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   4350440篇
  免费   364251篇
  国内免费   15964篇
耳鼻咽喉   62652篇
儿科学   135005篇
妇产科学   112879篇
基础医学   658819篇
口腔科学   119716篇
临床医学   400843篇
内科学   792735篇
皮肤病学   107404篇
神经病学   374221篇
特种医学   173319篇
外国民族医学   912篇
外科学   670234篇
综合类   126744篇
现状与发展   91篇
一般理论   2605篇
预防医学   365868篇
眼科学   102351篇
药学   303690篇
  24篇
中国医学   11393篇
肿瘤学   209150篇
  2021年   56993篇
  2020年   37949篇
  2019年   59534篇
  2018年   76603篇
  2017年   59175篇
  2016年   65839篇
  2015年   79046篇
  2014年   116528篇
  2013年   181862篇
  2012年   121322篇
  2011年   124542篇
  2010年   127759篇
  2009年   132092篇
  2008年   111392篇
  2007年   117338篇
  2006年   127517篇
  2005年   121859篇
  2004年   122243篇
  2003年   112672篇
  2002年   103108篇
  2001年   155649篇
  2000年   151394篇
  1999年   140557篇
  1998年   72765篇
  1997年   68989篇
  1996年   66535篇
  1995年   62345篇
  1994年   56120篇
  1993年   51997篇
  1992年   103918篇
  1991年   99400篇
  1990年   94414篇
  1989年   92039篇
  1988年   85607篇
  1987年   84041篇
  1986年   79728篇
  1985年   78087篇
  1984年   66067篇
  1983年   58951篇
  1982年   48228篇
  1981年   44949篇
  1980年   42227篇
  1979年   57865篇
  1978年   47083篇
  1977年   41644篇
  1976年   38688篇
  1975年   37875篇
  1974年   42452篇
  1973年   40585篇
  1972年   38050篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
Using hierarchical cluster analysis, applied to 47 cases of Guillain-Barre Syndrome (GBS) incident in South-West Stockholm (SWS) during the period from January 1973 to June 1992, we identified three major clinicoepidemiological subgroups. The first subgroup, 25.5% of the cases (26.7 ± 6.7 years), recorded a peak incidence at ages 20–29 years and presented significant differences from other subgroups, a high proportion of cases with onset at low age preceded by respiratory infection (83.3%) and with normal motor conduction velocity (50.0%). Also found, were less affected biological parameters, a rapidly progressive course and independence in gait at one month after onset. A second subgroup, 27.7% of cases, was severely affected, clinically and functionally. It consisted predominantly of young individuals (22.7 ± 11.1 years), with a high incidence (69.2% of cases) in autumn. A third subgroup, comprising 40.47; of cases, was older (61.1 ± 11.0 years) and, in general, also severely affected. The incidence of this form appeared to be invariant with time.  相似文献   
994.
995.
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   
996.
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   
997.
998.
999.
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   
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