The order in which parentheses are used in the paper: the first layer of the paper serial number is the Chinese numeral plus pause sign, such as one, two and three; The second layer contains Chinese characters and numbers in brackets, such as (1), (2) and (3); The third layer is Arabic numerals with footnotes, such as 1, 2, 3.

The fourth level is that there are Arabic numerals in brackets, such as (1) (2) (3); The fifth layer is circled Arabic numerals, such as ① ② ③; The sixth floor is capitalized English letters, such as A, B and C; The seventh layer is lowercase English letters, such as A, B and C.

Keyword definition

Keywords are selected from the title, abstract and text of the paper, which are words with substantial meaning to express the central content of the paper. Keywords are words used by computer systems to index the content characteristics of papers, which are convenient for information systems to collect and provide readers with retrieval. Generally, 3-8 words are selected as keywords for each paper, and a new line is set at the bottom left of the "abstract".

Subject words are standard words. When determining the subject words, we should analyze the theme of the paper and convert it into standard words in the thesaurus according to the rules of indexing and collocation.