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   958876篇
  免费   58516篇
  国内免费   1076篇
耳鼻咽喉   12618篇
儿科学   31634篇
妇产科学   25025篇
基础医学   157666篇
口腔科学   25277篇
临床医学   83765篇
内科学   176744篇
皮肤病学   22458篇
神经病学   66929篇
特种医学   35196篇
外国民族医学   116篇
外科学   142154篇
综合类   15680篇
现状与发展   2篇
一般理论   219篇
预防医学   71469篇
眼科学   22531篇
药学   74390篇
  1篇
中国医学   2015篇
肿瘤学   52579篇
  2018年   9886篇
  2016年   8251篇
  2015年   9189篇
  2014年   12420篇
  2013年   18911篇
  2012年   26677篇
  2011年   29187篇
  2010年   16992篇
  2009年   15671篇
  2008年   27423篇
  2007年   29780篇
  2006年   29587篇
  2005年   28263篇
  2004年   27598篇
  2003年   26551篇
  2002年   25840篇
  2001年   43316篇
  2000年   44764篇
  1999年   36852篇
  1998年   9965篇
  1997年   8523篇
  1996年   8835篇
  1995年   8210篇
  1994年   7509篇
  1992年   27778篇
  1991年   28981篇
  1990年   29111篇
  1989年   28276篇
  1988年   25974篇
  1987年   25735篇
  1986年   24150篇
  1985年   23125篇
  1984年   17251篇
  1983年   14693篇
  1982年   8032篇
  1981年   7342篇
  1979年   16680篇
  1978年   11999篇
  1977年   9906篇
  1976年   9959篇
  1975年   11681篇
  1974年   13495篇
  1973年   12977篇
  1972年   12206篇
  1971年   11741篇
  1970年   10929篇
  1969年   10361篇
  1968年   9781篇
  1967年   8771篇
  1966年   7826篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
Medullary thyroid carcinoma (MTC) is a rare form of thyroid cancer representing about 10% of all thyroid malignancies. It occurs mostly as a sporadic tumor or in association with autosomal dominant inherited cancer syndromes--multiple endocrine neoplasia (MEN) types 2A and 2B and familial MTC. Germline mutations in exons 8, 10, 11, 13, 14, 15 and 16 of the RET proto-oncogene are found in most of the familial cases. There are only a few published data reporting multiple germline mutations in the RET proto-oncogene. We have detected double germline mutations in 2 different exons on the same RET allele in two MEN 2 families. In the MEN 2A family, double germline mutation in exons 10 (Cys620Phe) and 13 (Tyr791Phe) was detected. In the MEN 2B family, beside the classical germline mutation in exon 16 (Met918Thr) a second germline mutation in exon 13 (Tyr791Phe) was found. This study revealed that MEN 2 syndromes can also be caused by double germline mutations in the RET proto-oncogene and these families can be added to small worldwide cohort of families with multiple germline mutations.  相似文献   
15.
The New Zealand obese mouse (NZO/Hl) is characterised by hereditary obesity and type-2 diabetes, including insulin resistance, hyperinsulinaemia, and glucose intolerance. In other diabetic models, it has been revealed that the proper functioning of the glucose transporter isoform 2 (GLUT2) is essential for adequate secretion of insulin. The aim of this study was to compare the distribution of islet cells and GLUT2, as well as the expression of GLUT2-mRNA, in the pancreas of NZO mice and metabolically unimpaired NMRI (Naval Medical Research Institute) mice. Pancreas tissue was obtained from different stages of development. For molecular determination of the expression level of GLUT2-mRNA, total-RNA was extracted from the pancreas and analysed by quantitative real-time RT-PCR. All investigated NZO mice displayed increased weight, elevated hyperinsulinaemia, and slightly enhanced blood glucose levels compared with the NMRI control mice. By means of immunofluorescence microscopy drastically reduced insulin levels were detected, which might be compensated by the observed islet cell hyperplasia and hypertrophy. Furthermore, the normally peripheral localisation of the alpha-cells within islets was disturbed. By contrast, there were no changes in somatostatin cell distribution. However, considerable differences appeared with regard to GLUT2: whereas the beta-cells of NMRI mice showed dense immunostaining of the GLUT2 transporter on the cell surface, in all age groups of NZO mice, GLUT2 on the plasma membranes was reduced and dispersed in the cytoplasm. These findings agree with the molecular biological results, which displayed decreased mRNA-expression of GLUT2. In summary, the observed alteration of islet morphology and of GLUT2 expression in diabetic mice complements our previous results from a superfusion protocol and further clarifies the mechanisms of diabetogenesis in NZO mice.  相似文献   
16.
17.
18.
The clinical outcome and appropriate management for patients showing 'borderline changes' on allograft biopsy after renal transplantation is still controversial. In an attempt to identify predictive factors of clinical outcome of patients with such lesions, we reviewed the clinical course of 91 patients with borderline changes. Multivariate analysis revealed significant and independent effects of histological stage (i + t < or = or > 2) and time to borderline changes (< or = or > 3 months after transplant) on serum creatinine levels at 1 year from borderline changes episodes (respectively, p = 0.04 and p = 0.02) and only a significant effect of time to borderline changes on serum creatinine levels at 2 years (p = 0.005). Renal function at 1 year and 2 years as 5- and 8-year graft survival were not significantly different in the group of patients treated with antirejection therapy (T group, n = 49) compared with the untreated group (UT group, n = 42). This study strongly suggests that borderline changes with histological score (i + t) > 2 and late episodes of borderline changes should be considered to be of poor prognosis.  相似文献   
19.
Endoscopic clips have been used mainly for control of gastrointestinal (GI) bleeding and occasionally for closure of GI perforations. However, closure of spontaneous esophageal perforation (Boerhaave's syndrome) by clipping has not been reported. We described successful non-surgical closure of spontaneous esophageal perforation by endoscopic clipping in a patient with bilateral pyopneumothorax and septicemia.  相似文献   
20.
Cutaneous plasmacytosis is a rare disorder characterized by a benign proliferation of mature plasma cells that appears as multiple dark-brown to purplish skin lesions, often associated with polyclonal hypergammaglobulinaemia. We present the case of a 55-year-old Caucasian man who suffered from a cutaneous plasmacytosis associated with two different carcinomas. Cutaneous plasmacytosis seems to be a reactive process because most cases reported are not associated with any apparent underlying disease. Nevertheless, because few reported cases were associated with malignancies, screening of additional neoplasms would be justified.  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