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   69329篇
  免费   5548篇
  国内免费   1993篇
耳鼻咽喉   1531篇
儿科学   1399篇
妇产科学   643篇
基础医学   7562篇
口腔科学   1866篇
临床医学   7920篇
内科学   13964篇
皮肤病学   901篇
神经病学   3503篇
特种医学   1188篇
外国民族医学   3篇
外科学   6751篇
综合类   10618篇
现状与发展   7篇
一般理论   2篇
预防医学   4171篇
眼科学   828篇
药学   7731篇
  48篇
中国医学   4788篇
肿瘤学   1446篇
  2024年   119篇
  2023年   1292篇
  2022年   1982篇
  2021年   3445篇
  2020年   2980篇
  2019年   2748篇
  2018年   2681篇
  2017年   2771篇
  2016年   3037篇
  2015年   3031篇
  2014年   5552篇
  2013年   6331篇
  2012年   4654篇
  2011年   5015篇
  2010年   4005篇
  2009年   3564篇
  2008年   3268篇
  2007年   3215篇
  2006年   2706篇
  2005年   2205篇
  2004年   1812篇
  2003年   1436篇
  2002年   1178篇
  2001年   1001篇
  2000年   815篇
  1999年   790篇
  1998年   620篇
  1997年   510篇
  1996年   507篇
  1995年   421篇
  1994年   371篇
  1993年   314篇
  1992年   279篇
  1991年   234篇
  1990年   226篇
  1989年   206篇
  1988年   191篇
  1987年   143篇
  1986年   129篇
  1985年   174篇
  1984年   157篇
  1983年   108篇
  1982年   108篇
  1981年   84篇
  1980年   105篇
  1979年   77篇
  1978年   57篇
  1977年   58篇
  1976年   47篇
  1974年   26篇
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
21.
IntroductionWe aimed to assess, in patients with Parkinson's disease (PD), the association between obstructive sleep apnea (OSA), progression of motor dysfunction and the effect of OSA treatment.MethodsData were analysed from a prospective cohort study of idiopathic PD patients from a movement disorders clinic. Patients found to have OSA on polysomnography (apnea-hypopnea index [AHI] ≥15 events/h, OSA+) were offered treatment using continuous positive airway pressure (CPAP). CPAP+ was defined as an average ≥ 2 h/night use at each follow-up. Motor symptoms were assessed using the motor section of the Movement Disorder Society Unified Parkinson's Disease Rating Scale (mUPDRS) and the Timed-Up-And-Go (TUG). Follow-up times were 3, 6 and 12 months. Mixed models were constructed, adjusting for age, sex, body mass index, levodopa equivalent dose and comorbidities.ResultsWe studied 67 individuals (61.2% male) of mean age 64.7 years (SD = 10.1). Baseline mUPDRS was higher in OSA+ compared to OSA- (24.5 [13.6] vs. 16.2 [7.2], p < 0.001). Motor dysfunction increased at comparable rates in OSA- and OSA+CPAP-. However, in OSA+CPAP+, mUPDRS change was significantly lower compared to OSA- (β = −0.01 vs. 0.61, p = 0.03; p = 0.12 vs. OSA+CPAP- [β = 0.39]) and TUG change was lower compared to OSA+CPAP- (β = −0.01 vs. 0.13, p = 0.002; p = 0.05 vs. OSA- [β = 0.02]).ConclusionsIn this PD cohort, OSA was associated with higher baseline mUPDRS. In those with OSA, CPAP use was associated with stabilization of motor function (mUPDRS and TUG) over 12 months. These observations support further research to clarify the role of OSA in PD pathophysiology and motor dysfunction.  相似文献   
22.
