(1) Cut to the chase and don't beat around the bush. Avoid long-winded narration of historical origin and research process.

(2) Be concise and focused. We shouldn't talk too much about the familiar common sense content of colleagues and textbooks. When it is really necessary to mention other people's research results and basic principles, we only need to mark them in the form of quotations. In the introduction, when putting forward the work and opinions of this paper, we should make the meaning clear and the language concise.

(3) Reviewing the history should be focused, the content should be closely related to the title of the article, and the background should be introduced around the title, which can be summarized in a few words; Don't write out the methods and results and don't discuss them when prompting the methods used; Although the contents of past documents can be quoted appropriately, they should not be listed in detail, and the preface should not be written as the historical development of research; Don't write the preface as a small summary of the literature, and don't repeat the common sense content already in the textbook or known by researchers in this field.

(4) Respect science and seek truth from facts. In the preface, we should properly evaluate the value of the paper, seek truth from facts and use scientific words. For the innovation of this paper, it is best not to use inappropriate self-evaluation such as "This study is the first report in China", "Filling the domestic blank", "High academic value", "This study has not been reported in China" and "This study is at the leading level at home and abroad".

(5) The content of the preface should not be the same as that of the abstract, so please avoid using polite expressions, such as "a little knowledge", "limited level", "please correct me" and "throwing a brick to attract jade". It is best not to discuss the preface in sections, not to illustrate and list, not to deduce and prove formulas.

(6) The preface should not be too long, too long will make readers bored, too short and difficult to explain clearly. For a paper of 3000-5000 words, the number of words in the preface should generally be 200-250 words.

The main contents of the introduction part of the paper are as follows:

(1) Explain the theme, scope and purpose of the paper.

(2) Explain the cause, background and brief historical review of related fields of this study (what have predecessors done? Which ones have not been solved? How's it going so far? )。

(3) Expected results or the significance of this study.

(4) The introduction is generally not segmented, and its length depends on the content of the paper. The introduction of papers involving basic research is long, and the clinical case analysis should be short. The introduction of most foreign papers is relatively long, generally around 1000 words, which may be related to the strict limitation of words in most foreign journals.