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   1485645篇
  免费   108568篇
  国内免费   2500篇
耳鼻咽喉   20851篇
儿科学   50421篇
妇产科学   39603篇
基础医学   212161篇
口腔科学   38524篇
临床医学   128985篇
内科学   302577篇
皮肤病学   33434篇
神经病学   119567篇
特种医学   56979篇
外国民族医学   715篇
外科学   221288篇
综合类   28031篇
现状与发展   1篇
一般理论   465篇
预防医学   115521篇
眼科学   31710篇
药学   109439篇
  3篇
中国医学   3060篇
肿瘤学   83378篇
  2021年   12156篇
  2019年   13386篇
  2018年   20159篇
  2017年   14741篇
  2016年   15741篇
  2015年   17722篇
  2014年   23217篇
  2013年   35251篇
  2012年   51414篇
  2011年   53475篇
  2010年   30432篇
  2009年   27745篇
  2008年   49318篇
  2007年   52756篇
  2006年   51804篇
  2005年   50470篇
  2004年   48751篇
  2003年   46565篇
  2002年   45228篇
  2001年   67626篇
  2000年   70158篇
  1999年   59719篇
  1998年   15927篇
  1997年   14426篇
  1996年   14789篇
  1995年   14009篇
  1994年   13246篇
  1993年   12223篇
  1992年   46632篇
  1991年   45364篇
  1990年   43988篇
  1989年   41733篇
  1988年   38484篇
  1987年   37674篇
  1986年   34981篇
  1985年   33551篇
  1984年   25116篇
  1983年   21102篇
  1982年   12250篇
  1981年   11107篇
  1979年   22185篇
  1978年   15434篇
  1977年   13092篇
  1976年   12150篇
  1975年   13222篇
  1974年   15411篇
  1973年   14864篇
  1972年   13619篇
  1971年   12358篇
  1970年   11646篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
The authors aimed at evaluating the impact of psychotraumas in psychiatric outpatients. One hundred forty psychiatric outpatients were consecutively included, without distinction of their current pathology. They filled in an inventory of potentially traumatic experiences, a psychological dissociative experiences scale, a somatoform dissociative experiences questionnaire, and underwent a structured interview for diagnosis of posttraumatic stress disorder (according to the DSM-IV). One hundred subjects related psychological trauma, and 76 patients suffered from posttraumatic stress disorder. Dissociative disorders are found significantly correlated with traumatic experience and to posttraumatic stress disorder. The traumatic impact is found more substantial as the number of events was elevated. This study confirms the elevated prevalence of the psychological traumas and psychotraumatic aftermaths in outpatients of a department of psychiatry, independently from the mental disorder.  相似文献   
102.
Duration of the speech disfluencies of beginning stutterers   总被引:1,自引:0,他引:1  
This study compared the duration of within-word disfluencies and the number of repeated units per instance of sound/syllable and whole-word repetitions of beginning stutterers to those produced by age- and sex-matched nonstuttering children. Subjects were 10 stuttering children [9 males and 1 female; mean age 4:1 (years:months); age range 3:2-5:1), and 10 nonstuttering children (9 males and 1 female; mean age 4:0; age range: 2:10-5:1). Mothers of the stuttering children reported that their children had been stuttering for 1 year or less. One 300-word conversational speech sample from each of the stuttering and nonstuttering children was analyzed for (a) mean duration of sound/syllable repetition and sound prolongation, (b) mean number of repeated units per instance of sound/syllable and whole-word repetition, and (c) various related measures of the frequency of all between- and within-word speech disfluencies. There were no significant between-group differences for either the duration of acoustically measured sound/syllable repetitions and sound prolongations or the number of repeated units per instance of sound/syllable and whole-word repetition. Unlike frequency and type of speech disfluency produced, average duration of within-word disfluencies and number of repeated units per repetition do not differentiate the disfluent speech of beginning stutterers and their nonstuttering peers. Additional analyses support findings from previous perceptual work that type and frequency of speech disfluency, not duration, are the principal characteristics listeners use in distinguishing these two talker groups.  相似文献   
103.
