首页 | 本学科首页   官方微博 | 高级检索  
  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   473篇
  国内免费   15篇
  完全免费   8篇
  临床医学   496篇
  2017年   1篇
  2015年   2篇
  2014年   14篇
  2013年   14篇
  2012年   17篇
  2011年   10篇
  2010年   18篇
  2009年   29篇
  2008年   26篇
  2007年   32篇
  2006年   33篇
  2005年   26篇
  2004年   22篇
  2003年   26篇
  2002年   12篇
  2001年   22篇
  2000年   14篇
  1999年   10篇
  1998年   14篇
  1997年   11篇
  1996年   4篇
  1995年   9篇
  1994年   8篇
  1993年   6篇
  1992年   11篇
  1991年   12篇
  1990年   12篇
  1989年   7篇
  1988年   19篇
  1987年   3篇
  1986年   11篇
  1985年   7篇
  1984年   14篇
  1983年   8篇
  1982年   6篇
  1981年   1篇
  1980年   4篇
  1979年   1篇
排序方式: 共有496条查询结果,搜索用时 31 毫秒
While radiofrequency catheter ablation is very effective, it does not allow for prediction of success prior to full delivery of the energy. We investigated the use of cryoablation using a new catheter on the AV node to determine (1) if a successful site might be identified prior to the ablation itself, and (2) the parameters of cryoablation of the AV node using a new cryocatheter. In eight dogs, the cryoablation catheter was advanced to the AV node to produce transient high degree AV block by lowering the temperature to a minimum of -40 degrees C (ice mapping). Transient high degree AV node block was obtained in seven of eight animals at a mean temperature of -39.9 +/- 11.6 degrees C. No significant pathological modification was found in all animals but one and, in all cases, electrophysiological parameters of the AV node measured before, 20 minutes, 60 minutes, and up to 56 days after cryoapplication were not significantly different. In the 12 other dogs, after ice mapping, cryoablation of the AV node was attempted with a single freeze-thaw cycle in 6 dogs (group I) and a double freeze-thaw cycle in the other 6 dogs (group II). Chronic complete AV block was obtained in only one animal in group I compared to all animals in group II. Ablation of the AV node is effective with a double freeze-thaw cycle using a percutaneous catheter cryoablation system. Ice mapping of the area allows for identification of the targeted site.  相似文献
加味炙甘草汤注射液治疗病态窦房结综合征的电生理研究   总被引:18,自引:1,他引:17  
观察加味炙甘草汤注射液对窦房结功能损伤兔电生理的影响,探讨加味炙甘草汤注射液治疗病态窦房结综合征的临床疗效和机制。方法:应用经静脉和经食管心房调搏方法观察加味炙甘草汤注射液的窦房结电生理作用。结果:应用加味炙甘草汤注射液后,SND兔的窦房结恢复时间(SNRT)、校正SNRT(SNRTc)较对照组明显缩短,心脏固有心率(IHRo)明显上升,总窦房传导时间(TSACT)无改变。临床电生理结果与动物实验  相似文献
Focal AF is frequently triggered by ectopic beats mostly originating from the pulmonary veins (PVs). So far, the morphological substrate for this entity is not well defined. Therefore, the distribution of myocardial cells within the PV were examined as potential target sites for RF application. The PVs (118) of 30 human autopsied hearts (age of death 63 +/- 13 years, 17 men) were dissected in their complete circumference starting 1 cm from the ostium. Tissue sections of the PV were stained with hematoxylin-eosin and with Masson's trichrome. To characterize the developmental state of the myocardial tissue in the PV, immunohistochemistry was performed with antibodies reacting with antigens which are stage specifically expressed during cardiac development (HNK1/Leu7, alpha-SMA, calponin and desmin). Furthermore, proliferative activity was assessed using antibodies against the Ki-67 antigen (MIB-1). In two hearts a left-sided common PV ostium was found. The other hearts showed four separated PV ostia. The ostium diameter of the right inferior PV (1.2 +/- 0.3 cm) was significantly smaller (P < 0.05) than remaining PV ostia (right superior 1.5 +/- 0.2, left superior, 1.5 +/- 0.3 and left inferior 1.4 +/- 0.3 cm) of the 118 specimen. There was no significant difference in the presence of myocardium in the PV 