A Corpus-based Study On Co-selection Of Keywords In Agricultural Engineering English Research Papers

Co-selection theory,advocated by Sinclair,plays a vital role in corpus linguistics,which consists of four aspects,namely,collocation,colligation,semantic preference and semantic prosody.It is the core mechanism of language description.With the increasing international communication and cooperation in agriculture,the teaching and researching of agricultural English for science and technology become more and more significant.As a branch of agricultural English for science and technology,the significance of agricultural engineering English papers should not be ignored.The research objects of this research are keywords chosen from a self-built Agricultural Engineering English Corpus(AEEC).Based on the co-selection theory,this research attempts to investigate the co-selection of keywords from collocation,colligation,semantic preference and semantic prosody respectively.The research fills the gap on the compilation of the agricultural engineering English corpus and fills the blank in agricultural engineering English research papers from the perspective of the co-selection theory.This research combines qualitative with quantitative analysis.Firstly,AEEC is compiled with the total size of 582,606 running words.This corpus collects 100 agricultural engineering English papers from Bioresource Technology,the top agricultural engineering journals in the world.The thesis uses the “keyword list” function in Word Smith,one of the linguistic analysis software,to identify the keywords list,among which biomass,acid and production with the highest keyness value are selected to examine their concordance lines,MI values,and to analyze their collocation,colligation,semantic preference and semantic prosody.The results show:In regard to collocation,(1)they come in three different types.First,fixed expressions already become an agricultural engineering technical term or are employed as a term by certain researchers in the academic articles.Second,the collocations intend to be in the form of phrases and to be adopted in various articles.The rests are the custom collocations which appear more often than other words in this particular genre;(2)most of collocates are the technical terms,which are considered as the most essential and distinctive part of EST(English for Science and Technology)vocabulary;(3)collocates are in the short form.In regard to colligation,five colligation patterns are identified in the research corpus,N+N,V+N,N+V,N+PREP+N and ADJ+N.The most commonly used colligation pattern of biomass is “N+N”;the most commonly used colligation pattern of acid is “AJD+N”;the most commonly used colligation pattern of production is “N+N”.In regard to semantic preference,biomass,acid and production seem to have a relatively wide semantic preference,but they all fall into the agricultural engineering genre.In regard to semantic prosody,biomass and production all show a combination of positive prosody,neutral prosody and negative one.Acid shows a combination of positive prosody and neutral one.Meanwhile,the frequency of neutral collocates is higher than the total frequency of positive collocates and negative ones.That indicates the researchers tend to adopt collocates with neutral meaning to illustrate a truth,to express a deduction or a hypothesis,and to describe a process,feature and function.The research has implications for English teaching and studies.In regard to theoretical significance,this study aims to enrich the co-selection theory.Corpus-based approach is a practical reference to build an agricultural engineering English corpus in the future.In regard to pedagogical implications,this study provides a new perspective to optimize the teaching materials and methods as well as provides guideline for vocabulary teaching and learning.