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   5367篇
  免费   351篇
  国内免费   14篇
耳鼻咽喉   78篇
儿科学   201篇
妇产科学   101篇
基础医学   694篇
口腔科学   89篇
临床医学   473篇
内科学   1328篇
皮肤病学   344篇
神经病学   357篇
特种医学   164篇
外科学   735篇
综合类   39篇
一般理论   7篇
预防医学   390篇
眼科学   63篇
药学   312篇
中国医学   2篇
肿瘤学   355篇
  2023年   52篇
  2022年   74篇
  2021年   122篇
  2020年   103篇
  2019年   151篇
  2018年   145篇
  2017年   121篇
  2016年   145篇
  2015年   122篇
  2014年   199篇
  2013年   277篇
  2012年   335篇
  2011年   355篇
  2010年   180篇
  2009年   199篇
  2008年   356篇
  2007年   312篇
  2006年   333篇
  2005年   296篇
  2004年   257篇
  2003年   266篇
  2002年   250篇
  2001年   66篇
  2000年   43篇
  1999年   67篇
  1998年   53篇
  1997年   38篇
  1996年   36篇
  1995年   46篇
  1994年   31篇
  1993年   23篇
  1992年   28篇
  1991年   28篇
  1990年   32篇
  1989年   29篇
  1988年   17篇
  1987年   18篇
  1986年   34篇
  1985年   16篇
  1984年   25篇
  1983年   27篇
  1982年   15篇
  1981年   20篇
  1980年   17篇
  1979年   13篇
  1973年   14篇
  1972年   13篇
  1971年   11篇
  1970年   14篇
  1967年   20篇
排序方式: 共有5732条查询结果,搜索用时 15 毫秒
61.
Pulsed Doppler (PW) and tissue Doppler imaging (TDI) measurements are part of every echocardiography examination for evaluation of left ventricular (LV) diastolic function and filling pressure. The purpose of this study was to summarize published data on normal values for PW and TDI measurements. A PubMed search was performed on the 10th of October 2016 to identify relevant articles. Studies were considered relevant if they included more than 200 healthy individuals. A total of 13 studies were identified. Of these, 13 studies with 7777 subjects reported PW measurement over the mitral valve, six studies with 4082 subjects reported PW measurement in the pulmonary vein and 10 studies with 5988 subjects reported TDI. We also report weighted mean values for 14 different variables. As expected, measurements varied with age. There were no major differences between men and women. In contrast, there was a large difference in reported values between studies, in corresponding age groups. This review therefore raises caution about relying on normal values from just one study.  相似文献   
62.
Journal of Thrombosis and Thrombolysis - The relationship between acidosis and coagulopathy has long been described in vitro and in trauma patients, but not yet in orthotopic liver transplantation...  相似文献   
63.
AIDS and Behavior - Social biases may influence providers’ judgments related to pre-exposure prophylaxis (PrEP) and patients’ consequent PrEP access. US primary and HIV care providers...  相似文献   
64.
Simian AIDS-related lymphomas (sARL) of cynomolgus monkeys infected with a simian immunodeficiency virus (SIVsm) were studied in relation to growth in severe combined immunodeficient (SCID) mice, karyotype abnormalities, and DNA sequence of the first noncoding region of the Bcl-6 gene. The tumors were diffuse large B cell lymphomas and expressed a simian homolog to Epstein-Barr virus (HVMF-1) in 12 of 13 primary tumors and corresponding cell lines. A tested cell line was tumorigenic in SCID mice. Tumors in the SCID mice showed cell growth features similar to those in the original lymphoma, suggesting that no subpopulation with growth advantage was selected for in the mice. Spectral karyotype analysis of sARL cell lines showed normal cytogenetic features except for a trisomy of monkey chromosome 2 (corresponding to human chromosomes 7 and 21) in two of five sARL lines, which was not recovered in SCID tumors established from the same cell line. Sequence analysis of a Bcl-6 gene fragment showed sequence variations indicative of population polymorphism(s) in 10 of 13 sARLs, and no evidence of Bcl-6 mutations. Thus Bcl-6 mutations in the first noncoding region are irrelevant for sARL development in cynomolgus monkeys and for tumorigenicity of sARL cell lines. We also demonstrate that no cytogenetic alterations are needed for the development of highly aggressive lymphomas in the SIV-immunosuppressed host.  相似文献   
65.
66.
67.
Multiple myeloma is characterized by a proliferation of clonal B lymphocytes and plasma cells. The idiotypic structure of clonal immunoglobulin (Ig) expressed on the tumour B-cell surface can be regarded as a tumour-specific antigen and, as such, a potential target for anti-idiotypic T and B cells in an immune regulation of the tumour-cell clone. Active immunization using the autologous monoclonal Ig as a 'vaccine' was shown to induce tumour-specific immunity in murine B-cell tumours and in human B-cell lymphoma. With the aim to induce or amplify an anti-idiotypic response in multiple myeloma, five stage I–III patients were repeatedly immunized with the autologous monoclonal IgG. Induction of idiotype-specific cellular immunity was analysed in vitro by an enzyme-linked immunospot assay (interferon-γ and interleukin-4 secreting cells). B cells secreting anti-idiotypic IgM antibodies were also analysed. An anti-idiotypic T-cell response was amplified 1.9–5-fold in three of the five patients during immunization. The number of B cells secreting anti-idiotypic antibodies also increased in these three patients. In two of the patients induction of idiotype-specific immunity was associated with a gradual decrease of blood CD19+ B cells. The induced T-cell response was eliminated during repeated immunization. Further studies are warranted to optimize the immunization schedule in order to achieve a long-lasting T-cell immunity against idiotypic determinants on the tumour clone. A role for immunity in controlling the tumour clone remains to be established.  相似文献   
68.
Hepatic nuclear triiodo-L-thyronine (T3) receptors were studied to investigate the mechanism of thyroid hormone resistance in Richardson's ground squirrels, Spermophilus richardsoni, during the hibernation phase of the annual cycle. The cycle is divided into an active phase and a hibernation phase, the latter composed of alternating dormancy and arousal bouts. In addition to animals in these three states, a group of cold-exposed animals was also examined (those animals held at 6 degrees which showed no indications of entering hibernation). Binding of T3, to squirrel hepatic nuclei from all groups, was characterized as high affinity, Kd ranging from 111 to 267 pM, and low capacity, 50 to 314 fmol T3/mg DNA. Based on these data, other criteria examined, and models established in the literature for other species, this binding site has been tentatively identified as a T3 receptor. Receptor concentrations in nuclei from dormant and aroused squirrels were only 15-20% of the concentration in active animals. There were no differences in the affinity of the T3 receptor over the annual cycle estimated by the in vitro assay at 24-26 degrees. The reduction in nuclear T3 receptors, together with the previously reported increase in serum binding of thyroid hormone, provides an explanation for thyroid hormone resistance during the hibernation phase in S. richardsoni.  相似文献   
69.
70.
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