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   17216篇
  免费   834篇
  国内免费   427篇
耳鼻咽喉   2篇
儿科学   187篇
妇产科学   27篇
基础医学   1220篇
口腔科学   19篇
临床医学   2701篇
内科学   6321篇
皮肤病学   20篇
神经病学   194篇
特种医学   1021篇
外科学   1237篇
综合类   2898篇
预防医学   577篇
眼科学   5篇
药学   1451篇
  7篇
中国医学   550篇
肿瘤学   40篇
  2023年   129篇
  2022年   339篇
  2021年   413篇
  2020年   416篇
  2019年   276篇
  2018年   345篇
  2017年   332篇
  2016年   364篇
  2015年   515篇
  2014年   1111篇
  2013年   974篇
  2012年   957篇
  2011年   1083篇
  2010年   1010篇
  2009年   1063篇
  2008年   1061篇
  2007年   1085篇
  2006年   1080篇
  2005年   878篇
  2004年   666篇
  2003年   607篇
  2002年   501篇
  2001年   460篇
  2000年   414篇
  1999年   336篇
  1998年   271篇
  1997年   236篇
  1996年   165篇
  1995年   186篇
  1994年   145篇
  1993年   102篇
  1992年   102篇
  1991年   96篇
  1990年   79篇
  1989年   75篇
  1988年   67篇
  1987年   71篇
  1986年   45篇
  1985年   61篇
  1984年   43篇
  1983年   25篇
  1982年   39篇
  1981年   23篇
  1980年   28篇
  1979年   30篇
  1978年   39篇
  1977年   21篇
  1976年   29篇
  1975年   18篇
  1973年   21篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
AimsMyocardial strain analysis enables more precise assessment of cardiac performance but is relatively load dependent. New tools have been developed with afterload adjustment. Our objective was to assess myocardial work (MW) in patients with repaired aortic coarctation (rACo).MethodsProspective study of consecutive patients with rACo who underwent a routine transthoracic echocardiogram in 2018 and 2019 at our center. Patients with significant aortic valve disease, pacemaker, or other congenital heart diseases (except for mild bicuspid aortic valve disease) were excluded. Global longitudinal strain with two dimensional speckle tracking analysis and MW were obtained (GWI:Global Work Index; GCW: Global Constructive Work; GWW: Global Wasted Work; GWE: Global Work Efficiency). Blood pressure was measured in the patient's right arm.ResultsWe included 42 patients in the analysis, mean age of 37±10 years, 38% males. In this group, 52% had hypertension and 64% had a concomitant bicuspid aortic valve. In comparison to previously published reference values, patients with rACo had significantly lower GWI (1807 vs. 1896 mmHg%) and GCW (2173 vs. 2232 mmHg%) (p<0.001), particularly in males. Systolic blood pressure is an independent predictor for GWI (β=0.432) and for GCW (β=0.534) and GLS an independent predictor of all MW parameters (β>0.594). Neither age nor gender were independent predictors.ConclusionsIn patients with rACo, there are some signs of left ventricular dysfunction with a reduction in GCW and GWI and with preserved GWE, despite normal ejection fraction and strain.  相似文献   
3.
4.
Coronary embolism (CE) is an uncommon and unique cause of acute myocardial infarction. In this report, we review 216 cases of CE including 2 new cases from our institution. The mean patient age was 52.5 years and 62% of the patients were males. Chest pain was the most common presenting symptom followed by dyspnea, and the most commonly affected vessel was the left anterior descending artery. Leading etiologies of the embolus were atrial fibrillation, septic emboli, and iatrogenic causes. Treatment approaches varied with thrombus aspiration being used in 30% of cases. In-hospital mortality rate was 36% and 13% of the cases were complicated by cerebrovascular accident. CE is a unique pathology that leads to acute myocardial infarction. It portends a high mortality rate and requires a high level of suspicion as symptoms may be misleading. Further research is needed in order to improve recognition and management and to lower associated mortality.  相似文献   
5.
6.
Shouwen Zhang  Jie Wang 《Drug delivery》2016,23(9):3696-3703
Context: Baicalin has many pharmacological activities, including protective function against myocardial ischemia by antioxidant effects and free radical scavenging activity. However, its rapid elimination half-life in plasma and poor water solubility limits its clinical efficacy.

Objective: Novel baicalin-loaded PEGylated nanostructured lipid carriers (BN-PEG-NLC) were developed to improve bioavailability of BN, to prolong retention time in vivo and to enhance its protective effect.

Methods: In this study, BN-PEG-NLC were prepared by the emulsion-evaporation and low temperature-solidification method using a mixture of glycerol monostearate and polyethylene glycol monostearate as solid lipids, and oleic acid as the liquid lipid. The physicochemical properties of NLC were characterized. The pharmacokinetic and pharmacodynamic behaviors of BN-PEG-NLC or BN-NLC were evaluated in acute MI rats.

Results and discussion: The particle size, zeta potential, and entrapment efficiency for BN-PEG-NLC were observed as 83.9?nm, ?32.1?mV, and 83.5%, respectively. The release profiles of BN from both BN-PEG-NLC and BN-NLC were fitted to the Ritger–Peppas modal, which presented burst release initially and prolonged release afterwards. Pharmacokinetics results indicated that BN-PEG-NLC exhibited a 7.2-fold increase in AUC in comparison to BN solution, while a 3-fold increase in comparison to BN-NLC. Biodistribution results revealed that BN-PEG-NLC exhibited higher heart drug concentration compared with BN-NLC as well as BN solution. In the present study, BN-PEG-NLC significantly ameliorated infarct size.

Conclusion: The results of the present study imply that PEG-NLC could be the biocompatible carriers for heart-targeted drug delivery to improve myocardial ischemia.  相似文献   
7.
8.
9.
10.
目的 评价缺血修饰性白蛋白(ischemia modified albumin,IMA)对急性缺血性胸痛(ICP)的早期诊断价值。方法 时206例发病〈12h、表现为急性胸痛的患者立即行12导联心电图(ECG)检查,并抽血进行IMA、肌钙蛋白I(cTnI)、肌酸激酶同工酶MB(CK-MB)测定。将ECG、IMA、cTnI、CK-MB的结果单独或结合与最终诊断为非缺血性胸痛(NICP)及ICP的相互关系进行比较。结果 最后诊断为ICP98例,NICP108例,ICP发病〈3h和3-6h组IMA水平明显升高,与NICP组比较差异有统计学意义(P〈0.001);ICP发病〉6h组IMA水平与NICP组比较差异无统计学意义(P〉0.05)。IMA诊断发病〈3hICP的敏感性和阴性预测值(NPV)为89.1%和88.8%,明显高于ECG、cTnI和CK-MB,四者结合为97.6%和96.9%;IMA诊断发病3~6hICP的敏感性和NPV为71.7%和74.5%,也高于ECG、cTnI、CK-MB,四者结合为95.5%和94.2%;但IMA对于发病〉6h的ICP则无诊断作用。结论 IMA是诊断ICP的早期敏感生化指标,对于发病〈6h(尤其是〈3h)的ICP诊断具有较高的敏感性和NPV,优于ECG、CK-MB、cTnI;将IMA与其他指标结合,可进一步提高对ICP的诊断价值。  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