Doctors are at the top of the degree tower, and qualified doctors should have a high theoretical level and research ability, reaching the top level in the industry, so as to become the reserve force of research forces in universities and scientific research units. So there are both at home and abroad, but all better universities generally have higher requirements for doctoral graduation, and doctoral students are not easy to graduate.

Involution leads to higher and higher requirements for doctoral students to graduate. In order to reflect enough theoretical and academic height, domestic doctoral students generally require to publish a number of high-quality papers. For science and engineering, publishing SCI/EI or first-class journal papers has become a standard. In recent years, with the increasing involution of academics, many tutors require students to publish papers in one or top journals. However, with the expansion of doctoral enrollment, the number of articles published in authoritative journals has not increased much, and it is more difficult to publish high-level papers year by year. Tutors want to reach a high academic level, and the number of places is very limited. Naturally, he also has great expectations for doctoral students.