1-cm distant from the ostium comparing the right superior (78%), the right inferior (81 %), the left superior (81%), and the left inferior (81%) PV. In 54% of cases the myocardial bundles covered the complete PV circumference. In up to 38% of the small extensions of the myocardial bundles myocardial cells, characterized by distinct cross-striations and spindle shape were found. However, since these cells could not be labeled for other markers than desmin, their immature state seems unlikely. The anatomic distribution of myocardium in the PV suggests that RF applied to the entire circumference may be frequently required for its electrical isolation. Whether spindle-shaped myocytes have different electrophysiological behavior has to be further investigated.  相似文献
2型糖尿病周围神经的电生理改变及其影响因素   总被引:10,自引:0,他引:10  
目的:观察2型糖尿病周围神经的电生理改变及其影响因素。方法:回顾分析了60例2型糖型病患者的临床、电生理及实验室检查资料。结果:周围神经有电生理改变的患者占糖尿病患者的71.6%,分别比较所检神经的各项电生理测定值与患者病程和果糖胺及糖化血红蛋白发现:和患者病程显著相关的是正中神经运动支的潜伏期延长和腓总神经的传导速度减慢。结论:病程和糖尿病性微血管病是影响患者出现周围神经病变的危险因素之一,电生理检查中正中神经和腓总神经的检测意义较大。  相似文献
海葵毒素的电生理作用   总被引:9,自引:0,他引:9  
海葵毒素是从海洋生腔肠动物海葵体内提取的多肽和蛋白质毒素,种类很多,包括Anemone Sulcata毒素,Actinia equina毒素和Anthopleurin毒素等。它们主要为心脏和神经毒素。多数毒素与电压依赖性钠通道结合,减慢钠通道的失活过程,且对不同组织的钠通道及不同钠通道亚型作用有差异。也有一些毒素是钾通道阻断剂。它们主要作为工具药研究离子通道的结构和功能。另外,有些毒素还表现其他作用,如抗病毒和细胞毒作用等。  相似文献
Video-Assisted Thoracoscopic Sympathectomy for Congenital Long QT Syndromes   总被引:7,自引:0,他引:7  
LI, J., et al .: Video-Assisted Thoracoscopic Sympathectomy for Congenital Long QT Syndromes. The feasibility, safety, and effectiveness of video-assisted thoracoscopic sympathectomy (VATS) for congenital long QT syndrome were assessed in four patients who had frequent syncopal events before the surgeries. Under general anaesthesia, the pleural cavity was entered via two small incisions in the left third and fifth intercostal spaces at the mid-axillary line. The left thoracic sympathetic chain was identified and resected from T2-T5. The lower one third of the left stellate ganglion was also resected. VATS resulted in a significant shortening in corrected QT intervals (QTc) in three patients, the average QTc of the four patients immediately before and after VATS was   538 ± 76   and   512 ± 57 ms   , respectively   (P = 0.047)   . The heart rate remained unchanged after the VATS (   67 ± 4   vs   69 ± 4 beats/min, P > 0.05   ). There were no major perioperative complications apart from mild ptosis of the left upper eyelid in one patient who recovered in the following days. There was no recurrence in syncopal events after a 3-month follow-up. VATS is a safe and effective technique for left cardiac sympathectomy in patients with congenital long QT syndromes. (PACE 2003; 26[Pt. I]:870–873)  相似文献
兔腰神经根慢性压迫模型的建立   总被引:7,自引:2,他引:5  
目的 :制作腰神经根慢性轻度压迫模型。方法 :取纯种新西兰成年兔 16只 ,将 4只做神经定位解剖 ,12只随机分成 3组 :10天组、30天组和 180天组 ,每组 4只。将长 12mm ,内径 1.5mm ,外径 2 .5mm的硅胶管从椎间外孔缓慢塞入兔椎间管内 ,压迫腰 6和腰 7左侧神经根 ,右侧为自身对照侧 ,硅胶管的截面积约为椎间管经关节突关节矢状面面积的 2 0 % ,约为椎间外孔面积的 5 0 %。结果 :10天组与 30天组比较 ,潜伏时明显延长 ,神经传导速度减慢。180天组虽然与对照侧比较潜伏时和神经传导速度均有显著性差异 ,但与 30天组比较已有明显改善。对照侧的潜伏时、神经传导速度各时间点均无明显差异。除 10天组潜伏时、神经传导速度与对照侧比较无明显差异外 ,30天组和 180天组潜伏时、神经传导速度与对照侧比较均有明显差异 ,潜伏时延长 ,神经传导速度减慢。结论 :将硅胶管从兔的椎间外孔缓慢塞入椎间管内使腰神经根慢性轻度受压 ,更接近于腰椎间盘突出和椎间管狭窄对神经根的压迫。慢性压迫后的神经有自行恢复的能力。  相似文献
