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   13328篇
  免费   1038篇
  国内免费   237篇
耳鼻咽喉   225篇
儿科学   40篇
妇产科学   58篇
基础医学   1873篇
口腔科学   746篇
临床医学   821篇
内科学   810篇
皮肤病学   59篇
神经病学   3367篇
特种医学   681篇
外科学   2054篇
综合类   1197篇
一般理论   1篇
预防医学   310篇
眼科学   1500篇
药学   458篇
  3篇
中国医学   254篇
肿瘤学   146篇
  2024年   53篇
  2023年   282篇
  2022年   575篇
  2021年   683篇
  2020年   559篇
  2019年   544篇
  2018年   548篇
  2017年   517篇
  2016年   495篇
  2015年   447篇
  2014年   787篇
  2013年   866篇
  2012年   677篇
  2011年   706篇
  2010年   579篇
  2009年   589篇
  2008年   516篇
  2007年   581篇
  2006年   479篇
  2005年   383篇
  2004年   308篇
  2003年   300篇
  2002年   271篇
  2001年   242篇
  2000年   182篇
  1999年   195篇
  1998年   189篇
  1997年   163篇
  1996年   153篇
  1995年   137篇
  1994年   97篇
  1993年   102篇
  1992年   104篇
  1991年   102篇
  1990年   85篇
  1989年   83篇
  1988年   77篇
  1987年   70篇
  1986年   107篇
  1985年   138篇
  1984年   130篇
  1983年   129篇
  1982年   93篇
  1981年   89篇
  1980年   78篇
  1979年   35篇
  1978年   26篇
  1977年   23篇
  1976年   17篇
  1975年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
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   
92.
目的 比较不同能流密度的体外冲击波(extracorporeal shock wave, ESW)治疗肱骨外上髁炎(lateral epicondylitis, LE)的短期临床疗效,探索ESW的最佳治疗剂量。方法 将120例LE患者分为A、B、C和D 4组,均使用ESW治疗4周,各组的能流密度分别为0.06、0.08、0.10、0.12 mJ/mm2。分别在治疗前及治疗后4、24及48周,比较4组患者疼痛视觉模拟量表(visual analogue scale, VAS)评分、肱骨外上髁炎功能评估(patient-rated tennis elbow evaluation, PRTEE)评分及末次随访患者满意度和复发率。结果 按时间点比较,各组VAS评分治疗前最高,治疗后48周降至最低(P<0.05),4组患者满意度及复发率比较差异无统计学意义(P>0.05),但C组患者满意度(96.67%)明显高于A组(80%),差异具有统计学意义(P=0.04)。按组间比较观察,治疗前各组患肘VAS评分差异无统计学意义(P>0.05);治疗后4、24和48...  相似文献   
93.
Summary We describe two patients with sporadic amyotrophic lateral sclerosis (ALS), who had developed progressive external ophthalmoplegia of a predominantly supranuclear type while they survived on respirators, and displayed histopathological abnormalities both typical and atypical of ALS. Patient 1 was a 43-year-old man with ALS of 5-year duration, who had initially exhibited fulminant ALS, and remained on a respirator for 4 years. Patient 2 was a 51-year-old man with ALS of 13-year duration, who remained on a respirator for 8 years. Both patients died in a totally locked-in state. Autopsy of both patients revealed not only histopathological abnormalities consistent with ALS, but also multisystem degeneration which involved the pontine tegmentum, substantia nigra, Clarke's dorsal nuclei and spinocerebellar tracts. In addition, Patient 2 displayed intracyto-plasmic neuronal basophilic inclusion bodies which exhibited marked immunoreactivity to anti-ubiquitin antibodies. Our case reports indicate that the longer survival which is possible through the use of respirators may make one subgroup of ALS patients prone to develop atypical clinical and neuropathological features which are not observed during the natural cours of ALS.Supported by a Grant-in-Aid from the Research Committee of CNS Degenerative Diseases, the Ministry of Health and Welfare of Japan, and by a Grant from Nihon University School of Medicine, Tokyo  相似文献   
94.
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   
95.
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   
96.
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   
97.
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   
98.
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   
99.
Summary Electron microscopic analysis of sections of the perigeniculate nucleus (PGN) of the cat processed with horseradish peroxidase (HRP) histochemistry after massive injections of this enzyme in the visual cortex showed two types of synaptic terminals labeled with HRP reaction products. One type (RLD terminals) is characterized by round synaptic vesicles, large size, dark mitochondria and asymmetrical synaptic contacts with somata and dendrites. The second type (RSD terminals) is characterized by round synaptic vesicles, small size, dark mitochondria and asymmetrical synaptic contacts with dendrites. The HRP + RSD terminals, which were also found in the dorsal lateral geniculate nucleus (LGN), are interpreted as terminals of cortical origin both in the PGN and LGN, since previous studies have identified cortical terminals as being of RSD type in the LGN and in other thalamic nuclei. The HRP + RLD terminals are interpreted as synaptic terminals of collaterals axons of geniculo-cortical relay cells in the PGN labeled by retrograde transport of HRP from the cortex. In addition, in semithin and ultrathin sections somata in the PGN were never found labeled with HRP products indicating the absence of a PGN projection to the visual cortex.  相似文献   
100.
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