人正常下颌升支区应力分布的三维有限元法分析

目的：对正常人下颌升支在不同咀嚼力作用时应力分布情况进行三维有限元分析。方法：采用三维有限元应力分析的方法，对正常离体人下颌升支在不同加载条件下的应力分布特征进行对比定量分析。结果：(1)所有载荷形式的各种应力值，随着单元距加载点的距离的增大，其应力值相对减小。(2)下颌骨下颌角、升支后缘的应力梯度变化较大。结论：下颌骨下颌角、升支后缘是应力相对集中的区域，也是临床上常见的下颌骨骨折区，同时还是下颌升支矢状骨劈开术后加强固定以及防止骨段移位的区域。     

下颌骨骨折坚固内固定应力遮挡的三维有限元分析

目的 :运用有限元法分析下颌骨功能状态下及坚固内固定时的应力分布 ,探讨可能发生的应力遮挡作用 ,为下颌骨骨折的治疗提供参考。方法 :对下颌骨体部骨折在骨愈合的不同时期及采用不同的内固定方法固定时的应力分布进行有限元法分析 ,计算各种工况下的应力遮挡率。结果 :骨折愈合的早期 ,单、双钢板固定时的应力遮挡率分别为98.90 %、99.63 % ,钛板为98.65%、99.58 % ;骨折愈合的中期 ,单、双钢板固定时的应力遮挡率分别为6.8%、22.96 % ,钛板为5.12 %、20.99 % ;骨折愈合的后期 ,单、双钢板固定时的应力遮挡率分别为5.73 %、14.14 % ,钛板为4.47 %、13.71 %。结论 :小型接骨板用于下颌骨体部骨折坚固内固定时 ,在骨折愈合的各个时期均存在明显的应力遮挡作用 ;钢板的应力遮挡作用大于钛板 ;接骨板固定位置的选择对骨断层的应力分布有重要的影响。     

CLONING AND CHARACTERIZATION OF A METAL RESPONSIVE ELEMENT-CONTAINING FRAGMENT FROM THE WILSON DISEASE GENE LOCUS BY JUNCTION TRAPPING

All mammalian metallothionaln genes studied to dare have several metal responsive elements (MRE) with consensus sequences of TGCRCNC (R, purlne) in their regulatory region. MRE-11ke sequeaees were also found in many other metal-related genes. To see whether there is also such a sequence at the genetic locus (13q14. 3) d Wilstm disease, which is a genetic disorder d copper metabolisa‘‘n, junction-trapping method baaed on the MRE sequence was used. A fragment containing MRE and MRE-like sequences from YAC 27D8 at the WND locus was successfully cloned and mapped back to the YAC by PC, R, Presence of such a sequence in the copper transporter gene at the W‘‘D locus might imply that it has a possible interesting role in the regulation of WD gene expression.     

儿宝冲剂对防治缺铁性贫血及缺锌症的疗效观察

目的探讨儿童缺铁、缺锌症的防治措施。方法用研制的药品，让有缺铁、缺锌症临床表现的７～１２岁儿童服用，而后检验其头发、血液中的微量元素Ｆｅ、Ｚｎ和Ｈｂ的含量，所得结果用ｔ检验法进行统计分析。结果服用该药品１ｍｏ后，儿童体内微量元素Ｆｅ、Ｚｎ和Ｈｂ含量显著提高（Ｐ＜０．０１），食欲增加，缺铁、缺锌症状明显改善，服２ｍｏ优于服１ｍｏ的治疗效果。结论该药品对儿童缺铁性贫血及缺锌症具有显著的防治效果。     

三种基牙材料对铸造玻璃瓷冠碎裂影响的研究

目的:研究不同种类和强度基牙材料与瓷冠破折碎裂的内在关系.方法:选用计算机建立上颌中切牙的三维有限元模型,模拟陶瓷层、牙本质、核桩等结构.分析在天然齿基牙、钴铬合金基牙及复合树脂基牙情况下,铸造玻璃陶瓷全冠的瓷层内及残余牙本质的应力分布情况.结果:高弹性模量的钴铬合金能够降低瓷层及残余牙本质内的最大主应力和最小主应力峰值,防止瓷层破折碎裂;而弹性模量与牙本质相近的复合树脂桩降低应力峰值的作用不明显.结论:对于有牙髓活力的牙本质基牙,尽量保存牙髓活力后行全冠修复.对于行根管治疗术后的无髓牙,进行核桩冠修复时,采用高弹性模量的高熔合金,尽量避免使用弹性模量较小的复合树脂核.     

