The preliminary research result of electromagnetic prospecting with the near field(transition region) of infinite-length line source in frequency domain is presented in this paper.
本文对频率域无限长线源近区（过渡区）测深的理论基础进行了探索性研究。
2
According to the law of geologic work, feasibility study may be divided into detailed prospecting feasibility study, preliminary exploring feasibility study and detailed exploring feasibility study.
根据地质工作的规律，可行性研究可划分为详查可行性研究、初勘可行性研究和详勘可行性研究。
3
Firstly, based on the preliminary evaluation for environment of dangerous source at the prospecting stage, the risk factors effect and construction of risk reduction can be determinated.