BackgroundSome chronic obstructive pulmonary disease (COPD) patients develop hypoxemia with disease progression, with some even requiring long-term oxygen therapy (LTOT). Lung function, especially diffusing capacity, and the annual decline in PaO2, are reported to be predictive factors of chronic respiratory failure. However, the association between lung morphometry evaluated using computed tomography (CT) images and LTOT initiation is unknown.MethodsWe retrospectively evaluated the relationship between clinical indices, including pulmonary function, body mass index (BMI), and CT parameters, at baseline and LTOT initiation in two prospective COPD cohorts. In the Nara Medical University cohort (n = 76), the low attenuation area (LAA) and its fractal dimension (fractal D) were adapted as the indices for parenchymal destruction in CT images. The association between these CT measurements and LTOT initiation was replicated in the Kyoto University cohort (n = 130).ResultsIn the Nara Medical University cohort, lower BMI (hazard ratio [HR]:0.70, p = 0.006), lower % diffusing capacity (%DLCO) (HR: 0.92, p = 0.006), lower %DLCO/VA (HR, 0.90, p = 0.008), higher RV/TLC (HR, 1.26, p = 0.012), higher LAA% (HR: 1.18, p = 0.001), and lower fractal D (HR: 3.27 × 10?8, p < 0.001) were associated with LTOT initiation. Multivariate analysis in the Kyoto University cohort confirmed that lower %DLCO and lower fractal D were independently associated with LTOT initiation, whereas LAA% was not.ConclusionFractal D, which is the index for morphometric complexity of LAA in CT analysis, is predictive of LTOT initiation in COPD patients.  相似文献   
23.
目的探讨经鼻间歇正压通气(NIPPV)在防治早产儿呼吸窘迫综合征(RDS)中的应用价值。方法选择2017年6月至2018年12月梧州市人民医院RDS早产儿90例,其中男性48例,女性42例;胎龄(29.03±0.58)周;出生体质量(996.91±98.52)g;病程(3.48±0.56)h;临床分级Ⅰ级58例,Ⅱ级32例;Apgar评分(6.85±1.06)分。依据随机数字表分为NIPPV组和持续气道正压通气(NCPAP)组,每组45例。NIPPV组给予NIPPV治疗,NCPAP组给予NCPAP治疗,若两组治疗后不能维持患儿生命体征则使用肺表面活性物质(PS)或行有创机械通气。结果NIPPV组和NCPAP组治疗12、24 h后和治疗结束时动脉血氧分压(PaO2)、氧合指数(OI)明显高于治疗前。NIPPV组治疗12、24 h后PaO2、OI明显高于NCPAP组,差异有统计学意义(P<0.05)。NIPPV组和NCPAP组治疗结束时PaO2、OI比较,差异无统计学意义(P>0.05);NIPPV组PS使用率(22.22%vs 44.44%)、有创通气率(17.78%vs 40.00%)、氧疗时间[(71.42±7.62)h vs(85.62±9.24)h]、有创通气时间[(46.78±5.32)h vs(55.27±6.14)h]、住院时间[(30.42±3.65)d vs(35.62±3.89)d]、并发症率(31.11%vs 53.33%)明显低于NCPAP组,差异有统计学意义(P<0.05)。结论NIPPV可有效改善RDS早产儿通气功能,有利于减少PS使用、有创通气及并发症,值得临床推广。  相似文献   
24.