来流温度不均匀对叉流换热器性能的影响

对来流温度不均匀叉流换热器,本文进行了熵产生和(火用)效率的数值分析。结果表明:①在相同的传热单元数和热容量比值下,对应于换热效果最好的来流温度分布,其熵产生单元数最小,(火用)效率最高。②在给定的条件下,换热器的(火用)效率并不是随传热单元数的增加而单调增加,而是存在一个极大值,它所对应的传热单元数要小于有效度ε_(max)对应的传热单元数。③熵产生单元数也并不是随传热单元数的增加而单调减少,而是有时单调增加,有时有极大值。并对以上现象作了一些物理机理的分析和讨论。     

青果微量元素的测定及其含量与功效的关系

用电感耦合等离子体发射光谱法(ICP—AES),同时测定了广州与潮州产青果中13种微量元素和宏量元素的含量,结果发现其含有多种人体必需和与乙型肝炎的发生发展有关的微量元素;初步讨论了它们与青果功效的关系。     

Otoconial alterations after embryonic development in hypergravity

The relation between prolonged hypergravity and structural adaptation of otoconia was studied in hamsters (n = 56). Three groups of hamsters (n = 27), were conceived and born in a centrifuge: group 1 (n = 10) 1 month under 2.5 G, group (2n = 9) 5 months under 2.5 G and 4 months under 1 G, group 3 (n = 8) 1 month under 2.5 G and 8 moths under 1 G. Control hamsters (n = 29) were conceived and born under 1 G (1 month old, n = 7; 9 months old, n = 22). Histological study of the otoconial layers (energy dispersive x-ray element analysis and scanning electron microscopy) showed similar calcium content, size, and shape in utricular and saccular otoconia in all groups. Different were the utricular otoconial size classes, large, medium-sized, a and small. The area with small otoconia increased in group 1 (p = 0.002). In group 2, the large otoconial area decreased (p < 0.001) and the medium-sized one increased (p < 0.001). In group 3, the large otoconial area decreased (p = 0.003) and the medium-sized one increased (p = 0.007). For age-related effects we found group 1 with an increased area of large otoconia (p = 0.001) and a decreased medium-sized one compared to groups 2 (p < 0.001) and 3 (p = 0.02). Hypergravity during formation of otoconia does not affect calcium content, size, or shape, but changes relative size of the areas with large, medium-sized, or small otoconia and the development of these areas. This resulted in a structural adaptation to hypergravity.     

新生鼠和成年鼠脑7种微量元素含量的比较

利用高频电感耦合等离子体原子发射光谱法（ICP－AES）测定Sprunge－Dawley大鼠新生期大脑皮层、海马、小脑、间脑和脑桥等部位的锌、铁、铜、锰、铬、锶、钼等7种微量元素的含量，并与成年动物做了比较。结果表明：（1）新生期大鼠全脑7种微量元素含量的多寡依次为：锌、铁、铬、锶、锰、铜、钼；成年期时钢跃居第四位，总含量低于新生期。（2）脑内不同部位微量元素的含量不同。新生大鼠海马和小脑内多数元素含量高于其他脑区，钼在间脑和海马中含量较高。成年鼠皮层、海马微量元素含量较高，皮层内铜、锶、钼含量最低。     

The intravascular contribution to fmri signal change: monte carlo modeling and diffusion-weighted studies in vivo

Understanding the relationship between fMRI signal changes and activated cortex is paramount to successful mapping of neuronal activity. To this end, the relative extravascular and intravascular contribution to fMRI signal change from capillaries (localized), venules (less localized) and macrovessels (remote, draining veins) must be determined. In this work, the authors assessed both the extravascular and intravascular contribution to blood oxygenation level-dependent gradient echo signal change at 1.5 T by using a Monte Carlo model for susceptibility-based contrast in conjunction with a physiological model for neuronal activation-induced changes in oxygenation and vascular volume fraction. The authors compared our Model results with experimental fMRI signal changes with and without velocity sensitization via bipolar gradients to null the intravascular signal. The model and experimental results are in agreement and suggest that the intravascular spins account for the majority of fMRI signal change on T₂^*-weighted images at 1.5 T.