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   6176篇
  免费   615篇
  国内免费   167篇
耳鼻咽喉   36篇
儿科学   111篇
妇产科学   45篇
基础医学   1150篇
口腔科学   210篇
临床医学   666篇
内科学   708篇
皮肤病学   149篇
神经病学   279篇
特种医学   652篇
外国民族医学   2篇
外科学   170篇
综合类   738篇
预防医学   738篇
眼科学   76篇
药学   400篇
中国医学   40篇
肿瘤学   788篇
  2023年   79篇
  2022年   98篇
  2021年   166篇
  2020年   238篇
  2019年   232篇
  2018年   217篇
  2017年   212篇
  2016年   247篇
  2015年   299篇
  2014年   412篇
  2013年   419篇
  2012年   420篇
  2011年   456篇
  2010年   326篇
  2009年   336篇
  2008年   321篇
  2007年   352篇
  2006年   348篇
  2005年   268篇
  2004年   233篇
  2003年   227篇
  2002年   182篇
  2001年   155篇
  2000年   94篇
  1999年   81篇
  1998年   68篇
  1997年   81篇
  1996年   61篇
  1995年   51篇
  1994年   35篇
  1993年   37篇
  1992年   27篇
  1991年   28篇
  1990年   21篇
  1989年   22篇
  1988年   14篇
  1987年   12篇
  1986年   9篇
  1985年   12篇
  1984年   9篇
  1983年   7篇
  1982年   10篇
  1981年   4篇
  1980年   10篇
  1979年   2篇
  1978年   4篇
  1977年   5篇
  1974年   2篇
  1973年   3篇
  1967年   1篇
排序方式: 共有6958条查询结果,搜索用时 31 毫秒
1.
PurposeEmergence of vancomycin variable enterococci (VVE) poses a challenge to empiric vancomycin therapy. Vancomycin-variable enterococci (VVE) are vanA-positive, yet phenotypically vancomycin-susceptible enterococci that can switch to a vancomycin-resistant phenotype when exposed to vancomycin. The aim of the present study was to determine the prevalence of VVE in India.MethodsIsolates of phenotypically vancomycin susceptible Enterococcus faecium from 20 tertiary care hospitals across India were collected and tested for the presence of vanA, vanR, vanS, vanB and vanC genes by conventional PCR using previously published primers. Isolates positive for vanA gene were considered as VVE.ResultsThe prevalence of VVE was 1.5% (5/340). Only one VVE isolate was positive for vanR and vanS, and all the isolates were negative for vanB and vanC.ConclusionsAlthough the prevalence is low, our finding emphasizes the importance of routinely screening for van genes in enterococci that are phenotypically susceptible. Silenced vanA able to escape detection and revert to resistance during vancomycin therapy represents a new challenge in clinical settings.  相似文献   
2.
BackgroundIdentifying the MIC wild-type distribution and its delineation of species targeted for receiving antimicrobial agent breakpoints is an important first step for determining clinical breakpoints. Having the main responsibility in the European Committee on Antimicrobial Susceptibility Testing (EUCAST) for characterizing the wild-type distributions and setting epidemiological cut-off values (ECOFFs), we explain the why, the how, and frequent misconceptions of wild-type MIC distributions and ECOFFs.ObjectivesTo clarify how wild-type MIC distributions and ECOFFs for agents and important target organisms are defined and determined and why these are important tools in microbiology, as well as to point to common misunderstandings and inappropriate use.SourcesThe EUCAST database of >40 000 MIC distributions; publications addressing the definition of wild-type MIC distributions, and ECOFFs in bacteria and fungi; and the EUCAST Standard Operating Procedure 10 Documents published by the European Centre for Disease Control and the European Food Safety Agency.ContentThe rationale for defining wild-type distributions and ECOFFs is explained. Setting breakpoints that bisect wild-type MIC distributions leads to poor methodological reproducibility and poor correlation between clinical outcome and susceptibility testing results. The methods applied by EUCAST to select distributions for aggregation and website display are described, highlighting the importance of incorporating data from multiple sources and methods. The methods used by EUCAST to estimate ECOFFs are outlined. Finally, the common misunderstandings of these processes are addressed.ImplicationsThe international community needs to agree on the phenotypic definitions of wild-type distributions. Systematic methods for developing and applying ECOFFs are essential to the conduct of phenotypic antimicrobial susceptibility testing and interpretation, which will remain the dominant laboratory method for the foreseeable future.  相似文献   
3.
