第二部分从理论上讨论了动力大地测量网络数据库系统的基础知识和数据模型，研究了网络数据库系统的特点、工作模式以及主要技术。
The second part discussed the theoretical knowledge and data models of DGNDBS; studied the feature, work model and main technique of the network database system.
从实验和理论上研究了手提电钻在工作时产生噪音的主要噪声源及其特点，为减少其噪音提供了依据。
This paper studys noise produced by portable electric drill on theory and experiment. It can help find methods of reducing portable electric drill noise.
本文主要在理论上研究了高温等离子体中相对论电子的集体行为。
My thesis is mainly related to the collective behavior of the relativistic electrons in the hot plasma.
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