药物分子必须通过与酶或受体结构等在分子水平上起交互作用呈现其生物活性。这些分子间的交互作用基本上取决于分子的大小、形状以及分子内电荷密度的分布和极化度。当若干分子相接近而足以使电子云重叠时,便存在短程作用力,如未共电子对(Lone electronpairs)的给予体和接受体的键合和产生电荷转移的复合作用。当分子间隔稍远时,则发生长程作用力,如静电作用(分子间固有电荷分布的交互作用)、诱导作用(受邻近分子固有电荷的影响致使电荷分布变形)、分散作用(电荷位置 Drug molecules must exhibit their biological activity at the molecular level by interacting with the enzyme or receptor structure. The interaction between these molecules basically depends on the size and shape of the molecule and the distribution and degree of polarization of the charge density within the molecule. When several molecules are close enough to make the electron cloud overlap, there are short-range forces such as the binding of the donor and acceptor of the unwanted electron pair and the complexing of charge transfer. When the molecular distance is slightly longer, long-range forces occur such as electrostatic interaction (intermolecular intrinsic charge distribution interaction), induction (charge distribution distortion caused by the intrinsic charges of neighboring molecules), dispersion (charge position