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   144905篇
  免费   13694篇
  国内免费   10204篇
耳鼻咽喉   1365篇
儿科学   1653篇
妇产科学   1707篇
基础医学   17452篇
口腔科学   2447篇
临床医学   18628篇
内科学   21729篇
皮肤病学   1933篇
神经病学   8167篇
特种医学   5254篇
外国民族医学   89篇
外科学   15626篇
综合类   24383篇
现状与发展   44篇
一般理论   25篇
预防医学   9402篇
眼科学   4439篇
药学   14479篇
  110篇
中国医学   8075篇
肿瘤学   11796篇
  2024年   355篇
  2023年   2113篇
  2022年   4170篇
  2021年   7545篇
  2020年   5628篇
  2019年   4878篇
  2018年   5180篇
  2017年   4596篇
  2016年   4442篇
  2015年   6567篇
  2014年   8085篇
  2013年   7251篇
  2012年   10657篇
  2011年   11598篇
  2010年   7186篇
  2009年   5735篇
  2008年   7618篇
  2007年   7589篇
  2006年   7372篇
  2005年   7453篇
  2004年   4954篇
  2003年   4481篇
  2002年   3883篇
  2001年   3420篇
  2000年   3559篇
  1999年   3714篇
  1998年   2390篇
  1997年   2348篇
  1996年   1804篇
  1995年   1745篇
  1994年   1492篇
  1993年   956篇
  1992年   1282篇
  1991年   1073篇
  1990年   935篇
  1989年   871篇
  1988年   731篇
  1987年   644篇
  1986年   593篇
  1985年   446篇
  1984年   241篇
  1983年   187篇
  1982年   116篇
  1981年   125篇
  1980年   90篇
  1979年   127篇
  1977年   52篇
  1974年   66篇
  1973年   60篇
  1972年   63篇
排序方式: 共有10000条查询结果,搜索用时 687 毫秒
71.
Abstract

Background

Comorbidities are commonly seen in patients with coronavirus disease 2019 (COVID-19), but the clinical implication is not yet well-delineated. We aim to characterize the prevalence and clinical implications of comorbidities in patients with COVID-19.  相似文献   
72.
目的 探讨类风湿关节炎患者外周血miR-150-5p、细胞因子信号抑制因子1(suppressor of cytokine signaling 1,SOCS1)mRNA的表达及对类风湿关节炎(Rheumatoid Arthritis,RA)疾病诊断、中医证型判断的意义。方法 纳入符合诊断标准的RA患者57例及健康对照组19例,根据《22个专业95个病种中医诊疗方案》有关RA的中医证候诊断标准,判断RA的中医证型。qPCR检测RA患者及健康对照组miR-150-5p、SOCS1mRNA的相对表达水平,同时检测血常规、肝功能、肾功能等常规指标。双荧光素酶分析方法判断两者是否存在靶向关系。统计分析miR-150-5p、SOCS1 mRNA对RA疾病的诊断意义及其与中医证型的相关性。结果 RA患者外周血miR-150-5p的相对表达水平下调,低于正常人群(t = -19.019,P < 0.05);其表达水平随疾病活动度升高,有下降趋势;患者外周血SOCS1 mRNA的相对表达水平上调,低于正常人群(t = 5.333,P < 0.05);其表达水平随疾病活动度升高,有上升趋势。MiR-150-5p与SOCS1 mRNA有靶向结合关系(P < 0.05)。通过AUC曲线比较,miR-150-5p的相对表达水平区分RA的敏感性及特异性分别为98.1%、92.1%(AUC = 0.972,P < 0.05);SOCS1 mRNA的相对表达水平无法区分RA(AUC = 0.472,P > 0.05)。RA患者中miR-150-5p的相对表达水平低于3.06,RA患者风湿痹阻证、寒湿痹阻证的相对风险分别为8.33、250.00(P < 0.05)。结论 miR-150-5p、SOCS1 mRNA在RA患者中有差异性表达,且有靶向结合关系。miR-150-5p可能是RA的疾病诊断及中医风湿痹阻证、寒湿痹阻证证型诊断的潜在生物标志物。  相似文献   
73.
