安全因素safety factors
复数基因；复合基因multiple factors (Nilson Ehle 1908， East 1910)
环境因素environmental factors
【经】 社会因素social factors
运气学说doctrine of five evolutive phases and six climatic factors
致伤因素causative factors of injury
R因子R Factors
抗性转移因子resistance transfer factors, RTF, R factor