浅论位移电流

位移电流是普通物理中一个较重要的概念,也是教学中的一个难点.本文从位移电流概念的提出及实验验证,位移电流的物理意义及其与传导电流异同等几方面对其加以阐述,以求对位移电流的教学有所帮助.     

电磁学与电信技术发展简述

本文简述了以法拉第电磁感应定律和麦克斯韦电磁场为中心的电磁学发展简史,论述了几种基于电磁理论建立起来的重要电信技术的工作原理和简单发展历程,并略论了未来电信技术的发展趋势.     

关于郑州中心城市辐射作用的思考

针对我国社会经济发展不平衡状况,区域经济发展应选择中心城市辐射与梯度推进相结合,并以中心城市辐射为主的发展战略.河南及中西部社会经济的发展需要中心城市带动,郑州有成为"龙头"城市的基础得天独厚的区位、交通、资源等优势,经济实力较强,西部大开发为其提供了发展良机.增强郑州中心城市辐射作用,要有新的战略构想框架,争取在10～20年的时间内,确立国家区域中心城市地位.为此,郑州需在制度创新、城市空间布局和产业结构布局、对外开放及发展科教事业等方面加快发展,使其向周边地区的辐射不断增强.     

Perceived Risks from Radiation and Nuclear Testing Near Semipalatinsk, Kazakhstan: A Comparison Between Physicians, Scientists, and the Public

Determining the difference in perception of risk between experts, or more educated professionals, and laypeople is important so that a potential hazard can be effectively communicated to the public. Many surveys have been conducted to better understand the difference between expert and public opinions, and often laypeople exhibit higher perceptions of risk to hazards in comparison to experts. This is especially true when health risk is due to radiation, nuclear power, and nuclear waste. This article focuses on one section of a risk perception survey given to two groups of individuals with a more specialized education (scientists and physicians) and laypeople (villagers) in the Semipalatinsk region of Kazakhstan. All of these groups live near the former Soviet nuclear test site. Originally, it was expected that the scientists and physicians would have similar perceptions of radiation risk, while the public perceptions would be higher, but this was not always the case. For example, when perceptions of risk pertain to the health impacts of nuclear testing or the dose-response nature of radiation exposure, the physicians tend to agree with the laypeople, not the scientists. The villagers are always the most risk-averse group, followed by the physicians and then the scientists. These differences are likely due to different frames of reference for each of the populations.     

电磁参数测试用部分填充试样矩形波导传感器

提出了一种新型的用于测试中高损耗材料电磁参数（复介电常数与复磁导率）的部分填充试样的矩形波导传感器模型。通过计算该类波导的电磁场的解和利用模式分析法，推导出被测材料的电磁参数（ε、μ）与传感器网络的Ｓ参数间的数学关系，给出了数值计算结果。     

Remedial Policies in Radiologically-Contaminated Forests: Environmental Consequences and Risk Assessment

As a result of the Chernobyl nuclear power plant accident in 1986, large forested areas in Europe were contaminated by radionuclides. Extensive societal pressure has been exerted to decrease the radiation dose to the population and to the environment. Thus, in making abatement and remediation policy decisions not only economic costs, but also human and environmental risk assessment are desired. Forest remediation by organic layer removal, one of the most promising cleanup policies, is considered in this paper. Ecological risk assessment requires evaluation of the radionuclide distribution in forests. The FORESTPATH model^(1,2) is used for predicting the radionuclide fate in forest compartments after deposition as well as for evaluating the application of the remedial policy. Time of intervention and radionuclide deposition profile was predicted as being crucial for the remediation efficiency. Risk assessment conducted for a critical group of forest users in Belarus shows that consumption of forest products (berries and mushrooms) leads to about 0.004% risk of a fatal cancer. Cost-benefit analysis for forest cleanup suggests that complete removal of organic layer is too expensive for application in Belarus.     

直流磁控溅射铂电阻薄膜

根据薄膜理论和通过成膜工艺实验，研究了影响铂薄膜电阻温度系数的主要因素。１）对铂靶材料的纯度要求高，含杂质极少；２）淀积薄膜要有一定厚度，通常近于１μｍ才能有较大的α；３）成膜以后，需经过高温热处理，减少缺陷，结晶化改善。通过大量实验，使用高铝陶瓷基片或微晶玻璃基片，溅射铂薄膜的厚度为８００ｎｍ，高温热处理１ｈ，可以获得电阻温度系数为３．８５０×１０－３／℃的铂电阻薄膜。     

浅析晚商中央王朝对周边地区的辐射作用

商王朝后期,随着中央王朝实力的增强,其对周边部族方国的辐射影响力也相应增强,这种辐射力在政治、经济、军事、文化等各方面都有具体表现。商王朝能够对周边地区产生辐射作用主要取决于它的绝对统治地位及占据天下之中的优越地理位置。这种辐射力为后世真正意义上的民族统一和国家统一创造了条件。     

区域经济发展模式的特点与选择

我国经济理论界和实际工作,根据国情特点,联系各地不平衡发展的现状,先后提出了梯度推进发展,点轴渐进发展,区域经济协调发展,城市圈域经济发展和网状交织发展等区域经济发展模式。它们有不同的特色和优势,但也存在某些不足。从长远看,比较起来,网状交织发展模式更有利于提高区域经济的运行质量,宜于进入工业化中后期阶段的地区采用。