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   3245篇
  免费   183篇
  国内免费   77篇
耳鼻咽喉   9篇
儿科学   228篇
妇产科学   52篇
基础医学   431篇
口腔科学   69篇
临床医学   359篇
内科学   726篇
皮肤病学   107篇
神经病学   160篇
特种医学   419篇
外科学   344篇
综合类   48篇
预防医学   145篇
眼科学   34篇
药学   194篇
  2篇
中国医学   7篇
肿瘤学   171篇
  2022年   13篇
  2021年   35篇
  2020年   24篇
  2019年   32篇
  2018年   56篇
  2017年   33篇
  2016年   40篇
  2015年   54篇
  2014年   81篇
  2013年   91篇
  2012年   100篇
  2011年   94篇
  2010年   120篇
  2009年   114篇
  2008年   102篇
  2007年   144篇
  2006年   111篇
  2005年   90篇
  2004年   83篇
  2003年   70篇
  2002年   74篇
  2001年   79篇
  2000年   71篇
  1999年   71篇
  1998年   144篇
  1997年   161篇
  1996年   137篇
  1995年   121篇
  1994年   120篇
  1993年   101篇
  1992年   60篇
  1991年   63篇
  1990年   63篇
  1989年   80篇
  1988年   75篇
  1987年   64篇
  1986年   71篇
  1985年   64篇
  1984年   45篇
  1983年   32篇
  1982年   34篇
  1981年   40篇
  1980年   38篇
  1979年   31篇
  1978年   15篇
  1977年   27篇
  1976年   28篇
  1975年   16篇
  1974年   15篇
  1972年   15篇
排序方式: 共有3505条查询结果,搜索用时 15 毫秒
991.

Background  

In population studies, body mass index (BMI) is generally calculated from self-reported body weight and height. The self-report of these anthropometrics is known to be biased, resulting in a misclassification of BMI status. The aim of our study is to evaluate the accuracy of self-reported weight, height and waist circumference among a Dutch overweight (Body Mass Index [BMI] ≥ 25 kg/m2) working population, and to determine to what extent the accuracy was moderated by sex, age, BMI, socio-economic status (SES) and health-related factors.  相似文献   
992.
Pallister–Killian syndrome (PKS) is the most frequent form of partial autosomal tetrasomy 12p in humans. Sufferers have a mosaic of isochromosome 12p [i(12p)]. We report the first pre-natal diagnosis on fetal blood cells after cordocentesis during the second trimester. The extra chromosome was first diagnosed by in situ hybridization. Fluorescence in situ hybridization (FISH) was used to count the interphase and/or metaphase cells containing the isochromosome. A review of the literature identified 27 other reports of PKS diagnosed pre-natally. We showed that the most consistent pre-natal ultrasound findings include hypertelorism, broad neck, shorts limbs, abnormal hands or feet, diaphragmatic hernia and hydramnios. Recognition of this congenital malformation pattern pre-natally may allow utilization of FISH.  相似文献   
993.
994.
Krukenberg tumor clinically mimics primary ovarian cancer. We report a series of 15 cases of Krukenberg tumor. The patients' age range from 13 to 71 years. Most ovarian tumors (14/15) were bilateral. A primary digestive tumor was diagnosed pre-operatively in 3 cases, per-operatively in 3 cases and post-operatively in 4 cases. No primary tumor was identified in the 5 other cases. Histological diagnosis of Krukenberg tumor is usually easy either on paraffin or frozen sections. Mucin stains are helpful. Two main histological types were found in our series : the classic form with sarcoma-like storiform tumoral stroma and an alternative cellular-acellular pattern. Mucinous carcinoid was microscopically challenged in two cases. Most patients died within 2 years (median survival 14 months). Nor surgery, neither chemotherapy is efficient but bilateral oophorectomy should be proposed in post-menopausal women with gastric linitis removed surgically.  相似文献   
995.
996.
