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   5454篇
  免费   514篇
  国内免费   138篇
耳鼻咽喉   109篇
儿科学   19篇
妇产科学   29篇
基础医学   635篇
口腔科学   352篇
临床医学   338篇
内科学   314篇
皮肤病学   19篇
神经病学   279篇
特种医学   493篇
外科学   1136篇
综合类   554篇
预防医学   130篇
眼科学   1349篇
药学   182篇
  2篇
中国医学   93篇
肿瘤学   73篇
  2024年   25篇
  2023年   121篇
  2022年   274篇
  2021年   323篇
  2020年   269篇
  2019年   246篇
  2018年   289篇
  2017年   225篇
  2016年   251篇
  2015年   209篇
  2014年   360篇
  2013年   385篇
  2012年   296篇
  2011年   312篇
  2010年   285篇
  2009年   254篇
  2008年   239篇
  2007年   254篇
  2006年   204篇
  2005年   178篇
  2004年   136篇
  2003年   105篇
  2002年   113篇
  2001年   97篇
  2000年   79篇
  1999年   70篇
  1998年   67篇
  1997年   50篇
  1996年   48篇
  1995年   31篇
  1994年   24篇
  1993年   28篇
  1992年   25篇
  1991年   29篇
  1990年   23篇
  1989年   20篇
  1988年   22篇
  1987年   15篇
  1986年   9篇
  1985年   19篇
  1984年   20篇
  1983年   9篇
  1982年   12篇
  1981年   19篇
  1980年   10篇
  1979年   7篇
  1978年   8篇
  1977年   4篇
  1976年   3篇
  1975年   3篇
排序方式: 共有6106条查询结果,搜索用时 15 毫秒
41.
目的:下颌角截骨是面型轮廓重塑中最常见的一种手术,为了提高手术的精确性,避免不必要的损伤,我们对各种下颌角截骨术操作技巧进行探讨.方法:术前进行面部测量、下颌骨曲面断层X线和头颅正侧位定位X线片投影测量,设计截骨线和去骨量,术式选择口内切口下颌角截骨术、口内切口下颌角外板矢状劈开截骨术、耳后切口下颌角截骨术、耳后和口内联合切口下颌角截骨术;结果:面下部过宽同时下颌角肥大者单纯下颌角截骨效果往往不会很理想,需要同时进行下颌角外侧骨板部分去除,减少面下部的宽度,206例术后两侧对称,效果良好;1例面瘫;2例下颌骨骨折,术中做内固定;3例下颌骨体部成角,3个月后第二手术将突出部分磨平.结论:术前测量设计下颌角截骨的术式和截骨线是十分必要的,根据下颌角肥大的不同类型选择相适应的截骨术式.  相似文献   
42.
Summary In 50 rats, different types of end-to-side carotid artery anastomoses were compared. In one technique, a longitudinal split in the long axis of the vessel was performed to enhance the diameter of the anastomosis. This theoretical advantage was not confirmed in this series. The clamping time, anastomoses time, and tamponade time were increased significantly when compared with a simple, slightly oblique end-to-side anastomosis. This study highlighted that the most simple type of end-to-side anastomosis gave less bleeding, achieved a quicker water-tight anastomosis and decreased the risk of late problems.  相似文献   
43.
目的探讨下颌骨侧位摄影分别采用一倾斜角度为α的垫板及未采用时,X线中心线倾斜角度各为β、γ之间的关系,为更简捷地拍好下颌骨提供理论参数和实践依据。方法立足于教科书,运用X线摄影原则与数学几何原理进行推理演绎。结果二者之间存在着可替换的关系,即γ=α+β,可以大胆地去除垫板进行直接拍摄。结论不用垫板,只需通过增大X线中心线倾斜角度的方法,同样也能拍摄出一张好照片,且可操作性强,简便易行,实际使用价值更大。  相似文献   
44.
The solid-state nuclear magnetic resonance (NMR) technique of carbon-13 cross-polarization/magic angle spinning (CP/MAS) has been successfully used to obtain high-resolution spectra of whole-thickness, hairy rat skin and to characterize the influence of hydration on the efficiency of cross-polarization and the proton spin-lattice relaxation time in the rotating frame (T1H). Spectra obtained with hydrated samples, which were obtained with 50% more accumulations, had comparable signal-to-noise ratio relative to spectra obtained with dried skin, indicating a disordering effect with the presence of water. The integrated area of spectra of low-shifted peaks rose more rapidly with increasing contact time relative to the high-shifted peaks for both hydrated and dried skin. In addition, the carbonyl intensity of the hydrated skin relative to dried skin reached a maximum at shorter times, reflecting an efficient relaxation mechanism of the protons. The shift of the peak maximum to shorter mixing times quantitatively reflects the interaction of the protons of water with the carbonyl moiety.  相似文献   
45.
