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   14275篇
  免费   1179篇
  国内免费   285篇
耳鼻咽喉   129篇
儿科学   178篇
妇产科学   82篇
基础医学   2121篇
口腔科学   963篇
临床医学   1110篇
内科学   535篇
皮肤病学   94篇
神经病学   2251篇
特种医学   345篇
外科学   481篇
综合类   1224篇
预防医学   457篇
眼科学   4196篇
药学   905篇
  3篇
中国医学   508篇
肿瘤学   157篇
  2024年   67篇
  2023年   262篇
  2022年   536篇
  2021年   777篇
  2020年   609篇
  2019年   471篇
  2018年   563篇
  2017年   568篇
  2016年   532篇
  2015年   479篇
  2014年   765篇
  2013年   1018篇
  2012年   711篇
  2011年   720篇
  2010年   609篇
  2009年   625篇
  2008年   628篇
  2007年   584篇
  2006年   594篇
  2005年   505篇
  2004年   457篇
  2003年   370篇
  2002年   349篇
  2001年   277篇
  2000年   255篇
  1999年   194篇
  1998年   209篇
  1997年   190篇
  1996年   155篇
  1995年   136篇
  1994年   115篇
  1993年   84篇
  1992年   99篇
  1991年   95篇
  1990年   85篇
  1989年   93篇
  1988年   63篇
  1987年   82篇
  1986年   67篇
  1985年   123篇
  1984年   121篇
  1983年   84篇
  1982年   88篇
  1981年   81篇
  1980年   68篇
  1979年   43篇
  1978年   43篇
  1977年   29篇
  1976年   17篇
  1973年   10篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
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   
52.
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   
53.
目的 探讨金珠滴眼液治疗慢性结膜炎的疗效。方法 将慢性结膜炎患者 36例 6 8眼随机分为2组 ,每组 34眼 ,实验组用 7.8%金珠滴眼液点眼治疗 ,对照组用 0 .2 5 %氯霉素点眼治疗。结果 金珠滴眼液1、2、4周疗效的综合分值判定均与对照组有显著差异 (P <0 .0 5 ) ,且无局部刺激性。结论 金珠滴眼液对慢性结膜炎有明显的治疗作用 ,可望为临床常见多发的慢性结膜炎患者消除或缓解症状  相似文献   
54.
55.
Summary The oculomotor reactions have recently attracted increasing attention for diagnostic purposes. This is in line with the view that the oculomotor system is one of the simpler, machine-like sensorimotor systems. This paper presents two examples to demonstrate that the complexity of sensorimotor processing may be higher than expected from the outcome of experiments under rather restricted stimulus conditions. In the first part it is shown that complex preprocessing including the evaluation of spatial gradients of visual structure is an integral part of the programming of reflex-like saccades. The second part concerns adaptivity of saccadic eye movements. The data demonstrate that saccadic gain control is highly specific to the direction of the saccade. It is suggested that many central deficits may be hidden as a consequence of the effect of specific adaptive mechanisms.This article was presented in part at the Symposium on Eye Movements and Psychopathology, Berlin, 23–24 June 1988  相似文献   
56.
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   
57.
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   
58.
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   
59.
Deprivation of form vision by the fitting of translucent occluders suppressed the diurnal cycling of enkephalinergic amacrine cells (the ENSLI amacrine cells), in the chicken. Daily periods of normal vision or enforcing temporal contrast using strobe lighting appeared to restore normal functioning of the ENSLI cells. These results suggest that the ENSLI cells are involved in retinal circuits that assess the quality of the visual image and control eye growth.  相似文献   
60.
The presence or absence of retinal detachment, especially detachment of the macula, was the most critical parameter predicting visual outcome, and long duration of detachment worsened the prognosis (P=0.0084). In contrast, the time interval from vitreous haemorrhage to surgery did not associate with the long-term visual outcome. Pre-operative visual acuity of counting fingers 1 m or better was associated with favourable visual outcome (P=0.0032). Other pre- or per-operative parameters (e.g. aphakia, iris rubeosis, extent of photocoagulation, retinal breaks) did not associate with visual prognosis significantly.Significant association between general parameters and visual outcome was found only in the group of traction retinal detachment where loss of vision was related to shorter duration of diabetes (P=0.0213), and shorter duration of background retinopathy (P=0.0300), and proliferative retinopathy (P=0.0072).  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