Finding specific types of manuscripts of a journal
First, try the Advanced Search interface of the specific journal or publisher. In this  case:


Open https://academic.oup.com/bioinformatics/advanced-search.
Under "Find a specific article", select Bioinformatics and press the Search button (the one in the first row).
One the left, under "Article type", select the desired type, e.g., "Brief report".
Again on the left, under "Section", select the desired section, e.g. "Systems biology".


Now only articles of type Brief report, in the section Systems biology are displayed.

If such a search interface is not available or gives irrelevant results, there are more general approaches:


In Scopus Advanced Search, use queries in the form:


  EXACTSRCTITLE(Journal Name) AND DOCTYPE(document_type)


You can find the list of possible document types in the help (field code DOCTYPE).
In Google Scholar, try queries in the form (include the quotes):


  source:"Journal name" "Article type"