《Journal of endodontics》2020,46(10):1455-1464
IntroductionThe aim of this study was to investigate whether mineral trioxide aggregate (MTA) can be modified with caffeic acid (CA) to form caffeic acid/mineral trioxide aggregate (CAMTA) cement and to evaluate its physicochemical and biological properties as well as its capability in immune suppression and angiogenesis.MethodsMTA was immersed in trishydroxymethyl aminomethane buffer with CA to allow coating onto MTA powders. X-ray diffractometry and tensile stress-strain tests were conducted to assess for physical characteristics of CAMTA and to evaluate for successful modification of MTA. Then, the CAMTA cement was immersed in simulated body fluid to evaluate its hydroxyapatite formation capabilities and Si release profiles. In addition, RAW 264.7 cells and human dental pulp stem cells were used to evaluate CAMTA’s immunosuppressive capabilities and cell responses, respectively. hDPSCs were also used to assess CAMTA’s angiogenic capabilities.ResultsThe X-ray diffractometry results showed that CA can be successfully coated onto MTA without disrupting or losing MTA’s original structural properties, thus allowing us to retain the initial advantages of MTA. CAMTA was shown to have higher mechanical properties compared with MTA and had rougher pitted surfaces, which were hypothesized to lead to enhanced adhesion, proliferation, and secretion of angiogenic- and odontogenic-related proteins. In addition, it was found that CAMTA was able to enhance hydroxyapatite formation and immunosuppressive capabilities compared with MTA.ConclusionsCAMTA cements were found to have improved physicochemical and biological characteristics compared with their counterpart. In addition, CAMTA cements had enhanced odontogenic, angiogenic, and immunosuppressive properties compared with MTA. All of the results of this study proved that CAMTA cements could be a biomaterial for future clinical applications and tissue engineering use.  相似文献   
25.
26.
ABSTRACT

Purpose

To investigate the expression of IL-11 and its receptor IL-11Rα and to quantify density of CD163+ M2 macrophages in proliferative diabetic retinopathy (PDR).  相似文献   
27.
目的:观察桂枝汤加减治疗营卫不和型慢性瘾疹的临床疗效。方法:将我院门诊2017年10月-2019年10月收治的48例营卫不和型慢性瘾疹患者,按随机数表法分成对照组(24例)与实验组(24例)。对照组实施常规西药治疗,实验组实施桂枝汤合地骨皮、白鲜皮加减治疗。对照两组治疗前后症状积分、临床疗效及并发症发生率。结果:两组治疗前症状积分相比无显著差异(P>0.05)。治疗后,两组症状积分均有所下降,实验组低于对照组;实验组临床总有效率为91.67%(22/24)高于对照组的66.67%(16/24);实验组并发症发生率0(0/24)低于对照组的16.67%(4/24),差异具有统计学意义(P<0.05)。结论:在营卫不和型慢性瘾疹治疗中,采取桂枝汤加减治疗,可明显降低症状积分,提高临床治疗效果,减少并发症,效果理想。  相似文献   
28.
29.
支气管哮喘是由多种细胞和细胞组分参与的气道慢性炎症性疾病,其气道炎症反应的复杂性,给临床诊断和治疗带来了困难[1]。2009年全球哮喘防治倡议(GINA)第一次提出“表型”这一概念,并提出基于表型分类有助于哮喘治疗及判断预后[2]。中医药治疗哮喘有其独特优势,但辨证分型缺乏明确统一的客观化、量化指标。  相似文献   
30.
目的:比较经鼻导管高流量吸氧(HFNC)与经鼻气道正压通气(nCPAP)在重症毛细支气管炎呼吸支持中的应用价值,为临床治疗方案的选择提供参考。方法:选取2016年12月至2018年12月我院儿科收治的重症毛细支气管炎患儿90例,采用随机数字表法分为观察组和对照组各45例。两组患儿入院后均给予常规综合治疗以保证呼吸道通畅,在此基础上观察组采用HFNC治疗,对照组采用nCPAP治疗,比较两组患儿治疗前和治疗24 h后呼吸频率、经皮血氧饱和度(TcSO2)、呼吸窘迫评分体系(CSS)评分、动脉血氧分压(PaO2)等呼吸相关指标及治疗前后临床症状体征改善情况。结果:两组患儿治疗24 h后呼吸频率、CSS评分均降低,且观察组降低程度更大,TcSO2、PaO2于治疗24 h后升高,观察组升高幅度较对照组明显;治疗后两组患儿咳嗽及肺部湿啰音、肺部炎症情况均改善,观察组症状体征消失时间早于对照组,差异均有统计学意义(P<0.05)。结论:重症毛细支气管炎患儿采用HFNC治疗可明显改善通气功能和临床症状,治疗效果优于nCPAP治疗,可扩大样本量进一步观察。  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