47.The isotopic composition of lead often varies from one sourceof common copper ore to another，with variations exceeding themeasurement error;and preliminary studies indicate virtually uniformis topic composition of the lead from a single copper-ore source. 1 w: v6 y+ n2 N! E6 d 铅的同位素构成经常在一种普通铜矿石来源与另一种铜矿石来源之间存在差异，其差异程度超出测量误差;而最初的研究表明，对于来自单独一个铜矿石来源的铅来说，其同位素构成几乎是毫无二致的。 8 [9 Y/ j7 e; R- b; i T- [48. More probable is bird transport，either externally，by accidental attachment of the seeds to feathers，or internally，by the swallowing of fruit and subsequent excretion of the seeds. 8 X- U& A( I1 E, e( }, O c 更有可能的是鸟类运输：或者是通过外部途径，即由于种籽偶然粘附在羽毛上;或者是通过内部方式，即由于鸟类吞食果子并随后将种籽排泄出来。
发表于 2012-8-15 13:05:25
