自然底数
自然底数-
只要水域直径在3m以上，水深2m，水中的放射性物质微弱，用此法可得到相当近似的自然底数。
In this way , a close approximation to the real value can be obtained when the diameter of water area is over 3 meters , its depth is about 2 meters , and it contains little radioactive material .
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本文讨论了三种测定γ辐射仪自然底数的方法：水面法、铅屏法和水中法。
In this paper , three methods for determining the natural background of Υ - radiometers are studied : the methods of water-surface , lead-screen and submersion .
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E属性返回自然对数的底数的值，或
The E property returns the value of the base of natural logarithms , or