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   1694064篇
  免费   126542篇
  国内免费   3780篇
耳鼻咽喉   21770篇
儿科学   55643篇
妇产科学   46180篇
基础医学   241432篇
口腔科学   48767篇
临床医学   151418篇
内科学   333947篇
皮肤病学   38682篇
神经病学   131221篇
特种医学   63900篇
外国民族医学   242篇
外科学   257437篇
综合类   38951篇
现状与发展   4篇
一般理论   531篇
预防医学   124298篇
眼科学   40229篇
药学   123767篇
  7篇
中国医学   4481篇
肿瘤学   101479篇
  2021年   12816篇
  2019年   13536篇
  2018年   19981篇
  2017年   15241篇
  2016年   16642篇
  2015年   18988篇
  2014年   26247篇
  2013年   37995篇
  2012年   52823篇
  2011年   55523篇
  2010年   32811篇
  2009年   30738篇
  2008年   51588篇
  2007年   54898篇
  2006年   55349篇
  2005年   52616篇
  2004年   50823篇
  2003年   48234篇
  2002年   46445篇
  2001年   91853篇
  2000年   93662篇
  1999年   77012篇
  1998年   19742篇
  1997年   17290篇
  1996年   17411篇
  1995年   16758篇
  1994年   15298篇
  1993年   14082篇
  1992年   57411篇
  1991年   55299篇
  1990年   52992篇
  1989年   50763篇
  1988年   46151篇
  1987年   44953篇
  1986年   42244篇
  1985年   40006篇
  1984年   29357篇
  1983年   24920篇
  1982年   13902篇
  1979年   25537篇
  1978年   17581篇
  1977年   14911篇
  1976年   13874篇
  1975年   14567篇
  1974年   17636篇
  1973年   16950篇
  1972年   15677篇
  1971年   14457篇
  1970年   13434篇
  1969年   12522篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
The triphalangeal thumb-brachyectrodactyly syndrome is a very rare autosomal dominant disorder of unknown etiology characterized by an unusual pattern of limb malformations: triphalangeal thumbs and brachyectrodactyly in the hands, and ectrodactyly in the feet. In a previous report, we described the clinical and radiographical features of three related subjects with the disease and suggest that due to the unusual combination of limb defects and to its phenotypic similarity with the limb malformative pattern induced by disrupting the Hoxd13 gene in mouse, the triphalangeal thumb-brachyectrodactyly syndrome might be caused by mutations in a HOX gene. After sequencing the entire coding region of HOXD13 and the highly conserved homeodomain encoding region of HOXA13, we do not detect any deleterious mutation in any of the patients excluding that alterations at these sequences are responsible for the disease. Mutations in regulatory regions of these genes or in other genes involved in limb development might be responsible for the disease.  相似文献   
993.
994.
The authors report the association of erythroleukemia (FAB M6) and fetal hemoglobin (HbF) level of at least 65% after therapy for ovarian carcinoma. The patient's erythrocytes had many signs of reversion to fetal-like erythropoiesis including: elevated HbF with a fetal G gamma/A gamma (gly/ala) of 3/1, low hemoglobin A2 (HbA2), macrocytosis, and increased i antigen. These data and data from other case reports suggest that elevation of HbF to greater than 25% with reversion to fetal-like erythropoiesis is useful in differentiating erythroleukemia from other preleukemic disorders.  相似文献   
995.
Ranitidine influences the uptake of oral midazolam.   总被引:1,自引:0,他引:1       下载免费PDF全文
In a randomised crossover study in volunteers plasma midazolam levels were estimated for 24 h following 15 mg by mouth, either preceded by no medication or following 24 h therapy with ranitidine. Administration of the H2-receptor blocker significantly increased bioavailability of the benzodiazepine and resulted in higher plasma levels for the first 6 h after taking midazolam. This was accompanied by a greater soporific effect.  相似文献   
996.
The development of identically sited carcinomas of the colon in monozygotic twins is described. Presentation occurred with 2 years of each other. They are discussed in the context of the cancer-family syndrome.  相似文献   
997.
998.
The authors present an improvement to a sigma-filter extrapolation method for the reconstruction of magnetic resonance (MR) images from symmetric discrete Fourier data. By making use of the phase information in the image data, the proposed method can overcome the data inconsistency problem of the original method for handling MR image data with large phase variations, such as those obtained in gradient-echo pulse sequences. Reconstruction results show that its performance is comparable with that of the modified complex sigma-filter method proposed previously to handle the inconsistency problem. However, the new approach has the advantage of reducing computation time by a factor of two with use of a sigma filter applied to real instead of complex images. It is expected that this method will be more practical for use in clinical MR imaging systems.  相似文献   
999.
Seventy seven antral biopsies were collected from patients attending endoscopy clinic at King Khalid University Hospital, Riyadh, Saudi Arabia during a period of six months between December 1988 to May 1989. Of these 69 (89.6%) showed chronic gastritis as well as Helicobacter-like organisms (HLOs) in the biopsy specimens while 63 (81.8%) of biopsies grew Helicobacter pylori on culture. These findings indicate a good correlation between the histological diagnosis of chronic gastritis and isolation of H. pylori on culture.  相似文献   
1000.
To measure prefrontal and subcortical activity during a cognitive task, we examined 19 newly diagnosed schizophrenics and patients with schizophreniform psychosis. Seven healthy volunteers served as controls. The patients were drug naive or had received neuroleptics for a few days only. Cerebral blood flow distribution was depicted by single photon emission computed tomography at rest and during activation with the Wisconsin Card Sorting Test. A significant relative activation deficit in the left inferior-prefrontal region was revealed during the Wisconsin Card Sorting Test in the patient group. Furthermore, the patients had impaired striatal suppression on the left side during the cognitive task. The test performance was significantly impaired in the patients. The inability to reduce striatal activity may be due to a lack of corticostriatal feedback during prefrontal activation.  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