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   7209篇
  免费   488篇
  国内免费   151篇
耳鼻咽喉   53篇
儿科学   157篇
妇产科学   86篇
基础医学   1431篇
口腔科学   921篇
临床医学   849篇
内科学   405篇
皮肤病学   29篇
神经病学   1664篇
特种医学   263篇
外科学   431篇
综合类   546篇
预防医学   233篇
眼科学   177篇
药学   242篇
  1篇
中国医学   240篇
肿瘤学   120篇
  2024年   12篇
  2023年   117篇
  2022年   186篇
  2021年   374篇
  2020年   273篇
  2019年   254篇
  2018年   283篇
  2017年   241篇
  2016年   250篇
  2015年   228篇
  2014年   397篇
  2013年   478篇
  2012年   321篇
  2011年   367篇
  2010年   292篇
  2009年   330篇
  2008年   363篇
  2007年   326篇
  2006年   322篇
  2005年   263篇
  2004年   232篇
  2003年   196篇
  2002年   185篇
  2001年   139篇
  2000年   129篇
  1999年   107篇
  1998年   118篇
  1997年   98篇
  1996年   88篇
  1995年   75篇
  1994年   56篇
  1993年   50篇
  1992年   40篇
  1991年   51篇
  1990年   53篇
  1989年   49篇
  1988年   34篇
  1987年   51篇
  1986年   45篇
  1985年   62篇
  1984年   68篇
  1983年   43篇
  1982年   45篇
  1981年   32篇
  1980年   41篇
  1979年   17篇
  1978年   18篇
  1977年   12篇
  1974年   7篇
  1973年   8篇
排序方式: 共有7848条查询结果,搜索用时 15 毫秒
21.
The purpose of this pilot study was to observe both relaxed and deep breathing patterns in a convenience sample to determine the incidence of normal versus faulty patterns of respiration. These observations were then combined with respondent answers to a survey on pain history to determine if there is any correlation between faulty breathing and musculo-skeletal pain patterns. If such a correlation can be made, then we propose that clinicians working with chronic pain patients may have improved outcomes if they address and correct faulty breathing patterns. Based on this study, it is suggested to include the evaluation and treatment of faulty respiration in the rehabilitation of chronic musculo-skeletal conditions, most notably cervical pain.  相似文献   
22.
As an avian embryo grows within a eggshell, the whole egg is moved by embryonic activity and also by the embryonic heartbeat. A technical interest in detecting minute biological movements has prompted the development of techniques and systems to measure the cardiogenic ballistic movement of the egg or ballistocardiogram. (BCG). In this context, there is interest in using an electromagnetic induction coil (solenoid) as another simple sensor to measure the BCG and examining its possibility for BCG measurement. A small permanent magnet is attached tightly to the surface of an incubated egg, and then the egg with the magnet is placed in a solenoid. Preliminary model analysis is made to design a setup of the egg, magnet and solenoid coupling system. Then, simultaneous measurement with a laser displacement measuring system, developed previously, is made for chicken eggs, indicating that the solenoid detects the minute cardiogenic ballistic movements and that the BCG determined is a measure of the velocity of egg movements.  相似文献   
23.
任存平  岑峰 《广西医学》1997,19(3):345-351
观察18例32眼下蹲运动与高眼压的关系,分为下蹲120次,100次及80次三且,每组分别观察10眼、11眼及11眼,结果各组运动后眼压均见下降,平均为1.027±0.486kPa,1.355±0.770kPa及1.325±0.422kPa,运动前后有非常显著性差异,但各组之间差异不显著。同时观察3小时内眼压动态变化,下蹲120次组眼压下降维持时间最长,在运动后3小时与运动前眼压比较及与其余两组第3  相似文献   
24.
25.
目的研究正常人眼球运动动态磁共振成像(MRI)4条直肌Pulley(滑车)的功能性位置。方法采用西门子公司Sonata1.5T超导型MRI扫描仪,应用眼球运动动态MRI技术,获取20名正常人(20个眼眶)眼球原在位及上转、下转、内转、外转20度时垂直于眶轴的眼眶冠状位MRI图像。以眼球中心为原点建立三维坐标系,应用ScionImage医学图像测量软件分别测量各层面眼球垂直转动时水平直肌、眼球水平转动时垂直直肌的横截面质心。根据各层面直肌横截面质心的坐标值建立直线回归方程,分别求得眼球垂直转动时内、外直肌径路及眼球水平转动时上、下直肌径路直线回归曲线斜率变化最大的一点,即为该直肌Pulley的功能性位置。对4条直肌Pulley相对于眼球中心的坐标值(X、Y)进行统计。结果内直肌Pulley位于眼球中心后4mm,内14.7mm,下0.3mm;外直肌Pulley位于眼球中心后8mm,外9.8mm,下0.3mm;上直肌Pulley位于眼球中心后6mm,内1.6mm,上11.5mm;下直肌Pulley位于眼球中心后6mm,内4.4mm,下12.7mm。结论应用眼球运动动态MRI技术,分析眼球转动时直肌径路的变化,可证实4条直肌Pulley的存在并确定其功能位置。  相似文献   
26.
