"1" . . "surface_radioactivity_content_of_209Bi"@en . "SDN:P07::1R3TWUI7" . "1" . . "" . "SDN:P07::1R3TWUI7" . "2018-02-12 16:53:18.0" . "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. \"Bi\" means the element \"bismuth\" and \"209Bi\" is the isotope \"bismuth-209\" with a half-life of 7.29e+20 days."@en . . . "accepted"@en . . "SDN:P07::1R3TWUI7" . "false" . "2018-02-12 16:53:18.0" . .