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   120752篇
  免费   9583篇
  国内免费   3004篇
耳鼻咽喉   1242篇
儿科学   7186篇
妇产科学   3799篇
基础医学   13623篇
口腔科学   1568篇
临床医学   13149篇
内科学   20736篇
皮肤病学   2366篇
神经病学   10493篇
特种医学   2711篇
外国民族医学   3篇
外科学   11065篇
综合类   17121篇
现状与发展   15篇
预防医学   7043篇
眼科学   2204篇
药学   6134篇
  52篇
中国医学   11041篇
肿瘤学   1788篇
  2024年   290篇
  2023年   2059篇
  2022年   4093篇
  2021年   5869篇
  2020年   5341篇
  2019年   4235篇
  2018年   4278篇
  2017年   4390篇
  2016年   4510篇
  2015年   4292篇
  2014年   8372篇
  2013年   8654篇
  2012年   6819篇
  2011年   7947篇
  2010年   6159篇
  2009年   5956篇
  2008年   5795篇
  2007年   5908篇
  2006年   5331篇
  2005年   4419篇
  2004年   3758篇
  2003年   3330篇
  2002年   2287篇
  2001年   2080篇
  2000年   1798篇
  1999年   1674篇
  1998年   1378篇
  1997年   1291篇
  1996年   1239篇
  1995年   1204篇
  1994年   1022篇
  1993年   915篇
  1992年   827篇
  1991年   642篇
  1990年   593篇
  1989年   495篇
  1988年   495篇
  1987年   443篇
  1986年   387篇
  1985年   504篇
  1984年   415篇
  1983年   256篇
  1982年   337篇
  1981年   305篇
  1980年   248篇
  1979年   205篇
  1978年   128篇
  1977年   101篇
  1976年   85篇
  1975年   39篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Specific antibody production and the proliferative response of peripheral blood lymphocytes (PBLs) to a variety of viruses, including herpes simplex virus-type-1 (HSV-1) and varicella zoster (VZ), were studied in 7 patients with Behçet's syndrome. None of the patients produced an antibody response against HSV-1 or VZ. Furthermore, none of the patients showed a proliferative response to VZ, and three of them also failed to mount a response to HSV-I. These results suggest that the PBLs of patients with Behçet's syndrome make an inappropriately poor antibody and proliferative response when stimulated by HSV-1 and VZ.  相似文献   
992.
A Weaver-like syndrome in a Japanese boy   总被引:2,自引:0,他引:2  
A 5½-year-old Japanese boy with a Weaver-like syndrome is reported. In addition to pre- and post-natal overgrowth, mental retardation, an unusual craniofacial appearance and other abnormalities characteristic of the Weaver syndrome, he had several clinical features not described in this syndrome. These unusual features included mongoloid slanting of the palpebral fissures, cleft lip, accessory nipples, pectus excavatum, a bifid xyphoid process, irregularly shaped vertebral bodies, inflexible right thumb, clinodactyly of the fifth fingers, abnormal dermatoglyphic patterns and deep plantar furrows. His carpal bone age corresponded to his chronological age, while the tubular bone age was accelerated.  相似文献   
993.
Summary We report on a sporadic case satisfied with a proposed diagnostic criteria for Cohen syndrome. This 10 year-old Japanese boy had truncal obesity, short stature, mild mental retardation, hypotonia, maxillary hypoplasia, micrognathia, narrow hands and feet, high-arched palate, prominent upper central incisors, high nasal bridge, but no pigmentary retinopathy. Autosomal recessive manner of inheritance was suggested by the pedigree.  相似文献   
994.
Catechol-O-methyltransferase (COMT) activity in erythrocytes was measured in six children with Down's syndrome and in their parents to determine if COMT activity is related to a gene on chromosome 21. A gene dosage effect was a possible explanation of the COMT value in three of the children but not in the other three.  相似文献   
995.
