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   7604篇
  免费   471篇
  国内免费   96篇
耳鼻咽喉   3篇
儿科学   280篇
妇产科学   31篇
基础医学   213篇
口腔科学   4篇
临床医学   1967篇
内科学   4385篇
皮肤病学   7篇
神经病学   72篇
特种医学   57篇
外科学   254篇
综合类   551篇
预防医学   55篇
药学   247篇
  1篇
中国医学   34篇
肿瘤学   10篇
  2024年   12篇
  2023年   160篇
  2022年   168篇
  2021年   269篇
  2020年   245篇
  2019年   279篇
  2018年   262篇
  2017年   135篇
  2016年   147篇
  2015年   179篇
  2014年   374篇
  2013年   374篇
  2012年   247篇
  2011年   305篇
  2010年   252篇
  2009年   250篇
  2008年   238篇
  2007年   295篇
  2006年   297篇
  2005年   292篇
  2004年   261篇
  2003年   216篇
  2002年   220篇
  2001年   252篇
  2000年   216篇
  1999年   214篇
  1998年   207篇
  1997年   217篇
  1996年   155篇
  1995年   152篇
  1994年   163篇
  1993年   141篇
  1992年   148篇
  1991年   135篇
  1990年   95篇
  1989年   70篇
  1988年   77篇
  1987年   51篇
  1986年   74篇
  1985年   65篇
  1984年   76篇
  1983年   41篇
  1982年   41篇
  1981年   21篇
  1980年   23篇
  1979年   18篇
  1978年   9篇
  1976年   14篇
  1975年   5篇
  1973年   6篇
排序方式: 共有8171条查询结果,搜索用时 0 毫秒
41.
目的 :推广应用射频消融治疗快速心律失常。方法 :穿剌动静脉 ,置入刺激和消融电极 ,经多导电生理仪明确消融靶点 ,在局部引入射频电流 ,破坏折返路径。结果 :经电生理检查诊断为室上性心动过速12例 ,特发性室性心动过速1例 ,在20~40W射频功率下经5~200s的放电消融 ,13例均获得成功(成功率100 %)。结论 :射频消融术是治疗室性心动过速 ,室上性心动过速的有效方法 ,且创伤小 ,安全可靠 ,有较高的推广价值  相似文献   
42.
Adenosine for the management of patients with tachycardias--a new protocol   总被引:1,自引:0,他引:1  
We developed a new protocol for diagnosis and treatment of patientswith sustained tachycardias (heart rate > 150 beats. min–1).The patients first underwent vagal manoeuvres; if those remainedunsuccessful, i.v. adenosine in increasing doses of 6, 12, and18 mg was administered until sinus rhythm (SR) or transientatrioventricular (AV) block, unmasking the underlying rhythm,was recorded. In the latter and in the non-responding casesother antiarrhythmics were applied. Ninety-three episodes of tachycardia in 46 patients were treatedaccording to this protocol. Six episodes (6%) were terminatedby carotid massage, 64 of the remaining 87 episodes (74%) respondedto adenosine with return to SR. Conversion to SR occurred moreoften in episodes with narrow- than in wide-complex tachycardia(81 vs 59%, P<005). To achieve SR, the mean adenosine dosewas lower in narrow- than in wide-complex tachycardia (13±8vs 21 ± 10 mg; P<0.01). The duration of asystole afteradenosine did not differ between these two groups, whereas theduration of arrhythmia after adenosine differed significantly(8.5 ± 5.8 vs 18.6 ± 22.9 s; P<0.05). Sideeffects of adenosine such as flush, dyspnoea, and chest paindid not seem to be dose dependent and occurred in about 20%. According to our protocol, in more than 75% SR was achievedin patients with sustained tachycardias after vagal manoeuvresand adenosine.  相似文献   
43.
