Not surprisingly, a cottage industry in making ivory look older than it is has grown up.
因此,让象牙看起来比实际年代更久的家庭手工业的发展壮大就并不奇怪了。
But a paper published in the Proceedings of the National Academy of Sciences, by Kevin Unoof the University of Utah and his colleagues, may deal with that.
犹他大学的Kevin Uno和他的同事发表在《美国国家科学院院刊》上的一篇论文可以解决这个问题。
For Dr Uno has worked out how to use one of science s less glorious episodes, theatmospheric testing of nuclear weapons, to work out exactly how old a piece of ivory reallyis.
因为Uno博士研究出了如何利用科学不甚光彩的一段核武器大气层实验,来算出一节象牙的真实年代是多少。
Dr Uno s method uses the ivory s carbon-14 content in a way that was not previouslyemployed.
博士Uno的方法用到了象牙的碳-14含量,他利用碳-14含量的方式从来没人用过。
What radiochemists call 14C forms naturally in the atmosphere by the action of cosmic rayson nitrogen atoms.
被放射化学家称作碳-14的物质是宇宙射线撞击空气中的氮原子而在大气中自然形成的,
It has a half-life of 5,730 years, which makes it ideal for dating objects pertinent to humanhistory, and it can do so to within a few decades of their true agewhich is great forarchaeology.
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