摘要:目的 探讨儿童肺炎克雷伯菌血流感染(Klebsiella pneumoniae bloodstream infection, KPBSI)临床特征及肺炎克雷伯 菌(Klebsiella pneumoniae, KP)对常用抗菌药物的敏感性,为儿童KPBSI合理治疗提供参考。方法 回顾性分析2014年1月至2019 年12月在重庆医科大学附属儿童医院住院的KPBSI患儿临床资料。结果 共纳入110例患儿,64例(58.2%)为院内感染,72例 (65.5%)有基础疾病,以血液系统肿瘤最多见。110例患儿PRISM Ⅲ评分为16.0(7.0~20.8),其中74例(67.3%)发生脓毒症,15例 (13.6%)发生脓毒性休克,18例(16.4%)发生呼吸衰竭,15例(13.6%)需有创机械通气,院内死亡共13例(11.8%)。KP菌株对阿米卡 星、碳青霉烯类抗菌药物敏感率>90%,对头孢噻肟、头孢曲松和头孢他啶的敏感率分别为58.3%、60.9%和70.9%,对头孢哌 酮/舒巴坦和哌拉西林/他唑巴坦的敏感率分别为59.5%和82.7%。检出ESBLs+菌株39株(39/86,45.3%),耐碳青霉烯类肺炎克雷 伯菌(CRKP)菌株10株(10/110,9.1%),ESBLs+KP菌株和CRKP在各年龄组间分布无统计学差异。结论 儿童KPBSI多见于有基 础疾病的患儿,脓毒症、脓毒性休克和呼吸衰竭发生率高;KP菌株对头孢他啶和哌拉西林/他唑巴坦敏感性较高,可经验性治 疗轻症KPBSI患儿。  相似文献   
4.
摘要:目的以分子测序为参考 ,评估形态学、基质辅助激光解吸电离飞行时间质谱对毛霉目真菌的鉴定能力,分析毛霉目真菌对两性霉素B、泊沙康唑的体外药敏特点。方法收集 2018年1月-2022年2月广东省人民医院25例毛霉病住院患者标 本,进行镜检并对培养的茵落行形态学鉴定、质谱鉴定、分子测序和体外药敏试验。结果KOH 湿片法阳性率(76%)高于革兰染色法(32%),差异有统计学意义(P<0.05);形态学鉴定可将68%的菌株鉴定到属水平,3株鉴定错误,2株无法鉴定;将所 有菌株进行质谱鉴定,单用IVD和RUO数据库鉴定率分别为56%和44%,两库联合可将鉴定率提高为64%。毛霉目真菌对两性霉素B的抑制50%菌株生长的最小抑菌浓度(MIC3o)为1μg/mL,根霉属相比其他属对两性霉素B表现出较高的MIC 值,其中2株MIC>32 μg/mL,另2株MIC为8 μg/mL;根霉属对泊沙康唑的MICso为0.5 μg/mL,横梗霉属MICgo为4 μg/ mL,小克银汉霉属MICg0为2 μg/mL,有部分菌株表现出较低MIC值,同样亦有部分菌株对泊沙康唑表现出较高的MIC 值。结论 将传统镜检、培养与质谱技术和分子技术相结合,尽量将毛霉目真菌准确鉴定到种,并积极开展毛霉体外药敏试验,可为临床治疗提供参考依据。  相似文献   
5.
IntroductionThe incidence of infections caused by aerobic actinomycetes is increasing. Recent changes in taxonomy and the variability in susceptibility patterns among species make necessary a proper identification and antibiotic susceptibility testing.Material and methodsFifty-three strains of aerobic actinomycetes were identified by MALDI-TOF MS using the VITEK MS Mycobacterium/Nocardia kit (bioMérieux, France) in a tertiary hospital in Spain during a six-year period. Antimicrobial susceptibility testing of the isolates was performed using the Sensititre Rapmycoi microdilution panel (Thermo Fisher Scientific, Massachusetts, USA).ResultsForty strains of Nocardia spp. were identified in the study, being N. farcinica and N. cyriacigeorgica the most prevalent ones. All isolates were susceptible to linezolid and the resistance to amikacin was only observed in one isolate of Gordonia sputi. Resistance to cotrimoxazole was only found in five isolates.ConclusionsRoutine identification and antimicrobial susceptibility testing of aerobic actinomycetes is advisable for an efficient identification of species and effective treatment.  相似文献   
6.
Bedaquiline is a new ATP synthesis inhibitor developed as an anti-tuberculosis agent. It has resistance-associated variants (RAV), regardless of preceding bedaquiline exposure. Herein, we describe the case of a patient with multidrug-resistant tuberculosis (MDR-TB) who had no history of bedaquiline therapy but presented a relatively high minimum inhibitory concentration (MIC) of bedaquiline (1 μg/mL). Whole genome sequencing revealed a mutation in the resistance-associated gene Rv0678. The patient was first treated with a five-drug regimen (bedaquiline, delamanid, levofloxacin, cycloserine, and amikacin), which induced negative sputum culture conversion. Despite the successful treatment outcome, several questions remain regarding the efficacy of bedaquiline in this patient. Bedaquiline is an indispensable drug for MDR-TB treatment, but its clinical efficiency in the presence of Rv0678 mutations remains unclear. Therefore, evaluating the MIC of bedaquiline even in patients without a history of bedaquiline use is important for therapeutic regimen selection and may emphasize the importance of therapeutic drug monitoring in cases of bedaquiline RAV.  相似文献   
7.
