article chemical structure chemistry Molecular Structure 142 Models, Molecular 130 unclassified drug 56 metabolism 54 Crystallography, X-Ray 48 X ray crystallography 48 synthesis 46 Humans 42 animal 42 human 42 Animals 40 Ligands 40 nuclear magnetic resonance spectroscopy 40 ligand 38 Magnetic Resonance Spectroscopy 36 conformation 36 methodology 36 isolation and purification 34 nonhuman 34 controlled study 30 drug effect 28 hydrogen bond 28 Oxidation-Reduction 26 Quantum Theory 26 oxidation reduction reaction 26 quantum theory 26 Copper 24