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   3739篇
  免费   276篇
  国内免费   36篇
耳鼻咽喉   85篇
儿科学   234篇
妇产科学   41篇
基础医学   538篇
口腔科学   1076篇
临床医学   368篇
内科学   400篇
皮肤病学   39篇
神经病学   38篇
特种医学   16篇
外科学   83篇
综合类   268篇
预防医学   550篇
眼科学   23篇
药学   228篇
中国医学   26篇
肿瘤学   38篇
  2023年   30篇
  2022年   62篇
  2021年   115篇
  2020年   99篇
  2019年   80篇
  2018年   67篇
  2017年   75篇
  2016年   104篇
  2015年   108篇
  2014年   180篇
  2013年   291篇
  2012年   216篇
  2011年   254篇
  2010年   220篇
  2009年   222篇
  2008年   226篇
  2007年   200篇
  2006年   182篇
  2005年   186篇
  2004年   157篇
  2003年   147篇
  2002年   117篇
  2001年   101篇
  2000年   80篇
  1999年   63篇
  1998年   60篇
  1997年   53篇
  1996年   47篇
  1995年   35篇
  1994年   28篇
  1993年   20篇
  1992年   26篇
  1991年   26篇
  1990年   33篇
  1989年   17篇
  1988年   15篇
  1987年   23篇
  1986年   14篇
  1985年   10篇
  1984年   9篇
  1983年   9篇
  1982年   13篇
  1981年   2篇
  1980年   5篇
  1979年   5篇
  1978年   4篇
  1977年   3篇
  1975年   8篇
  1974年   1篇
  1972年   2篇
排序方式: 共有4051条查询结果,搜索用时 31 毫秒
1.
An 81-year-old man with a history of gingival bleeding presented with a fever, headache, and drowsiness. His mouth and full dentures were unsanitary. Laboratory tests revealed Streptococcus oralis meningitis caused by odontogenic bacteremia. We reviewed eight reported cases, including the present case, because S. oralis meningitis is rare. Our review indicated that S. oralis meningitis needs to be considered when encountering cases of a fever, disturbance of consciousness, and headache with episodes of possible odontogenic bacteremia.  相似文献   
2.
目的:探讨孕晚期产妇生殖道B族链球菌(group B Streptococcus,GBS)感染与胎膜早破及新生儿结局的相关性。方法:搜集2017年5月至2019年8月首都医科大学附属北京世纪坛医院产科门诊的2100例孕妇,选取其中122例孕晚期胎膜早破产妇作为观察组,另选取120例同期健康孕晚期产妇作为健康对照组,比较两组GBS感染率,依据观察组患者是否合并GBS感染,将其分为GBS阴性组与GBS阳性组,采用单因素和多因素logistic回归分析影响胎膜早破孕妇GBS感染的危险因素,观察不同组别不良妊娠情况及新生儿结局。结果:健康对照组GBS感染率显著低于观察组(P<0.05);两组孕妇胎位异常、双胎或多胎妊娠和巨大儿发生率比较差异具有统计学意义(P<0.05);经多因素logistic回归模型分析结果显示胎位异常、双胎或多胎妊娠和巨大儿为影响胎膜早破孕妇GBS感染的危险因素(P<0.05)。GBS阴性组早产、产后出血和宫内感染率均显著低于GBS阳性组(P<0.05);GBS阳性组新生儿窒息和新生儿肺炎感染发生率均高于GBS阴性组(P<0.05);两组新生儿感染率比较,差异无统计学意义(P>0.05)。结论:胎位异常、双胎或多胎妊娠和巨大儿均可影响孕晚期胎膜早破产妇GBS感染,GBS感染可致新生儿窒息、新生儿感染和新生儿肺炎的发生,同时引起早产、产后出血和宫内感染等不良妊娠结局的发生。临床需要对孕晚期产妇生殖道GBS感染进行及时监测和处理,以降低其不良母婴结局的发生率。  相似文献   
3.
4.
5.

