It is the essence of the full text, a summary of a scientific research work or technical practice, and a summary of research purposes, methods and results.

Before the main part, the purpose is to let readers know the content of the paper first, so as to decide whether to read the full text. Generally speaking, this abstract is written after the full text is completed. The number of words is limited to 100 ~ 150. The content includes the research purpose, research methods, research results and main conclusions. In other words, the abstract must answer questions such as "what to study", "how to study", "what results have been achieved" and "what does the result show".

Short and pithy is the main feature of academic journal abstracts. Just briefly summarize the research objectives, methods, results and conclusions in 1 ~ 2 sentences respectively.

There are only five sentences in the abstract of the example. The first sentence is hypothesis, the second and third sentences are research contents, and the fourth and fifth sentences cover the research methods and results. The purpose of the study is omitted here. If the research purpose is supplemented, a sentence can be added before the abstract, for example, "the construction control calculation of the space curve main cable suspension bridge is the key to ensure the design alignment and internal force realization of the completed bridge." As can be seen from the abstract, the main work of this paper is to establish a new model for construction control calculation of space curve main cable suspension bridge, and the correctness of the new model is verified by an example.

The main task of introduction is to outline the basic content and outline of the full text to readers. It can include all or several of the following five contents:

Introduce the background, significance, development and current level of a research field;

Review and summarize the literature in related fields, including previous research results and solved problems, and make appropriate evaluation or comparison;

Pointing out the unsolved problems and technical gaps left by predecessors, we can also put forward new problems, new methods and new ideas to solve these new problems, thus leading to the motivation and significance of our own research topic;

Explain the purpose of your research project;

Summarize the main contents of the paper or outline its general outline.

It is not easy to arrange these contents reasonably and describe them clearly to readers in an orderly way. Experience tells us that the introduction is actually the most difficult part of the full text. This is because of the author's familiarity with related disciplines, whether the author's knowledge is profound or poor, what is the significance and value of the research, and so on. , are fully reflected in the introduction between the lines.

We can arrange introductions at three or four levels. The first layer consists of research background, significance and development, including literature review in a certain research field; The second layer puts forward unsolved or urgent problems, which leads to its own research motivation and significance; The third layer explains the specific purpose and content of his research; Finally, it is the end of the introduction, and you can introduce the components of the paper.

It is worth noting that the length of each level in the introduction can vary greatly. This is very different from abstraction. The proportion of purpose, method, result and conclusion in this paper is roughly the same. In the introduction, the first level often occupies most of the space. The research background and present situation are introduced in detail. The purpose of the study may be shorter.

Another difference between the introduction and the abstract is that the main research results must be listed in the abstract, but these results can be omitted in the introduction (if the abstract is published with the text), because there is a special section in the text to write the results, so there is no need to repeat them in the introduction.

For shorter papers, the introduction can also be relatively short. In order to shorten the space, you can briefly introduce the importance, significance or problems to be solved in a certain research field in one or two sentences. Then the literature review. Then introduce my research motivation, purpose and main content. As for the research methods, research results and the components of the paper, they can be completely omitted.