| Abstract | 第8-10页 |
| 摘要 | 第11-13页 |
| List of Abbreviations | 第13-17页 |
| Chapter One Introduction | 第17-21页 |
| 1.1 Background of the Study | 第17-18页 |
| 1.2 Purpose of the Study | 第18页 |
| 1.3 Significance of the Study | 第18-19页 |
| 1.4 Organization of the Thesis | 第19-21页 |
| Chapter Two Literature Review | 第21-46页 |
| 2.1 Studies of Modality | 第21-26页 |
| 2.1.1 Definition and Classification of Modality | 第21-23页 |
| 2.1.2 Studies of Modality from the Perspective of Systemic FunctionalGrammar | 第23-25页 |
| 2.1.3 Studies of Modality from Other Perspectives | 第25-26页 |
| 2.2 Studies of English Academic Discourse | 第26-38页 |
| 2.2.1 Studies of English Academic Discourse from the Perspective ofSystemic Functional Grammar | 第27-31页 |
| 2.2.1.1 Studies from the Perspective of Patterns of Thematic Progression | 第28-29页 |
| 2.2.1.2 Studies from the Perspective of Appraisal Theory | 第29-31页 |
| 2.2.1.3 Studies from the Perspective of Grammatical Metaphor Theory | 第31页 |
| 2.2.2 Studies of Academic Discourse from Other Perspectives | 第31-38页 |
| 2.2.2.1 John Swales' Genre Analysis | 第31-35页 |
| 2.2.2.2 Douglas Biber's Multi-dimensional Analysis | 第35-38页 |
| 2.3 Studies of Modality in English Academic Discourse | 第38-45页 |
| 2.3.1 Studies from the Perspective of Traditional Grammar | 第38-39页 |
| 2.3.2 Studies from the Perspective of Systemic Functional Grammar | 第39-45页 |
| 2.3.2.1 Studies of the Interpersonal Meaning Realized through Modality | 第40-42页 |
| 2.3.2.2 Studies of Modality's Other Functions in English AcademicDiscourse | 第42-43页 |
| 2.3.2.3 Comparative Studies of Modality in English Academic Discourse | 第43-45页 |
| 2.4 Research Gaps | 第45页 |
| 2.5 Summary | 第45-46页 |
| Chapter Three Theoretical Framework | 第46-52页 |
| 3.1 An Overview of Modality System from the Perspective of SystemicFunctional Grammar | 第46-47页 |
| 3.2 The System of Modality from the Perspective of Systemic FunctionalGrammar | 第47-51页 |
| 3.2.1 Types of Modality | 第47-48页 |
| 3.2.2 Orientations of Modality | 第48-49页 |
| 3.2.3 Values of Modality | 第49-50页 |
| 3.2.4 Metaphorical Realizations of Modality | 第50-51页 |
| 3.3 Summary | 第51-52页 |
| Chapter Four Methodology | 第52-60页 |
| 4.1 Research Questions | 第52-53页 |
| 4.2 Data Collection | 第53-57页 |
| 4.2.1 Selection of Disciplines | 第53页 |
| 4.2.2 Selection of Academic Journals | 第53-54页 |
| 4.2.3 Selection of Academic Research Articles | 第54-57页 |
| 4.3 Data Pretreatment | 第57页 |
| 4.4 Data Coding | 第57-58页 |
| 4.5 Data Analysis | 第58-59页 |
| 4.6 Summary | 第59-60页 |
| Chapter Five Results and Discussion | 第60-114页 |
| 5.1 Distributions of Modality Usage in Corpus 1,Corpus 2 and Corpus 3 | 第60-69页 |
| 5.1.1 Distributions of Modality Usage in Corpus 1 | 第60-63页 |
| 5.1.2 Distributions of Modality Usage in Corpus 2 | 第63-66页 |
| 5.1.3 Distributions of Modality Usage in Corpus 3 | 第66-69页 |
| 5.2 Cross-Disciplinary Comparison of Modality Usage | 第69-103页 |
| 5.2.1 Comparison of the Usage of Types of Modality | 第72-83页 |
| 5.2.1.1 Similarities of the Usage of Types of Modality | 第82-83页 |
| 5.2.1.2 Differences of the Usage of Types of Modality | 第83页 |
| 5.2.2 Comparison of the Usage of Orientations of Modality | 第83-98页 |
| 5.2.2.1 Similarities of the Usage of Orientations of Modality | 第97页 |
| 5.2.2.2 Differences of the Usage of Orientations of Modality | 第97-98页 |
| 5.2.3 Comparison of the Usage of Values of Modality | 第98-103页 |
| 5.2.3.1 Similarities of the Usage of Values of Modality | 第102-103页 |
| 5.2.3.2 Differences of the Usage of Values of Modality | 第103页 |
| 5.3 Reasons for the Similarities and Differences in Modality Usage | 第103-113页 |
| 5.3.1 Evaluative Function of Modality | 第104-110页 |
| 5.3.2 Dialogic Space Constructed through Modality | 第110-113页 |
| 5.4 Summary | 第113-114页 |
| Chapter Six Conclusion | 第114-119页 |
| 6.1 Major Findings of the Study | 第114-117页 |
| 6.2 Implications of the Study | 第117页 |
| 6.3 Limitations of the Study | 第117-118页 |
| 6.4 Suggestions for Future Research | 第118-119页 |
| References | 第119-130页 |
| Appendig | 第130-138页 |
| Acknowledgements | 第138-139页 |
| 附件 | 第139页 |