Dry powder inhalers (DPIs) are gaining popularity for the delivery of drugs. A cost effective and efficient delivery device is necessary. Developing new DPIs by modifying an existing device may be the simplest way to improve the performance of the devices. The aim of this research was to produce a new DPIs using computational fluid dynamics (CFD). The new DPIs took advantages of the Cyclohaler® and the Rotahaler®. We chose a combination of the capsule chamber of the Cyclohaler® and the mouthpiece and grid of the Rotahaler®. Computer-aided design models of the devices were created and evaluated using CFD. Prototype models were created and tested with the DPI dispersion experiments. The proposed model 3 device had a high turbulence with a good degree of deagglomeration in the CFD and the experiment data. The %fine particle fraction (FPF) was around 50% at 60?L/min. The mass median aerodynamic diameter was around 2.8–4?μm. The FPF were strongly correlated to the CFD-predicted turbulence and the mechanical impaction parameters. The drug retention in the capsule was only 5–7%. In summary, a simple modification of the Cyclohaler® and Rotahaler® could produce a better performing inhaler using the CFD-assisted design.  相似文献   
74.
目的探讨自血穴位注射疗法联合马来酸茚达特罗治疗老年稳定期慢性阻塞性肺疾病(COPD)的临床疗效及其对患者炎性因子、免疫功能及肺功能的影响。 方法将2015年5月至2016年5月我院收治的86例老年缓解期COPD患者分为观察组与对照组。对照组给予马来酸茚达特罗治疗,观察组在对照组治疗基础上另给予自血穴位注射疗法。治疗12周后,评价2组临床疗效。治疗前及治疗12周后,分别检测2组患者肺功能指标(FEV1、FVC与PEF),炎性因子(IL-8、α1-AT、IL-6及TNF-α),免疫功能指标(IgG、IgA、CD3及CD4)水平。治疗期间,对2组患者的不良反应进行密切观察。 结果治疗后二组患者各项检测指标均优于治疗前。治疗12周后,观察组总有效率为90.7%,明显高于对照组的72.1%(P<0.05)。治疗12周后,观察组FEV1、FVC与PEF等肺功能指标,IgG、IgA、CD3及CD4等免疫功能指标水平均明显高于对照组(P<0.05),而IL-8、α1-AT、IL-6及TNF-α含量分别为(23.23±3.87)ng/L、(3.43±0.41)g/L、(52.25±5.38)ng/L及(43.12±3.98)ng/L,改善程度均明显优于对照组(P<0.05)。治疗期间,2组患者均未出现严重不良反应。 结论自血穴位注射疗法联合马来酸茚达特罗治疗老年稳定期COPD疗效确切,可有效改善患者炎症水平,值得进行深入研究。  相似文献   
75.
Ferroptosis is an iron-dependent novel cell death pathway. Deferoxamine, a ferroptosis inhibitor, has been reported to promote spinal cord injury repair. It has yet to be clarified whether ferroptosis inhibition represents the mechanism of action of Deferoxamine on spinal cord injury recovery. A rat model of Deferoxamine at thoracic 10 segment was established using a modified Allen's method. Ninety 8-week-old female Wistar rats were used. Rats in the Deferoxamine group were intraperitoneally injected with 100 mg/kg Deferoxamine 30 minutes before injury. Simultaneously, the Sham and Deferoxamine groups served as controls. Drug administration was conducted for 7 consecutive days. The results were as follows:(1) Electron microscopy revealed shrunken mitochondria in the spinal cord injury group.(2) The Basso, Beattie and Bresnahan locomotor rating score showed that recovery of the hindlimb was remarkably better in the Deferoxamine group than in the spinal cord injury group.(3) The iron concentration was lower in the Deferoxamine group than in the spinal cord injury group after injury.(4) Western blot assay revealed that, compared with the spinal cord injury group, GPX4, xCT, and glutathione expression was markedly increased in the Deferoxamine group.(5) Real-time polymerase chain reaction revealed that, compared with the Deferoxamine group, mRNA levels of ferroptosis-related genes Acyl-CoA synthetase family member 2(ACSF2) and iron-responsive element-binding protein 2(IREB2) were up-regulated in the Deferoxamine group.(6) Deferoxamine increased survival of neurons and inhibited gliosis. These findings confirm that Deferoxamine can repair spinal cord injury by inhibiting ferroptosis. Targeting ferroptosis is therefore a promising therapeutic approach for spinal cord injury.  相似文献   
76.
77.
