The last 50 years have seen considerable changes in both research and publication practices in international English-medium arenas, and also witnessed a shift in argument styles in academic texts over these years (e.g. Hyland and Jiang, 2019). However, little attention was given to the rhetorical roles of nouns in diachronic studies of professional research writing. This is surprising since academic writing is an extremely noun-heavy register and novice writers often find nominal expressions difficult. In this study, we examine what are called metadiscursive nouns, a type of unspecific abstract nouns, in our diachronic corpus of disciplinary research writing to see whether they have increased in recent decades. It is found that this N pattern is most frequent overall, but hard scientists made increased use of quality nouns to promote the value of their research outcome while writers in the soft disciplines prefer evidential nouns for factual support to their knowledge claims. All these point to the need to include metadiscursive nouns into the rhetorical repertoire of metadiscourse and to emphasise their functions in the course of using English for research and publication purposes.

在过去的50年中，国际英语媒体领域的研究和出版实践发生了巨大变化，并且这些年来学术文献中的论据风格也发生了变化（例如Hyland和Jiang，2019年）。但是，很少有人注意名词在专业研究写作历时研究中的修辞作用。这是令人惊讶的，因为学术写作是一个极其名词化的记录，而新手作家通常会发现名词表达很困难。在这项研究中，我们在学科研究历时历年的语料库中研究了所谓的元离散名词（metasdiscursive nouns），一种非特定的抽象名词，以了解它们在最近几十年中是否有所增加。发现这个N模式总体上是最常见的，但是勤奋的科学家更多地使用质量名词来提高其研究成果的价值，而软学科的作者则倾向于使用证据性名词来为他们的知识主张提供事实依据。所有这些都表明需要将元话语名词包括在元话语的修辞库中，并强调其在将英语用于研究和出版目的的过程中的功能。