Background

Group B Streptococcus (GBS) infection is one of the major causes of neonatal morbidity and mortality. Universal GBS screening with intrapartum antibiotic prophylaxis (IAP) in pregnant women were initiated in 2012 in Taiwan. This study aimed to analyze the most recent maternal GBS colonization rate and the changes in neonatal GBS infection rate from 2011 to 2016.

Methods

All pregnant women and their live born neonates between January 2011 and June 2016 were retrospectively reviewed. Whether GBS screening was done, screening results, presence of risk factors, the use of antibiotics, and neonatal outcome were analyzed. In addition, hospitalized neonates diagnosed with GBS infections were retrieved for comparison of early onset disease (EOD) (<7 days) and late onset disease (LOD) (≥7 days).

Results

A total of 9535 women delivered babies during the study period. The maternal GBS screening rate was 71.0% and the colonization rate was 22.6%. The overall neonatal invasive GBS infection rate was 0.81 per 1000 live births and the vertical transmission rate was 1.2%. After 2012, the invasive neonatal GBS infection rate declined from 1.1–1.6‰ to 0.6–0.7‰ in 2014 and thereafter, the GBS EOD incidence rate declined from 2.8‰ to 0.0–0.6‰, but the LOD incidence rate remained approximately 0.7‰. Infants with EOD had strong association with obstetric risk factors.

