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   132341篇
  免费   8972篇
  国内免费   3522篇
耳鼻咽喉   944篇
儿科学   3875篇
妇产科学   1457篇
基础医学   8682篇
口腔科学   1078篇
临床医学   17517篇
内科学   37209篇
皮肤病学   657篇
神经病学   3260篇
特种医学   3045篇
外国民族医学   1篇
外科学   13662篇
综合类   23545篇
现状与发展   6篇
一般理论   5篇
预防医学   7161篇
眼科学   271篇
药学   12442篇
  131篇
中国医学   8375篇
肿瘤学   1512篇
  2024年   212篇
  2023年   1982篇
  2022年   3537篇
  2021年   5413篇
  2020年   5202篇
  2019年   4545篇
  2018年   4412篇
  2017年   4322篇
  2016年   4486篇
  2015年   4553篇
  2014年   9829篇
  2013年   9812篇
  2012年   7997篇
  2011年   8826篇
  2010年   7011篇
  2009年   6500篇
  2008年   6307篇
  2007年   6370篇
  2006年   5662篇
  2005年   5033篇
  2004年   3994篇
  2003年   3454篇
  2002年   2878篇
  2001年   2634篇
  2000年   2165篇
  1999年   2086篇
  1998年   1697篇
  1997年   1590篇
  1996年   1370篇
  1995年   1259篇
  1994年   1254篇
  1993年   925篇
  1992年   876篇
  1991年   801篇
  1990年   688篇
  1989年   649篇
  1988年   578篇
  1987年   493篇
  1986年   433篇
  1985年   491篇
  1984年   440篇
  1983年   265篇
  1982年   308篇
  1981年   268篇
  1980年   253篇
  1979年   212篇
  1978年   176篇
  1977年   152篇
  1976年   137篇
  1975年   81篇
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
61.
ObjectiveTo investigate the feasibility of transnasal heated humidified high flow nasal cannula oxygen therapy (HFNC) in the treatment of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) with respiratory failure in elderly patients. MethodsA total of 176 elderly patients with AECOPD complicated with respiratory failure who were hospitalized at Peking University Shougang Hospital from December 2016 to January 2022 were enrolled, including 82 patients in an HFNC group and 94 patients in an NPPV group. After treatment, pulse oxygen saturation (SPO2), arterial partial pressure of carbon dioxide (PaCO2), oxygenation index (OI), respiratory rate (RR), heart rate (HR), mean arterial pressure (MAP), comfort score, discharge rate, rate of endotracheal intubation, rate of transfer to intensive care unit (ICU), and mortality were compared between the two groups. The independent sample t-test was used for comparison between the two groups. Statistical data are expressed in percentage or number of cases and the χ2 test was used for their comparisons. ResultsThe SPO2 values at 30 min, 1 h, and 6 h were significantly higher in the HFNC group than in the NPPV group (t=-2.049,-2.618, and -3.314, P=0.043, 0.010, and 0.001, respectively). SPO2 before discharge was significantly lower than that of the NPPV group (t=2.162, P=0.033), but OI at each time point and before discharge had no statistical significance (P>0.05). MAP at 6 h was significantly higher in the HFNC group than in the NPPV group (t=-2.209, P=0.029), but within the normal range. HRs at 2 h and 3 h in the HFNC group were significantly higher than those of the NPPV group (t=-2.199 and -2.336, P=0.030 and 0.021, respectively). There were no significant differences in RR, HR, or MAP between the two groups at other time points and before discharge (P>0.05). There was no significant difference in PaCO2 between the two groups (P>0.05). Comfort score in the HFNC group was significantly higher than that of the NPPV group (t=-46.807, P<0.001). There were no significant differences in discharge rate, ICU transfer rate, endotracheal intubation rate, and mortality between the two groups (P>0.05). ConclusionHFNC is as effective as NPPV in treating elderly patients with AECOPD complicated with type Ⅰ or mild type Ⅱ respiratory failure, and HFNC is more comfortable than NPPV.  相似文献   
62.
63.
64.
65.
BackgroundCoronary artery bypass grafting (CABG) improves survival in patients with heart failure and severely reduced left ventricular systolic function (LVEF). Limited data exist regarding adverse cardiovascular event rates after CABG in patients with heart failure with midrange ejection fraction (HFmrEF; LVEF > 40% and < 55%).MethodsWe analyzed data on isolated CABG patients from the Veterans Affairs national database (2010-2019). We stratified patients into control (normal LVEF and no heart failure), HFmrEF, and heart failure with reduced LVEF (HFrEF) groups. We compared all-cause mortality and heart failure hospitalization rates between groups with a Cox model and recurrent events analysis, respectively.ResultsIn 6533 veterans, HFmrEF and HFrEF was present in 1715 (26.3%) and 566 (8.6%) respectively; the control group had 4252 (65.1%) patients. HFrEF patients were more likely to have diabetes mellitus (59%), insulin therapy (36%), and previous myocardial infarction (31%). Anemia was more prevalent in patients with HFrEF (49%) as was a lower serum albumin (mean, 3.6 mg/dL). Compared with the control group, a higher risk of death was observed in the HFmrEF (hazard ratio [HR], 1.3 [1.2-1.5)] and HFrEF (HR, 1.5 [1.2-1.7]) groups. HFmrEF patients had the higher risk of myocardial infarction (subdistribution HR, 1.2 [1-1.6]; P = .04). Risk of heart failure hospitalization was higher in patients with HFmrEF (HR, 4.1 [3.5-4.7]) and patients with HFrEF (HR, 7.2 [6.2-8.5]).ConclusionsHeart failure with midrange ejection fraction negatively affects survival after CABG. These patients also experience higher rates myocardial infarction and heart failure hospitalization.  相似文献   
66.
