Expression of Human Epidermal Growth Factor Gene in Cyanobacteria Purification and characterization of hydrogenase from Synechococcus sp. PCC 7942 Distribution Pattern of Photosynthetic Picoplankton and Heterotrophic Bacteria in the Northern South China Sea SUMMER DISTRIBUTION OF PICOPHYTOPLANKTON IN THE NORTH YELLOW SEA Establishment of a Highly Efficient Ammonia Secreting Mutant of Synechococcus sp. PCC 7942 and the Glutamine Synthetase Activity, Photosynthesis and Growth in Its Immobilized Cells Cloning and Expression of Human Pro-urokinase Gene in the Cyanobacterium Synechococcus sp. PCC 7002 Synechococcus and Prochlorococcus growth and mortality rates in the northern China Sea: range of variations and correlation with environmental factors Distribution of autotrophic picoplankton and its effect factors in the waters around Leizhou Peninsula in summer and winter