首页 | 本学科首页   官方微博 | 高级检索  
  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   279篇
  完全免费   39篇
  基础医学   318篇
  2019年   4篇
  2018年   17篇
  2017年   10篇
  2016年   14篇
  2015年   13篇
  2014年   9篇
  2013年   16篇
  2012年   16篇
  2011年   26篇
  2010年   16篇
  2009年   22篇
  2008年   20篇
  2007年   18篇
  2006年   2篇
  2005年   2篇
  2004年   8篇
  2003年   5篇
  2001年   4篇
  2000年   1篇
  1999年   1篇
  1998年   4篇
  1997年   6篇
  1996年   9篇
  1995年   9篇
  1994年   12篇
  1993年   6篇
  1992年   3篇
  1991年   4篇
  1990年   4篇
  1989年   1篇
  1988年   3篇
  1987年   1篇
  1986年   3篇
  1985年   4篇
  1984年   3篇
  1983年   3篇
  1982年   2篇
  1981年   4篇
  1980年   4篇
  1979年   2篇
  1978年   2篇
  1977年   1篇
  1974年   1篇
  1972年   1篇
  1970年   1篇
  1968年   1篇
排序方式: 共有318条查询结果,搜索用时 31 毫秒
Modeling of Sound Transmission from Ear Canal to Cochlea   总被引:5,自引:0,他引:5  
A 3-D finite element (FE) model of the human ear consisting of the external ear canal, middle ear, and cochlea is reported in this paper. The acoustic-structure-fluid coupled FE analysis was conducted on the model which included the air in the ear canal and middle ear cavity, the fluid in the cochlea, and the middle ear and cochlea structures (i.e., bones and soft tissues). The middle ear transfer function such as the movements of tympanic membrane, stapes footplate, and round window, the sound pressure gain across the middle ear, and the cochlear input impedance in response to sound stimulus applied in the ear canal were derived and compared with the published experimental measurements in human temporal bones. The frequency sensitivity of the basilar membrane motion and intracochlear pressure induced by sound pressure in the ear canal was predicted along the length of the basilar membrane from the basal turn to the apex. The satisfactory agreements between the model and experimental data in the literature indicate that the middle ear function was well simulated by the model and the simplified cochlea was able to correlate sound stimulus in the ear canal with vibration of the basilar membrane and pressure variation of the cochlear fluid. This study is the first step toward the development of a comprehensive FE model of the entire human ear for acoustic-mechanical analysis.  相似文献
颞骨内面神经管的解剖测量及其临床意义   总被引:3,自引:0,他引:3  
目的为避免中耳手术中对面神经的损伤。方法对50例(100侧)成人尸头颞骨内面神经管进行解剖测量。结果面神经管迷路段为4.53±1.21mm,鼓室段为9.32±1.25mm,乳突段为13.25±1.53mm,面神经管总长为29.86±0.57mm。结论熟悉颞骨内面神经管的解剖结构,可避免对面神经的损伤,减少和避免面瘫的发生。  相似文献
人耳鼓膜病变数值分析   总被引:3,自引:0,他引:3  
目的研究鼓膜厚度和硬度对人耳传声的影响。方法利用CT获取志愿者耳部结构临床资料,使用Matlab软件提取相关结构的边界,将边界文件导入ANSYS建立人耳结构数值有限元模型。结果利用本文人耳数值模型,在外耳道口施加105dB声压,进行200~8000Hz频率范围的谐响应分析。以此研究在鼓膜病变情况下,鼓膜和镫骨底板位移幅值的变化规律。结论用数值方法解释了鼓膜病变对传声的影响,为鼓膜修补提供了力学参考。  相似文献
