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   18371篇
  免费   1647篇
  国内免费   1288篇
耳鼻咽喉   48篇
儿科学   134篇
妇产科学   294篇
基础医学   3375篇
口腔科学   423篇
临床医学   1302篇
内科学   2017篇
皮肤病学   202篇
神经病学   1325篇
特种医学   616篇
外国民族医学   6篇
外科学   947篇
综合类   4425篇
现状与发展   5篇
一般理论   1篇
预防医学   1123篇
眼科学   96篇
药学   1968篇
  43篇
中国医学   1422篇
肿瘤学   1534篇
  2024年   45篇
  2023年   735篇
  2022年   1141篇
  2021年   1167篇
  2020年   1220篇
  2019年   775篇
  2018年   610篇
  2017年   708篇
  2016年   819篇
  2015年   1054篇
  2014年   1484篇
  2013年   1285篇
  2012年   1483篇
  2011年   1489篇
  2010年   1259篇
  2009年   1034篇
  2008年   651篇
  2007年   887篇
  2006年   689篇
  2005年   441篇
  2004年   357篇
  2003年   296篇
  2002年   221篇
  2001年   153篇
  2000年   130篇
  1999年   127篇
  1998年   144篇
  1997年   106篇
  1996年   94篇
  1995年   90篇
  1994年   69篇
  1993年   60篇
  1992年   45篇
  1991年   30篇
  1990年   56篇
  1989年   27篇
  1988年   32篇
  1987年   37篇
  1986年   40篇
  1985年   28篇
  1984年   35篇
  1983年   14篇
  1982年   24篇
  1981年   39篇
  1980年   21篇
  1979年   6篇
  1978年   13篇
  1977年   10篇
  1976年   5篇
  1975年   5篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
重庆地区驾驶员血液中乙醇浓度与驾驶能力的关系   总被引:5,自引:0,他引:5  
目的 探讨重庆地区驾驶员血液中乙醇浓度 (BAC)和驾驶能力的关系 ,为交通安全立法提供科学依据。 方法 随机选择重庆地区 59名驾驶员志愿者 ,建立饮酒后驾车模型、科学的BAC测定以及驾驶能力评价体系 ,对不同BAC下驾驶能力进行测评。 结果 受试者出现驾驶能力损害时的BAC均数为 685.9mg/L ,最小值 190 .0mg/L ,最大值 152 0 .0mg/L ,总体均数 95%可信区间为 60 2 .4~ 70 9.5mg/L。汉族和土家族间、汉族男性和女性间、2 3~ 3 5岁和 3 6~ 56岁年龄组间差异无显著性意义 (P >0 .0 5) ,而既往饮酒量不同的三个组别间差异有显著性意义 (P <0 .0 5)。随着BAC增高 ,驾驶能力受损人数增加。在 2 0 0 .0mg/L有 3 % (2 / 59)的受试者驾驶能力降低 ,80 0 .0mg/L则达到 68% (40 / 59)。 结论 随着BAC增高 ,重庆地区驾驶员驾驶能力受损人数比例增加 ,出现驾驶能力明显损害时BAC为 60 2 .4~ 70 9.5mg/L ,既往酒量较大人群中该值较高  相似文献   
992.
Infection with Epstein–Barr virus (EBV) is associated with multiple sclerosis (MS), and patients with MS have an increased antibody response to some EBV antigens. The major antigens of EBV are only partly defined. Our hypothesis is that the antibody response to EBV is altered in MS. With ELISA, we found that antibodies to EB virions were increased in both serum and CSF of MS patients. Western blots demonstrated that there are multiple different antigens recognized. The antibody response was generally higher in MS to all EBV antigens, with particularly significant increases for certain antigens. We conclude that the antibody response to EBV in MS is generally increased with altered specificity.  相似文献   
993.
Parkinson’s disease (PD) is the second most prevalent, progressive neurodegenerative disease and is characterized by the irreversible and selective loss of nigrostriatal dopaminergic (DA) neurons. Glial cell line-derived neurotrophic factor (GDNF), which is a potent protective factor for DA  neurons, is considered a promising neuroprotective candidate for PD. microRNAs (miRNAs) have been shown to be involved in a number of neurodegenerative diseases. Both miRNAs and GDNF affect DA neuronal processes, but the molecular crosstalk between these molecules remains unclear. The present study aimed to evaluate whether GDNF modulates miRNA expression. We used microarray analysis and real-time polymerase chain reaction (RT-PCR) to investigate miRNAs expression in 6-hydroxydopamine (6-OHDA)-injured MN9D cells treated with GDNF for 30 min, 1 h, or 3 h. Our results showed that GDNF treatment led to differential expression of 143 miRNAs. To further identify mechanisms by which GDNF exerts its effects, we compared miRNAs and mRNAs microarray data at the 1-h time point. We found that various biological processes and pathways were regulated at the miRNA level following GDNF treatment. Collectively, these results provide evidence of the capacity of GDNF to influence miRNAs expression, suggesting a new mechanism of GDNF action.  相似文献   
994.
