外壳名词在学术写作中的使用已有诸多研究，然而，其在口语学术交流中的使用却未得到足够的关注。尽管众多研究已经探讨了外壳名词在学科写作中的使用情况，但对于这种名词性资源在学科口语中的使用情况，例如在大学课堂教学等场合的应用，却缺乏足够的重视。本研究以约130万字的大学课堂教学语料库为基础，对外壳名词在三个学科领域（哲学、经济学和物理学）的课堂教学中的使用情况进行了深入研究。这三个学科分别是人文学科、社会科学和自然科学的典型代表。
本研究基于Halliday（1985，1994）的语言元功能理论，将外壳名词分为三个主要类别：倾向于概念意义的外壳名词、倾向于人际意义的外壳名词和倾向于文本意义的外壳名词。倾向于概念意义的外壳名词通常表达概念和心理状态等意义（如“concept”和“belief”）；倾向于人际意义的外壳名词指的是标示说话者对事物的态度或评价（如“difficulty”和“advantage”）；倾向于文本意义的外壳名词指的是指向文本本身或某种语篇类型的名词（如“text”和“lecture”）。基于系统功能语言学中的相关概念，这三大类外壳名词又分为一些子类型，如：心理过程名词、情态名词和态度名词等。
为了探索外壳名词在大学课堂话语中的使用，本文围绕三个研究问题展开：（1）学科课堂教学中的外壳名词有哪些种类？外壳名词的频率分布是怎样的？（2）外壳名词如何助力大学课堂教学话语组织？（3）大学课堂话语中的外壳名词体现出哪些学科差异性/相似性？
研究发现，在整个语料库中，倾向于概念意义的外壳名词所占比例最高（76%），其次是倾向于人际意义的外壳名词（19%）和倾向于文本意义的外壳名词（5%），这反映了大学课堂教学中更注重“传递学科知识和内容”（Liu ＆ Chen，2022，p. 9）。相比于物理学和经济学教师，哲学教师使用外壳名词的频率更高，这表明哲学更依赖于其知识实践中的“知者语码”（Maton，2000）来建构知识，或者说，哲学教师在传授学术知识时需要更多的语言/修辞资源。在使用外壳名词的子类型方面，本研究发现一些跨学科差异，如：话语类名词在哲学中的出现频率远远高于物理学。此外，本研究表明，外壳名词之间的互动模式（如重复式模式和同义式模式）以及外壳名词的各种局部功能（如复习与预习课堂知识/内容）有助于大学课堂话语组织。本研究也验证了“知识/知者结构”这一概念（Maton，2000，2014）确实能为解释外壳名词跨学科使用差异提供有效的理论视角。
本研究基于大学课堂教学话语来研究外壳名词，因此，有助于人们理解这种名词性资源在学术口语中的使用特征。本文最后讨论了理论启示和教学启示，同时也指出了本研究的局限性并针对未来研究提出了建议。
 

There is a wealth of documentation regarding the prevalence of “shell nouns” (Schmid, 2000) in written academic texts; however, their utilization in oral academic discourses has remained relatively underexplored. While many previous studies investigate shell nouns in disciplinary writing, fewer studies explore such nominal resources in disciplinary speaking, such as university lectures. Seeking to remedy this gap, this study examines shell nouns in academic lectures from three disciplines, i.e., philosophy, economics and physics, three representatives in Humanities, Social Sciences and Natural Sciences respectively, based on a corpus of about 1.3 million words.

Drawing upon Halliday’s (1985) theory of language metafunctions, this research classifies shell nouns into three primary categories: ideationally-oriented nouns, interpersonally-oriented nouns, and textually-oriented nouns. Ideationally-oriented nouns are those that typically express ideational meanings, such as those involving concepts and psychological states (e.g., concept and belief). Interpersonally-oriented nouns refer to those demarcating speakers’ attitude towards or appraisal of messages (e.g., difficulty and advantage). Textually-oriented nouns refer to nouns that denote the text itself or certain text types, (e.g., text and lecture). These broad noun types, informed by other SFL-related notions, are further categorized into subtypes, such as mental process nouns, modalization nouns, and attitude nouns.

To investigate the use of shell nouns in disciplinary lectures, three main research questions are raised to guide this thesis, i.e., (1) What types of shell nouns are there in disciplinary lectures? And what are their frequency distributions? (2) How do shell nouns contribute to the organization of academic lectures? (3) What are the differences/similarities in the use of shell nouns across academic lectures of the three disciplines (i.e., physics, economics and philosophy)?

Results show that ideationally-oriented nouns are proportionally highest (76%) in the whole corpus, followed by interpersonally-oriented nouns (19%) and textually-oriented nouns (5%) respectively, reflecting the “knowledge-delivering and content-focused features” of university lectures (Liu & Chen, 2022, p. 9). Philosophy lecturers are found to employ shell nouns significantly more frequently than their counterparts in either physics or economics, suggesting the heavier reliance of philosophy on “knower codes” (Maton, 2000) in its knowledge-making practices or the stronger need of the philosophy lecturers for linguistic scaffolding when delivering academic knowledge. Moreover, cross-disciplinary differences were revealed concerning the use of a number of (sub)types of shell nouns, e.g., verbal process nouns have a far higher frequency in philosophy than in physics. Additionally, the study reveals that shell nouns can contribute to the organization of lecture discourse via interactive patterns (e.g., repetitive pattern and synonymous pattern) or various local functions associated with these nouns (e.g., reviewing previous lectures and previewing forthcoming lectures). The present work also proves the effectiveness of “knowledge/knower structures” (Bernstein, 1999; Maton, 2000, 2014) in interpreting the cross-disciplinary variations in using shell nouns.

Focusing on the use of shell nouns in university lectures, this research is conducive to our understanding of such nominal resources in academic spoken discourse. Theoretical and pedagogical implications are also discussed, along with the limitations and suggestions for future research.