目的:探讨房室结折返性心动过速(AVNRT)射频消融术后的电生理改变及不同手术终点与复发率的关系。 方法:本组56 例AVNRT患者慢径消融前、后作各项电生理参数测定,并随访观察远期疗效。 结果:38 例慢径消失者(A组)无一例复发,残存慢径12 例(B组)有一例复发(8.33% ),残存慢径有1~2 个心房回波者6例(C组)有2例复发(33.3% )。53 例无复发者消融前后的房室束最大值(A-Hm ax )分别为(280±27)和(196±56)m s(P<0.01),快径不应期分别为(330±44)和(287±31)m s(P< 0.01)。而3 例复发者消融前、后的A-Hm ax分别为(287±31)和(262±38)m s(P> 0.05),快径不应期分别为(324±38)和(313±28)m s(P> 0.05)。 结论:AVNRT的复发与慢径残存和A-Hm ax 及快径不应期无明显改变有关。  相似文献   
44.
射频能量时间递增法治疗房室结折返性心动过速   总被引:2,自引:1,他引:1  
目的:评估射频能量时间递增法治疗40 例房室结内折返性心动过速的疗效及安全性。 方法:标测到理想的慢径路靶点后,从小功率(10~15 W)、短时间(5~10 s)放电开始,如出现交界区早搏或交界区心律,逐渐增加放电功率(20~25 W)和持续时间(30~60 s),并密切观察房室传导阻滞的迹象和先兆。 结果:临床治愈率97.5% ,无一例产生严重并发症。 结论:射频能量时间递增法是一种安全、高效的治疗方法。  相似文献   
45.
目的:利用超声心动图检测正常人左侧房室平面位移幅度。方法:被检对象为144 例正常人,男72 例,女72 例。按不同年龄分为6 组,分别为:Ⅰ组(n= 24 ,3~6 岁);Ⅱ组(n=24 ,7~14 岁) ;Ⅲ组(n=24,15~19 岁) ;Ⅳ组(n= 24,20~39 岁);Ⅴ组(n=24 ,40 ~59 岁) 及Ⅵ组(n= 24 ,≥60 岁)。结果:①左心收缩期房室平面位移测值在Ⅰ组~Ⅴ组之间无显著性差异( P>0-05),而Ⅵ组测值较Ⅰ组~Ⅴ组的测值均低( P< 0-05);②左心收缩期房室平面位移测值不受心率、血压、体表面积及性别的影响。结论:①左侧房室平面位移测值受年龄因素影响;②制定正常左侧房室平面位移测值可以不考虑心率、血压、体表面积及性别的影响  相似文献   
46.
观察微波消融犬室性心动过速(简称室速)疗效和微波消融对血液动力学的影响。健康犬40只,随机分成5组,Ⅰ组(对照组,n=8),Ⅱ、Ⅲ、Ⅳ和Ⅴ组(消融组,n=8),由股动脉、股静脉穿刺进行血液动力学监测。用0.01ml0.03%乌头碱注入心室壁诱发室性心动过速。消融释放功率和时间Ⅱ组为40W×30s,Ⅲ组为40W×60s,Ⅳ组为80W×30s,Ⅴ组为80W×60s。结果:自发放微波能量至室速终止时间Ⅱ、Ⅲ组为(10.1±2.4)s,与对照组比,P<0.001;Ⅳ、Ⅴ组为(5.3±1.5)s,与对照组比,P<0.001。消融前后血液动力学各项指标差异无统计学意义(P>0.05),消融后组间血液动力学各项指标差异无统计学意义(P>0.05)。微波产生的心肌损伤,显微镜下观察均为凝固性坏死,与周围组织存在清晰的界限。结论:微波消融室速具有较好的疗效,消融能量与时间在一定范围内对血液动力学无明显影响,可望成为室速治疗的1种新方法。  相似文献   
47.
Radiofrequency (RF) catheter ablation has ushered in a new era in the management of patients with symptomatic tachyarrhythmias. By providing the ability to cure the underlying arrhythmic substrate, RF catheter ablation obviates the need for life-long antiarrhythmic drugs. In the reported series, the success has been high and the complications have been infrequent and relatively minor. Not unexpectedly, RF catheter ablation has become the treatment of choice for patients with symptomatic paroxysmal tachyarrhythmias. The role of radiofrequency catheter ablation in infants and small children remains controversial, and awaits a larger experience and longer follow-up data.  相似文献   
48.
