二次曲线的对称轴方程及二次曲线位置的确定

利用不变量可以判定二次曲线的类型和形状,并求出最简方程,但却很难确定二次曲线的位置,本文独辟路径,推导出用原方程系数表示的二次曲线的对称轴方程,从而能迅速确定二次曲线的位置,并作出二次曲线的图形,使二次曲线一般方程的化简和位置的确定的运算过程大大简化.     

小儿异位甲状腺二例

<正> 散发性先天性甲状腺功能减低症又称散发性克汀病(Sporadic cretinism)。其中部分患儿是由异位甲状腺所致。由于异位甲状腺的临床症状出现较迟且不典型,易于误诊而严重影响患儿的智能和体格发育。我院近6年共收治8例先天性甲低,其中异位甲状腺2例,为提高对本病的认识现报告如下。     

基于ANSYS的细长轴车削加工分析

在对细长轴传统车削(正向)弯曲变形分析的基础上,提出细长轴逆向车削的加工方法,并对细长轴的逆向车削进行弯曲变形分析,再利用有限元法分别对两种车削方案的加工精度进行仿真,最后通过实验验证逆向车削可以在一定程度上提高细长轴类零件的车削加工精度。     

MEMS手势轨迹绘制系统设计

基于传统人机交互方式如触摸屏、语音识别等技术,存在着在生活中的某些场合应用不便等问题,设计了一种基于微电子机械系统(MEMS)惯性传感器的手势轨迹绘制系统。该系统通过惯性传感器采集九轴原始数据并在单片机中实现姿态解算算法,然后在上位机完成轨迹重构。实验结果表明,设计的系统可以清晰地体现出手势轨迹的图形形状和尺寸大小,为生活增加便利。     

Drainage after total thyroidectomy or lobectomy for benign thyroidal disorders

Objective: This prospective randomized clinical trial was conducted to evaluate the necessity of drainage after total thyroidectomy or lobectomy for benign thyroidal disorders. Methods: A total of 116 patients who underwent total thyroidectomy or lobectomy for benign thyroidal disorders were randomly allocated to be drained or not. Operative and postoperative outcomes including operating time, postoperative pain assessed by visual analogue scale (VAS), total amount of intramuscular analgesic administration, hospital stay, complications, necessity for re-operation and satisfaction of patients were all assessed. Results: The mean operating time was similar between two groups (the drained and non-drained groups). The mean VAS score was found to be significantly low in the non-drained group patients in postoperative day (POD) 0 and POD 1. The mean amount of intramuscular analgesic requirement was significantly less in the non-drained group. One case of hematoma, two cases of seroma and three cases of transient hypoparathyroidism occurred in the non-drained group, whereas one case of hematoma, two cases of seroma, two cases of wound infections and two cases of transient hypoparathyroidism occurred in the drained group. No patient needed re-operation for any complication. The mean hospital stay was significantly shorter and the satisfaction of patients was superior in the non-drained group. Conclusion: These findings suggest that postoperative complications cannot be prevented by using drains after total thyroidectomy or lobectomy for benign thyroid disorders. Furthermore, the use of drains may increase postoperative pain and the analgesic requirement, and prolong the hospital stay. In the light of these findings, the routine use of drains might not be necessary after thyroid surgery for benign disorders.     

旋转圆盘与轴套装后最小松脱转速的理论计算

应用弹性力学理论导出旋转圆盘与轴套装后最小松脱转速的计算公式，这对确定旋转圆盘的额定转速提供了理论依据。     

一道双曲线方程的数形结合的解法

已知双曲线上一点坐标和两条渐近线方程,求双曲线的标准方程.在这种未知双曲线实轴的条件下,可用两类方法解决问题.一是直接利用代数知识进行运算得到所需结果.二是借助于几何知识和图形推断出双曲线的实轴,再进行运算得到所需结果.本文主要介绍简便易行的第二种方法.     

对于直角轴测投影明显性的判断

重点讨论回转体结构在直角轴测投影中,判断明显性的临界条件及直角轴测坐标系的选择范围;对一般常用的几种轴测图的明显性作了说明。     

鼠股骨弹性模量的测定

本文采用微机控制电子万能试验机及三点弯曲装置，对老鼠股骨进行三点弯曲试验，从而到定老鼠股骨的弹性模量为3．06—6.01GPa。