Studies on Exploiting Actinomycetic Strain Resources for Drug Screening by a New Approach Using Antibiotic-resistance Mutation Technique; In vitro Antibacterial Activity of Combined Antimicrobial Agents Against Multidrug-resistant Acinetobacter baumannii 抗生素抗性筛选组合技术拓展放线菌药源活性菌株资源的研究联合抗菌药物对多药耐药鲍氏不动杆菌的体外抗菌活性研究