Rather than conforming to a widely accepted standard, journals in the sciences commonly have their own styles. Resources provided here are for the style of the Council of Science Editors (CSE), on which the styles of many journals are based.
See these resources to learn about this style, but ask your professor what style to use in class.
This style from the Council of Science Editors is common in the sciences, especially biology.
Note: Most academic science journals have their own styles. Ask your professor what citation style to use in class.
Find the style guide at the library or explore the linked websites to learn how to use this style.