The degree of metabolic acidosis at birth has been calculated in cord artery and vein samples from 21 term fetuses with cord artery pH less than 7.20. The aim of the study was to compare base deficit values calculated from either Siggaard-Andersen alignment nomogram (BD blood) or the Acid-Base chart (BD extra cellular fluid, BDecf). BDblood was found to be consistently higher in the cord artery as compared with BDecf, 13.2 +/- 3.5 and 9.9 +/- 2.9 mmol/l (Mean +/- SD), respectively. A significant correlation was found between cord artery PCO2 and BDblood whereas BDecf appeared unaffected by PCO2. In cases with cord entanglement BDecf a-v differences were increased to 3.4 +/- 2.3 mmol/l as compared with the small a-v difference noted in acidotic cases without cord entanglement, 1.1 +/- 1.25 mmol/l. It is speculated that with acutely emerging, intermittent asphyxia due to cord compression, a cord artery and vein difference in metabolic acidosis may exist and where the vein captures the basal level and the artery the acute changes. It is concluded that BDecf in both cord artery and vein add valuable information on the mechanisms behind metabolic acidosis.  相似文献   
104.
The Authors examine the correlation between hypertensive disorders of pregnancy and fetal growth. The results of a study of 342 pregnancies, confirm a significant correlation between hypertension and fetal growth retardation. These findings, so evident in moderate and severe hypertension, have also been confirmed in cases of mild hypertension. The medical treatment also in the pregnancies with mild hypertension, and a larger utilisation of operative deliveries, determined a decrease in perinatal mortality and morbidity.  相似文献   
105.
Background The appearance of eosinophils is a hallmark sign of the allergic late-phase response (LPR). Eosinophil cationic protein (ECP), a readily measurable product released from activated eosinophils, has so far not been evaluated in the ocular LPR. Objective Two sets of trials were performed in order to investigate changes of local and systemic eosinophil activity and their possible link with symptoms and hyper-reactivity in the allergic LPR in the eye. Methods In the first experiment, ECP was analysed in tears and serum and the clinical reaction was evaluated during a 72-h time–course after a single, high-dose allergen challenge out of season in one eye of 15 pollen-sensitized volunteers. In a second experiment, the hypothesis of an increased clinical response to an allergen challenge in an eye that had been provoked with allergen 48h previously was tested in nine sensitized individuals. Results In the first experiment, symptoms at 10 min and 2, 4, 6, 8 and 24 h significantly exceeded base line scores of the challenged eyes. Tear ECP was significantly elevated in challenged eyes compared to contralateral eyes at 6, 8 and 24 h. In addition, symptoms and ECP release correlated significantly at the 24-h evaluation. Serum ECP remained unchanged throughout the study period. In the second experiment, conjunctival hyperreactivity 48h after an allergen challenge was not confirmed. Conclusion ECP secretion occurs in the experimental ocular LPR and is in part associated with the magnitude of the clinical reaction, which suggests a truly pathogenic role of the activated eosinophil in pollen-induced allergic conjunctivitis.  相似文献   
106.
107.
108.
109.
110.
Birth weight on 12,644 singleton infants from 6,196 sibships born in Maryland between 1980 and 1984 were used to estimate the effects of nine maternal and infant covariates on the sibship correlation in birth weight. Assuming a homogeneous correlation across all families, the estimated intraclass correlation was 0.4664 (+/- 0.0099). This high sibship correlation makes it possible to predict, with reasonable accuracy, the birth weight of a child given information on previous sibs, as well as covariates on the mother and/or infant pertinent to a given pregnancy. The reduction in variance associated with incorporating information on the nine covariates used here was approximately equal to that obtained by conditioning on a single previous sib. Testing for heterogeneity in correlation among different groups of families showed that a crude measure of parity (first live birth vs. other), time between births, mother's marital status, and maternal age at the birth of the last child significantly influenced the sibship correlation in birth weight.  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