选择62例拔除第一双尖牙的样本,分为平弓丝组、带“U”型阻滞曲组、固定舌弓组,采用方丝弓细丝弓技术,以磨牙作支抗拉尖牙向远中移动,对支抗磨牙进行观察。为期4周的观察发现,平弓丝组、带“U”型阻滞曲组的支抗磨牙均有近中舌向扭转,第二双尖牙中央窝间距亦比治疗前减少;而固定舌弓组支抗磨牙未见有近中舌向扭转。作者认为:以磨牙为支抗移动尖牙时,应注意支抗控制。本文对力的使用及支抗失控的预防、处理问题进行了讨论。  相似文献   
27.
目的:研究不同剂量美维松对膈肌和拇收肌的抑制时程与恢复过程。方法:30例ASAⅠ级的成年手术患者,按美维松用量分成两组,Ⅰ组:0.16mg/kg,Ⅱ组:0.20mg/kg,每组15例。同步测定跨膈肌压(Pdi)和拇收肌对连续四次刺激(TOF)反应的T1(APT1)及TOFr值。结果:显示两组APT1最大抑制相近,是Pdi的1.7倍。Pdi达到最大抑制及恢复到75%的时间比APT1快得多。结论:提示美维松对膈肌收缩功能的抑制比拇收肌差,但恢复迅速。  相似文献   
28.
In this work the electrophysiologic mechanisms of ventricular arrhythmias have been briefly summarized. Ventricular arrhytmias can be caused either by pacemaker activity or by reentrant excitation. Enhancement of normal automaticy can generate a parasystolic rhythm in normal fibers. Abnormal automaticity may arise fom fibers in which maximum diastolic potential has been reduced by a variety of interventions. Triggered activity is caused by either an early (EAD) or delayed (DAD) afterdepolarization and requires a prior normal action potential for initiation. While there is growing evidence that EAD-induced triggered activity plays a significant role in the Long QTU syndrome and Torsade de Pointes, no clinical arrhythmias has definitely been ascribed to DADs, although DADs have been recorded in man after acute digoxin intoxication.Ventricular arrhytmias can be also caused by reentrant excitation, which can be subdivided into reflection or circus movement reentry (CMR). In the reflection model impulses in both directions are transmitted over the same pathway. In the CMR three models can be differentiated: the ring model, which requires a fixed anatomical obstacle; the figure-eight model and the leading circle model, where functional rather than fixed anatomical obstacles are involved.Abbreviations AV atrio-ventricular - CMR circus movement reentry - DAD delayed afterdepolarization - EAD early afterdepolarization - ECG electrocardiogram - LV left ventricle - MAP monophasic action potential - MF muscle fiber - PF Purkinje fiber - RV right ventricle - TdP Torsade de Pointes  相似文献   
29.
膈疝的CT诊断价值(附15例分析)   总被引:3,自引:0,他引:3  
目的:探讨膈疝的CT诊断及其临床手术指导价值。方法:通过以横膈部位为中心行胸腹部螺旋CT扫描,获得理想的CT扫描图像,通过15例膈疝患者的扫描图像,结合临床综合分析。结果:膈上有疝囊15例,囊内有液平面13例,有小肠及结肠肠型的1例,有脂肪组织1例,胸腔内有积液2例。结论:CT检查对膈疝的诊断应当作为首选的检查方法,其不仅能对膈疝做出正确的诊断,而且,对临床手术指导具有重要的临床治疗意义。  相似文献   
30.
Abstract Idiopathic Parkinson’s disease (IPD) patients have abnormal visual evoked potentials (VEPs) and pattern electroretinograms (PERGs), attributed to dopaminergic transmission deficiency in visual pathway, probably the retina. VEP abnormalities are not reported in multiple system atrophy (MSA). The aim of this study was to investigate and compare chromatic (Ch) red-green (R-G) and blue-yellow (B-Y), and luminance yellow-black (Y-Bk) PERGs in patients with MSA and IPD. We investigated 6 MSA patients (mean age: 62±7.4 years) not undergoing any pharmacological treatment, as well as 12 early IPD patients (mean age: 60.1±8.3 years) and 12 age-matched normal observers. ChPERGs were recorded monocularly in response to full-field equiluminant R-G, B-Y and Y-Bk horizontal gratings. In MSA only responses to R-G stimuli showed minimal insignificant changes (slight but not significant amplitude reduction without any significant latency delay); no significant abnormality was detected for B-Y and luminance Y-Bk stimuli. By contrast, in IPD all responses were reduced in amplitude and delayed in latency, above all for B-Y stimuli. Present data indicate that both chromatic and achromatic PERGs are virtually unaffected in MSA, whereas in early IPD they are clearly impaired, suggesting different pathogenic retinal mechanisms and a useful simple tool for distinguishing MSA from IPD.  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