Conclusions

Taiwan's universal GBS screening with IAP program reduced the incidence rate of neonatal GBS EOD to be lower than 1‰ after 2012. Pediatricians still should pay attention to infants with GBS LOD since its incidence rate remained unchanged.  相似文献   
6.
《Vaccine》2019,37(24):3190-3198
The development of a group B Streptococcus (GBS) vaccine for maternal immunization constitutes a global public health priority, to prevent GBS-associated early life invasive disease, stillbirth, premature birth, maternal sepsis, adverse neurodevelopmental consequences, and to reduce perinatal antibiotic use. Sample size requirements for the conduct of a randomized placebo-controlled trial to assess vaccine efficacy against the most relevant clinical endpoints, under conditions of appropriate ethical standards of care, constitute a significant obstacle on the pathway to vaccine availability. Alternatively, indirect evidence of protection based on immunologic data from vaccine and sero-epidemiological studies, complemented by data from opsonophagocytic in vitro assays and animal models, could be considered as pivotal data for licensure, with subsequent confirmation of effectiveness against disease outcomes in post-licensure evaluations. Based on discussions initiated by the World Health Organization we present key considerations about the potential role of correlates of protection towards an accelerated pathway for GBS vaccine licensure and wide scale use. Priority activities to support progress to regulatory and policy decision are outlined.  相似文献   
7.
目的构建2型猪链球菌荚膜多糖基因簇中cps2D基因敲除株(Δcps2D),比较野毒株05ZYH33与敲除株Δcps2D基本生物学特性的差异。方法设计合成引物L1/L2、R1/R2、Spc1/Spc2,分别扩增cps2D基因上、下游同源臂L片段、R片段及Spc^(R)抗性基因S片段,将3个片段连接至pUC19线性载体上,构建敲除质粒pUC19::cps2D。将敲除质粒电转导入05ZYH33感受态细胞后,利用Spc^(R)抗性平板筛选敲除株,并通过组合PCR和RT-PCR进一步验证。比较野毒株05ZYH33和敲除株Δcps2D细菌生长特性、溶血活性、革兰染色、细菌链长、荚膜形态等方面的异同。结果L1/L2、R1/R2、Spc1/Spc2三组引物分别扩增出L(1030 bp)、R(1030 bp)以及S(1130 bp)基因片段;通过无缝克隆的方法成功构建出敲除质粒pUC19::cps2D;电转入感受态细胞后获得69个克隆,筛选出26个疑似敲除株;组合PCR以及RT-PCR筛选后获得cps2D基因敲除株Δcps2D;与野毒株05ZYH33相比,Δcps2D对数期生长变缓,链长显著变短,荚膜稀疏变薄。结论成功构建cps2D基因敲除株,为后续进一步研究其调控荚膜合成的作用机制奠定基础。  相似文献   
8.
肺炎球菌性疾病免疫预防专家共识(2020版)   总被引:4,自引:2,他引:2       下载免费PDF全文
肺炎球菌性疾病是全球严重的公共卫生问题之一,也是导致中国儿童及成年人发病和死亡的重要原因。肺炎球菌性疾病的临床治疗用药以抗生素为主,由于抗生素的广泛应用,肺炎球菌的耐药性问题日益严重。采用肺炎球菌疫苗预防肺炎球菌性疾病并减少细菌耐药性,尤为必要和迫切。本文在《肺炎球菌性疾病免疫预防专家共识(2017版)》基础上,结合WHO肺炎球菌疫苗立场文件(2019年)和国内外最新研究进展,对肺炎球菌性疾病的病原学、临床学、流行病学、疾病负担、疫苗学等方面进行系统综述,目的是为公共卫生和预防接种专业人员在科学使用疫苗与发挥疫苗最佳预防作用方面提供证据,提高肺炎球菌性疾病防控水平。  相似文献   
9.
《Vaccine》2020,38(27):4273-4280
BackgroundIn Alaska, while introduction of 13-valent pneumococcal conjugate vaccine led to declines in invasive pneumococcal disease, carriage prevalence remained stable because of replacement with non-vaccine serotypes. We assessed antibiotic non-susceptibility of carried pneumococci during serotype redistribution, determined the contributions of within-serotype shifts, and assessed factors that could explain changes in non-susceptibility.MethodsEach year from 2008 to 2015, at multiple sites in Alaska, we collected nasopharyngeal swabs and completed surveys for a convenience sample of participants. Pneumococcal serotyping and antimicrobial susceptibility testing for penicillin and erythromycin were performed. We described changes in non-susceptibility of isolates from 2008–2011 to 2012–2015, and assessed the contributions of serotype redistribution and within-serotype changes in non-susceptibility by comparing observed data to modeled data removing either factor. We used weighted logistic regression to assess whether reported risk factors could explain changes over time in non-susceptibility within serotypes.ResultsFrom 2008–2011 to 2012–2015, the overall proportion of isolates non-susceptible to penicillin or erythromycin increased by 3%, from 23% (n = 1,183) to 26% (n = 1,589; P < 0.05). However, a decrease of 3% would be expected if serotype redistribution occurred without within-serotype changes in non-susceptibility. Standardization by either factor produced hypothetical data significantly different to observed data. Within serotypes, the average annual increase in odds of non-susceptibility to penicillin or erythromycin was 1.08 (95% CI 1.05–1.11). Recent antibiotic exposure, urban residence and increased household size of participants predicted isolate non-susceptibility but did not explain the increase over time.DiscussionAn overall increase in non-susceptibility of carried pneumococcal isolates to penicillin or erythromycin resulted from increases in non-susceptibility within serotypes, which outweighed a protective effect of serotype redistribution. Characterization of emerging resistant clones within carried non-vaccine serotypes, including risk factors for colonization and disease, would support disease prevention efforts and inform vaccine strategies.  相似文献   
10.
目的 观察人β-防御素2(hBD2)对肺炎链球菌(SP)感染人肺腺癌细胞(A549)细胞凋亡的影响。方法 建立SP感染A549细胞模型,hBD2以10、20和30ng/mL的浓度梯度干预该模型,观察细胞形态变化,CCK-8法检测细胞活力,qRT-PCR检测细胞Bax、Bcl-2及caspase-3mRNA表达,免疫细胞化学法检测细胞Bax、Bcl-2蛋白的表达。结果 SP感染引起A549细胞皱缩、空泡化,hBD2一定程度上保护细胞活力,抑制Bax表达,上调Bcl-2的表达。结论 hBD2对SP感染的A549细胞凋亡具有保护作用。  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