全文获取类型
收费全文 | 21033篇 |
免费 | 43篇 |
国内免费 | 1篇 |
出版年
2022年 | 8篇 |
2021年 | 7篇 |
2020年 | 10篇 |
2019年 | 17篇 |
2018年 | 3495篇 |
2017年 | 2828篇 |
2016年 | 2262篇 |
2015年 | 202篇 |
2014年 | 89篇 |
2013年 | 150篇 |
2012年 | 595篇 |
2011年 | 2399篇 |
2010年 | 2532篇 |
2009年 | 1481篇 |
2008年 | 1719篇 |
2007年 | 2192篇 |
2006年 | 48篇 |
2005年 | 235篇 |
2004年 | 179篇 |
2003年 | 132篇 |
2002年 | 82篇 |
2001年 | 38篇 |
2000年 | 61篇 |
1999年 | 25篇 |
1998年 | 27篇 |
1997年 | 28篇 |
1996年 | 16篇 |
1995年 | 11篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 18篇 |
1989年 | 6篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 10篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1978年 | 10篇 |
1977年 | 8篇 |
1976年 | 11篇 |
1975年 | 9篇 |
1974年 | 10篇 |
1972年 | 6篇 |
1970年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Electrical activity was recorded from single neurons in the medial prefrontal cortex of rabbits during differential Pavlovian heart rate (HR) conditioning. A heterogeneous population of cells were found, some of which showed CS-evoked increases and others CS-evoked decreases in discharge, while some cells were biphasic. A subset of cells also showed trial-related changes in discharge that were related to acquisition of the HR discrimination between the reinforced CS+ and non-reinforced CS-. Administration of the peripheral cholinergic antagonist, methylscopolamine, and the andrenergic antagonist, atenolol, either increased or decreased maintained baseline activity of many cells, but had little or no effect on the CS-evoked activity of these cells. Waveform changes also did not result from administration of these drugs. This finding suggests that CS-evoked mPFC activity is not being driven by cardiac afferent input to CNS cardiac control centers. Previous studies have shown that ibotenic acid lesions of this area greatly decreases the magnitude of decelerative heart rate conditioned responses; the latter finding, plus the results of the present study, suggest that processing of CS/US contingencies by the prefrontal cortex contributes to the acquisition of autonomic changes during Pavlovian conditioning. 相似文献
102.
Throughout the U.S., state laws require professionals who work with children to report cases of suspected child abuse to child protection services. Both practically and conceptually, however, significant problems arise from a lack of clarity regarding the threshold that has been set for reporting. Specifically, there is no consensus as to what constitutes reasonable suspicion, and little direction for how mandated reporters should gauge their legal and professional responsibilities when they harbor suspicion. In this paper we outline the context of the problem, discuss the nature and scope of its conceptual underpinnings, and offer recommendations for moving towards a concrete, practical solution. 相似文献
103.
How rapidly can attention move from one object to the next? Previous studies in which the dwell time paradigm was used have estimated attentional switch times of 200–500 msec, results incompatible with the search rate estimates of 25–50 msec shown in numerous visual search studies. It has been argued that dwell times are so long in the dwell time paradigm because the attentional shifts measured are unlike those used in visual search. In the present experiment, a variation of a visual search task was used, in which serial endogenous (volitional) deployments of attention were measured directly by means of a probe reaction time task. The experiment revealed a dwell time of about 250 msec, consistent with the faster estimates from other dwell time studies. This result suggests that endogenous shifts of attention may be relatively slow and that the faster attentional shifts estimated from visual search tasks may be due to the involvement of bottom-up processes. 相似文献
104.
Catalano GD 《Science and engineering ethics》2004,10(2):409-415
A senior level capstone design experience has been developed and offered with a particular emphasis on many of the professional
issues raised in Accreditation Board for Engineering and Technology (ABET) Engineering Criterion IV. The course has sought
to develop student awareness of the ethical foundation of the engineering profession, the global and societal framework within
which engineers practice, and the environmental impact on engineering. The capstone design course also focused upon improving
the technical communications skills of the graduating senior class with both extensive instruction in writing and multiple
workshops dealing with the art of making an effective oral presentation. The effectiveness of the design course was assessed
using Kirkpatrick’s model for evaluating training programs.
An earlier version of this paper was presented at the “Ethics and Social Responsibility in Engineering and Technology” meeting,
New Orleans, 2003. 相似文献
105.
The present experiment examined the one-target advantage (OTA) with regard to saccadic eye movements. The OTA, previously found with manual pointing responses, refers to the finding that movements are executed faster when the limb is allowed to stop on the target compared to the situation where it has to proceed and hit a second target. Using an adapted limb movement OTA task, saccades of 5 degrees and 15 degrees were made to (a) a single target (one-target), (b) one target and immediately to another target without a change in direction (two-target-extension), and (c) one target and immediately back to the start location (two-target-reversal). Unlike manual movements, the movement times for the initial saccade in the two-target-extension condition were not prolonged compared to either of the other two conditions. Moreover, this pattern of results was found for both the shorter and longer amplitude saccades. The results indicate that the OTA does not occur in the oculomotor system and therefore is not a general motor control phenomenon. 相似文献
106.
