Internal standard is added, impure elements are determined by spark source mass spectrometry single exposure method.

定量加入内标，利用火花源质谱单曝光法测定杂质元素。

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In the part of theoretical study the classical method and Moire method were used to analysis the single exposure and the double expo - sure of two-wavelength, respectively.

理论研究部分采用经典方法和莫尔法分别对双波长单次曝光法和双波长双曝光法进行了分析。

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Walter Lewin, though, has asked APOD to pose this as a challenge to astrophotographers: create a real single-exposure image of a clear night sky that features 360 degree star trails.

沃尔特·卢因通过APOD向广大天体摄影师发起挑战——拍摄一幅360度星流迹的单曝光晴朗夜空照片。

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Walter Lewin, though, has asked APOD to pose this as a challenge to astrophotographers: create a real single-exposure image of a clear night sky that features 360 degree star trails.

沃尔特·卢因通过APOD向广大天体摄影师发起挑战——拍摄一幅360度星流迹的单曝光晴朗夜空照片。

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