Dynamic susceptibility contrast (DSC) MRI is clinically used to measure brain perfusion by monitoring the dynamic passage of a bolus of contrast agent through the brain. For quantitative analysis of the DSC images, the arterial input function is required. It is known that the original assumption of a linear relation between the R2(*) relaxation and the arterial contrast agent concentration is invalid, although the exact relation is as of yet unknown. Studying this relation in vitro is time-consuming, because of the widespread variations in field strengths, MRI sequences, contrast agents, and physiological conditions. This study aims to simulate the R2(*) versus contrast concentration relation under varying physiological and technical conditions using an adapted version of an open-source simulation tool. The approach was validated with previously acquired data in human whole blood at 1.5 T by means of a gradient-echo sequence (proof-of-concept). Subsequently, the impact of hematocrit, field strength, and oxygen saturation on this relation was studied for both gradient-echo and spin-echo sequences. The results show that for both gradient-echo and spin-echo sequences, the relaxivity increases with hematocrit and field strength, while the hematocrit dependency was nonlinear for both types of MRI sequences. By contrast, oxygen saturation has only a minor effect. In conclusion, the simulation setup has proven to be an efficient method to rapidly calibrate and estimate the relation between R2(*) and gadolinium concentration in whole blood. This knowledge will be useful in future clinical work to more accurately retrieve quantitative information on brain perfusion.  相似文献   
8.
Premature neonates are at particularly increased risk to develop invasive infections with excessive case fatality due to their low birth weight, enteral malabsorbtion, insufficient microbial defenses and underdeveloped anatomic barriers. We present a case of Moesziomyces aphidis (syn. Pseudozyma aphidis) fungemia in a newborn with severe morbidity and prolonged hospital stay. Phenotypic tests failed to identify the isolate whereas commercial antifungal susceptibility tests failed to detect resistance to fluconazole. To the best of our knowledge, this is the first case of M. aphidis fungemia in a premature neonate in whom complete clinical resolution occurred after liposomal amphotericin B administration. Our case is the third Pseudozyma spp. infection described in Europe. Twenty-one cases have been described globally. Common risk factors were central venus catheter (80%), previous antibiotic treatment (80%), hematologic malignancies (27%) and solid tumors (20%) with 3 cases reported in neonates. The most commonly used antifungal therapy was amphotericin B followed by oral voriconazole or itraconazole. Our report highlights the clinical importance of rare yeasts species in neonates, emphasizes the roles of prematurity and lower birth weight as major risk factors for invasive infections with high morbidity. Reliable identification and susceptibility testing of these rare yeasts is a key issue for an adequate therapy and better outcome.  相似文献   
9.
Background/purpose: Rapid detection of β-lactamases is important in a recent situation where resistant bacteria are increasing. By using the drug susceptibility testing microfluidic device (DSTM), rapid screening of extended spectrum β-lactamases (ESBLs) and metallo-β-lactamases (MBLs) has become possible.Methodsβ-lactams and β-lactamase inhibitors were pre-fixed in the DSTM for use. A bacterial suspension in Mueller-Hinton broth (McF 0.25) was introduced into the device, and the effects of β-lactamase inhibitor on morphological changes caused by β-lactam were evaluated after 3 h incubation.ResultsClinical isolates genetically confirmed to produce β-lactamase were used. Of the 84 ESBL-producing strains, 80 strains (95%) turned to be ESBL positive, and five strains (6%) of them MBL were positive as well as ESBL. Four strains (5%) were negative for both ESBL and MBL. Of the 24 MBL-producing strains, 23 strains (96%) were positive for MBL. All the 43 AmpC-producing strains were negative for both ESBL and MBL. Of the 156 ESBL- and MBL-nonproducing strains, 155 strains (99%) were negative for both ESBL and MBL, and one strain was positive for ESBL. With this method, the detection sensitivity was 95% and the specificity was 100% for ESBL, whereas the detection sensitivity was 96% and the specificity was 98% for MBL. These results were not significantly different from the results of the disc diffusion method.ConclusionThe DSTM method allows rapid detection of β-lactamases in 3 h and may be a useful replacement for the disc diffusion method.  相似文献   
10.
《Pancreatology》2022,22(7):959-964
BackgroundEndoplasmic reticulum (ER) stress-inducing variants in several pancreatic secretory enzymes have been associated with pancreatic disease. Multiple variants in CEL, encoding carboxyl ester lipase, are known to cause maturity-onset diabetes of the young (MODY8) but have not been implicated in pancreatic cancer risk.MethodsThe prevalence of ER stress-inducing variants in the CEL gene was compared among pancreatic cancer cases vs. controls. Variants were identified by next-generation sequencing and confirmed by Sanger sequencing. Variants of uncertain significance (VUS) were assessed for their effect on the secretion of CEL protein and variants with reduced protein secretion were evaluated to determine if they induced endoplasmic reticulum stress.ResultsER stress-inducing CEL variants were found in 34 of 986 cases with sporadic pancreatic ductal adenocarcinoma, and 21 of 1045 controls (P = 0.055). Most of the variants were either the CEL-HYB1 variant, the I488T variant, or the combined CEL-HYB1/I488T variant; one case had a MODY8 variant.ConclusionThis case/control analysis finds ER stress-inducing CEL variants are not associated with an increased likelihood of having pancreatic cancer.  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