The study objectives were to compare in vitro transportability and physical properties of respiratory mucus, obtained invasively by direct collection (DC) right after endotracheal intubation and non-invasively by sputum induction with 3% hypertonic saline solution inhalation (SI) 24 h before the anesthesia. Twenty-two patients with no pulmonary disease scheduled for elective abdominal surgical procedures were studied. The parameters analyzed and the main results are as follows. (1) Transportability by cilia (MCT), SI was higher than DC (0.94+/-0.25 and 0.62+/-0.25; P<0.001). There was a significant correlation between the two methods and DC could be estimated by: DC=0.21+(0.44 SI) (r=0.44; P<0.001). (2) Transportability by cough (CC), SI was higher than DC (68.23+/-32.1 and 33.58+/-19.04 mm; P=0.002). (3) Contact angle (CA), SI was lower than DC (10+/-3 degrees and 22+/-14 degrees ; P=0.025). (4) Rheological properties (no significant difference obtained between SI and DC). These results indicated that SI changes mucus physical properties and transportability in non-expectorators.  相似文献   
46.
The effects of the local blood circulation and absolute torque on muscle endurance at different knee-joint angles were determined. The rate of muscle deoxygenation (using near-infrared spectroscopy), and the rate of muscle fatigue (using the slope of integrated electromyography, iEMG) were evaluated concurrently. Nine healthy subjects performed submaximal (50% maximal voluntary contraction, MVC) static knee extension at 50° (extended position, EXT) and 90° (flexed position, FLEX) joint angles until the target torque could no longer be maintained: that time was measured as the endurance time. They exercised with the circulation occluded (OCCL), and without (FREE) to study the possible effects of the local circulation. Although MVC torque was independent of joint angle [mean (SD) FLEX 250.6 (51.7) N·m and EXT 246.5 (46.6) N·m], significantly shorter (P<0.01) endurance time in FLEX [FREE 71.1 (10) s and OCCL 63.1 (8.8) s] than at EXT [FREE 115.3 (30) s and OCCL 106.7 (29.1) s] were obtained in both circulatory conditions. The iEMG-time slope was significantly greater in FLEX at the proximal and distal portion (P<0.05) in both circulatory conditions. Muscle deoxygenation rate in OCCL was significantly greater (P<0.05) at FLEX [20.8 (8.0)%] than EXT [10.9 (4.0)%]. The results would suggest that different knee-joint angle affects muscle endurance even if the local circulation is controlled. Circulatory disturbance would further reduce muscle endurance in EXT, but not in FLEX. Because of the greater muscle internal force in FLEX, local blood flow might be already limited even with a free circulation. The greater muscle deoxygenation and muscle fatigability would be related to the shorter muscle endurance in FLEX. Electronic Publication  相似文献   
47.
The epicondylar axis is a reliable reference to check the rotation of the femoral implant in total knee prostheses (TKPs). However, during the operation it seems easier to use the posterior condylar axis as a landmark. The angle between these two axes is called the posterior condylar angle (PCA). The aim of this study was to measure the PCA in arthritic knees to assess the reliability of the posterior condylar axis as a reference for the control of the rotation of the femoral implant and to look for correlation with other radiological measurements. This prospective study consisted of 103 arthritic knees (81 varus, 22 valgus) before a TKP had been done in 103 patients (75 women, 28 men). The assessment of the PCA was made by computed tomographic scanning (CT). The HKA, HKS and HKT angles were measured on the pangonogram. The posterior condylar axis was internally rotated with respect to the epicondylar axis. The average value for all the patients was 2.65° degrees with a range from 0° to 7°. The PCA was significantly increased in the valgus knees. There was no correlation between the angles on the pangonogram and the posterior condylar axis. While the preoperative assessment of the PCA by CT scanning is reliable, the results obtained indicate the marked variability in its value. If one wishes to use the posterior condylar axis as a guide for rotation, it is therefore necessary to assess the PCA for each patient using adjustable jigs according to the value obtained. No measurement on standard radiographs allowed an extrapolation of the value of the PCA, and CT scanning seems to be the preferable radiological examination.