Neuronal expression of cyclooxygenase-2 (COX-2) and cell cycle proteins is suggested to contribute to neurodegeneration during Alzheimer's disease (AD). The stimulus that induces COX-2 and cell cycle protein expression in AD is still elusive. Activated glia cells are shown to secrete substances that can induce expression of COX-2 and cell cycle proteins in vitro. Using post mortem brain tissue we have investigated whether activation of microglia and astrocytes in AD brain can be correlated with the expression of COX-2 and phosphorylated retinoblastoma protein (ppRb). The highest levels of neuronal COX-2 and ppRb immunoreactivity are observed in the first stages of AD pathology (Braak 0–II, Braak A). No significant difference in COX-2 or ppRb neuronal immunoreactivity is observed between Braak stage 0 and later Braak stages for neurofibrillary changes or amyloid plaques. The mean number of COX-2 or ppRb immunoreactive neurons is significantly decreased in Braak stage C compared to Braak stage A for amyloid deposits. Immunoreactivity for glial markers KP1, CR3/43 and GFAP appears in the later Braak stages and is significantly increased in Braak stage V-VI compared to Braak stage 0 for neurofibrillary changes. In addition, a significant negative correlation is observed between the presence of KP1, CR3/43 and GFAP immunoreactivity and the presence of neuronal immunoreactivity for COX-2 and ppRb. These data show that maximal COX-2 and ppRb immunoreactivity in neurons occurs during early Braak stages prior to the maximal activation of astrocytes and microglia. In contrast to in vitro studies, post mortem data do not support a causal relation between the activation of microglia and astrocytes and the expression of neuronal COX-2 and ppRb in the pathological cascade of AD.  相似文献   
997.
998.
Summary Among conjoined twins (1 out 50000 births), thoracopagus occurs most frequently and is generally lethal. Our anatomical study of five sets of sternopagus twins (3 female, 2 male) was performed to determine the ability of prenatal sonography to detect these anomalies. Autopsy in four cases revealed identical malformations: common sternum, single malformed heart, joined hepatic parenchyma, and a common small bowel leading to a cystic dilatation situated on the ileal segment at the end of the superior mesenteric artery. The diagnosis of conjoined twins was made in all cases by prenatal sonography at the mean time of 24.6 gestation weeks (range 19–34). The malformations detected by prenatal sonography were a single cardiac mass (all cases), joined hepatic parenchymas (3 cases), and an ileal cystic dilatation (1 case). Pregnancy was terminated in four cases. In one case cesarean delivery was performed, and the infants died 48 hours later. Prenatal sonography currently seems to be the best examination for diagnosis of sternopagus twins and the detection of lethal malformations thus allowing interruption of pregnancy.
Etude anatomique de cinq jumeaux conjoints sternopages de diagnostic anté-natal
Résumé Les jumeaux conjoints représentent 1 pour 50000 naissances, les thoracopages sont les plus fréquents et présentent le plus souvent des malformations léthales. Une étude anatomique des malformations rencontrées chez les jumeaux conjoints sternopages a été effectuée dans le but d'évaluer l'intérêt de l'échographie anté-natale pour le diagnostic de ces malformations. Nous avons étudié anatomiquement cinq jumeaux conjoints (3 féminins, 2 masculins). Un examen nécropsique a été réalisé quatre fois, montrant dans tous les cas les mêmes malformations: sternum commun, coeur unique malformatif, union des parenchymes hépatiques, grèle commun aboutissant à une poche kystique située sur le segment iléal de l'intestin grèle, à la terminaison de l'artère mésentérique supérieure. Le diagnostic de jumeaux conjoints avait dans tous les cas été porté en anté-natal par les échographies, à un terme moyen de 26,6 semaines d'aménorrhée (extrèmes 21–26). Les malformations retrouvées par les échographies étaient: dans tous les cas une masse cardiaque unique, trois fois une union des parenchymes hépatiques, une fois une poche kystique du grèle. Le diagnostic avait conduit quatre fois à une interruption médicale précoce de la grossesse. Dans un cas une césarienne avait été pratiquée, les enfants étaient morts 48 heures après. L'échographie anté-natale nous semble actuellement le meilleur examen pour faire le diagnostic de jumeaux conjoints et rechercher des malformations léthales conduisant à une interruption de la grossesse.
  相似文献   
999.
A review of the literature over the last five years reveals that the results of treatment of pancreatic carcinoma have barely improved over the last thirty years, except in terms of the operative mortality which has markedly improved over the last decade. Pancreatectomy still constitutes the only, although slight, chance of cure. It must be reserved to the rare macroscopically curable cases, i.e. small tumours of the head of the pancreas, apparently confined to the pancreas. Palliative treatments should preferably be surgical. Endoscopic biliary drainage should only be performed in inoperable cases. Adjuvant radiotherapy and chemotherapy must be integrated into curative and palliative strategies. These various therapeutic modalities can only be evaluated by means of prospective studies and controlled trials.  相似文献   
1000.
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