67.
陈科第 《传染病信息》2022,35(2):135-140
[摘要] 目的 探究HBV相关慢加急性肝衰竭(HBV-related acute-on-chronic liver failure, HBV-ACLF)患者血清中微小核糖核酸(microRNA, miR)-122和高迁移率族蛋白1(high-mobility group box-B1, HMGB1)水平及其与病情、预后的关系。方法 回顾性分析2016年1月—2018年1月我院收治的120例HBV-ACLF患者的一般及临床资料。根据临床结局,将患者分为存活组(53例)和死亡组(67例)。比较2组患者的一般资料、实验室检查指标及血清miR-122、HMGB1水平。多因素Logistic回归分析影响患者预后的因素。Pearson检验分析miR-122、HMGB1水平分别与TBIL、PA、终末期肝病评分模型(the model of end-stage liver disease score, MELD)评分的相关性。ROC曲线分析miR-122和HMGB1水平对患者的死亡预测价值,获得最佳临界值。根据临界值将患者分为A组、B组和C组,用Kaplan-Meier法绘制生存曲线,比较3组患者在3年随访期间的生存率。结果 存活组和死亡组患者的年龄、身体质量指数、并发症、病情分期、MELD评分、ALB、球蛋白、TBIL、ALT、AST、LDH、PT、PTA、HBV DNA、miR-122、HMGB1相比,差异均具有统计学意义(P均<0.05)。年龄、并发症、病情分期、MELD评分、TBIL、PT、PTA、miR-122、HMGB1均是影响患者预后的危险因素(P均<0.05)。miR-122、HMGB1水平分别与TBIL、MELD评分呈显著正相关,与PTA呈显著负相关(P均<0.05)。miR-122和HMGB1预测患者死亡的最佳临界值分别为31.42和14.56 μg/L。A组患者预后3年内生存率显著高于B组和C组(P均<0.05)。结论 miR-122和HMGB1水平与HBV-ACLF患者的病情和死亡预后密切相关,可间接反映患者的病情严重程度,在HBV-ACLF的诊断及预后中具有重要价值。  相似文献   
68.
Plasticity enables alterations in transmission in nociceptive systems. It is this plasticity in the nervous system that can alter the linear relation between noxious stimuli and the perception of pain and is important in the switch from acute to chronic pain. In this way, a number of CNS mechanisms can alter neuronal activity, leading to abnormal ongoing and stimulus-evoked pains due to peripheral and central changes. Peripheral nerves can become sensitized, spinal cord neurons can be rendered hyperexcitable and ascending projections to higher centres can further trigger changes in descending controls from the midbrain and brainstem. Together, these changes, all of which appear to involve reversible physiological and pharmacological plasticity, can alter the relationship between an applied stimulus and the perceived response and so lead to persistent pain states.  相似文献   
69.
70.
BackgroundIschemia reperfusion (I/R) play an imperative role in the expansion of cardiovascular disease. Sinomenine (SM) has been exhibited to possess antioxidant, anticancer, anti-inflammatory, antiviral and anticarcinogenic properties. The aim of the study was scrutinized the cardioprotective effect of SM against I/R injury in rat.MethodsRat were randomly divided into normal control (NC), I/R control and I/R + SM (5, 10 and 20 mg/kg), respectively. Ventricular arrhythmias, body weight and heart weight were estimated. Antioxidant, inflammatory cytokines, inflammatory mediators and plasmin system indicator were accessed.ResultsPre-treated SM group rats exhibited the reduction in the duration and incidence of ventricular fibrillation, ventricular ectopic beat (VEB) and ventricular tachycardia along with suppression of arrhythmia score during the ischemia (30 and 120 min). SM treated rats significantly (P < 0.001) altered the level of antioxidant parameters. SM treatment significantly (P < 0.001) repressed the level of creatine kinase MB (CK-MB), creatine kinase (CK) and troponin I (Tnl). SM treated rats significantly (P < 0.001) repressed the tissue factor (TF), thromboxane B2 (TXB2), plasminogen activator inhibitor 1 (PAI-1) and plasma fibrinogen (Fbg) and inflammatory cytokines and inflammatory mediators.ConclusionOur result clearly indicated that SM plays anti-arrhythmia effect in I/R injury in the rats via alteration of oxidative stress and inflammatory reaction.  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