Several atrial pacing modes have been reported to be effective in the prevention of atrial fibrillation (AF); they included biatrial pacing, dual site right atrial pacing, Bachmann's bundle (BB) pacing, and coronary sinus pacing. However, the relative efficacy and electrophysiological mechanisms of these pacing modes in the prevention of AF are not clear. In 15 patients (age 54 +/- 14 years) with paroxysmal AF, P wave duration, effective refractory period, and atrial conduction time were determined with six different atrial drive pacings, that were right atrial appendage (RAA), BB, right posterior interatrial septum (RPS), distal coronary sinus (DCS), RAA plus RPS simultaneously (DSA), and RAA plus DCS simultaneously (BiA). All these patients consistently had AF induced with early RAA extrastimulation coupling to RAA drive pacing. No patient had AF induced with RAA extrastimulation coupled to BB, RPS, or DCS drive pacing, but seven and eight patients had AF induced with RAA extrastimulation coupled to DSA and BiA drive pacing, respectively. The P wave duration was longest during RAA pacing, and became shorter during other atrial pacing modes. Analysis of electrophysiological change showed that early RAA extrastimulation coupled to RAA drive pacing caused the longest atrial conduction delay among these atrial pacing modes; BB, RPS, and DCS drive pacing caused a greater reduction of this conduction delay than DSA and BiA drive pacing. In addition, the effective refractory periods of RAA determined with BB, RPS, and DCS drive pacing were similar and longer than that determined with DSA and BiA drive pacing. In patients with paroxysmal AF, this arrhythmia was readily induced with RAA extrastimuli coupled to RAA drive pacing. BB, RPS, and DCS pacing were similar and more effective than DSA and BiA pacing in preventing AF.  相似文献
The International Affective Picture System (IAPS) is increasingly used in brain imaging studies to examine emotional processes. This task allows valence and arousal content to be systematically investigated; however, previous studies have generally failed to select images that vary in one dimension as well as hold constant the variability on the other dimension. In addition, no studies have investigated the temporal structure associated with the conscious, ongoing processing of emotional stimuli following systematic selection of IAPS images. The aim of the present study was therefore to use steady-state probe topography (SSPT) to examine the steady-state visually evoked potentials (SSVEPs) associated with the processing of pleasant and unpleasant images low in arousal content. Seventy-five IAPS images, categorized as unpleasant, neutral, or pleasant, were presented to 16 healthy subjects while brain activity was recorded from 64 scalp sites. Analysis subtracted the activity associated with the presentation of neutral images from the activity associated with the presentation of pleasant as well as unpleasant images. Results demonstrate that both pleasant and unpleasant valence is associated with transient, widespread, and bilateral frontal SSVEP latency reductions. Unpleasant images were also associated with a transient bilateral anterior frontal amplitude decrease. Latency reductions are interpreted as increases in neural information processing speed, while amplitude reductions are interpreted in the current paper as analogous to an event-related desynchronisation commonly associated with the alpha bandwidth. These key findings support previous literature in terms of there being substantial overlap in frontal neural circuitry when the brain processes pleasant and unpleasant valence relative to neutral valence.  相似文献
急性河豚鱼中毒患者的神经电生理测定的特点及意义   总被引:7,自引:1,他引:6  
目的 分析急性河豚毒素(tetrodotoxin,TTX)中毒患者的神经电生理变化的特点与意义。方法 检测64例患者的运动神经传导速度(mote never conduction velocity,MCV)、感觉神经传导速度(sensory never conduction velocity,SCV)、F波、H反射和体感诱发电位(somatosensory evoked potentiols,SEP)。结果MCV、SCV均有减慢,以SCV减慢最为显著,MCV远段动作电位潜伏期明显延长,神经传导速度(NCV)的异常检出率高;F反应、H反射异常提示部分TIX中毒累及神经根;SEP的异常率达45.9%,说明TTX中毒伴有中枢神经的损害。结论 神经电生理检测可用来动态观察’FTX中毒患者神经系统损害程度、病稃,范围,亦旱,TTX中毒时早期检杏的重要手段之一。  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