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   173799篇
  免费   7751篇
  国内免费   155篇
  181705篇
  2021年   1497篇
  2020年   2778篇
  2019年   3432篇
  2018年   3500篇
  2017年   3974篇
  2016年   4599篇
  2015年   3920篇
  2014年   4795篇
  2013年   23436篇
  2012年   4480篇
  2011年   3642篇
  2010年   3895篇
  2009年   4754篇
  2008年   3889篇
  2007年   3371篇
  2006年   4001篇
  2005年   3962篇
  2004年   3458篇
  2003年   3120篇
  2002年   2898篇
  2001年   3502篇
  2000年   3362篇
  1999年   3272篇
  1998年   2844篇
  1997年   2664篇
  1996年   2570篇
  1995年   2411篇
  1994年   2379篇
  1993年   2337篇
  1992年   2700篇
  1991年   2545篇
  1990年   2390篇
  1989年   2294篇
  1988年   2258篇
  1987年   2278篇
  1986年   2243篇
  1985年   2484篇
  1984年   2547篇
  1983年   2304篇
  1982年   2379篇
  1981年   2349篇
  1980年   2179篇
  1979年   2201篇
  1978年   2192篇
  1977年   2168篇
  1976年   1941篇
  1975年   2016篇
  1974年   2067篇
  1973年   1950篇
  1972年   1542篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
801.
The purpose of the present study was to develop an easily administered scale to assess adolescents' perceptions of both their own social competence and social participation in relationships. Six items were used to generate two factors that accounted for about 68% of the variance.  相似文献   
802.
When a formant transition and the remainder of a syllable are presented to subjects' opposite ears, most subjects perceive two simultaneous sounds: a syllable and a nonspeech chirp. It has been demonstrated that, when the remainder of the syllable (base) is kept unchanged, the identity of the perceived syllable will depend on the kind of transition presented at the opposite ear. This phenomenon, called duplex perception, has been interpreted as the result of the independent operation of two perceptual systems or modes, the phonetic and the auditory mode. In the present experiments, listeners were required to identify and discriminate such duplex syllables. In some conditions, the isolated transition was embedded in a temporal sequence of capturing transitions sent to the same ear. This streaming procedure significantly weakened the contribution of the transition to the perceived phonetic identity of the syllable. It is likely that the sequential integration of the isolated transition into a sequence of capturing transitions affected its fusion with the contralateral base. This finding contrasts with the idea that the auditory and phonetic processes are operating independently of each other. The capturing effect seems to be more consistent with the hypothesis that duplex perception occurs in the presence of conflicting cues for the segregation and the integration of the isolated transition with the base.  相似文献   
803.
The rod-and-frame effect (RFE) was investigated with the use of a frame that oscillated about an axis at its center at five different frequencies, ranging from .013 to .213 Hz. The resultant RFE shifted continuously with the roll motion of the frame, and it was significantly larger at the lowest frequency (.013 Hz) than under comparable static conditions. The dynamic RFE was lowest at the higher oscillation frequencies. Oscillatory roll vection--apparent self-motion--was reported by 3 of the 9 subjects when the frame was oscillating at its highest frequency (.213 Hz). The subjects yielded large increases in the RFE during the sessions with reports of vection. Surrounding the kinetic frame with a circular contour eliminated all reports of vection and significantly interacted with frequency to reduce the RFE--but only at low frequencies. The reduction amounted to 21.2% averaged over all 9 subjects at the three lowest frequencies. A surrounding contour, therefore, suppressed low-frequency kinetic visual orientation information that might otherwise have produced larger changes in apparent self-orientation and perceived vertical. Vection-sensitive subjects differed from nonvection subjects by exhibiting (1) a high-frequency fall-off in real-motion gain, (2) a high-frequency enhancement in illusory-motion gain, and (3) only a small and nonsignificant increase in illusory-movement phase lag with increases in frequency.  相似文献   
804.
