介质中点电荷所受电场力的研究

研究了一般情况下,在无限均匀介质中,点电荷所受到的电场力与在真空中一样,满足库仑定律,并研究了介质中点电荷所受电场力满足库仑定律的充要条件．     

Open Access,Open Business,Closed Fairness!

A strong trend to move from print to online publication is largely perceived in scientific and nonscientific fields. A growing number of publishers increasingly opt for online publication as an option or a compulsory alternative. From readers’ perspective, this is a highly appreciated facility, but from the author’s, things are different mainly because of excessive article processing charges (APC) that make the open access system sometimes as a hindrance for many authors but a lucrative enterprise for many shareholders, enticing the most traditional and conservative publishers.     

科技特派行动运行模式影响因素分析

辽宁省科技特派行动开始于2002年,在近几年的发展实践中不断创新,形成了科技特派团、科技特派组、科技特派员和农民技术员培训一体化的运行模式,但也存在一些问题。从辽宁省54个县（市、区）中选取5个具有代表性的样本县进行实地调研,对影响科技特派行动运行模式的因素从政策与体制、利益与风险以及知识与能力3个主要方面进行分析,指出其中存在的问题主要表现在资金支持、保障措施、有偿服务、风险补贴、人才缺乏、地区差异等方面,并就此提出政策建议。