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   937357篇
  免费   59264篇
  国内免费   2357篇
耳鼻咽喉   12970篇
儿科学   29623篇
妇产科学   26789篇
基础医学   130969篇
口腔科学   25395篇
临床医学   78054篇
内科学   189539篇
皮肤病学   19964篇
神经病学   74716篇
特种医学   37626篇
外国民族医学   338篇
外科学   146634篇
综合类   19259篇
一般理论   261篇
预防医学   67174篇
眼科学   20524篇
药学   66040篇
  15篇
中国医学   1841篇
肿瘤学   51247篇
  2018年   9964篇
  2017年   7908篇
  2016年   8508篇
  2015年   9528篇
  2014年   13165篇
  2013年   20605篇
  2012年   27784篇
  2011年   29552篇
  2010年   17634篇
  2009年   16588篇
  2008年   28000篇
  2007年   29798篇
  2006年   29777篇
  2005年   29190篇
  2004年   27943篇
  2003年   27037篇
  2002年   26553篇
  2001年   42128篇
  2000年   43372篇
  1999年   36895篇
  1998年   10174篇
  1997年   9303篇
  1996年   9213篇
  1995年   8601篇
  1994年   8235篇
  1993年   7698篇
  1992年   28453篇
  1991年   27249篇
  1990年   26637篇
  1989年   25573篇
  1988年   23759篇
  1987年   23388篇
  1986年   22441篇
  1985年   21370篇
  1984年   15976篇
  1983年   13638篇
  1982年   8219篇
  1981年   7177篇
  1979年   14728篇
  1978年   10314篇
  1977年   8724篇
  1976年   8229篇
  1975年   9071篇
  1974年   10807篇
  1973年   10290篇
  1972年   9764篇
  1971年   9013篇
  1970年   8660篇
  1969年   8102篇
  1968年   7772篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
ObjectivesParapneumonic pleural effusions/empyema (PPE/PE) are severe complications of community-acquired pneumonia. We investigated the bacterial aetiology and incidence of paediatric PPE/PE in Germany after the introduction of universal pneumococcal conjugate vaccine (PCV) immunization for infants.MethodsChildren <18 years of age hospitalized with pneumonia-associated PPE/PE necessitating pleural drainage or persisting >7 days were reported to the German Surveillance Unit for Rare Diseases in Childhood between October 2010 and June 2017. All bacteria detected in blood or pleural fluid (by culture/PCR) were included, with serotyping for Streptococcus pneumoniae.ResultsThe median age of all 1447 PPE/PE patients was 5 years (interquartile range 3–10). In 488 of the 1447 children with PPE/PE (34%), 541 bacteria (>40 species) were detected. Aerobic gram-positive cocci accounted for 469 of 541 bacteria detected (87%); these were most frequently Streptococcus pneumoniae (41%), Streptococcus pyogenes (19%) and Staphylococcus aureus (6%). Serotype 3 accounted for 45% of 78 serotyped S. pneumoniae strains. Annual PPE/PE incidence varied between 14 (95%CI 12–16) and 18 (95%CI 16–21) PPE/PE per million children. Incidence of S. pneumoniae PPE/PE decreased from 3.5 (95%CI 2.5–4.6) per million children in 2010/11 to 1.5 (95%CI 0.9–2.4) in 2013/14 (p 0.002), followed by a re-increase to 2.2 (95%CI 1.5–3.2) by 2016/17 (p 0.205).ConclusionsIn the era of widespread PCV immunization, cases of paediatric PPE/PE were still caused mainly by S. pneumoniae and, increasingly, by S. pyogenes. The re-increase in the incidence of PPE/PE overall and in S. pneumoniae-associated PPE/PE indicates ongoing changes in the bacterial aetiology and requires further surveillance.  相似文献   
55.
ObjectivesStaphylococcus argenteus has been increasingly reported since the species was defined as a novel staphylococcal species in 2015. This study aims to investigate genetic epidemiological links and antimicrobial susceptibilities of methicillin-resistant S. argenteus isolates recovered in Stockholm.MethodsSixteen methicillin-resistant S. argenteus isolates were identified from a collection of methicillin-resistant Staphylococcus aureus in Stockholm 2007–2018, by using whole-genome sequencing and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The genomes of the isolates were investigated by pulsed-field gel electrophoresis, single-nucleotide polymorphism (SNP)-based phylogeny, k-mer analysis, core-genome multi-locus sequence typing (cgMLST), resistance traits and virulence factors. The MICs of 19 antimicrobial agents for each isolate were determined by using the broth microdilution method.ResultsOf the 16 isolates, seven, seven and two isolates were assigned to ST1223, ST2250 and ST2793, respectively, with the S. aureus MLST-scheme. Analyses based on SNPs and cgMLST revealed a likely clonal spread of methicillin-resistant S. argenteus in 2007. Four isolates were found to be resistant to non-β-lactams in antimicrobial susceptibility testing.ConclusionsA transmission event of methicillin-resistant S. argenteus in family was identified by this study. Among our limited number of isolates, non-β-lactam resistance was detected, which highlights the necessity of a continued surveillance on this emerging pathogen. S. argenteus could be correctly identified by MALDI-TOF MS with the updated database, enabling its detection also in clinical laboratories.  相似文献   
56.
Archives of Women's Mental Health - Tobacco and/or alcohol use during pregnancy is a major public health concern. The aim of our study was to identify risk factors associated to maternal...  相似文献   
57.
Archives of Women's Mental Health - Optimal maternal caregiving is critical for children’s healthy development, yet quality of maternal caregiving may be influenced by a negative birth...  相似文献   
58.
59.
60.
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