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   2598篇
  免费   107篇
  国内免费   12篇
耳鼻咽喉   73篇
儿科学   57篇
妇产科学   28篇
基础医学   386篇
口腔科学   47篇
临床医学   167篇
内科学   613篇
皮肤病学   7篇
神经病学   308篇
特种医学   148篇
外科学   335篇
综合类   5篇
一般理论   1篇
预防医学   124篇
眼科学   5篇
药学   197篇
中国医学   5篇
肿瘤学   211篇
  2023年   9篇
  2022年   21篇
  2021年   31篇
  2020年   22篇
  2019年   29篇
  2018年   29篇
  2017年   32篇
  2016年   46篇
  2015年   46篇
  2014年   52篇
  2013年   86篇
  2012年   143篇
  2011年   152篇
  2010年   91篇
  2009年   88篇
  2008年   144篇
  2007年   153篇
  2006年   153篇
  2005年   169篇
  2004年   163篇
  2003年   178篇
  2002年   190篇
  2001年   43篇
  2000年   20篇
  1999年   42篇
  1998年   56篇
  1997年   52篇
  1996年   43篇
  1995年   27篇
  1994年   33篇
  1993年   33篇
  1992年   36篇
  1991年   28篇
  1990年   25篇
  1989年   19篇
  1988年   20篇
  1987年   10篇
  1986年   9篇
  1985年   12篇
  1984年   21篇
  1983年   16篇
  1982年   15篇
  1981年   18篇
  1980年   19篇
  1979年   8篇
  1978年   15篇
  1977年   15篇
  1974年   5篇
  1970年   5篇
  1957年   6篇
排序方式: 共有2717条查询结果,搜索用时 15 毫秒
41.
42.
OBJECTIVES: To assess the myocardium-reperfusing effect of a distal protection device, GuardWire Plus (GuardWire Plus), in patients with acute myocardial infarction (AMI). BACKGROUND: Distal embolization may result in reduced myocardial perfusion, increasing the risk of non-Q-wave myocardial infarction and death. Distal protection devices may protect the microcirculation from embolic debris, improving short- and long-term clinical outcomes. METHODS: From February 2002 to July 2003, a total of 341 AMI patients at 22 institutions in Japan were enrolled in the present, multicenter, prospective, randomized trial. Patients experiencing AMI within 12 hr of symptom onset, who were considered treatable by stenting and who met the inclusion criteria, were eligible for randomization. Stenting with and without GuardWire Plus was conducted to examine whether the device provides faster and more complete ST-segment resolution, smaller infarct size, and improved myocardial blush score. RESULTS: The rates of slow flow and no-reflow immediately after PCI were 5.3 and 11.4% in the GuardWire Plus and control groups, respectively (P = 0.05). Blush score 3 acquisition rates immediately after PCI were 25.2 and 20.3% in the GuardWire Plus and control groups, respectively (P = 0.26), and the rates at 30 days after PCI were 42.9 and 30.4%, respectively (P = 0.035). CONCLUSIONS: A significant difference was found between the GuardWire Plus and control groups with respect to the total incidence of distal embolization, indicating that GuardWire Plus angiographically improved myocardial perfusion without demonstrating the preventive effect of myocardial damage.  相似文献   
43.
44.
45.
OBJECTIVE: CD22 is believed to be restricted to normal and neoplastic B cells. Human basophils were found to express CD22 molecules. Among the antibodies against CD22, Leu14, which recognized the ligand binding domain, reacted to basophils, and B3 and 4KB128, which recognized the amino terminus side and carboxy terminus side of the ligand binding epitope, respectively, did not. To clarify the difference of CD22 antigenicity in human B cells and basophils, we investigated RNA sequence and structures of CD22 molecules. MATERIALS AND METHODS: Purified B cells and basophils were obtained from normal human volunteers by using a MACS magnetic cell sorting system and anti-CD19 and anti-Fc epsilon R1 antibodies, respectively. RT-PCR and sequencing of CD22 mRNA were performed in the exons 3 to 8. Western blotting analysis of CD22 was also performed. RESULTS: The sequence of CD22 mRNA extracted from the basophils was the same as that of B cells in exons 3 to 8 (epitopes recognized by Leu14, B3, and 4KB128 were translated from exons 4 and 5). Reduced CD22 peptide extracted from the basophils reacted to Leu14 as well as B3 and 4KB128, and the molecular size of the reduced and nonreduced products was 130 kDa as expected. CONCLUSION: Disulfide bonds and the resulting 3D conformation of the CD22 molecules may have important roles in the difference of antigenicity of CD22 beta in B cells (CD22 beta 1) and basophils (CD22 beta 2). The difference in molecular structure surrounding the ligand-binding domain of CD22 may imply a specialization of the conformational forms of CD22 according to the ligand isoforms.  相似文献   
46.
47.
48.
49.
International Journal of Paediatric Dentistry 2012; 22: 265–270 Background. A device based on infrared laser fluorescence (IRLF) has become available as an adjunct for the diagnosis of dental caries. Aims. The objective of this study was to clarify the differences of IRLF readings in the mesial, central and distal occlusal pits of first permanent molars. Design. Sixty‐four children (average age 8.0 years) were examined using IRLF. The mesial, central and distal pits of clinically healthy first permanent molars were measured. The instrument provides measurements in arbitrary units on an open‐ended interval scale. Results. Mean (± SE) IRLF values in the mesial pits were 4.9 ± 0.4 (upper) and 6.5 ± 0.4 (lower) and were significantly lower than those in the central (8.8 ± 0.6 and 11.5 ± 0.9) and distal (9.6 ± 0.7 and 10.4 ± 0.8) pits in the maxilla and mandible. There was no significant difference between the right (7.3 ± 0.5, 9.4 ± 0.6) and left (8.2 ± 0.5, 9.5 ± 0.6) dental arches. IRLF measurements in the mesial pits of human first permanent sound molars were lower than the central and distal pits in children whose second molars had not erupted. Conclusions. The inherently higher IRLF values of some sites should not be misinterpreted and trigger early invasive treatment.  相似文献   
50.
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