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   1412600篇
  免费   113720篇
  国内免费   3324篇
耳鼻咽喉   18407篇
儿科学   46578篇
妇产科学   41052篇
基础医学   200945篇
口腔科学   37731篇
临床医学   126187篇
内科学   284849篇
皮肤病学   33396篇
神经病学   117197篇
特种医学   54018篇
外国民族医学   464篇
外科学   210620篇
综合类   32763篇
现状与发展   3篇
一般理论   487篇
预防医学   110080篇
眼科学   31555篇
药学   98557篇
  32篇
中国医学   3349篇
肿瘤学   81374篇
  2021年   11052篇
  2019年   11684篇
  2018年   16580篇
  2017年   12674篇
  2016年   14277篇
  2015年   16020篇
  2014年   22588篇
  2013年   33409篇
  2012年   45420篇
  2011年   47947篇
  2010年   28182篇
  2009年   27072篇
  2008年   44343篇
  2007年   46851篇
  2006年   47417篇
  2005年   45872篇
  2004年   43769篇
  2003年   41715篇
  2002年   40200篇
  2001年   73014篇
  2000年   74552篇
  1999年   61578篇
  1998年   16992篇
  1997年   15445篇
  1996年   15591篇
  1995年   14796篇
  1994年   13396篇
  1993年   12585篇
  1992年   45850篇
  1991年   43489篇
  1990年   41494篇
  1989年   39561篇
  1988年   36189篇
  1987年   35355篇
  1986年   32862篇
  1985年   31279篇
  1984年   23825篇
  1983年   20027篇
  1982年   12210篇
  1981年   10780篇
  1979年   20704篇
  1978年   14580篇
  1977年   12091篇
  1976年   11366篇
  1975年   11624篇
  1974年   13989篇
  1973年   13537篇
  1972年   12640篇
  1971年   11470篇
  1970年   10915篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
143.
144.
Fungi from the Conidiobolus genus have been implicated in the development of chronic invasive fungal rhinosinusitis, mainly in tropical countries. The mycosis associated to these fungi may cause irreversible facial deformities and is potentially fatal. The authors present the first case of a chronic invasive fungal rhinosinusitis due to Conidiobolus coronatus diagnosed in a 66-year-old Caucasian male patient, living in Portugal without any travels abroad and complaining of progressive refractory nasal obstruction, facial pain and anosmia. Upon the culture of samples collected during sinus endoscopic surgery, colonies that presented a macroscopic aspect remembering wax were detected. The microscopic evaluation allowed the observation of simple conidiophores forming spherical conidia, and of conidiophores that presented hair-like appendages. Together, these characteristics allowed the identification of the fungi as a Conidiobolus, which was confirmed upon the DNA sequencing. The authors emphasised the role of this fungi as an emergent microorganism as well as the difficulties associated to the diagnosis and treatment.  相似文献   
145.
ObjectivesThis study was conducted to compare clinical outcomes of fidaxomicin versus oral vancomycin in the management of severe Clostridium difficile infection (CDI).MethodsThe investigation was a retrospective, multicentre, propensity score-matched analysis using a national clinical administrative database. Veterans treated for severe CDI from any Veterans Affairs Medical Center between 1 June 2011 and 30 June 2017 were included if they received fidaxomicin or an oral vancomycin regimen for treatment. The two groups were matched by the nearest-neighbour method from a propensity score derived from independent variables associated with the selection of a fidaxomicin course.ResultsPropensity score matching resulted in two well-matched cohorts consisting of 213 fidaxomicin and 639 oral vancomycin courses. No statistically-significant difference was found for the primary outcome of combined clinical failure or recurrence (68/213 (31.9%) versus 163/639 (25.5%), respectively, p 0.071). Additionally, no statistically significant differences were found for the secondary outcomes of 30-day (23/213 (10.8%) versus 75/639 (11.7%), respectively, p 0.71), 90-day (48/213 (22.5%) versus 140/639 (21.9%), respectively, p 0.85), and 180-day mortality (62/213 (29.1%) versus 186/639 (29.1%), respectively, p 1.0) between the two treatment groups.ConclusionsCourses of fidaxomicin or oral vancomycin for severe CDI resulted in similar treatment outcomes. Study findings are consistent with current treatment guideline recommendations for the use of either agent in the management of severe CDI.  相似文献   
146.
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   
147.
BackgroundFluoroquinolones are a popular alternative to trimethoprim-sulfamethoxazole for Stenotrophomonas maltophilia infections.ObjectivesTo compare the effects of fluoroquinolones and trimethoprim-sulfamethoxazole on mortality of S. maltophilia infections.Data sourcesPubMed and EMBASE.Study eligibility criteriaClinical studies reporting mortality outcomes of S. maltophilia infections.ParticipantsPatients with clinical infections caused by S. maltophilia.InterventionsFluoroquinolone monotherapy in comparison with trimethoprim-sulfamethoxazole monotherapy.MethodsSystematic review with meta-analysis technique.ResultsSeven retrospective cohort and seven case–control studies were included. Three cohort studies were designed to compare the two drugs, whereas others had other purposes. A total of 663 patients were identified, 332 of which were treated with trimethoprim-sulfamethoxazole (50.1%) and 331 with fluoroquinolones (49.9%). Three cohort studies were designed to compare the effect of the two drugs, whereas the others had other purposes. Levofloxacin was most frequently used among fluoroquinolones (187/331, 56.5%), followed by ciprofloxacin (114/331, 34.4%). The overall mortality rate was 29.6%. Using pooled ORs for the mortality of each study, fluoroquinolone treatment (OR 0.62, 95% CI 0.39–0.99) was associated with survival benefit over trimethoprim-sulfamethoxazole treatment, with low heterogeneity (I2 = 18%). Specific fluoroquinolones such as ciprofloxacin (OR 0.44, 95% CI 0.17–1.12) and levofloxacin (OR 0.78, 95% CI 0.48–1.26) did not show a significant difference in comparison with trimethoprim-sulfamethoxazole. In the sub-group analyses of adult and bacteraemic patients, significant differences in mortality were not observed between fluoroquinolones and trimethoprim-sulfamethoxazole.ConclusionsBased on a meta-analysis of non-randomized studies, fluoroquinolones demonstrated comparable effects on mortality of S. maltophilia infection to trimethoprim-sulfamethoxazole, supporting the use of fluoroquinolones in clinical S. maltophilia infections. Although the pooled analysis of overall studies favoured fluoroquinolones over trimethoprim-sulfamethoxazole, the studies included were observational, and sub-group analyses of certain fluoroquinolone agents did not show statistical differences with trimethoprim-sulfamethoxazole. Randomized clinical studies are needed to address these issues.  相似文献   
148.
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   
149.
150.
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   
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