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   636篇
  免费   75篇
  国内免费   5篇
耳鼻咽喉   1篇
儿科学   29篇
妇产科学   16篇
基础医学   67篇
口腔科学   7篇
临床医学   64篇
内科学   128篇
皮肤病学   8篇
神经病学   22篇
特种医学   82篇
外科学   107篇
综合类   42篇
预防医学   53篇
眼科学   6篇
药学   36篇
肿瘤学   48篇
  2023年   3篇
  2022年   5篇
  2021年   8篇
  2020年   5篇
  2019年   6篇
  2018年   14篇
  2017年   9篇
  2016年   8篇
  2015年   10篇
  2014年   10篇
  2013年   28篇
  2012年   12篇
  2011年   15篇
  2010年   26篇
  2009年   27篇
  2008年   9篇
  2007年   22篇
  2006年   33篇
  2005年   18篇
  2004年   41篇
  2003年   21篇
  2002年   19篇
  2001年   5篇
  2000年   7篇
  1999年   12篇
  1998年   29篇
  1997年   24篇
  1996年   21篇
  1995年   31篇
  1994年   20篇
  1993年   7篇
  1992年   10篇
  1991年   14篇
  1990年   15篇
  1989年   24篇
  1988年   18篇
  1987年   16篇
  1986年   18篇
  1985年   5篇
  1984年   12篇
  1983年   14篇
  1982年   3篇
  1981年   7篇
  1980年   8篇
  1978年   5篇
  1977年   7篇
  1972年   4篇
  1969年   3篇
  1968年   5篇
  1967年   4篇
排序方式: 共有716条查询结果,搜索用时 15 毫秒
21.
Indian Journal of Thoracic and Cardiovascular Surgery -  相似文献   
22.
23.
Kauppila J H, Takala H, Selander K S, Lehenkari P P, Saarnio J & Karttunen T J
(2011) Histopathology 59 , 643–649 Increased Toll‐like receptor 9 expression indicates adverse prognosis in oesophageal adenocarcinoma Aims: Toll‐like receptor 9 (TLR‐9) is a cellular DNA receptor that has been linked previously to invasion in various cancers. The aim of this study was to investigate TLR‐9 expression and its possible association with prognosis in oesophageal adenocarcinoma. Methods and results: Immunohistochemical TLR‐9 expression was graded in clinical specimens (n = 76) of oesophageal adenocarcinoma. The TLR‐9 immunostaining intensity was compared with tumour grade, stage and indicators of proliferation, apoptosis and tumour vascular supply. High TLR‐9 expression correlated with advanced tumour stage, tumour unresectability, poor differentiation and high proliferation. Strong immunoreactivity of TLR‐9 also indicated poor overall survival. Conclusions: High TLR‐9 expression is associated with poor differentiation, a high proliferation rate and disseminated disease. Accordingly, increased TLR‐9 expression may contribute to the growth and metastatic properties of oesophageal adenocarcinoma.  相似文献   
24.
25.
Toll‐like receptor 9 (TLR9) recognizes both bacterial and self‐DNA and it is abundantly expressed in the gastrointestinal tract. In this study, we investigated the influences of both bacterial DNA and specific short DNA sequences on TLR9‐mediated gastrointestinal cancer cell invasion. We assessed the effect of various DNA ligands on cellular invasion and on TLR9 and matrix metalloproteinase expression of three gastrointestinal cancer cell lines. DNA‐ligands described in this study include CpG‐ODN M362, 9‐mer (hairpin), human telomeric sequence h‐Tel22 G‐quadruplex, and bacterial DNAs from Escherichia coli and Helicobacter pylori. All of the DNAs studied were demonstrated to induce invasion in the studied cells. The DNA‐induced invasion was inhibited with a broad‐spectrum MMP inhibitor and partly also with chloroquine suggesting that it could be mediated via MMP activation, endosomal signaling, and TLR9. Interestingly, H. pylori DNA was shown to induce a more pronounced invasion in a gastric cancer cell line than in the other cell lines. Our results suggest that bacterial DNA as well as deoxynucleotides having stable secondary structures (i.e. hairpins or G‐quadruplex structures) may serve as endogenous, invasion‐inducing TLR9‐ligands and promote local progression and metastasis of cancers in the alimentary tract.  相似文献   
26.
Forty-six Escherichia coli isolates of serotype O2:K1 from human urinary tract infections, chicken sepsis, and bovine mastitis were obtained from laboratories in England, Denmark, Sweden, and Finland. The bacteria were compared for outer membrane protein (OMP) pattern, lipopolysaccharide pattern, electrophoretic mobilities of enzymes, and flagellar serotype and were tested for fimbriation, biotype, hydroxamate production, hemolysin production, antibiotic resistance, plasmid content, colicin production, and virulence in neonatal rats. Isolates from humans were assigned to two clonal groups; poultry isolates belonged to one of these clonal groups, whereas bovine isolates belonged to the other. Poultry and human isolates of the same clonal group could be distinguished only by their plasmid content. Strains within this group were heterogeneous with respect to biotype, fimbriation, virulence, and flagellar serotype. Human and bovine isolates of the second clonal group were distinguished by a minor change in OMP pattern and by their plasmid content. It is concluded that meaningful clonal groupings are best recognized by the combination of OMP and electrophoretic enzyme patterns. The O:K serotype can aid in the recognition of important subclones, whereas the other microbiological properties tested can vary widely within clonal groupings. Furthermore, we conclude that certain O:K serotypes can contain very different clonal groupings having little genetic relatedness.  相似文献   
27.
Guillain-Barr啨综合征(GBS)和Miller Fisher综合征(MFS)的诊断标准随着临床研究的深入在不断演变。2011年1月,《疫苗》杂志发表了国际疫苗安全性监测Brighton合作组关于GBS/MFS的诊断定义和研究资料收集规范。此文献中未采用"诊断标准"而采用"诊断定义"是因为其主要目的为评价疫苗安全性而制定,而非用于神经科的GBS/  相似文献   
28.
Genic Variability and Strategies of Adaptation in Animals   总被引:5,自引:3,他引:5       下载免费PDF全文
Levels of genic heterozygosity, as measured by surveys of allozymic variation, are much lower in populations of large, mobile animals (most vertebrates) than in those of small, relatively immobile animals (most invertebrates). This difference is not consistent with theories relating variability to population size (species number) or dispersal ability (gene flow), but it is predicted by Levins' theory of adaptive strategies in relation to environmental uncertainty ("grain"). Mobility and degree of homeostatic control apparently are important factors influencing levels of genic heterozygosity in natural populations. The results argue indirectly that at least a major proportion of allozymic variation is maintained by natural selection.  相似文献   
29.
30.
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