Epithelial cell height was measured in order to estimate the cell volume of dark cells from the ampullae of the semicircular canal of the gerbil. Under control conditions, addition of 10–4 mol/l piretanide, 10–5 mol/l 5-nitro-2(3-phenylpropylamino)-benzoic acid (NPPB), 5 mmol/l barium or 10–3 mol/l quinidine had no significant effect on cell height. Addition of 10–4 mol/l NPPB or 10–3 mol/l ouabain led to a small significant decrease in cell height which was not reversible. Substitution of Na+ by N-methyl-d-glucamine or of Cl by gluconate led to a significant and reversible reduction in cell height. Isotonic elevation of [K+] from 3.6 to 25 mmol/l in a PO4-buffered, HCO3-free solution led to an increase in cell height from 5.8±0.1 (SEM) to 8.7±0.2 (n= 62) during the first 40 s. During prolonged exposure to elevated [K+] (3–5 min; n=19), some tissue samples underwent a regulatory volume decrease. K+-induced swelling was absent in both isotonic Cl -free and isotonic Na+-free solutions and was inhibited by the loop diuretic piretanide (10–5 and 10–4 mol/l) or by the (Na++ K+) ATPase inhibitor ouabain (10–3 mol/l) or by 10–4mol/l NPPB. After the removal of ouabain or 10–4 mol/l NPPB, K+-induced swelling under control conditions was enhanced and was less reversible as compared to control conditions before the experiment. K+-induced swelling was not altered by NPPB (10–5 mol/l) or barium (5 mmol/l); however, barium slowed shrinking upon return of [K+] to control level. In the presence of 10–3 mol/l quinidine, K+-induced swelling was enhanced and not reversible. These data suggest that dark cells from the semicircular canal possess an Na+2ClK+ cotransporter as a solute uptake mechanism and a solute efflux mechanism which is sensitive to barium and inhibited by quinidine.  相似文献
磁共振3D-CISS与CT高分辨率成像在电子耳蜗植入前的应用   总被引:2,自引:1,他引:1  
目的利用中、内耳高分辨C计算机X线断层照相术(computed tomography,CT)扫描及磁共振(magnetic resonance imaging,MRI)高分辨3D-CISS序列成像对拟行人工耳蜗植入术的患者作术前检查,分析、比较两种方法的临床价值。方法选择30例拟行电子耳蜗植入的感音性耳聋患者。行中内耳CT高分辨放大扫描,层厚1mm,层间隔1mm,放大倍数2。磁共振高分辨率三维稳态干扰序列(three dimensional constructive inference insteady state,3D-CISS)扫描(TR12.30ms,TE5.9ms),翻转角70°,层厚0.7mm,无间隔扫描,最大信号强度投影(maximum intensity projection,MIP)内耳重建。比较两种方法提供的信息。结果CT可观察中耳内耳、骨性结构;MRI可显示内耳膜迷路情况及内听道的神经。结论将中、内耳螺旋CT高分辨成像与磁共振高分辨3D-CISS序列其联合应用可为人工耳蜗植入提供更精确可靠的术前信息。  相似文献
中耳病变及人工镫骨形体研究   总被引:2,自引:0,他引:2       下载免费PDF全文
目的 研究听骨韧带、肌腱硬化和切除以及人工镫骨置换对声音传导的影响。方法 基于CT扫描数据,通过自编C++程序读取CT数据中体单元建立人耳结构几何模型,将几何模型导入PATRAN中赋予材料参数、设置关节接触面以及相应其他边界条件生成数值模型。结果 利用本文人耳数值模型进行正常耳和病变耳的谐响应分析,得到正常耳和病变耳镫骨底板和鼓膜凸的振幅变化规律。并由此构建了套型人工镫骨。结论 正常耳的模拟结果与实验测试结果吻合,证明了本模型准确性,可以模拟人传声功能。本模型模拟病变耳的计算结果可以从力学角度解释病变对声音传导的影响,为病变耳治疗提供参考。本文的套型人工镫骨较我国临床用的环型人工镫骨更吻合人耳的生理功能,其重建听力效果更好。  相似文献
The patch-clamp technique was used to investigate ion channels in the basolateral perilymph-facing membrane of freshly isolated outer hair cells (OHCs) from the guinea-pig cochlea. These sensory cells probably determine, via their motile activity, the fine tuning of sound frequencies and the high sensitivity of the inner ear. A Ca2+-activated nonselective cationic channel was found in excised inside-out membrane patches. The current/voltage relationship was linear with a unit conductance of 26.3±0.3 pS (n=15) under symmetrical inger conditions. The channel excluded anions (P Na/P Cl=18 whereP Na/P Cl denotes the relative permeability of Na to Cl); it was equally permeant to the Na+ and K+ ions and exhibited a low permeability toN-methyl-D-glucamine and Ba2+ or Ca2+. Channel opening required a free Ca2+ concentration of about 10–6 mol/l on the internal side of the membrane and the open probability (P o) was maximal at 10–3 mol/l (P o=0.72±0.06,n=12). Adenosine 5mono-, tri- and di-phosphate reducedP o to 29±14 (n=5), 42±10 (n=8) and 51±12 (n=5) % of controlP o, respectively, when they were added at a concentration of 10–3 mol/l to the internal side. The channel was partially blocked by flufenamic acid (10–4 mol/l) and 3,5-dichlorodiphenylamine-2-carboxylic acid (DCDPC, 10–5 mol/l). This type of channel, together with Ca2+-activated K+ channels, might participate in the control of membrane potential and modulate the motility of OHCs.  相似文献
 The anti-diuretic hormone vasopressin (AVP) regulates water excretion from the kidney by increasing the water permeability of the collecting duct. AVP binds to V2-receptors and induces the translocation of aquaporin-2 water channels (AQP-2) into the apical plasma membrane of principal cells. By this mechanism AVP controls water reabsorption in the kidney. The effects of AVP on the endolymphatic sac (ES) of the inner ear, which is thought to mediate reabsorption of endolymph, were investigated. Both the V2-receptor and the AQP-2 water channel were found to be expressed in the ES epithelium. In the ES AVP binds to receptors most probably of the V2-subtype. Application of AVP to organotypically cultured ES inhibits membrane turnover in ribosomal-rich cells of the ES epithelia, which is thought to mediate translocation of AQP-2 into the surface membrane. This suggests that AVP has contrasting effects in the inner ear and kidney, which may be physiologically useful for maintaining endolymphatic pressure during severe hypovolemia. Animal experiments show that AVP causes endolymphatic hydrops after systemic application to guinea-pigs, which suggests a causal role for the increased AVP levels found in humans suffering from Ménière’s disease. Received: 3 July 1998 / Accepted: 13 July 1998  相似文献
医学影像导出三维模型并建立3D PDF文件的方法   总被引:1,自引:1,他引:0       下载免费PDF全文
目的 探讨医学影像导出为三维模型并建立交互3D PDF文件。 方法 使用了3个开源软件包括3D Slicer、MeshLab和TeXstudio,进行感兴趣区体裁剪、模型分割和3D PDF制作。 结果 3D Slicer可以多种方法进行模型分割,MeshLab可以进行模型清理和分割,并在导出U3D格式文件的同时生成TEX格式文件,通过TeXstudio编译生成3D PDF文件。 结论 这种方法步骤简单易学,推广普及容易,有利于促进更多3D PDF的制作和使用。  相似文献
中耳显微解剖标志与面神经定位   总被引:1,自引:1,他引:0       下载免费PDF全文
目的 观察中耳手术中面神经相关的显微解剖结构,并探讨其临床应用。方法 30具(60侧颞骨)中国人成年湿性头颅标本经乳突入路对颞骨进行显微解剖,重点观察面神经并根据其周围的固定解剖标志对其进行定位。 结果 面神经乳突段前缘和后缘至假想定位线的距离分别为(-0.11±0.36)mm和(-0.14±0.38)mm,鼓室段面神经下缘与假想定位线的距离为(0.31±0.12)mm,砧骨短脚末端至外半规管下缘的距离为(1.73±0.24)mm,外半规管至面神经锥段上缘的距离为(2.65±0.25)mm,砧骨短脚最末端至面神经锥段上缘的距离为(2.20±0.41)mm,镫骨头上缘至面神经水平段下缘的距离为(2.24±0.23)mm等。结论 外半规管、砧骨短突、鼓环、二腹肌嵴、前庭窗、匙突、卵圆窗、锥隆起和鼓索神经等是中耳显微手术的重要解剖标志,并与面神经关系极其密切和恒定。  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