...a very long time and different species should be appear in different time, 2008-12-12 22:26:10 補充： and this has...補充： Fossil record can only shows that a particular species was on the earth at some time, but what...
...genus Streptomyces. With advances in organic chemistry many antibiotics are now also...specificity: "narrow-spectrum" antibiotics target particular types of bacteria, such as Gram-negative...
