The optimal weight fraction is 0.1%, for under this condition, the wear scar diameter is decreased 35.6% and lubricating oil has great time-release effect.

当铜镍复合粉体的质量分数达到0.1%时，磨斑直径降低幅度最大，达35.6%，并具有很好的长效减摩性能。

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The effect of the end group on the weight fraction of the individual mono-disperse species both for the experimental UV response data and the theoretical distribution function was discussed.

讨论了端基对实验的紫外吸收响应以及理论的链长分布函数中各个半分散组分重量分数的影响。

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Today you can get an iPod nano for $179 that’s a fraction of the original iPod’s size and weight, with double the storage, a color display, video playback, and a built-in video camera.

今天你可以只花179美元就能得到一个iPod nano，今天的产品只是最初的iPod大小和重量的一小部分，但是会有最初的两倍的存储容量，彩色的显示屏，能录放而且还有一个内置的摄像头。

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That might not seem like much, but considering most rigid robot arms can only lift a fraction of their own weight, it represents a sizable gain in strength-to-weight ratio.

ENGADGET: iRobot's AIRarm prototype bot has an inflatable arm for manipulating objects, was built at DARPA's behest

The NX20 is the perfect match for enthusiast amateur or professional photographers looking for a highly portable camera that gives the professional look and feel of a DSLR but at a fraction of the size and weight, with the addition of an ergonomic grip to fit comfortably into the hand.

ENGADGET: Samsung's NX20, NX210 and NX1000 mirrorless camera trio hands-on (video)