目的回顾性分析与总结颈深部多间隙脓肿的临床诊治经验,以提高临床医生对本病的认识与诊疗水平。方法选取2008年3月~2018年3月于陆军军医大学第一附属医院就诊的颈深部多间隙脓肿182例患者,对其临床特点、相关检查、治疗及随访情况进行回顾性分析。结果182例患者中,男女患者数之比为1.98∶1,27例合并有全身系统性疾病,其中25例为糖尿病,1例高血压3级,1例慢性肾病2期。最常见的临床症状为颈部包块和颈部疼痛。下颌下间隙是最常累及的间隙,其次是咽旁间隙,牙源性和上呼吸道感染是最常见的致病原因。对所有患者的脓液进行细菌学培养,其中45例(24.7%)培养阳性,阳性结果中最常见的致病菌为链球菌属(43.6%)。在糖尿病患者中,4例细菌培养阳性,全为肺炎克雷伯杆菌。所有患者选用敏感抗生素治疗,其中152例患者行脓肿切开引流术;最常见并发症为气道阻塞,其中33例(18.1%)行气管切开术;有合并症患者给予对症处理。住院治疗2~43 d,151例患者获治愈,31例患者缓解,没有死亡病例。出院后随访1个月情况良好,感染无复发。结论颈深部多间隙脓肿男性患病率较女性高,起病急,进展迅速,脓肿切开引流和联合应用敏感抗生素仍然是本病的主要治疗方法。脓液细菌培养呈现出大量的阴性结果,因此细菌学培养仅仅作为使用抗生素的参考,气管切开仍然是保障术后安全的必要条件,对于减少并发症及改善预后起到了重要作用。治疗中要特别关注合并全身系统性疾病和老年患者并发症的处理。  相似文献   
995.
骨创伤修复基础研究的若干新进展   总被引:1,自引:1,他引:1  
分子生物学技术的迅猛发展给骨创伤后组织修复的基础研究和临床治疗提供了新的思路和手段。本文概述近年来在生长因子、基因治疗以及组织工程三方面进展对骨创伤后组织修复基础研究和临床治疗的促进作用。转化生长因子(TGF-β)、骨形成蛋白(BMP)、成纤维细胞生长因子(FGF)、血小板源性生长因子(PDGF)和胰岛素样生长因子(IGF)在骨修复中起重要作用,基因治疗将在软组织修复、骨形成和神经再生方面发挥作用。组织工程化骨与软骨、皮肤、血管等研究也将对骨科创伤修复产生积做影响。  相似文献   
996.
目的:探讨地衣芽胞杆菌C01在模型小鼠体内对大肠杆菌、沙门氏菌抑制作用以及对乳杆菌等有益菌的促进作用。方法:用地衣芽胞杆菌C01灌胃肠道感染模型小鼠,采用体外活菌培养,分析粪便菌群数量的变化。结果:C01灌胃治疗组(EPEC C01)中乳杆菌的数量显著高于EPEC灌胃模型组(EPEC N)(P<0.01),肠杆菌数量下降极显著(P<0.01),而(EPEC N)组肠杆菌数显著高于正常对照组(NS)(P<0.05);肠炎沙门氏菌处理后C01灌胃治疗组(SL C01)和处理后肠炎沙门氏模型组(SL N)比较,乳杆菌、肠球菌和总厌氧菌的变化不明显,但肠杆菌数量下降极显著(P<0.01);形态病理学观察结果显示,C01芽胞杆菌灌胃治疗组肠粘膜病变明显减轻,肠粘膜及绒毛高度明显增加,绒毛轻度水肿,绒毛排列整齐、致密。结论:地衣芽胞杆菌C01在体内对肠炎沙门氏菌和致病性大肠杆菌有较强的抑制作用,能促进乳杆菌等生理性有益菌的增殖,可保护肠粘膜结构的完整性免受病原菌的侵袭。  相似文献   
997.
