| 摘要 |
A cephalosporin derivative of the formula I: <IMAGE> (I) in which X is S, O, CH2 or SO, <IMAGE> represents one of the C-7 acyl groups known in the cephalosporin art, R3 is hydrogen or methoxy, R4 is hydrogen, optionally substituted alkyl, allyl, furfuryl or benzyl, and R5 is an aromatic heterocyclic ring system which is linked via carbon, and which contains a quaternized nitrogen atom. |
