Mezzo-soprano is a special voice part which can show the rich, beautiful, pure and changeable tone-color and timber.

Comparative approach is a good way of learning, which shares both sameness and difference between Chinese traditional canto and bel canto in breathing, voice, the using of echoing cavities, giving vent to words, and the division of parts.

Due to the different cultural background and aesthetics between China and Europe, the two operas have both similarities and difference in part division, timbre and characteristics of parts and the four aspects of singing skill, i e.

Within a two-band tight-binding model driven by a dc-ac electric field,we investigate the effect of external noise on the transport property of electrons in superlattices.

In this thesis, we investigate the transport properties of an ac driving double-bridged quantum dot arrays coupled to electronic leads with an uniform magnetic field applied perpendicularly on it and the effect of external noise on the dynamical localization of two coupling electrons in an isolated quantum dot array.

Objective To study the value of diagnosing ectopic pregnancy with abdominal ultrasonography.

Conclusions Abdominal ultrasonography is a simple and effective way,unlimited by equipments and apparatus.