Both alcohol and practice affect choice reaction time. The present study was conducted to investigate the possibility that impairment from alcohol and improvement with practice could be attributed to changes in the efficiency of control mechanisms (Rabbitt, 1979a), some of which depend upon the ability to judge response speed accurately. Twenty subjects participated in a four-choice reaction time experiment in which they received no alcohol (NA) in Session 1 and either no alcohol (10 subjects) or 0.8 ml alcohol (A) per kilogram of body weight (10 subjects) in Session 2. The task was to respond as fast and as accurately as possible to each stimulus. In addition, subjects were required to press a fifth key after any response that they considered to be both fast and accurate. Subjects had no difficulty in performing this task: (1) there was a significant difference of 122 msec between the mean response time for correct responses indicated as fast and that for correct responses not indicated as fast, and (2) subjects indicated 1 in 4 correct responses but only 1 in 64 errors. Alcohol increased all response times by approximately 40 msec. In contrast, practice decreased response times less for correct responses not indicated as fast than for correct responses indicated as fast. The ability to distinguish between fast and slow responses was thus unaffected by alcohol, but was improved by practice. Responses indicated as "fast" were significantly faster than errors, and appeared to occur without warning (unlike errors, which tended to end a sequence of increasingly fast correct responses). The results suggest that alcohol and practice influence choice reaction time in qualitatively different ways: Alcohol impairs overall response speed but has no effect on the ability to judge response speed, whereas practice improves both.  相似文献   
805.
Reaction times (RTs) to four groups of substances that provoke different taste qualities were measured. Measurements for all substances with the same taste, equalized in perceived intensity and provoking a very strong taste, were made concurrently for each subject. The comparisons were made on the individual level. No significant differences in RTs to substances with the same taste quality were found. When the factor of perceived intensity is kept constant, no effect of the stimulus chemical composition on RTs seems to be present. RTs to stimuli with different tastes differ significantly, the shortest being to salt and the longest to bitter. The difference in RTs for sour and sweet substances is small, and the subjects were not all alike in terms of the order of RTs with respect to these stimuli.  相似文献   
806.
This paper reports on the application in practice of a program for diagnosis and basic cognitive achievement training. The program concentrates on performance and its growth in children with encephalopathy-typical behavior. It is demonstrated how deficient cognitive performance may be influenced by level-raising training and transfer effects.  相似文献   
807.
808.
S Becker  U Clement 《Psyche》1989,43(8):698-709
The authors warn against a trivialization of the AIDS problem and against the call for state control. Since sexuality is ultimately uncontrollable, they plead instead for the greater clarification of the conflicts which those who are infected with HIV and those who are not infected experience in dealing with each other. The continuing mystification of these conflicts would result in mutual jeopardy through acting-out.  相似文献   
809.
810.
An Extended Two-Way Euclidean Multidimensional Scaling (MDS) model which assumes both common and specific dimensions is described and contrasted with the standard (Two-Way) MDS model. In this Extended Two-Way Euclidean model then stimuli (or other objects) are assumed to be characterized by coordinates onR common dimensions. In addition each stimulus is assumed to have a dimension (or dimensions) specific to it alone. The overall distance between objecti and objectj then is defined as the square root of the ordinary squared Euclidean distance plus terms denoting the specificity of each object. The specificity,s j , can be thought of as the sum of squares of coordinates on those dimensions specific to objecti, all of which have nonzero coordinatesonly for objecti. (In practice, we may think of there being just one such specific dimension for each object, as this situation is mathematically indistinguishable from the case in which there are more than one.)We further assume that ij =F(d ij ) +e ij where ij is the proximity value (e.g., similarity or dissimilarity) of objectsi andj,d ij is the extended Euclidean distance defined above, whilee ij is an error term assumed i.i.d.N(0, 2).F is assumed either a linear function (in the metric case) or a monotone spline of specified form (in the quasi-nonmetric case). A numerical procedure alternating a modified Newton-Raphson algorithm with an algorithm for fitting an optimal monotone spline (or linear function) is used to secure maximum likelihood estimates of the paramstatistics) can be used to test hypotheses about the number of common dimensions, and/or the existence of specific (in addition toR common) dimensions.This approach is illustrated with applications to both artificial data and real data on judged similarity of nations.  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