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   4102篇
  免费   334篇
  国内免费   87篇
儿科学   49篇
妇产科学   5篇
基础医学   122篇
口腔科学   3篇
临床医学   575篇
内科学   2479篇
皮肤病学   1篇
神经病学   96篇
特种医学   86篇
外国民族医学   1篇
外科学   591篇
综合类   428篇
预防医学   14篇
眼科学   6篇
药学   51篇
  2篇
中国医学   6篇
肿瘤学   8篇
  2024年   7篇
  2023年   97篇
  2022年   163篇
  2021年   301篇
  2020年   262篇
  2019年   282篇
  2018年   212篇
  2017年   124篇
  2016年   105篇
  2015年   135篇
  2014年   252篇
  2013年   205篇
  2012年   144篇
  2011年   144篇
  2010年   124篇
  2009年   104篇
  2008年   138篇
  2007年   105篇
  2006年   114篇
  2005年   113篇
  2004年   88篇
  2003年   99篇
  2002年   74篇
  2001年   78篇
  2000年   85篇
  1999年   85篇
  1998年   100篇
  1997年   92篇
  1996年   74篇
  1995年   80篇
  1994年   70篇
  1993年   66篇
  1992年   52篇
  1991年   42篇
  1990年   29篇
  1989年   27篇
  1988年   22篇
  1987年   35篇
  1986年   25篇
  1985年   32篇
  1984年   29篇
  1983年   24篇
  1982年   26篇
  1981年   14篇
  1980年   16篇
  1979年   7篇
  1978年   9篇
  1977年   2篇
  1976年   4篇
  1973年   4篇
排序方式: 共有4523条查询结果,搜索用时 15 毫秒
61.
62.
63.
Accessory mitral valve leaflet is a rare congenital anomaly. More than half of the cases show other congenital cardiac defects and almost all of the cases show subaortic obstruction. We report a case of an accessory mitral valve tissue without outflow obstruction associated with mitral cleft of the posterior mitral leaflet. To our knowledge, this is the first reported case of the combination of these two congenital anomalies.  相似文献   
64.
Periprosthetic regurgitation (PPR) is a common complication of mitral valve replacement (MVR). The management of moderate and minor PPR remains controversial. The goal of this prospective study was to determine the incidence, predictors and outcome of PPR discovered using omniplan transoesophageal echocardiography (TEE) performed at the early postoperative period (14.7 days) of MVR with SJM prosthesis. Our study enrolled 56 patients, the mean age was 44.5 +/- 11.9 years. The incidence of PPR was 59% (33 patients). TEE showed one jet in nine patients (27%), two jets in 23 patients (70%) and three jets in one patient (3%). PPR is minor in 24 patients (63%) and moderate in nine patients (27%). No patient developed hemolytic anemia or congestive heart failure. In univariate analysis, diameter of prostheses > 27 mm, number of suture knots < 17 and diameter of prostheses/number of knot ratio > 1.7 independently predicted the presence of PPR. In multivariate analysis only a rapport diameter of protheses/number of suture knots > 1.7 mm is predictif of PPR (odd ratio = 9, P = 0.036). Ninety percent of PPR remained present at six weeks and only 29% were present after 12.5 months. CONCLUSION: Mild and minor PPR were frequent during the early postoperative period after MVR. The clinical significance and natural history is benign and they do not require any specific treatment.  相似文献   
65.
66.
Color Flow Doppler Observations on Mitral Valve Flow in Tamponade   总被引:1,自引:0,他引:1  
We studied the M-mode and two-dimensional imaging of color Doppler mitral flow in eight patients with pericardial effusion and tamponade, and in ten control subjects. Pulsed-Doppler recordings of mitral flow were also obtained in all. Marked phasic changes (presumably respiratory) were consistently recorded in all patients with tamponade with respect to brightness, hue, width (duration), and length of the M-mode Doppler color stream; in these patients, phasic changes were noted in width, length, and color of the mitral flow stream on the two-dimensionalechocardiographic recording, with reciprocal changes in tricuspid flow. In the normal subjects, only minimal fluctuations in these color Doppler characteristics were present. Phasic differences in flow velocity of mitral flow by pulsed Doppler were found between the tamponade and the control groups. Large phasic fluctuations in various characteristics of color Doppler mitral flow on M-mode and two-dimensional imaging may constitute yet another echocardiographic sign of tamponade. (ECHOCARDIOGRAPHY, Volume 8, September 1991)  相似文献   
67.
