PubChem

pubchem.ncbi.nlm.nih.gov

NIH का मुफ्त chemistry reference — लाखों compounds की properties, safety और bioactivity। हर compound का पेज Website source के तौर पर अच्छे से काम करता है।

Run by NIH and free to use, it's a solid reference point for a chemistry or pharmacology notebook that needs compound properties, safety data, or bioactivity numbers rather than narrative explanation. Individual compound pages import cleanly as standalone sources. It's a reference database, so pair it with a paper or review article if the notebook needs interpretation, not just data.