Helicobacter pylori (H. pylori) is a main risk factor for gastric cancer (GC). Epithelial-mesenchymal transition (EMT) is involved in the development and progression of H. pylori-associated GC. However, the exact molecular mechanism of this process remains unclear. The AKT/GSK3β signaling pathway has been demonstrated to promote EMT in several types of cancer. The present study investigated whether H. pylori infection induced EMT, and promoted the development and metastasis of cancer in the normal gastric mucosa, and whether this process was dependent on AKT activation. The expression levels of the EMT-associated proteins, including E-cadherin and N-cadherin, were determined in 165 gastric mucosal samples of different disease stages by immunohistochemical analysis. The expression levels of E-cadherin, N-cadherin, AKT, phosphorylated (p-)AKT (Ser473), GSK3β and p-GSK3β (Ser9) were further determined in H. pylori-infected Mongolian gerbil gastric tissues and cells co-cultured with H. pylori by immunohistochemical analysis and western blotting. The results indicated that the expression levels of the epithelial marker E-cadherin were decreased, whereas the expression levels of the mesenchymal marker N-cadherin were increased during gastric carcinogenesis. Their expression levels were associated with H. pylori infection. Furthermore, H. pylori infection resulted in downregulation of E-cadherin expression and upregulation of N-cadherin expression in Mongolian gerbils and GES-1 cells. In addition, an investigation of the associated mechanism of action revealed that p-AKT (Ser473) and p-GSK3β (Ser9) were activated in GES-1 cells following co-culture with H. pylori. Furthermore, following pretreatment of the cells with the AKT inhibitor VIII, the expression levels of E-cadherin, N-cadherin, p-AKT and p-GSK3β did not show significant differences between GES-1 cells that were co-cultured with or without H. pylori. The levels of p-AKT and p-GSK3β were increased in H. pylori-infected Mongolian gerbils. In conclusion, the present study demonstrated that H. pylori infection activated AKT and resulted in the phosphorylation and inactivation of GSK3β, which in turn promoted early stage EMT. These effects were AKT-dependent. This mechanism may serve as a prerequisite for GC development.  相似文献   
78.
The developing CNS is exposed to physiological hypoxia, under which hypoxia-inducible factor α (HIFα) is stabilized and plays a crucial role in regulating neural development. The cellular and molecular mechanisms of HIFα in developmental myelination remain incompletely understood. A previous concept proposes that HIFα regulates CNS developmental myelination by activating the autocrine Wnt/β-catenin signaling in oligodendrocyte progenitor cells (OPCs). Here, by analyzing a battery of genetic mice of both sexes, we presented in vivo evidence supporting an alternative understanding of oligodendroglial HIFα-regulated developmental myelination. At the cellular level, we found that HIFα was required for developmental myelination by transiently controlling upstream OPC differentiation but not downstream oligodendrocyte maturation and that HIFα dysregulation in OPCs but not oligodendrocytes disturbed normal developmental myelination. We demonstrated that HIFα played a minor, if any, role in regulating canonical Wnt signaling in the oligodendroglial lineage or in the CNS. At the molecular level, blocking autocrine Wnt signaling did not affect HIFα-regulated OPC differentiation and myelination. We further identified HIFα–Sox9 regulatory axis as an underlying molecular mechanism in HIFα-regulated OPC differentiation. Our findings support a concept shift in our mechanistic understanding of HIFα-regulated CNS myelination from the previous Wnt-dependent view to a Wnt-independent one and unveil a previously unappreciated HIFα–Sox9 pathway in regulating OPC differentiation.SIGNIFICANCE STATEMENT Promoting disturbed developmental myelination is a promising option in treating diffuse white matter injury, previously called periventricular leukomalacia, a major form of brain injury affecting premature infants. In the developing CNS, hypoxia-inducible factor α (HIFα) is a key regulator that adapts neural cells to physiological and pathologic hypoxic cues. The role and mechanism of HIFα in oligodendroglial myelination, which is severely disturbed in preterm infants affected with diffuse white matter injury, is incompletely understood. Our findings presented here represent a concept shift in our mechanistic understanding of HIFα-regulated developmental myelination and suggest the potential of intervening with an oligodendroglial HIFα-mediated signaling pathway to mitigate disturbed myelination in premature white matter injury.  相似文献   
79.
随着“健康中国”战略的实施,需要建立与之相匹配的“新医科”人才培养体系,“基于医疗卫生系统的需求,以职业胜任力为导向”的教育教学改革势在必行。因此修订人才培养方案时要以胜任力为目标驱动重新梳理培养目标和毕业要求;采用“课程矩阵”设计法,反向设计、正向施工的原则优化课程体系;根据课程目标凝炼课程内容、精炼核心课程;充分利用网络开放课程资源,选修课分模块化设置;通过多种形式将创新创业教育贯穿人才培养全过程。  相似文献   
80.
随着对肿瘤热疗和肿瘤免疫微环境(TIME)的深入研究,近年来热疗对TIME的作用越来越受到学者们的重视。本文就目前国内外研究进展,对热疗与TIME中几类主要免疫细胞和免疫相关细胞因子的影响及作用机制作一综述。全面而透彻的了解热疗对TIME的调控作用,有助于为肿瘤治疗提供新的思路和方法。  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