In this report, we evaluated the cardiac findings of 15 children with polyarteritis nodosa. The age range of the patients was 4–14 years; with a mean of 10 years. All have had systemic involvement of the disease. The most common findings in cardiac evaluation were diminished left ventricular systolic functions and mild mitral and/or tricuspid valve regurgitation. One patient had pericardial thickening with no effusion. One had sinus tachycardia. There were no signs of myocardial infarction or ischemia clinically or electrocardiographically. In conclusion, we did not find cardiac complications, such as pericarditis or myocardial infarction, to be as frequent as in previous reports. However, even in asymptomatic patients, systolic dysfunction or valvular involvement were common findings in patients with polyarteritis nodosa, which were not reported previously. These findings may be due to the histological changes of the myocardium or atrioventricular valves. Although these were not severe and fatal lesions, long-term follow-up of these patients with echocardiography may help to determine the course of cardiac involvement.  相似文献   
68.
Percutaneous mitral valvuloplasty using the Inoue technique was complicated by the failure to pass the dilator or balloon catheter above the vertebral level of L5 due to compression of the right common iliac vein by the right common iliac artery. The procedure was accomplished when a long sheath was used to pass the Inoue balloon catheter beyond the obstruction. © Wiley-Liss, Inc.  相似文献   
69.
BACKGROUND AND AIM: Balloon-occluded retrograde transvenous obliteration (B-RTO) is a novel therapeutic method for the treatment of large gastric fundal varices with spontaneous splenorenal shunt (SRS). However, the effects of B-RTO on liver function remain unknown. METHODS: Fourteen patients with portal hypertension and gastric varices with SRS were studied, consisting of four patients with acute bleeding, five with high-risk varices, and five with refractory portosystemic encephalopathy. Hepatic venous catheterization was performed to evaluate hepatic blood flow and liver function using the continuous indocyanine green (ICG) infusion method. To assess the metabolic activity of the hepatocyte, the intrinsic clearance of ICG was calculated. In all patients, endoscopic study was performed before and 1 week and 1 month after the B-RTO, and followed every 6 months thereafter. After baseline measurements, B-RTO was performed. Four weeks after the B-RTO, the same catheter measurements were repeated. RESULTS: The B-RTO was successful in all patients. Contrast-enhanced computed tomography showed complete obliteration of the SRS prior to the follow-up measurements. Endoscopic eradication of the fundal varices was obtained 6 months after B-RTO in all patients and encephalopathy was improved within 1 week after B-RTO. Following the B-RTO, hepatic blood flow (441 +/- 214 vs 668 +/- 299 mL/min, P < 0.0001) and the intrinsic clearance of ICG (233 +/- 123 vs 285 +/- 148 mL/min, P < 0.05) were significantly increased. Furthermore, intrahepatic resistance decreased after the B-RTO (P < 0.005). CONCLUSION: From short-term assessment, B-RTO increases hepatic blood flow and improves the metabolic activity of the liver in patients with portal hypertension.  相似文献   
70.
ObjectivesThe aim of this study was to characterize left atrial (LA) pathology in explanted hearts with transthyretin amyloid cardiomyopathy (ATTR-CM); LA mechanics using echocardiographic speckle-tracking in a large cohort of patients with ATTR-CM; and to study the association with mortality.BackgroundThe clinical significance of LA involvement in ATTR-CM is of great clinical interest.MethodsCongo red staining and immunohistochemistry was performed to assess the presence, type, and extent of amyloid and associated changes in 5 explanted ATTR-CM atria. Echo speckle tracking was used to assess LA reservoir, conduit, contractile function, and stiffness in 906 patients with ATTR-CM (551 wild-type (wt)-ATTR-CM; 93 T60A-ATTR-CM; 241 V122I-ATTR-CM; 21 other).ResultsThere was extensive ATTR amyloid infiltration in the 5 atria, with loss of normal architecture, vessels remodeling, capillary disruption, and subendocardial fibrosis. Echo speckle tracking in 906 patients with ATTR-CM demonstrated increased atrial stiffness (median [25th-75th quartile] 1.83 [1.15-2.92]) that remained independently associated with prognosis after adjusting for known predictors (lnLA stiff: HR: 1.23; 95% CI: 1.03-1.49; P = 0.029). There was substantial impairment of the 3 phasic functional atrial components (reservoir 8.86% [5.94%-12.97%]; conduit 6.5% [4.53%-9.28%]; contraction function 4.0% [2.29%-6.56%]). Atrial contraction was absent in 22.1% of patients whose electrocardiograms showed sinus rhythm (SR) “atrial electromechanical dissociation” (AEMD). AEMD was associated with poorer prognosis compared with patients with SR and effective mechanical contraction (P = 0.0018). AEMD conferred a similar prognosis to patients in atrial fibrillation.ConclusionsThe phenotype of ATTR-CM includes significant infiltration of the atrial walls, with progressive loss of atrial function and increased stiffness, which is a strong independent predictor of mortality. AEMD emerged as a distinctive phenotype identifying patients in SR with poor prognosis.  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