It should be the digital literature database bought by the library, and most of them are issued by academic publishing companies. International academic publishing houses, such as Elsevier, springer, Nature, Wiley, EBSCO, etc. A large number of academic journals and documents are published every year, covering various research fields. Many documents published every year represent the world's most advanced level of research in a certain field, which has a good guiding role and reference for the research of school students. Especially now, all major universities regard scientific research as the main means to promote teaching development and show the academic level of the school, so it is even more important to browse the latest literature database. So what happens if you don't buy these databases? First, you can still find these resources, but you can't look at the content, or all the content. In academic research, you may have to look at dozens or even hundreds of documents to filter out what is useful to you, so it is very important to see all the contents. To see the content, you have to pay the publisher, which is also a big source of income for academic publishers. Second, blindly searching for documents on the Internet will face a complicated document retrieval system. When it comes to academic publishing, we have to mention retrieval methods. According to what you are looking for, you can narrow your search scope by publishing year, subject background, database, author, institution, etc., so that your search is more accurate and effective, which is why many school libraries will offer some courses to teach you how to use academic database search. Thirdly, the retrieval of the database will not only present simple retrieval results, but also give some other data, such as the number of articles published in recent years and the detailed classification under the classification of major disciplines. These data are helpful to analyze the research trends of specific disciplines in recent years. ?