几十年来，欧洲核子研究中心和其他地方的物理学家一直在想方设法克服反氢原子的这些局限。反氢原子由一个正电子与一个反质子构成，正电子绕反质子运行。
For decades, physicists at CERN and elsewhere have been trying to overcome these limitations with antihydrogen, which consists of a single positron orbiting a single antiproton.
目的：探讨弹性包绕式垫加螺旋扩弓器矫治替牙期后牙反的适用性及治疗前后的牙颌结构变化。
Objective:To evaluate the maxillary expansion effects of posterior crossbite patients treated with elastic wrapping bite guard and screw expansion mechanic in the mixed dentition.
本文讨论了填充介质腔为弹性波绕射的平面及反平面问题，详细地给出了波场的计算方法。
In this paper, the plane and anti-plane problems of the diffraction of elastic waves by a cavity filled with another medium are discussed. The method calculation, of the wave field is given in detail.
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