Congenital dysmorphic features are prevalent in schizophrenia and may reflect underlying neurodevelopmental abnormalities. A cluster analysis approach delineating patterns of dysmorphic features has been used in genetics to classify individuals into more etiologically homogeneous subgroups. In the present study, this approach was applied to schizophrenia, using a sample with a suspected genetic syndrome as a testable model. Subjects (n = 159) with schizophrenia or schizoaffective disorder were ascertained from chronic patient populations (random, n = 123) or referred with possible 22q11 deletion syndrome (referred, n = 36). All subjects were evaluated for presence or absence of 70 reliably assessed dysmorphic features, which were used in a three‐step cluster analysis. The analysis produced four major clusters with different patterns of dysmorphic features. Significant between–cluster differences were found for rates of 37 dysmorphic features (P < 0.05), median number of dysmorphic features (P = 0.0001), and validating features not used in the cluster analysis: mild mental retardation (P = 0.001) and congenital heart defects (P = 0.002). Two clusters (1 and 4) appeared to represent more developmental subgroups of schizophrenia with elevated rates of dysmorphic features and validating features. Cluster 1 (n = 27) comprised mostly referred subjects. Cluster 4 (n = 18) had a different pattern of dysmorphic features; one subject had a mosaic Turner syndrome variant. Two other clusters had lower rates and patterns of features consistent with those found in previous studies of schizophrenia. Delineating patterns of dysmorphic features may help identify subgroups that could represent neurodevelopmental forms of schizophrenia with more homogeneous origins. © 2001 Wiley‐Liss, Inc.  相似文献   
996.
We describe a family with at least seven living persons who are affected by an hitherto undescribed autosomal-dominant syndrome with variable expression, bearing close resemblance to the EEC syndrome and related disorders. The main manifestations are hypodontia and/or early loss of permanent teeth, ectrodactyly, obstruction of lacrimal ducts, onychodysplasia, and excessive freckling. We propose the acronym ADULT (acro-der-mato-ungual-lacrimal-tooth)-syndrome for this condition. © 1993 Wiley-Liss, Inc.  相似文献   
997.
Approximately 5% of children with neural tube defects (NTDs) have a congenital heart defect and/or cleft lip and palate. The cause of isolated meningomyelocele, congenital heart defects, or cleft lip and palate has been largely thought to be multifactorial. However, chromosomal, teratogenic, and single gene causes of combinations of NTDs with congenital heart defects and/or cleft lip and palate have been reported. We report on 3 patients with meningomyelocele, congenital heart defects, and 22q11 deletions. Two of the children had the clinical diagnosis of velo-cardio-facial syndrome (VCFS); both also have bifid uvula. The third child had DiGeorge sequence (DGS). The association of NTDs with 22q11 deletions has not been reported previously. An accurate diagnosis of the 22q11 deletions is critical as this micro-deletion and its associated clinical problems is transmitted as an autosomal dominant trait due to the inheritance of the deletion-bearing chromosome. We recommend that all children with NTDs and congenital heart defects, with or without cleft palate, have cytogenetic and molecular studies performed to detect 22q11 deletions. © 1994 Wiley-Liss, Inc.  相似文献   
998.
The recent demonstration that about 20–30% of cases of Down syndrome are of paternal origin has again raised interest in the question of the possible contribution of paternal age independent of maternal age to a couple's risk of a Down syndrome live birth. In this paper the nature of the available evidence is critically reviewed, interpretations reconciling differences between studies that reached opposite conclusions are presented, and an approach to genetic counseling in the face of such apparent differences in the literature is discussed. It is not likely that data from ad hoc studies of parental origin of the extra chromosome will be sufficient to judge the existence or magnitude of paternal age-specific risk, and reliance must be made on statistical studies that searched for paternal age effects while controlling for maternal age. The literature is consistent with an apparent doubling of risk for paternal age 55 and over, but no effect at younger paternal ages. With regard to remarriage, it is suggested that if members of a couple with a 47, +21 child remarry it be assumed that the excess risk “travels” to that new couple which includes the parent in whom non-disjunction occurred in the previous marriage. If parental origin is not known, it is suggested that the risk be calculated on the assumption of a 20–30% likelihood that it was of paternal origin and a 70–80% likelihood that it was of maternal origin, and that the excess empiric risks be apportioned accordingly in the new marriages.  相似文献   
999.
The second case of virilism as a late manifestation of Bardet-Biedl syndrome (BBS) is described, with endocrine and histological evaluation. Both cases manifested ovulatory cycles and developed virilism in adulthood. Elevated plasma testosterone and 17-OH-progesterone were not suppressed by dexamethasone but were suppressed by medroxyprogesterone acetate. Peripheral and ovarian venous blood obtained at the time of surgery demonstrated a marked gradient for testosterone in both ovaries and for progesterone in the ovary bearing the corpus luteum. Histological evaluation of the ovaries demonstrated bilateral ovarian stromal hyperplasia with focal hyperthecosis. Bilateral ovariectomy resulted in complete correction of the endocrine abnormality, although the established hirsutism remains a mark of previous androgen excess.  相似文献   
1000.
We report 3 cases of Pallister-Hall syndrome involving hypothalamic hamartoblastoma, hypopituitarism, cranial, and limb abnormalities. The first 2 cases represent the first apparent sibs reported with this syndrome. Patient 1 represents the first known patient with this syndrome with an abnormal karyotype.  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