Electronic Supplementary Material The french version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer Link server located at
Etude tomodensitométrique de l'angle condylien postérieur dans les genoux arthrosiques. Intérêt dans le positionnement en rotation de l'implant fémoral dans les prothèses totales de genou
Résumé L'axe épicondylien est une référence fiable pour le contrôle de la rotation de l'implant fémoral dans les prothèses totales de genou (PTG). Mais, lors de l'intervention, il semble plus facile d'utiliser l'axe condylien postérieur comme repère. L'angle entre ses deux axes est appelé angle condylien postérieur (ACP). Le but de cette étude était de mesurer l'ACP dans les genoux arthrosiques, d'évaluer la fiabilité de l'axe condylien postérieur comme référence pour le réglage de la rotation de l'implant fémoral, de rechercher une corrélation avec d'autres mesures radiologiques. Une étude prospective comportant 103 genoux arthrosiques (81 varus et 22 valgus), avant PTG a été effectuée, chez 103 patients (75 femmes et 28 hommes). L'évaluation de l'ACP a été faite par examen tomodensitométrique (TDM). Les angles HKA, HKS et HKT ont été mesurés sur le pangonogramme. L'axe condylien postérieur était en rotation interne par rapport à l'axe épicondylien. La valeur moyenne pour tous les patients était de 2.65°, avec des valeurs de 0 à 7°. La valeur de l'angle CP augmentait avec une différence significative dans le groupe des genu valgum. Il n'y avait pas de corrélation entre les angles du pangonogramme et l'ACP. Si l'évaluation pré-opératoire de l'ACP par TDM est fiable, les résultats obtenus mettent en évidence une variabilité importante de sa valeur. Il faut donc, si l'on veut utiliser l'axe condylien postérieur comme repère de rotation, évaluer pour chaque patient l'ACP, et utiliser un ancillaire réglable reportant la valeur obtenue. Aucune mesure sur des radiographies standard ne permettant d'extrapoler la valeur de l'ACP, la TDM semble l'examen radiologique de choix.
  相似文献   
48.
乙状窦后进路内窥镜手术解剖学研究   总被引:2,自引:1,他引:2  
目的:为乙状窦后进路相关内窥镜手术提供解剖学依据。方法:测量30例干颅骨表面标志位置关系,准确定位乙状窦后进路骨窗;利用10具甲醛固定成年头标本模拟内窥镜下乙状窦后进路,验证其可行性。结果:(1)以星点至乳突点连线中点为中心作直径2.0cm的骨窗适于暴露桥脑小脑角区结构;(2)内镜下乙状窦后进路可在尽量减少压迫小脑的情况下充分暴露桥脑小脑角区神经、血管等重要结构。结论:精确定位乙状窦后进路骨窗能够最大限度减少牵托小脑,对临床开展锁孔手术有指导意义。  相似文献   
49.
目的:探讨指背腱膜滑动距离与近侧指间关节(PIP)屈曲关系,为临床修复提供解剖学基础。方法:男性成人新鲜尸体标本10侧30指(示、中、环指各10指),切除手指皮肤,不破坏腱鞘、屈肌支持带、伸肌支持带、内在肌及外在肌,使肌腱保持正常的生理状态,分别测量各指中央束(CS)、侧束(LB)在PIP屈曲45°和90°时的滑动距离。结果:当PIP屈曲45°时,CS滑动距离为(2.7±0.4)mm,LB滑动距离为(2.8±0.6)mm;当PIP屈曲90°时,CS滑动距离为(4.3±0.7)mm,LB滑动距离为(4.8±0.6)mm。结论:指背腱膜滑动距离减少,严重影响手指的屈曲功能。对于指背腱膜的新鲜性损伤应予以精确修复;对于陈旧性损伤的修复应确保指背腱膜的正常滑动范围。  相似文献   
50.
内耳门周结构对内镜下脑桥小脑三角区手术的影响   总被引:3,自引:3,他引:3  
目的:研究内耳门周结构对颞骨径路内镜下处理脑桥小脑三角区病变手术的影响,为临床开展相应手术提供参考。方法:在20例40侧成人尸头上模拟颞骨径路内窥镜手术,观察小脑下前动脉及内耳门后唇的变异,了解其对内窥镜导入及其手术的影响。结果:内耳门后唇隆起超过面神经脑桥小脑角段1/3以上者占27.5%(11侧)。小脑下前动脉在Ⅶ、Ⅷ脑神经外侧成袢者占22.5%(9侧)。内耳门后唇隆起合并小脑下前动脉袢在Ⅶ、Ⅷ脑神经之外侧者占7.5%(3侧)。结论:当内耳门后唇隆起超过面神经脑桥小脑角段1/3或小脑下前动脉弓在Ⅶ、Ⅷ脑神经之前时将对内窥镜导入有阻碍,当两种情况合并存在时要将内窥镜导入脑桥小脑三角区相当困难,不宜采用此种手术方式。  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