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   37016篇
  免费   2165篇
  国内免费   1849篇
耳鼻咽喉   32篇
儿科学   411篇
妇产科学   112篇
基础医学   2815篇
口腔科学   38篇
临床医学   4411篇
内科学   9532篇
皮肤病学   28篇
神经病学   4041篇
特种医学   1883篇
外科学   3302篇
综合类   7346篇
预防医学   835篇
眼科学   232篇
药学   3445篇
  9篇
中国医学   2470篇
肿瘤学   88篇
  2023年   248篇
  2022年   542篇
  2021年   788篇
  2020年   794篇
  2019年   597篇
  2018年   702篇
  2017年   766篇
  2016年   922篇
  2015年   1089篇
  2014年   2071篇
  2013年   2159篇
  2012年   2025篇
  2011年   2313篇
  2010年   2097篇
  2009年   2111篇
  2008年   2279篇
  2007年   2361篇
  2006年   2289篇
  2005年   1996篇
  2004年   1712篇
  2003年   1607篇
  2002年   1356篇
  2001年   1216篇
  2000年   1042篇
  1999年   868篇
  1998年   705篇
  1997年   669篇
  1996年   448篇
  1995年   464篇
  1994年   371篇
  1993年   283篇
  1992年   289篇
  1991年   282篇
  1990年   207篇
  1989年   159篇
  1988年   166篇
  1987年   129篇
  1986年   114篇
  1985年   145篇
  1984年   114篇
  1983年   61篇
  1982年   80篇
  1981年   63篇
  1980年   62篇
  1979年   49篇
  1978年   55篇
  1977年   37篇
  1976年   36篇
  1975年   23篇
  1973年   22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.
目的探讨衰减伪影对冠心病患者门控心肌灌注显像(GMPI)图像质量及灌注结果的影响。资料与方法回顾性分析2020年3月—2021年3月在郑州大学第一附属医院核医学科经冠状动脉造影证实且于造影前后1周行GMPI的99例冠心病患者的图像,定性及半定量分析衰减校正前后GMPI图像结果,比较衰减校正前后左心室各壁段平均放射性计数及灌注结果的差异,进一步分析衰减校正前后灌注结果不一致部分的受检者的节段性室壁运动及增厚情况。结果与衰减校正前比较,衰减校正后左心室间隔、下后壁及侧壁的平均放射性计数较高(Z=-7.302、-8.014、-3.991,P均<0.001),心尖部较低(Z=-8.021,P<0.001)。其中女性衰减校正后前壁平均放射性计数减低(Z=-2.314,P=0.021)。男性衰减校正前后下后壁放射性计数差值明显高于女性(t=-8.408,P<0.05)。衰减校正后44%(44/99)的左前降支及37%(37/99)的右冠状动脉分支供血区域显像结果发生改变,结合超声心动图及GMPI结果显示其中85%(35/41)的左前降支及81%(29/36)的右冠状动脉分支供血区域室壁运动及室壁增厚率均正常。结论衰减伪影对GMPI的图像质量和灌注结果有较大影响,结合室壁运动和增厚情况等有助于鉴别衰减伪影,提高诊断准确度与特异度。  相似文献   
4.
5.
6.
7.
Monitoring vascular perfusion of transferred tissue is essential in reconstructive surgery to recognize early flap failure. The aim of this study was to evaluate the ability of a digital surface scanner to detect vascular perfusion disorders through the monitoring of skin colour changes. A total of 160 surface scans of the forearm skin were performed with a TRIOS 3D scanner. Vascular compromise was simulated at different time-points by intermittent occlusion of the blood supply to the forearm skin (first the arterial blood supply and then the venous blood supply). Skin colour changes were examined according to the hue, saturation, and value colour scale. Colour differences were analysed with a paired t-test. Significant differences were observed between the colour of the normal skin and that of the vascular compromised skin (P < 0.01). The surface scanner could distinguish between arterial occlusion and venous congestion (P < 0.01). A digital surface scan is an objective, non-invasive tool to detect early vascular perfusion disorders of the skin.  相似文献   
8.
This position paper was intended to update the former consensus between the French Societies of Radiology and Cardiology about the use of stress cardiac magnetic resonance imaging (MRI) in chronic coronary syndrome published in 2009. The Delphi method was used to build the present consensus. This expert panel consensus includes recommendations for indications, procedure with patient preparation, stress inducing drugs, acquisition protocol, interpretation and risk stratification by stress MRI.  相似文献   
9.
《Indian heart journal》2021,73(4):487-491
IntroductionThe time from symptom onset to arrival at healthcare facility, and door to reperfusion time in treatment of acute coronary syndrome (ACS) can be improved significantly if the patient or the relatives can record a 12-lead ECG at home and transmit it to the physician for prompt interpretation. To make this widely applicable, the 12-lead ECG recording device has to be simple and user friendly. In this regard, torso ECG (T-ECG) electrode positions that are less cumbersome than the conventional ECG (C-ECG) electrode positions are an alternative worthy of consideration.Objectiveand setting: To study the utility of T-ECG versus C-ECG in ACS patients.Designand intervention: We proposed torso electrode positions in which upper limb electrodes were placed in the respective deltopectoral grooves below the lateral end of the clavicle; the right lower limb electrode was placed 2 finger breadths above the umbilicus and the left lower limb electrode, 2 finger breadths to the left of the umbilicus. We then studied the ECGs recorded, to ascertain whether T-ECGs miss or over-diagnose ACS changes. Twelve lead ECGs were recorded by both techniques (C-ECG & T-ECG) in 1361 patientsfrom the coronary care unit & out-patient department of a tertiary care hospital. A total of 1526 sets of ECGs (each set consisting of one C-ECG and one T -ECG) were read by two trained cardiologists independently and in a blinded fashion. There were 457 ECG sets from 342 patients with ACS. Of these, 116 ECG sets from 112 patients of anterior infarction who had changes restricted to precordial leads were excluded. Finally, 341 ECG sets from 230 patients with ACS and 324 sets of patients diagnosed to be normal on C-ECG were considered for the purpose of this study.Main resultsAll 341 ECG sets from the 230 patients of ACS diagnosed by C-ECG were correctly diagnosed by T-ECG (100% sensitivity) and all 324 normal ECGs on C-ECG were also identified as normal on T-ECG (100% specificity). Of the ACS ECGs, ST elevation was seen in 234 ECGs and ST depressions 154 ECGs. The localizations of ST elevation and ST depression were also accurately diagnosed by the T-ECG.ConclusionThe ECG recorded by our novel proposed torso electrode positions is comparable to a conventional ECG for the diagnosis of ACS.  相似文献   
10.
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