats are able to build complex spatial representations of their surroundings during exploration, the nature of the
encoded information is still a matter for debate. In particular, it is not well established if rats can process the topological
structure of the environment in such a way that they are aware of the connections existing between remote places. Here, rats
were first exposed for four 5-min trials to a complex environment divided into several sectors that were separated by doors
allowing either unrestricted or restricted access to other sectors. In the fifth test trial, we measured the behavior of the
animals while they explored the same environment in which, however, they faced changes that either altered or did not alter
the topological structure of the environment. In experiment 1, closing previously opened doors prevented the rat from having
direct access between corresponding sectors. In experiment 2, opening previously closed doors allowed direct access between
sectors that had not been directly accessible. In each experiment, control doors allowed us to discard the mere influence
of door manipulation. We compared the rats’ exploratory behavior in response to door manipulations that either strongly altered
or did not alter the ability to commute between sectors and found evidence that the animals displayed differential reactions
to the two types of door manipulations. This implies that during exploration rats build a precise map of the connectivity
of space that can be flexibly updated and used for efficient navigation. 相似文献
254.
Uneconomical choices by humans or animals that evaluate reward options challenge the expectation that decision-makers always
maximize the return currency. One possible explanation for such deviations from optimality is that the ability to sense differences
in physical value between available alternatives is constrained by the sensory and cognitive processes for encoding profitability.
In this study, we investigated the capacity of a nectarivorous bat species (Glossophaga commissarisi) to discriminate between sugar solutions with different concentrations. We conducted a two-alternative free-choice experiment
on a population of wild electronically tagged bats foraging at an array of computer-automated artificial flowers that recorded
individual choices. We used a Bayesian approach to fit individual psychometric functions, relating the strength of preferring
the higher concentration option to the intensity of the presented stimulus. Psychometric analysis revealed that discrimination
ability increases non-linearly with respect to intensity. We combined this result with a previous psychometric analysis of
volume perception. Our theoretical analysis of choice for rewards that vary in two quality dimensions revealed regions of
parameter combinations where uneconomic choice is expected. Discrimination ability may be constrained by non-linear perceptual
and cognitive encoding processes that result in uneconomical choice. 相似文献
255.
Different event-related potentials (ERPs) have been shown to correlate with learning from feedback in decision-making tasks
and with learning in explicit memory tasks. In the present study, we investigated which ERPs predict learning from corrective
feedback in a multiple-choice test, which combines elements from both paradigms. Participants worked through sets of multiple-choice
items of a Swahili–German vocabulary task. Whereas the initial presentation of an item required the participants to guess
the answer, corrective feedback could be used to learn the correct response. Initial analyses revealed that corrective feedback
elicited components related to reinforcement learning (FRN), as well as to explicit memory processing (P300) and attention
(early frontal positivity). However, only the P300 and early frontal positivity were positively correlated with successful
learning from corrective feedback, whereas the FRN was even larger when learning failed. These results suggest that learning
from corrective feedback crucially relies on explicit memory processing and attentional orienting to corrective feedback,
rather than on reinforcement learning. 相似文献
256.
Ravizza SM Goudreau J Delgado MR Ruiz S 《Cognitive, affective & behavioral neuroscience》2012,12(1):193-206
Disruption of the dorsal frontostriatal pathways in Parkinson’s disease (PD) is associated with impairments in motivation,
as well as in executive function. The goal of this study was to investigate whether these impairments are related and, if
so, whether the disruption of frontostriatal pathways compromises the ability to process the motivational aspects of feedback
in such tasks. In Experiment 1, informative feedback improved the performance of young, healthy participants in a task-switching paradigm. This task-switching
paradigm was then used in Experiment 2 to test whether feedback would improve the performance of 17 PD patients and age-matched controls. The PD group benefitted
from feedback to the same degree as control participants; however, depression scores on the Beck Depression Inventory were
significantly related to feedback usage, especially when response selection demands were high. Regardless of feedback, PD
patients were more impaired when response demands were high than in an equally difficult condition with low action demands.
These results suggest that response selection is a core impairment of insufficient dopamine to the dorsal frontal striatal
pathways. 相似文献
257.
