As aerosols are important sources of infection, care should be taken to reduce the extent of their formation and dispersion Hazardous aerosols can be generated by many laboratory operations, e.g. blending, mixing, grinding, shaking, stirring, sonicating and centrifuging of infectious materials. Even when safe equipment is used, it is best to carry out these operations in an approved biological safety cabinet whenever possible

习题课 1(15分)图示结构,刚性梁CD,铰接于C点,AB为一钢杆, 直径d=30mm,E=200GPa,L=1m,若AB杆材料许用应力 [o]=160MPa,求结构的许用载荷P及此时D点的位移

1，核能和爱因斯坦的E＝mc2 2，恒星的能源和寿命 3，恒星上元素的分布 4，恒星上元素的合成 5，福勒的贡献和获1983年诺贝尔奖

变压器习题 9-3答:为了得到正弦感应电势,根据E=知,就必须使磁通也是正弦 dt 量,当铁心不饱和时中∝,故,此时空载电流也是正弦变化量,即呈正弦波。当铁心 饱和时,空载电流比磁通变化大,此时空载电流呈尖顶波形

2.1 物理层的基本概念 *2.2 数据通信的基础知识 2.2.1 数据通信系统的模型 2.2.2 有关信道的几个基本概念 2.2.3 信道的最高码元传输速率 2.2.4 信道的极限信息传输速率 2.3 物理层下面的传输媒体 2.3.1 导向传输媒体 2.3.2 非导向传输媒体 2.4 模拟传输与数字传输 2.4.1 模拟传输系统 *2.4.2 调制解调器 *2.4.3 数字传输系统 *2.5 信道复用技术 2.5.1 频分复用、时分复用和统计时分复用 2.5.2 波分复用 2.5.3 码分复用 *2.6 同步光纤网SONET和同步数字系列SDH 2.7 物理层标准举例 2.7.1 EIA-232-E接口标准 2.7.2 RS-449接口标准

Lesson nine Requirement By the end of this lesson, you should be able to have a good command of D e-commerce terms given in the lesson writing a brief introduction to an organization or products

Lesson eleven Key point: useful terms and definitions of e-commerce Difficult points: two different writing methods of ads

Lesson Seven Requirement By the end of this lesson, you should be able to have a good command of e-commerce terms given in the lesson writing skill s of letters of acceptance

2三角分解法Matrix Factorization*1 高斯消元法的矩阵形式Matrix Form of G..e.*1

Lesson one Kev point. word-formation in the computer and e-commerce fields Difficult points derivation