Energy and the Relative Stability Kinetic energy is the energy an object has because of its motion. Potential energy is stored energy. It exists only when an attractive or repulsive force exists between objects

The C—X bond of alkyl halides is polarized. The carbon atom bears a partial positive charge, The halogen atom a partial negative charge

In the addition of HX to an unsymmetrically substituted alkene, the hydrogen atom adds to the carbon atom of the double bond that already has the greater number of hydrogen atoms and that the X group adds to the carbon having more alkyl substituents. Markovnikov’s rule can be restated by saying that, in the addition of HX to an alkene, the more stable carbocation intermediate is formed

A mass spectrometer produces a spectrum of masses based on the structure of a molecule. It is a spectrum or plot of the distribution of ion masses corresponding to the formula weight of a molecule, fragments derived from the molecule, or both

一、药物化学的定义 二、药物化学的研究内容 三、药物化学的任务 四、药物化学发展的动力 五、新药创制

中国人民大学：《数据库系统概论 An Introduction to Database System》课程教学资源（PPT课件讲稿）第一章 绪论（1.1-1.2）数据库系统概述、数据模型

1.1 数据库系统概述 1.2 数据模型 1.3 数据库系统结构 1.4 数据库系统的组成 1.5 数据库技术的研究领域 1.6 小结

2.1 关系模型概述 2.2 关系数据结构 2.3 关系的完整性

3.1 SQL概述 3.2 数据定义

3.4 数据更新 3.5 视图