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   35734篇
  免费   691篇
  国内免费   6篇
  36431篇
  2020年   419篇
  2019年   529篇
  2018年   693篇
  2017年   685篇
  2016年   782篇
  2015年   527篇
  2014年   627篇
  2013年   2788篇
  2012年   1160篇
  2011年   1161篇
  2010年   704篇
  2009年   758篇
  2008年   992篇
  2007年   1005篇
  2006年   892篇
  2005年   781篇
  2004年   771篇
  2003年   726篇
  2002年   716篇
  2001年   1109篇
  2000年   1113篇
  1999年   819篇
  1998年   363篇
  1997年   340篇
  1995年   345篇
  1992年   667篇
  1991年   627篇
  1990年   611篇
  1989年   575篇
  1988年   576篇
  1987年   507篇
  1986年   513篇
  1985年   571篇
  1984年   463篇
  1983年   446篇
  1982年   355篇
  1979年   510篇
  1978年   348篇
  1977年   333篇
  1976年   346篇
  1975年   387篇
  1974年   460篇
  1973年   489篇
  1972年   416篇
  1971年   352篇
  1970年   329篇
  1969年   345篇
  1968年   442篇
  1967年   388篇
  1966年   370篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
861.
862.
A novel three-dimensional eye tracker is described and its performance evaluated. In contrast to previous devices based on conventional video standards, the present eye tracker is based on programmable CMOS image sensors, interfaced directly to digital processing circuitry to permit real-time image acquisition and processing. This architecture provides a number of important advantages, including image sampling rates of up to 400/sec measurement, direct pixel addressing for preprocessing and acquisition, and hard-disk storage of relevant image data. The reconfigurable digital processing circuitry also facilitatesin-line optimization of the front-end, time-critical processes. The primary acquisition algorithm for tracking the pupil and other eye features is designed around the generalized Hough transform. The tracker permits comprehensive measurement of eye movement (three degrees of freedom) and head movement (six degrees of freedom), and thus provides the basis for many types of vestibulo-oculomotor and visual research. The device has been qualified by the German Space Agency (DLR) and NASA for deployment on the International Space Station. It is foreseen that the device will be used together with appropriate stimulus generators as a general purpose facility for visual and vestibular experiments. Initial verification studies with an artificial eye demonstrate a measurement resolution of better than 0.1° in all three components (i.e., system noise for each of the components measured as 0.006° H, 0.005° V, and 0.016° T. Over a range of ±20° eye rotation, linearity was found to be <0.5% (H), <0.5% (V), and <2.0% (T). A comparison with the scierai search coil technique yieldednear equivalent values for the systemnoise and the thickness of Listing’s plane.  相似文献   
863.
In this study, we investigated when visual perception begins in fixations. During picture viewing, the picture was degraded at the beginning of selected saccades and changed back to the original after varying intervals. Participants manually responded whenever they detected changes. The change-backs were undetected when they occurred <6 msec after the end of the saccade, marked by the peak of the overshoot in dual Purkinje image eyetracker data, and detection reached asymptote 32 msec after that marker. Eye velocity at the change-backtime also affected detection likelihood. Apparently, perception begins around the time at which the eyes stop rotating at the end of a saccade, giving a psychological justification for measuring fixation durations from then. This also specifies the deadline for gaze-contingent display changes to occur without detectable image motion. Investigators using the dual PurMnje image eyetracker should consider the peak of the overshoot as the fixation onset time and measure intrafixational presentation times from then.  相似文献   
864.
Recent research has characterized categorical thinking as an essential component of the person perception process. Yet relatively little is known about the myriad factors that moderate the accessibility of this mode of thought. With regard to this we hypothesized that the subjective familiarity of a person's forename may play an important role in triggering categorical thinking. Specifically, category-based knowledge may be more accessible when triggered by familiar than unfamiliar forenames. We report the results of three experiments that supported this prediction. Relative to unfamiliar names, participants required less time to verify the gender of familiar forenames (Experiment 1) and semantic priming was more pronounced when stereotype-related material followed the presentation of familiar than unfamiliar items (Experiment 2). Also, familiar forenames attracted more extreme gender-based evaluations than their unfamiliar counterparts (Experiment 3). We consider the theoretical and methodological implications of these findings for a variety of issues in person perception.  相似文献   
865.
High- and low-trait socially anxious individuals classified the emotional expressions of photographic quality continua of interpolated ("morphed") facial images that were derived from combining 6 basic prototype emotional expressions to various degrees, with the 2 adjacent emotions arranged in an emotion hexagon. When fear was 1 of the 2 component emotions, the high-trait group displayed enhanced sensitivity for fear. In a 2nd experiment where a mood manipulation was incorporated, again, the high-trait group exhibited enhanced sensitivity for fear. The low-trait group was sensitive for happiness in the control condition. The mood-manipulated group had increased sensitivity for anger expressions, and trait anxiety did not moderate these effects. Interpretations of the results related to the classification of fearful expressions are discussed.  相似文献   
866.
In the current investigation, we compared two methods of food presentation (simultaneous vs. sequential) to increase consumption of nonpreferred food for 3 children with food selectivity. In the simultaneous condition, preferred foods were presented at the same time as nonpreferred food (e.g., a piece of broccoli was presented on a chip). In the sequential condition, acceptance of the nonpreferred food resulted in presentation of the preferred food. Increases in consumption occurred immediately during the simultaneous condition for 2 of the 3 participants. For 1 participant, increases in consumption occurred in the simultaneous condition relative to the sequential condition, but only after physical guidance and re-presentation were added to treatment. Finally, consumption increased for 1 participant in the sequential condition, but only after several sessions. These results are discussed in terms of possible mechanisms that may alter preferences for food (i.e., establishing operations, flavor-flavor conditioning).  相似文献   
867.
868.
869.
Reconsolidation Reconsidered   总被引:3,自引:0,他引:3  
Some of the considerations that led to a consolidation interpretation of retrograde amnesia (RA), which states that RA results from the disruption of memory processing and storage when neural activity is interrupted by a brain insult, are reviewed here. The time-dependent gradient of memory loss (i.e., new memories are more vulnerable to amnesia than old memories) that characterizes RA seemed to fit nicely with the notion of a cascade of cellular events occurring during the immediate post-acquisition period that would transform a labile representation into a more stable form (i.e., consolidate the memory). However, a variety of observations came to challenge the storage-disruption model, and among these was the finding of amnesia for old but reactivated memories. A recent study by Nader, Schafe, and LeDoux (2000) provides an important analytic extension of the work on "reconsolidation" by showing that inhibition of protein synthesis in the lateral and basal nuclei of the amygdala immediately following the reactivation of old memory will induce retrograde amnesia. We offer a retrieval-oriented conceptualization to account for the temporal gradient and the "reconsolidation" phenomena.  相似文献   
870.
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