 系统基本配置 hostnamectl timedatectl localctl  查看系统信息 who id uname date ip addr dmidecode lspci  用户权限管理 groupadd groupmod groupdel useradd passwd usermod userdel  chmod chown chgrp umask  文件目录操作 cd mkdir touch file mv cp rm rmdir find whereis which ln  文本处理操作 ls cat more less head tail grep sort uniq sed vi wc diff awk paste  磁盘存储管理 zip gzip bzip2 tar fdisk df du mkfs mdadm mount umount  网络接口管理 nmcli nmtui bond  其他操作命令 man help echo export history clear

氢键 Hydrogen bond 水分子的极性 Polarity of water molecule 弱酸、弱碱、等电点 (Weak acid, weak base and isoelectric piont)

Thorndike called the association between sense impressions and impulses to action a bond or a connection. This marked the first formal attempt to link sensory events to behavior. Earlier brands of associationism attempted to show how ideas became linked together; thus Thorndike's

一、 商业票据（commercial paper） 二、 国债（treasury bill） 三、 银行存单（certificate of deposit） 四、公司债券（corporate bond） 五、 抵押债券（mortgage） 六、回购协议（repurchase agreement）

7.1 Introduction 7.2 Homolytic bond dissociation nergies 7.3 The reactions of alkanes with halogens

Chapter 6 Ionic Reactions--- Nucleophilic substitution and elimination reactions of alkylhalides (卤代烃的亲核取代反 Because halogen atoms are more electronegative 应和消除反应） than carbon, the carbon-halogen bond of alkyl halides is polarized; the carbon atom bears a partial positive charge, the halogen atom a partial negative charge

12.1 Introduction Systems that have a p orbital on an atom adjacent to a double bond---molecules with delocalized pi￾bonds– are called conjugated unsaturated systems

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

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

The most characteristic reaction of aldehydes and ketones is nucleophilic addition to the carbon-oxygen double bond