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   6195篇
  免费   281篇
  国内免费   81篇
耳鼻咽喉   70篇
儿科学   57篇
妇产科学   131篇
基础医学   812篇
口腔科学   88篇
临床医学   484篇
内科学   1343篇
皮肤病学   94篇
神经病学   464篇
特种医学   446篇
外科学   916篇
综合类   19篇
预防医学   172篇
眼科学   63篇
药学   663篇
中国医学   92篇
肿瘤学   643篇
  2023年   29篇
  2022年   99篇
  2021年   220篇
  2020年   103篇
  2019年   151篇
  2018年   158篇
  2017年   141篇
  2016年   193篇
  2015年   252篇
  2014年   286篇
  2013年   338篇
  2012年   528篇
  2011年   523篇
  2010年   351篇
  2009年   230篇
  2008年   395篇
  2007年   369篇
  2006年   314篇
  2005年   296篇
  2004年   253篇
  2003年   209篇
  2002年   168篇
  2001年   152篇
  2000年   146篇
  1999年   119篇
  1998年   50篇
  1997年   36篇
  1996年   31篇
  1995年   25篇
  1994年   14篇
  1993年   11篇
  1992年   30篇
  1991年   35篇
  1990年   30篇
  1989年   29篇
  1988年   28篇
  1987年   29篇
  1986年   17篇
  1985年   22篇
  1984年   20篇
  1983年   12篇
  1981年   8篇
  1979年   8篇
  1977年   6篇
  1976年   6篇
  1974年   13篇
  1973年   7篇
  1971年   12篇
  1969年   9篇
  1968年   6篇
排序方式: 共有6557条查询结果,搜索用时 31 毫秒
61.
Factors affecting the registration error (RE) and motion of focal hepatic lesions (FHLs) in image fusion of real-time ultrasonography (US) with computed tomography (CT) images were prospectively assessed by focusing on respiratory movement and FHL location. Real-time US and pre-acquired CT images at end-inspiration were fused with FHLs for 103 patients. Three-dimensional US data containing FHLs were obtained during end-inspiratory/expiratory phases. Multivariate analysis revealed that diaphragm motion (p < 0.001), chronic liver disease (p = 0.02) and the absolute difference in distance between the FHL and the central portal vein (CPV) during respiration (p = 0.03) were the independent factors that revealed the maximum effect on RE. In contrast, diaphragm motion (p < 0.001) and distance between the FHL and CPV at inspiration (p = 0.036) revealed the maximum effect on FHL motion. In conclusion, RE and FHL motion are affected by the degree of respiratory movement and the location of the FHL. Therefore, image fusion with CT images should be used with caution if the degree of respiratory motion is significant or if the FHL is located at the periphery of the liver.  相似文献   
62.
63.
Background and Aim: Limited data are available regarding the use of endoscopic submucosal dissection (ESD) for superficial esophageal cancers ≥50 mm in diameter. The aim of the present study was to investigate the safety and success of ESD for superficial esophageal cancers ≥50 mm. Methods: A total of 39 patients with superficial esophageal squamous cell carcinoma ≥50 mm were treated with ESD at Osaka Medical Center for Cancer and Cardiovascular Diseases between January 2004 and April 2011, and were analyzed in a retrospective study. Results: En bloc resection was achieved in all patients. One mediastinal emphysema without perforation occurred during the procedure. Stricture developed in 11 of 39 patients, requiring a median of five endoscopic balloon dilatation procedures. Thirty‐three clinical epithelial or lamina propria mucosal cancers were treated by ESD with curative intent, of which invasion into the muscularis mucosa or deeper was detected in seven and lymphovascular involvement in three. The en bloc resection rate was 100% with a tumor‐free margin achieved in 92% of lesions. The curative resection and complication rates during ESD were 70% and 2.5%, respectively. Conclusion: ESD achieved a high en bloc resection rate of 92% with a tumor‐free margin. Curative resection rate of ESD in patients with clinical epithelial or lamina propria mucosal cancers was not low at 70%. However, the risk of stricture must be taken into account when considering the use of ESD in lesions ≥50 mm.  相似文献   
64.
Background: Pylephlebitis, which has high rates of morbidity and mortality, is thrombosis in the hepatic and portal veins. Hypercoagulability and intra-abdominal sepsis can lead to pylephlebitis, which can progress to liver abscess, mesenteric ischemia, and infarction. Case Report: A 47-year-old man presented to the Emergency Department complaining of fever, epigastric pain, and jaundice. He was diagnosed with pylephlebitis secondary to diverticulitis, as well as having a diverticular abscess, and was treated with antibiotic therapy without surgery or anticoagulation. Conclusion: Early diagnosis is essential for the treatment of pylephlebitis. Antibiotics and anticoagulants are the mainstay of treatment for pylephlebitis; although the use of anticoagulants remains controversial. In the present case, pylephlebitis was treated successfully without anticoagulants.  相似文献   
65.
66.
67.
Pericardial fat necrosis is an infrequent cause of acute chest pain and this can mimic acute myocardial infarction and acute pericarditis. We describe here a patient with the magnetic resonance imaging (MRI) findings of pericardial fat necrosis and this was correlated with the computed tomography (CT) findings. The MRI findings may be helpful for distinguishing pericardial fat necrosis from other causes of acute chest pain and from the fat-containing tumors in the cardiophrenic space of the anterior mediastinum.  相似文献   
68.
Cronobacter sakazakii is an opportunistic pathogen that causes neonatal meningitis and necrotizing enterocolitis. Its interaction with intestinal epithelium is important in the pathogenesis of enteric infections. In this study, we investigated the involvement of the inv gene in the virulence of C. sakazakii ATCC 29544 in vitro and in vivo. Sequence analysis of C. sakazakii ATCC 29544 inv revealed that it is different from other C. sakazakii isolates. In various cell culture models, an Δinv deletion mutant showed significantly lowered invasion efficiency, which was restored upon genetic complementation. Studying invasion potentials using tight-junction-disrupted Caco-2 cells suggested that the inv gene product mediates basolateral invasion of C. sakazakii ATCC 29544. In addition, comparison of invasion potentials of double mutant (ΔompA Δinv) and single mutants (ΔompA and Δinv) provided evidence for an additive effect of the two putative outer membrane proteins. Finally, the importance of inv and the additive effect of putative Inv and OmpA were also proven in an in vivo rat pup model. This report is the first to demonstrate two proteins working synergistically in vitro, as well as in vivo in C. sakazakii pathogenesis.  相似文献   
69.
Brillouin light scattering offers a unique label-free approach to measure biomechanical properties non-invasively. While this technique is used in biomechanical analysis of cells and tissues, its potential for visualizing structural features of tissues based on the biomechanical contrast has not been much exploited. Here, we present high-resolution Brillouin microscopy images of four basic tissue types: muscular, connective, epithelial, and nervous tissues. The Brillouin contrast distinguishes between muscle fiber cells and endomysium in skeletal muscle and reveals chondrocytes along with spatially varying stiffness of the extracellular matrix in articular cartilage. The hydration-sensitive contrast can visualize the stratum corneum, epidermis, and dermis in the skin epithelium. In brain tissues, the Brillouin images show the mechanical heterogeneity across the cortex and deeper regions. This work demonstrates the versatility of using the Brillouin shift as histological contrast for examining intact tissue substructures via longitudinal modulus without the need for laborious tissue processing steps.  相似文献   
70.
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