"SDN:P07::4FH5X1PP" . "SDN:P07::4FH5X1PP" . . "false" . "SDN:P07::4FH5X1PP" . "surface_radioactivity_content_of_77Ge"@en . "2018-02-12 16:53:18.0" . . "" . . "accepted"@en . . "2018-02-12 16:53:18.0" . "1" . . "1" . . "The surface called \"surface\" means the lower boundary of the atmosphere. \"Content\" indicates a quantity per unit area. \"Radioactivity\" means the number of radioactive decays of a material per second. \"Ge\" means the element \"germanium\" and \"77Ge\" is the isotope \"germanium-77\" with a half-life of 4.72e-01 days."@en .