β-内酰胺环的化学反应性是影响头孢菌素类抗菌活性的因素之一。中小分子如头孢菌素及其类似物的生物活性可用近似的半经验分子轨道法(MO)来计算,如果理论计算指标与观察的生物活性相一致,那么在化合物合成之前,用电子计算机就可寻找这类化合物的新成员。以3位不同取代基的7-乙酰氨基头孢菌素为例, The chemical reactivity of β-lactam rings is one of the factors affecting the antibacterial activity of cephalosporins. The biological activity of small and medium molecules such as cephalosporins and their analogs can be calculated using an approximate semiempirical molecular orbital method (MO). If the theoretical calculation is consistent with the observed biological activity, the computer can be used before compound synthesis Look for new members of this class of compounds. For example, 7-acetylaminocephalosporanes with 3 different substituents,