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   1698832篇
  免费   126658篇
  国内免费   3784篇
耳鼻咽喉   21960篇
儿科学   55826篇
妇产科学   46375篇
基础医学   242169篇
口腔科学   48873篇
临床医学   151740篇
内科学   334661篇
皮肤病学   38827篇
神经病学   131612篇
特种医学   64227篇
外国民族医学   247篇
外科学   258143篇
综合类   38985篇
现状与发展   4篇
一般理论   532篇
预防医学   124719篇
眼科学   40276篇
药学   124070篇
  7篇
中国医学   4479篇
肿瘤学   101542篇
  2021年   12858篇
  2019年   13592篇
  2018年   20035篇
  2017年   15268篇
  2016年   16698篇
  2015年   19047篇
  2014年   26322篇
  2013年   38092篇
  2012年   52975篇
  2011年   55656篇
  2010年   32939篇
  2009年   30865篇
  2008年   51780篇
  2007年   55047篇
  2006年   55529篇
  2005年   52821篇
  2004年   50989篇
  2003年   48369篇
  2002年   46574篇
  2001年   91979篇
  2000年   93827篇
  1999年   77163篇
  1998年   19804篇
  1997年   17330篇
  1996年   17446篇
  1995年   16789篇
  1994年   15326篇
  1993年   14099篇
  1992年   57487篇
  1991年   55372篇
  1990年   53092篇
  1989年   50875篇
  1988年   46212篇
  1987年   45047篇
  1986年   42321篇
  1985年   40083篇
  1984年   29423篇
  1983年   24952篇
  1982年   13940篇
  1979年   25604篇
  1978年   17623篇
  1977年   14975篇
  1976年   13925篇
  1975年   14636篇
  1974年   17706篇
  1973年   17015篇
  1972年   15742篇
  1971年   14511篇
  1970年   13480篇
  1969年   12582篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
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   
992.
993.
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   
994.
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   
995.
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   
996.
997.
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   
998.
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   
999.
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   
1000.
Blood bank staff, 8 out of 25 (32%) have been exposed to hepatitis B virus (HBV) and the prevalence of HBV markers in blood bank employees handling high risk subjects show hepatitis B surface antigen (n = 1), hepatitis B surface antibody (n = 7), hepatitis B core antibody (n = 6) and combined hepatitis B surface antibody and hepatitis B core antibody (n = 6) seropositivity but all are negative to human immunodeficiency virus (HIV). Serum alanine aminotransferase was raised in the employees than normal subjects and it is suggestive of sub-clinical hepatitis. The employees of blood bank should be trained for proper handling of test materials and must be periodically monitored for HBV and HIV. Immunisation for HBV is mandatory only for the employees of transfusion centre which handles high risk subjects.  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