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   53324篇
  免费   2131篇
  国内免费   30篇
  2020年   603篇
  2019年   749篇
  2018年   1083篇
  2017年   1092篇
  2016年   1144篇
  2015年   766篇
  2014年   936篇
  2013年   4673篇
  2012年   1691篇
  2011年   1841篇
  2010年   1069篇
  2009年   1092篇
  2008年   1669篇
  2007年   1656篇
  2006年   1450篇
  2005年   1318篇
  2004年   1292篇
  2003年   1177篇
  2002年   1238篇
  2001年   1771篇
  2000年   1673篇
  1999年   1291篇
  1998年   687篇
  1997年   596篇
  1996年   530篇
  1995年   530篇
  1994年   512篇
  1993年   531篇
  1992年   1034篇
  1991年   969篇
  1990年   958篇
  1989年   867篇
  1988年   827篇
  1987年   818篇
  1986年   825篇
  1985年   874篇
  1984年   685篇
  1983年   591篇
  1982年   478篇
  1979年   674篇
  1978年   514篇
  1976年   456篇
  1975年   600篇
  1974年   633篇
  1973年   602篇
  1972年   551篇
  1971年   479篇
  1968年   540篇
  1967年   545篇
  1966年   478篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
901.
Taste sensitivity for sodium chloride in solution and sensitivity and preference for sodium chloride in bread were measured in 14 male patients undergoing hemodialysis. There was an increase in sensitivity to salt taste following dialysis only when assessed using the bread samples. Patients on a lower sodium diet were more sensitive to salt taste in bread. Although the taste changes were not related to the decreases in serum sodium or to copper, greater increases in sensitivity were related to greater increases in serum zinc during dialysis.  相似文献   
902.
For 40 males who smoked 20 cigarettes a day titratable acidity of the urine was significantly correlated with nicotine/cotinine excretion at several sample intervals, as was urinary pH, but not urinary acidity and daily cigarette consumption or serum COHB.  相似文献   
903.
6 adult subjects (3 men, 3 women) produced highly similar spontaneous speech utterances in quiet and with 90-dB SPL white noise. The frequency of occurrence of perceptual judgments of primary stressing in an utterance was not affected by the masking noise. This finding supplements our previous report that variability for stress production of fundamental frequency (fo) during spontaneous speech was preserved under short-term auditory disruption. Also, it adds further support to the contention that fo is under open-loop regulation.  相似文献   
904.
Children's perception of parental exercise: influence of sex and age   总被引:1,自引:0,他引:1  
The purpose of the study was to document children's perception of parental exercise, relating these perceptions to (1) the self-reported parents' habits of exercise, and (2) the children's own activity patterns. The subjects were 198 students of both sexes, aged 12 to 14 yr. and enrolled in school Grades 7 to 9. A standard questionnaire assessed their perceptions of parental and personal physical activity. Both parents of each subject also reported their respective levels of habitual physical activity. Congruence between the children's perceptions and the self-reported exercise habits of the opposite-sex parent differed for boys and girls, increasing for boys and decreasing for girls between Grades 7 and 9. No significant associations were observed between the children's perception of parental exercise patterns and their own like habits. This suggests that during adolescence parental influences are minimized by other factors, personal or environmental.  相似文献   
905.
The lexical decision task has been employed to investigate the effects of semantic context on word recognition. A frequent finding from the task is that “word” responses are slower when the target is preceded by an unrelated word than when it is preceded by a neutral stimulus. This inhibition effect has been interpreted as indicating that the unrelated prime interferes with word-recognition processes operating on the target. In three experiments, the effects of unrelated primes were compared for a lexical decision and word naming task. Although large inhibition effects were found for the lexical decision task in all experiments, no inhibition effects were observed for the naming task. The results are interpreted as demonstrating that inhibition effects in the lexical decision task are not on recognition processes; rather they are located at processes operating after recognition of the target has occurred.  相似文献   
906.
Punctuation in 20 radio homilies by four speakers accounted for 76% of pause time and 64% of pause number. Pause duration varied systematically according to punctuation type. Commas accounted for 82% of punctuated positionsnot used for pausing.RRelevance for theories of text unitization is discussed. Both typographical and temporal measures are compared with a similar corpus of German homilies.  相似文献   
907.
908.
Mothers' and fathers' responses on the Personality Inventory for Children (PIC) were compared for 360 clinic-referred children and adolescents. Interparent agreement was measured by several different indices. Correlations between parental pairs of scale T-scores derived from each parent averaged .66 for 13 of the profile scales; 9 of the scales exceeded this value. In contrast, mothers and fathers agreed in the classification of the presence of clinical significance an average of 77% of the time across these 13 scales, and pairs of parental PIC profiles contained an average of 3 scales in disagreement. The type of index used to measure interparent agreement was found to affect the results. The discussion examines the nature of interparent disagreement and addresses the implications regarding the use of fathers as informants on this instrument.This article is based on Thomas A. Hulbert's master's thesis. The authors extend their appreciation to James Orisell and Dena Mussaff for their assistance in data preparation and analysis.  相似文献   
909.
The purpose of this study was to analyze asymmetry in echoic memory as a relevant factor in language perception. Two experimental procedures were used: the presentation of temporally segmented words in fragments of 40, 80, 120 and 240 msec, separated by intervals of 40, 80, 120 and 240 msec, similar to the procedures used by A. W. F. Huggins (1975, Perception & Psychophysics, 18, 149-157); the presentation of two tones of short duration, "high" and "low," followed by an interference tone equivalent to the mean frequency of the two tones, closely following the procedure used by D. W. Massaro (1975, in D.W. Massaro (Ed.), Understanding language, New York: Academic Press). A stereophonic tape recorder was used as follows: one channel was employed for the presentation of the words or tones while, through the other channel, the subject received a white noise equivalent in intensity. All subjects carried out the task twice (right ear, left ear) and the order of presentation was counterbalanced. Only the first task showed differences between ears. Implications of the results are analyzed.  相似文献   
910.
Decision processes in visual discrimination of line orientation   总被引:4,自引:0,他引:4  
The contribution of decision factors to the meridional variations in line orientation discrimination was determined for two-alternative forced-choice experimental designs. Using Johnson's (1980) formalization of decision processes in discrimination tasks, we identified three decision factors: the decision rule, memory variance, and criterial noise. In a first experiment, we showed the effect of experimental design on orientation discrimination to be similar at horizontal and oblique standard orientations, indicating that the meridional variations in orientation discrimination were not due to a decision rule anisotropy. In a second experiment, the effect of the interstimulus interval was also found to be similar at both standard orientations, suggesting that the memory variance is isotropic in the orientation domain. The results of two other experiments supported the hypothesis that the meridional variations in orientation discrimination are not due to a criterial noise anisotropy. These different results strongly suggested that the oblique effect in line orientation discrimination is due to sensorial factors rather than to decision factors. Therefore, they further support the hypothesis linking the anisotropy of the preferred orientation distribution of Area 17-S cells (a single physiologically defined class of cells in the primary visual cortex) and the meridional variations in line orientation discrimination.  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