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   51658篇
  免费   2147篇
  国内免费   30篇
  53835篇
  2020年   625篇
  2019年   749篇
  2018年   1034篇
  2017年   1086篇
  2016年   1113篇
  2015年   807篇
  2014年   960篇
  2013年   4082篇
  2012年   1748篇
  2011年   1797篇
  2010年   1121篇
  2009年   1064篇
  2008年   1519篇
  2007年   1526篇
  2006年   1348篇
  2005年   1177篇
  2004年   1129篇
  2003年   1060篇
  2002年   1070篇
  2001年   1700篇
  2000年   1664篇
  1999年   1234篇
  1998年   533篇
  1997年   519篇
  1996年   455篇
  1995年   462篇
  1993年   455篇
  1992年   1014篇
  1991年   901篇
  1990年   985篇
  1989年   866篇
  1988年   895篇
  1987年   828篇
  1986年   870篇
  1985年   787篇
  1984年   698篇
  1983年   647篇
  1982年   454篇
  1979年   713篇
  1978年   535篇
  1975年   608篇
  1974年   699篇
  1973年   683篇
  1972年   574篇
  1971年   525篇
  1970年   479篇
  1969年   577篇
  1968年   648篇
  1967年   571篇
  1966年   511篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
921.
922.
923.
924.
We examined the effect of reducing the interval between a patient's call for an appointment and the appointment itself. In Experiment 1, patients calling a family planning unit of a public health department were assigned appointments within either 1 or 3 weeks of their call. Data on patient “shows” and “no-shows” were recorded weekly for 6 weeks. Show rates for those in the 1-week appointment group were significantly higher than those in the 3-week group. In Experiment 2, patients were assigned to appointment dates either the next operating clinic day (next-day group) or 2 weeks from the call date (2-week group). Show rates for those in the next-day group were significantly better than show rates for patients in the 2-week group. Clinic productivity, time spent with patients, and consumer satisfaction were also assessed. Implications for appointment scheduling are discussed.  相似文献   
925.
Five-year-old children were tested for perceptual trading relations between a temporal cue (silence duration) and a spectral cue (F1 onset frequency) for the “say-stay” distinction. Identification functions were obtained for two synthetic “say-stay” continua, each containing systematic variations in the amount of silence following the /s/ noise. In one continuum, the vocalic portion had a lower F1 onset than in the other continuum. Children showed a smaller trading relation than has been found with adults. They did not differ from adults, however, in their perception of an “ay-day” continuum formed by varying F1 onset frequency only. The results of a discrimination task in which the two acoustic cues were made to “cooperate” or “conflict” phonetically supported the notion of perceptual equivalence of the temporal and spectral cues along a single phonetic dimension. The results indicate that young children, like adults, perceptually integrate multiple cues to a speech contrast in a phonetically relevant manner, but that they may not give the same perceptual weights to the various cues as do adults.  相似文献   
926.
In two longitudinal studies, infants were trained at 12 and 18 months to find an object hidden in one of two identical wells in a Plexiglas box. On the test trial, normal access was blocked and infants were either guided by their mother or allowed to move on their own to another opening on the opposite side. In Experiment 1 significantly more correct responding occurred after active movement than after passive at 12 months, with correct responding related to high visual tracking. In contrast, at 18 months correct search without tracking predominated among both movement conditions. A difference between the conditions in the position of the mother on the test trial was ruled out as a contributor to performance on the basis of data from Experiment 2. When opaque sides were inserted to prevent tracking in Experiment 3, active movement no longer facilitated correct search at 12 months, thus indicating that the tracking and not the active movement per se was the critical factor.  相似文献   
927.
Nursery schoolers and first- and third-graders participated in an interview which assessed recall, comprehension, and perceived importance of three sources of self-knowledge: social feedback, self-observation, and social comparison. For recall measures, these sources were embedded in stories about a child making a self-discovery. Recall of all three sources improved with grade level, and feedback was the best remembered self-validational process. Comprehension was defined as the ability to identify the sources as depicted in line drawings, and it, too, increased with grade level. All three sources were well understood by older children, but preschoolers had difficulty with the concept of social comparison. Ratings of importance, also assessed using line drawings, were independent of grade level. When selecting their own “very best” source of self-knowledge, children cited self-observation most frequently. A supplementary sample of preschoolers nominated the best source of self-knowledge for other children rather than for themselves; under these instructions, feedback from others emerged as the preferred source.  相似文献   
928.
Figure drawings obtained from 758 white male medical students were scored using three different methods. Method I involved 16 different physical size measurements; Method II involved six separate sophistication of body concept ratings; and Method III involved 42 separate aspects of the drawings weighted in direct proportion to their relative frequency of occurrence in the sample studied (conventionality scoring). Separate factor analyses of the scores derived from each method revealed that Methods I and II each reflect only a single underlying factor, and that these factors are uncorrelated in the population studied. Method III yielded eight meaningful factors, each of which may be construed as an independent area of conventionality/deviancy. An overall conventionality/deviancy score was also derived. It is believed that these three methods of scoring capture most of the variance inherent in existing figure drawing scoring systems, but that use of all three is necessary for a comprehensive analysis.  相似文献   
929.
The purpose of the present study was to investigate the influence of race (black, white) on the MMPI performance of alcoholic and nonalcoholic inpatients. Subjects were 73 (27 black, 46 white) male alcoholic inpatients and 73 (27 black, 46 white) male nonalcoholic psychiatric inpatients. While black and white alcoholics failed to differ on the MMPI, white alcoholics presented as less disturbed and black alcoholics as less defensive and distressed, compared to their respective nonalcoholic counterparts. Furthermore, only white alcoholics were accurately identified by the MMPI 2-4/4-2 high-point pair combination and only white alcoholics achieved more high-point pairs containing Scale 4 relative to nonalcoholic controls.  相似文献   
930.
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