胎儿房室结微血管构筑的扫描电镜观察   总被引:4,自引:1,他引:3  
用血管铸型结合扫描电镜方法观察了7例胎儿房室结微血管构筑.微动脉反复分支呈树状,行走方式呈波浪形或螺旋形.毛细血管网可分为内外两层:外层纵行为主,以"H"或"Y"形吻合;内层弯曲行走为主,并互相交错吻合.以房室结动脉主干为界,其下方毛细血管密度较大,其上方及前方较小.房室结的上方、前下方和后下方均有微动脉连接毛细血管网.整个结的毛细血管大致可分为结后部上方、下方及前部三个区域.靠毛细血管网外层处可见管径较粗、呈袋状的微静脉.  相似文献   
49.
Fascicular tachycardia sensitive to calcium antagonists   总被引:3,自引:0,他引:3  
Five patients with recurrent tachycardias exhibiting right bundlebranch block with left axis deviation were referred for investigation.In each case, a supraventricular mechanism was suspected. Duringsinus rhythm, the QRS morphology and axis (–10 to +60degrees) and HV intervals were normal. Tachycardia was initiatedby timed ventricular premature stimuli in 4 patients, rapidventricular pacing in 3 patients and rapid atrial pacing in2 patients. The tachycardia cycle length varied from 275 to380 ms with right bundle branch block and a leftward axis changeof 30 to 125 degrees at the onset of the tachycardia. The HVinterval ranged from +15 to –20 ms. In each patient ventriculoatrialdissociation occurred spontaneously or could be induced. Alltachycardias could be terminated or greatly slowed by calciumantagonists. These data are consistent with an unusual reentrantmechanism of tachycardia located in the posterior fascicle ofthe left bundle branch.  相似文献   
50.
Summary DPI 201-106 (DPI), a novel and potent cardiotonic agent, exhibits its effects by prolonging the open state of Na+ channels, resulting in an increase in action potential duration, and thus, is supposed to share the class III antiarrhythmic activity. The effects of DPI on the hemodynamics, intraventricular conduction and refractoriness of heart, and the incidence of arrhythmias induced by programmed electrical ventricular stimulation (PES) were compared with (±)-dobutamine. Dogs which survived for 5 to 7 days after the induction of myocardial infarction were used as the model. The presence of sub-acute myocardial infarction caused by occluding the left anterior descending coronary artery elicited a mild left ventricular dysfunction represented by a significant decrease in peak LV dp/dt by about 20%.Both i.v. bolus injection of DPI (1, 3 and 5 mg/kg) and i. v. continuous infusion of dobutamine (3, 5 and 10 g/kg/min), which were administered in a cumulative manner, dose-dependently improved the hemodynamic parameters. At the higher doses of both DPI (3 and 5 mg/kg) and dobutamine (5 and 10 g/kg/min) the control values were reached or even exceeded. DPI dose-dependently increased the effective refractory period (ERP) of both non-infarcted and infarcted ventricular myocardia to a similar degree, but the conduction time showed a frequency-dependent increase in the infarcted myocardium to a greater degree than in the non-infarcted myocardium after DPI. In contrast, dobutamine decreased the ERP in both non-infarcted and infarcted myocardia, and slightly increased the difference of refractoriness between the non-infarcted and infarcted zones with no effect on the intraventricular conduction. In the PES study, DPI (3 and 5 mg/kg) produced a significant decrease in the incidence of ventricular tachycardia, whereas dobutamine (5 and 10 g/kg/min) tended to worsen the arrhythmias. These findings suggest that cardiotonic agents with a class III antiarrhythmic property such as DPI may be potentially useful for the management of heart failure accompanied by ischemic heart disease.Abbreviations DPI, DPI 201-106; PES programmed electrical ventricular stimulation - LV dp/dt the rate of rise of left ventricular pressure - ERP effective refractory period - RVOT right ventricular outflow tract - VT ventricular tachycardia - LAD left anterior discending coronary artery Send offprint requests to T. Uematsu at the above address  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