Searchable classes: concept, author, abstract, title, date, doi and all fields
If you want to search in all fields, just enter your search term, e.g. fever.
If you want to get more specific search results, e.g. search for a MeSH concept, enter: concept:D045169.
A specific doi can be (for example) searched via: doi:10.1101/2020.05.29.20115824
Similarly, you can search for an author entering author:"Max Mustermann"
If you only know the last name, search for author:*Mustermann.
Dates can be in various formats, for example date:2020-05-15 if you are looking for a specific day or date:2020-05 if you want to query for a month.
However, the following expressions will also work:
date:"last tuesday to today"
date:"-1 week to now"