ScienceDraw

ScienceDraw lets you create science diagrams by using an extensive collection of science symbols. Easy to create physics, chemistry, mathematics, and biology illustrations for academic papers or education materials. It runs on Mac, Windows and Linux systems. ScienceDraw integrates the drag-and-drop and pen-drawing functions together so that you can create any science diagram you want. The streamlined user interface makes it easy for new starters to get familiar with. No difficult commands to learn and no drawing skills required, users of all levels could make professional-looking science diagrams easily.

Limitations:

30-day trial