Faculty members at Canadian business schools were surveyed regarding their ethical perceptions of behaviours related to undergraduate instruction. Fifty-five behavioural statements were listed and respondents were asked to rate the extent to which they felt each behaviour was ethical or unethical. The only item that respondents endorsed as unequivocally unethical (90% indicated it was definitely unethical) was Becoming sexually involved with an undergraduate in one of your classes. We also compared the results of our sample to those of an American sample. Overall, an interesting pattern of differences emerged between the responses obtained in Canada and the U.S. In general, the direction of the significant differences was such that Canadian professors viewed the behaviours in question as less ethical than did their American counterparts. 相似文献
107.
Symbolic control of visual attention: The role of working memory and attentional control settings 总被引:4,自引:0,他引:4
Pratt J Hommel B 《Journal of experimental psychology. Human perception and performance》2003,29(5):835-845
This study examined how 1 symbol is selected to control the allocation of attention when several symbols appear in the visual field. In Experiments 1-3, the critical target feature was color, and it was found that uninformative central arrows that matched the color of the target were selected and produced unintentional shifts of attention (i.e., involuntary, initiated slowly, producing long-lasting facilitatory effects). Experiment 4 tested whether such selection is the result of an attentional filter or of a competition bias due to a match of incoming information against integrated object representations stored in working memory. Here, the critical feature was shape and color was irrelevant, but matching color arrows were still selected. Thus, features of objects in working memory will bias the selection of symbols in the visual field, and such selected symbols are capable of producing unintentional shifts of attention. ((c) 2003 APA, all rights reserved) 相似文献
108.
Serotonin (5-HT) modulates numerous processes in the central nervous system that are relevant to neuropsychiatric function and dysfunction. It exerts significant effects on anxiety, mood, impulsivity, sleep, ingestive behavior, reward systems, and psychosis. Serotonergic dysfunction has been implicated in several psychiatric conditions but efforts to more clearly understand the mechanisms of this influence have been hampered by the complexity of this system at the receptor level. There are at least 14 distinct receptors that mediate the effects of 5-HT as well as several enzymes that control its synthesis and metabolism. Pharmacologic agents that target specific receptors have provided clues regarding the function of these receptors in the human brain. 5-HT is also an important modulator of neural development and several groups have employed a genetic strategy relevant to behavior. Several inactivation mutations of specific 5-HT receptors have been generated producing interesting behavioral phenotypes related to anxiety, depression, drug abuse, psychosis, and cognition. In many cases, knockout mice have been used to confirm what has already been suspected based on pharmacologic studies. In other instances, mutations have demonstrated new functions of serotonergic genes in development and behavior. 相似文献
109.
In modern digital applications, users often interact with virtual representations of themselves or others, called avatars. We examined how these avatars and their perspectives influence stimulus–response compatibility in a Simon task. Participants responded to light/dark blue stimuli with left/right key presses in the presence of a task-irrelevant avatar. Changes in stimulus–response compatibility were used to quantify changes in the mental representation of the task and perspective taking toward this avatar. Experiments 1 and 2 showed that perspective taking for an avatar occurred in orthogonal stimulus–response mappings, causing a compatibility effect from the avatar’s point of view. In the following two experiments we introduced a larger variety of angular disparities between the participant and avatar. In Experiment 3, the Simon effect with lateralized stimulus positions remained largely unaffected by the avatar, pointing toward an absence of perspective taking. In Experiment 4, after avatar hand movements were added in order to strengthen the participants’ sense of agency over the avatar, a spatial compatibility effect from the avatar’s perspective was observed again, and hints of the selective use of perspective taking on a trial-by-trial basis were found. Overall, the results indicate that users can incorporate the perspective of an avatar into their mental representation of a situation, even when this perspective is unnecessary to complete a task, but that certain contextual requirements have to be met. 相似文献
110.
Ronald Jay Werner-Wilson Toni Schindler Zimmerman Kathrine Daniels Stephanie M. Bowling 《Contemporary Family Therapy》1999,21(4):545-550
Although the feminist critique of marriage and family therapy has been a significant part of the literature for many years, its impact has been blunted by two criticisms. The first suggests that the feminist critique lacks empirical support. The second suggests that the feminist critique promotes an alliance with women clients at the expense of men. The first criticism has been addressed in recent years. The present study examined the relationship between feminist principles and therapeutic alliance. Results suggest that feminist principles actually enhance therapeutic relationship for men clients but has no effect on therapeutic relationship for women clients.of the Marriage and Family Therapy Program 相似文献