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   3719057篇
  免费   311649篇
  国内免费   13773篇
耳鼻咽喉   50994篇
儿科学   118664篇
妇产科学   97460篇
基础医学   581936篇
口腔科学   103238篇
临床医学   332352篇
内科学   663424篇
皮肤病学   95286篇
神经病学   317891篇
特种医学   148901篇
外国民族医学   497篇
外科学   573569篇
综合类   113905篇
现状与发展   23篇
一般理论   2388篇
预防医学   310617篇
眼科学   86127篇
药学   260438篇
  22篇
中国医学   10128篇
肿瘤学   176619篇
  2021年   55116篇
  2020年   35107篇
  2019年   58042篇
  2018年   71507篇
  2017年   54524篇
  2016年   60332篇
  2015年   74295篇
  2014年   108602篇
  2013年   173767篇
  2012年   97907篇
  2011年   98405篇
  2010年   117941篇
  2009年   122243篇
  2008年   86182篇
  2007年   89603篇
  2006年   100554篇
  2005年   95695篇
  2004年   98251篇
  2003年   88664篇
  2002年   78563篇
  2001年   120995篇
  2000年   115287篇
  1999年   111844篇
  1998年   67070篇
  1997年   64622篇
  1996年   62622篇
  1995年   58246篇
  1994年   52399篇
  1993年   48945篇
  1992年   83036篇
  1991年   79504篇
  1990年   76054篇
  1989年   74695篇
  1988年   69532篇
  1987年   68227篇
  1986年   65027篇
  1985年   64887篇
  1984年   56643篇
  1983年   51361篇
  1982年   44808篇
  1981年   41958篇
  1980年   39550篇
  1979年   49035篇
  1978年   41002篇
  1977年   36827篇
  1976年   34106篇
  1975年   32870篇
  1974年   35576篇
  1973年   34236篇
  1972年   31732篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
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   
992.
993.
994.
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   
995.
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   
996.
997.
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   
998.
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   
999.
1000.
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   
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