Although the amount or scale of biographical knowledge held in store about a person may differ widely, little is known about
whether and how these differences may affect the retrieval processes triggered by the person’s face. In a learning paradigm,
we manipulated the scale of biographical knowledge while controlling for a common set of minimal knowledge and perceptual
experience with the faces. A few days after learning, and again after 6 months, knowledge effects were assessed in three tasks,
none of which concerned the additional knowledge. Whereas the performance effects of additional knowledge were small, event-related
brain potentials recorded during testing showed amplitude modulations in the time range of the N400 component—indicative of
knowledge access—but also at a much earlier latency in the P100 component—reflecting early stages of visual analysis. However,
no effects were found in the N170 component, which is taken to reflect structural analyses of faces. The present findings
replicate knowledge scale effects in object recognition and suggest that enhanced knowledge affects both early visual processes
and the later processes associated with semantic processing, even when this knowledge is not task-relevant. 相似文献
258.
The present study addressed the hypothesis that emotional stimuli relevant to survival or reproduction (biologically emotional
stimuli) automatically affect cognitive processing (e.g., attention, memory), while those relevant to social life (socially
emotional stimuli) require elaborative processing to modulate attention and memory. Results of our behavioral studies showed
that (1) biologically emotional images hold attention more strongly than do socially emotional images, (2) memory for biologically
emotional images was enhanced even with limited cognitive resources, but (3) memory for socially emotional images was enhanced
only when people had sufficient cognitive resources at encoding. Neither images’ subjective arousal nor their valence modulated
these patterns. A subsequent functional magnetic resonance imaging study revealed that biologically emotional images induced
stronger activity in the visual cortex and greater functional connectivity between the amygdala and visual cortex than did
socially emotional images. These results suggest that the interconnection between the amygdala and visual cortex supports
enhanced attention allocation to biological stimuli. In contrast, socially emotional images evoked greater activity in the
medial prefrontal cortex (MPFC) and yielded stronger functional connectivity between the amygdala and MPFC than did biological
images. Thus, it appears that emotional processing of social stimuli involves elaborative processing requiring frontal lobe
activity. 相似文献
259.
Giovanna Leone 《Cognitive processing》2012,13(2):477-485
In face-to-face interactions, some social signals are aimed at regulating scaffolding processes, by which more knowledgeable people try to help less knowledgeable ones, to enable them to learn new concepts or skills (Vygotsky 1978). Observing face-to-face scaffolding interactions might not only allow us to grasp a large variety of these highly interesting social signals but may also be useful for the sake of scaffolding processes themselves. It often happens, in fact, that the empowering intentions implicit in these processes end up falling short, if the social signals regulating this specific kind of face-to-face interaction are misunderstood. Interestingly, many of these misunderstood aspects are related to the recipient’s role. Indeed, attention is usually focused on the behavior of those imparting the knowledge, while skills already mastered by the learners, as well as their feedback, tend not to be taken as much into account. For the purpose of exploring the often very subtly nuanced social signals regulating on-going scaffolding processes in real-life interactions, an example of a methodological tool is presented: one already used to observe the interactions of dyads of Italian primary school teachers and their pupils, and mothers and their children. The article leads to two main conclusions: that the results of instances of scaffolding may be predicted as to their success or otherwise simply by telescoping crucial social signals during the scaffolding’s initial phases, and that when helpers disregard these signals the effects of their actions may be detrimental or even humiliating for the receivers, notwithstanding the helper’s intentions. 相似文献
260.
Sabrina Brigadoi Simone Cutini Fabio Scarpa Pietro Scatturin Roberto Dell’Acqua 《Cognitive processing》2012,13(1):97-101
Studies employing functional magnetic resonance imaging (fMRI) have highlighted a covariation between the amplitude of hemodynamic responses recorded in primary and supplementary motor areas (M1 and SMA) and the duration of a motor task. A subset of these studies have hinted to a possible functional dissociation between processing carried out in these areas, with SMA primarily involved in action preparation, while M1 involved in action execution. This proposed functional dissociation was explored in the present study using a different technique—functional near-infrared spectroscopy—which enabled a finer-grained monitoring of the temporal characteristics of the hemodynamic response compared to fMRI. Here, hemodynamic responses in M1 and SMA were recorded in 7 participants during a right-finger-tapping task of short (1 s) or long (3 s) duration. Hemodynamic responses of larger amplitude were recorded from both contralateral M1 and SMA during long-duration than short-duration tapping. Furthermore, the analysis of the temporal profiles of these responses revealed a more sustained and prolonged activity for long-duration versus short-duration tapping in M1, but not in SMA. Rather than functionally dissociable areas, the present results are more compatible with the hypothesis that M1 and SMA subserve different, though strongly interacting, functional subroutines subtended in motor task preparation and execution. 相似文献