In the pioneering studies by Biber et al.(1999),lexical bundles were defined theway in their book Longman Grammar of Spoken and Written English in which wordforms often co-occur in longer sequences,which can be regarded as extendedcollocations,such as do you want me to,I said to him,going to be a,I don't know what.In this book,lexical bundles were described as“recurrent expressions,regardless oftheir idiomaticity,and regardless of their structural status”and“sequences of words thatmost commonly co-occur in a register”(Biber et al.1999:989,992).
The scholars generally explained the concept of multi-word unit from three aspects:formula language/sequence,lexical bundle and chunk.The formula language defined byWray(2002)has the following characteristics:1)It can be a combination of words or not;2)It can be continuous or be discontinuous;3)It is a prefabricated language thatcan be used at any time.This definition’s logic is to emphasize that some multi-word ormulti-language units have psychological integrity.It is not always the result ofconventional grammar rules.The reason it is irrational is because this definition is a partof the borderless definition.Biber et al.(1999)distinguished multi-word units accordingto idioms,collocations and lexical grammatical relations.On this basis,the concept oflexical bundles is put forward.The co-occurrence relationship between two words isreferred as collocation.Lexical bundles,on the other hand,refer to the co-occurrence ofthree or more words.It is an example of extended collocation.The high frequency andhigh distribution co-occurrence of multiple words is the recognition feature of wordbundles.Römer(2010)explained the word chunk as:“Divide a sentence into severalparts.These different parts are called‘blocks’”.They also pointed out that the wordchunk is sometimes called a constituent or an idiom.It can be seen that multi-word unitis a complex concept.Any attempt to define multi-word unit will involve manytheoretical and practical issues.
2.2 The study of abstracts
Abstract is the highly concentrated essence of the paper,which plays a vital role asa medium to effectively demonstrate the academic value and increase the impact of thepaper.Along with the increasing international exchanges of science and technology,more and more scholars need to read a lot of English academic papers to get the latestdevelopments in related fields.A good abstract can make the reader clearly understandthe purpose,method,main research results and research significance,and further helpthe reader to make a more accurate judgment on the academic value of the paper so asto decide whether to read the paper.Therefore,it is particularly important to understandand be familiar with the structural features and writing patterns of the abstract,so as tohelp scholars read and write the abstract correctly and effectively using the targetlanguage.The standardization and comprehensiveness of the format and content will undoubtedly contribute to the promotion of the research results of the paper and theacademic exchanges with peers at home and abroad.In recent years,English abstractsof academic journals have attracted extensive attention.In this research,the study on theabstracts is mainly carried out from the following two aspects:macro-level study ofabstracts,micro-level study of abstracts.
Chapter Three Theoretical Basis......................21
3.1 The theoretical basis of lexical bundles theory............................21
3.1.1 Psycholinguistics foundation...............................21
3.1.2 Corpus linguistics foundation.................................22
Chapter Four Research Methodology............................27
4.1 Research questions...........................27
4.2 Research corpus.................................
