学术essay写作（academic writing），无论是论文还是专著，间架要稳固，才有可读性，才有说服力。
稳，有几个应然特征：部块（parts）关联紧密；部块不外生枝叶；部块之间没有杂质干扰。稳固间架，有多种建构方法。
其中，主界定要素间架法（core-definition-factors framing）最稳固、最简单，最合适年轻学术essay写作者（academic writers），也最合适面向年轻读者的学术读物。主界定，是对研究对象（object of research）的本质（nature）、基本特征（fundamental characters,essential qualities）与界域（scope,territory）的描述。
做主界定，目的是锁定研究对象。不做主界定，研究对象会游移，研究视域会漂移。一切界定，如果有效，都简明扼要，都有三至五个要素（key factors of definition），用三至五个关键词或三五个语句呈现。但是，因为研究对象不同，也因为写作目的不同，界定有时一步到位，因此，只包含一套要素；有时两步或多步到位，因此，包含两套或多套要素。
实例一
…education is understood to involve organized and sustained communication designed to bring about learning.
--UNESCO,International Standard Classification of Education,ISCED 1997.
例一界定“教育”，一步到位，用一个语句描述教育的本质。
实例二
Management is the process of designing and maintaining an environment in which individuals,working together in groups,efficiently accomplish selected aims.This basic definition needs to be expanded.
As managers,people carry out the managerial functions of planning,organizing,staffing,leading,and controlling.
Management applies to any kind of organization.
It applies to managers at all organizational levels.
The aim of all managers is the same:to create a surplus.
Managing is concerned with productivity,which implies effectiveness and efficiency.
--Koontz,H.,&Weihrich,H.Essentials of Management.
这个界定“管理”，两步到位。第一步做基本界定，描述管理的本质，指出管理是“实现所选目标”的“设计与维持过程”。但是，这还不足以说清管理是什么，因此，第二步做扩展界定，说明管理的功能、界域与目标等。
实例三
This small book attempts to explain a rationale for viewing,analyzing and interpreting the curriculum and instruction.…
The rationale developed here begins with identifying four fundamental questions which must be answered in developing any curriculum and plan of instruction.These are:
1.What educational purposes should the school seek to attain?
2.What educational experiences can be provided that are likely to attain these purposes?
3.How can we determine whether these purposes are being attained?
4.How can we determine whether these purposes are being attained?
--Tyler,R.W.Basic Principles of Curriculum and Instruction.
例三界定“课程与教学原理”，也两步到位。第一步做基本界定，描述课程与教学原理的本质，指出它是“观测、分析与阐释课程与教学的原理”。但是，这还不足以说清“课程与教学原理”是什么，因此，第二步做扩展界定，指出它是观测、分析与阐释四个基本问题。
主界定要素间架法，是以主界定的要素为根据构建学术essay写作的间架，即：有几个要素就打造几个主体部块，每个主体部块对应一个要素，按要素呈现顺序将部块连成整体。
实例四
Contents
Part 1:The Basic of Global Management Theory and Practice(Chapters 1-3)
Part 2:Planning(Chapters 4-6)
Part 3:Organizing(Chapters 7-10)
Part 4:Staffing(Chapters 11-13)
Part 5:Leading(Chapters 14-17)
Part 6:Controlling(Chapters 18-20)
--Koontz,H.,&Weihrich,H.Essentials of Management.
这部书的主体部块，完全对应（例二所示）主界定之管理功能。
实例五
Contents
Introduction
1.What Educational Purposes Should the School Seek to Attain?
2.How Can Learning Experiences Be Selected Which Are Likely to Be Useful in Attaining These Objectives?
3.How Can Learning Experiences Be Organized for Effective Instruction?
4.How Can the Effectiveness of Learning Experiences Be Evaluated?
5.How a School or College Staff May Work on Curriculum Building
--Tyler,R.W.Basic Principles of Curriculum and Instruction.
这部书的主体部块，完全对应（例三所示）主界定之四个基本问题，只是措辞不同。
作为间架构建根据的主界定要素必须是平行要素。
如果主界定包含两套或多套要素，依据只能是其中一套。不能将基本界定的要素与扩展界定的要素上下位乱搭,也不能将扩展界定不同部分的要素左右位交错。
实例六
Part 1:Management Theory and Practice
Part 2:Designing
Part 3:Maintaining
Part 4:Planning and Organizing
Part 5:Staffing
Part 6:Leading and Controlling
实例七
Part 1:Management Theory and Practice
Part 2:Planning and Organizing
Part 3:Staffing,Leading and Controlling
Part 4:Organizations
Part 5:Managers
Part 6:Productivity
例二、例四所示，是一本大书。例三、例五所示，是一本小书，篇幅相当于学位论文。
主界定要素间架法，是学术essay写作最稳最简间架法，于大部头著作如此，于期刊论文如此，于学术论文更是如此。