Natural index journal is the top journal in the world selected by Nature Publishing Group, which is used to count the number of papers published by universities and research institutes (countries) in the world's most influential research-oriented academic journals.

"Small Journal" is a journal published by Wiley Publishing House in Germany, which focuses on the research of materials and material properties at nano and micro levels. Although small journals have a high influence in the field of nano-materials, they have not been included in the category of natural index journals.