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   3745282篇
  免费   312352篇
  国内免费   13858篇
耳鼻咽喉   51516篇
儿科学   119478篇
妇产科学   97942篇
基础医学   584659篇
口腔科学   103616篇
临床医学   334984篇
内科学   668325篇
皮肤病学   95648篇
神经病学   320397篇
特种医学   149682篇
外国民族医学   502篇
外科学   578126篇
综合类   114262篇
现状与发展   23篇
一般理论   2437篇
预防医学   312760篇
眼科学   86592篇
药学   262062篇
  22篇
中国医学   10202篇
肿瘤学   178257篇
  2021年   55454篇
  2020年   35284篇
  2019年   58278篇
  2018年   71974篇
  2017年   54812篇
  2016年   60678篇
  2015年   74538篇
  2014年   108952篇
  2013年   174221篇
  2012年   100480篇
  2011年   101217篇
  2010年   118835篇
  2009年   122727篇
  2008年   88626篇
  2007年   92277篇
  2006年   103051篇
  2005年   98132篇
  2004年   100561篇
  2003年   90820篇
  2002年   80525篇
  2001年   121012篇
  2000年   115329篇
  1999年   111868篇
  1998年   67146篇
  1997年   64694篇
  1996年   62688篇
  1995年   58280篇
  1994年   52406篇
  1993年   48959篇
  1992年   83033篇
  1991年   79498篇
  1990年   76044篇
  1989年   74691篇
  1988年   69527篇
  1987年   68200篇
  1986年   65003篇
  1985年   64892篇
  1984年   56677篇
  1983年   51336篇
  1982年   44816篇
  1981年   41962篇
  1980年   39574篇
  1979年   49009篇
  1978年   40999篇
  1977年   36814篇
  1976年   34118篇
  1975年   32871篇
  1974年   35571篇
  1973年   34248篇
  1972年   31735篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
SUMMARY. Samples from 1828 donations were screened for anti-HBc at seven sites in the UK using kits supplied by 10 manufacturers. Only 10 (0.55%) donations were considered to have true anti-HBc reactivity and these were detected by all 10 kits. Additional markers of HBV infection were found in nine of these 10 donations. Additional reactives were found by all kits, the number ranging from 1 to 43.
In the four more specific kits, the 10 true reactives were clearly distinguished from the 'false reactives' by the strength of the reaction. It is concluded that the reliance on a single ELISA test for anti-HBc diagnosis is unwise. The use of a second test known to be more specific than the screening ELISA is recommended.  相似文献   
994.
In the present study, we examined the effect of CsA on the in vitro production of Ig and on the in vitro production of molecules known to have B-cell growth and differentiation activities, such as IL-6 and sCD23. For the purpose of this study, we developed an experimental In vitro system closely resembling an In vivo model of ongoing B-cell activation. Pre-activated B cells proliferated and produced IgM optimally when they were re-cultured in the presence of IL-2/IL-6. CsA down-regulated the IL-2/IL-6-induced proliferative responses of pre activated B cells by at least 50%., but it up-regulated IgM production in the same experiments. This up regulating effect was not cytokine-related since it was also seen when cells were re-cultured in the absence of any cytokines. Optimal release of sCD23 was observed when SAC-pre-activated B cells were re cultured in the presence of IL-4 or IL-4 plus IL-2 and CsA up-regulated significantly the release of this molecule in these cultures. Finally, CsA was shown to inhibit PHA-induced cell proliferation of PBMC and to up-rcgulate IL-6 production in the same cultures. We conclude that CsA can amplify in vitro both the production of Ig and the release of sCD23 by pre activated B cells. This finding, in combination with the CsA-induced up-regulation of lectin-induced IL-6 production, may have clinical implications in disease states with an ongoing immune activation, where prolonged administration of CsA might be anticipated.  相似文献   
995.
996.
Summary Squamous cell carcinoma of the head and neck is a disease predominantly of males and is due to a variety of known environmental irritants, notably cigarette smoke. Dietary, viral and immunological factors may also be relevant. Head and neck squamous cancers express epidermal growth factor receptors and some show weak levels of oestrogen receptor activity, but a reliable serum marker of tumour burden remains to be identified. The prognosis is found to be less favourable in females, in those with advanced T stage, in association with multiple node involvement, especially where extracapsular spread is present and where the T4/T8 ratio is elevated. Administration of heterologous blood during therapy may also have an adverse effect on prognosis. Interested clinicians must remember that most cases are preventable. Correspondence to: A.G.D. Maran  相似文献   
997.
Data on 232 members of a single pedigree, descended from two pairs of original parents, were made available to the participants of Genetic Analysis Workshop 8 (GAW8). In addition to information concerning age and sex, measurements for 10 quantitative traits and genotypes at 22 polymorphic marker loci were also provided for a subset of 193 of these family members. © 1993 Wiley-Liss, Inc.  相似文献   
998.
999.
We have presented a rare case of primary involvement of the anterior mediastinum by osteogenic sarcoma in which CT was useful in demonstrating calcium within the mass, and in distinguishing the mass from surrounding bony structures. Although rare, extraosseous osteogenic sarcoma should be included in the differential diagnosis of a calcified anterior mediastinal mass.  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