《Alzheimer's & dementia》2014,10(6):704-712
BackgroundThis study examined the predictive value of different classes of markers in the progression from mild cognitive impairment (MCI) to Alzheimer's disease (AD) over an extended 4-year follow-up in the Alzheimer's Disease Neuroimaging Initiative (ADNI) database.MethodsMCI patients were assessed for clinical, cognitive, magnetic resonance imaging (MRI), positron emission tomography–fluorodeoxyglucose (PET-FDG), and cerebrospinal fluid (CSF) markers at baseline and were followed on a yearly basis for 4 years to ascertain progression to AD. Logistic regression models were fitted in clusters, including demographics, APOE genotype, cognitive markers, and biomarkers (morphometric, PET-FDG, CSF, amyloid-β, and tau).ResultsThe predictive model at 4 years revealed that two cognitive measures, an episodic memory measure and a Clock Drawing screening test, were the best predictors of conversion (area under the curve = 0.78).ConclusionsThis model of prediction is consistent with the previous model at 2 years, thus highlighting the importance of cognitive measures in progression from MCI to AD. Cognitive markers were more robust predictors than biomarkers.  相似文献   
998.
BackgroundLongitudinal neuroimaging studies could provide insights into pathophysiology of cognitive impairment in PD. We examined the role of hippocampal atrophy and cerebral white matter disease as risk factors for mild cognitive impairment and dementia in PD.MethodsProspective longitudinal study of patients with mild PD in a tertiary neurology center. All subjects underwent baseline MRI brain and had baseline and 6 monthly cognitive evaluations. Cognitive impairment was diagnosed based on the Movement Disorder Society Criteria. The predictive role of hippocampal volume and white matter hyperintensity at baseline on progression of cognitive impairment was studied.Results97 subjects with mean age 65.3 years, mean education of 10.3 years and mean Hoehn & Yahr of 1.9 were studied. Over 2 years, 16 subjects developed mild cognitive impairment and 8 subjects with mild cognitive impairment progressed to dementia. After adjusting for age and vascular risk factors, hippocampal volume was a significant predictor for mild cognitive impairment (OR 7.05, CI 1.5–34.1; p = 0.015) and dementia (OR 7.03, CI 2.39–25.2; p = 0.001). With Cox regression, hippocampal volume was a significant predictor for “time to cognitive impairment” (HR 7.67; CI 3.47–16.95, p < 0.001). Difference between survival curves based on volume of white matter hyperintensity in predicting “time to mild cognitive impairment” was significant (p = 0.0295).ConclusionsHippocampal volume is a major factor predicting the development of mild cognitive impairment and dementia in PD. White matter hyperintensity also contributes to the longitudinal cognitive status in PD.  相似文献   
999.
1000.
Disturbances in neurocognitive performance are a core feature of the acute sickness response to infection; however the underlying mechanisms remain unclear. The current study used a computerised battery to assess neurocognitive functioning in subjects enrolled in the Dubbo Infection Outcomes Study (n = 107) – a prospective cohort of subjects followed from documented acute infection with Epstein Barr virus, Ross River virus, or Coxiella burnetii until recovery. Subjects were assessed when ill, and a subset again after complete recovery. Associations between sickness-related cognitive disturbances and single nucleotide polymorphisms (SNPs) in cytokine (interleukin [IL]-6, IL-10, tumor necrosis factor-α and interferon-γ) and neurobehavioral genes (serotonin transporter and catechol-O-methyltransferase) were explored.During acute infection, subjects exhibited slower matching-to-sample responses (p = 0.03), poorer working memory capacity (p = 0.014), mental planning (p = 0.045), and dual attention task performance (p = 0.02), and required longer to complete discordant Stroop trials (p = 0.01) compared to recovery. Objective impairments correlated significantly with self-reported symptoms (p < 0.05) as well as levels of the inflammation marker, C-reactive protein (p = 0.001). Linear regression analysis identified an association between neurocognitive disturbance during acute illness and functional polymorphisms in inflammatory cytokine genes. Specifically, the high cytokine producing G allele of the IL-6-174G/C SNP was associated with poorer neurocognitive performance when subjects were ill (p = 0.027).These findings confirm that acute infection impacts on neurocognitive performance, manifesting as slowed responses and impaired performance on complex tasks requiring higher-order functioning which has important real-world implications. The data provide the first preliminary evidence for a role of a genetic predisposition to more intense inflammatory responses in objective neurocognitive disturbances during acute infections. These associations require replication in a larger sample size.  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