1、第四章 背景材料与文献回顾 导论部分之一n 导论有两个主要的功能，即 阐述研究的动机 和 说明研究的目的 。n 导论往往被认为是论文最难写的部分之一。因为，必须在较少的篇幅内提及很多研究信息，必须采用适当地撰写方法和组织形式来叙述论文的主题。n 不要直接重复摘要中的内容，更不要直接抄录摘要中的句子。第四章 背景材料与文献回顾导论之一第四章 背景材料与文献回顾4.1 基本内容及组织形式一般，好的导论应清楚地说明以下四个项目：n 主要的研究工作n 研究工作的目的n 进行研究的动机或背景n 本研究工作在相关领域中的地位第四章 背景材料与文献回顾4.1 基本内容及组织形式导论至少包括以下四个基本步骤：
2、n 步骤一，背景资料 。介绍有关的研究领域信息，并针对研究论文将要探讨的问题或现象提供背景知识。n 步骤二，文献回顾 。介绍并评论其他学者对该问题或现象曾经发表的相关研究。n 步骤三，指出问题 。作者指出仍然有某个问题或现象值得进一步研究。n 步骤四，介绍作者的研究目的或研究活动 。第四章 背景材料与文献回顾4.1 基本内容及组织形式几乎每一篇科技研究论文的导论中都会包含上述四个步骤。而步骤五、六可有可无。n 步骤五， 指出本研究工作的理论价值或应用价值。n 步骤六， 说明本研究论文的组织结构，以便读者对作者介绍研究结果的方式有大致的了解。4.2 背景资料（步骤一）4.2.1 背景资料的介绍n
3、 约定俗成的办法，即先指出和论文内容所属研究领域有关的一般事实；接着转到此较大研究领域中的其中一个次研究领域；最后应该把焦点转到该次领域中的更狭窄的主题。n 所以，从介绍背景资料的句子的内容来看，通常先有一两个范围比较广的句子，然后句子内容的范围逐渐缩小，最后一两句的范围应该相当狭窄。4.2 背景资料（步骤一）4.2.1 背景资料的介绍例 4-1The separation of mixtures of alkanes is an important activity in the petroleum and petrochemical industries. For example, the
4、 products from a catalytic isomerization reactor consist of a mixture of linear, mono-methyl and di-methyl alkanes. Of these, the di-branched molecules are the most desired ingredients in petrol because they have the highest octane number. It is therefore required to separate the di-methyl alkanes a
5、nd recycle the linear and mono-methyl alkanes back to the isomerizatio reactor. In the detergent industry, the linear alkanes are the desired components and need to be separated from the alkanes mixture.4.2 背景资料（步骤一）4.2.1 背景资料的介绍例 4-1The separation of mixtures of alkanes is an important activity in
6、the petroleum and petrochemical industries. For example, the products from a catalytic isomerization reactor consist of a mixture of linear, mono-methyl and di-methyl alkanes. Of these, the di-branched molecules are the most desired ingredients in petrol because they have the highest octane number.
7、It is therefore required to separate the di-methyl alkanes and recycle the linear and mono-methyl alkanes back to the isomerizatio reactor. In the detergent industry, the linear alkanes are the desired components and need to be separated from the alkanes mixture.4.2 背景资料（步骤一）4.2.1 背景资料的介绍例 4-1The se
8、paration of mixtures of alkanes is an important activity in the petroleum and petrochemical industries. For example, the products from a catalytic isomerization reactor consist of a mixture of linear, mono-methyl and di-methyl alkanes. Of these, the di-branched molecules are the most desired ingredi
9、ents in petrol because they have the highest octane number. It is therefore required to separate the di-methyl alkanes and recycle the linear and mono-methyl alkanes back to the isomerizatio reactor. In the detergent industry, the linear alkanes are the desired components and need to be separated fr
10、om the alkanes mixture.4.2 背景资料（步骤一）4.2.1 背景资料的介绍Selective sorption on zeolites is often used for separation of alkanes mixtures 1-7. The choice of the zeolite depends on the specific separation task in hand. For example, small-pore zeolite A are used for separation of linear alkanes using the molecular sieving principle; the branched molecules cannot enter the zeolite structure. Both linear and branched molecules are allowed inside the medium-pore MFI matrix and the sorption hierarchy in MFI will be dictated both by the alkanes chain length and degree of branching.
