关于电矢量和磁矢量的讨论

本文通过对电场强度、电位移、磁感应强度、磁场强度的讨论得知电场强度和电位移不仅与自由电荷有关,而且与极化电荷有关;磁感应强度和磁场强度不仅与传导电流有关,而且与磁化电流有关.     

一种旧的新逻辑:实质归纳理论

诺顿在古德曼和亨普尔等人的启发下,结合他的科学哲学研究背景,提出一种不同于他所定义的“形式归纳理论”的“实质归纳理论”,强调归纳的局部应用性,拒斥普遍的归纳推理模式。归纳推理的基础往往建立在具体领域的事实之上,因此所有的归纳推理都是局部的。诺顿认为归纳推理模式是由事实授权的,我们可以通过考察这些事实的可靠性来评估归纳风险。同时实质归纳理论不再区分归纳的事实部分和模式部分,所以不易受休谟问题的影响。但我们发现,诺顿的归纳辩护面临着亟待解决的问题,其理论也遭受多方面的批评。实质归纳理论是归纳逻辑领域的前沿性成果,引起了逻辑学界和科学哲学界的广泛关注,一定程度上体现了归纳逻辑的强劲生命力和广阔的发展前景。     

单相电动机变频调速研究

单相异步电动机广泛应用于家用电器,是家用电器的主要驱动部件,必须掌握单相电动机的基本特点、启动方法以及实现变频调速的方法,特别是单相异步电动机变频调速的关键技术。     

浅谈搞好电磁学实验的方法

本文介绍了作者对搞好电磁学实验的一点体会.     

Study on the Crystallization Mechanism of Spectinomycin Dihydrochloride

Dilutionisonekindofcrystallizationsthatiswidelyusedintheproductionofpharmaceuticals ,especiallyantibi otics.Dilutionhasmanyadvantagessuchashigherthrough putsbypreparingveryconcentratedinitialsolutions,loweroperatingtemperatureforheat labilesubstancesandbetterpu rificationasthemotherliquorretainsundesiredimpurities[1] .Oneofthecharacteristicsofdilutionisthatthesolventcom positionvarysastheprocessproceeds.Thesolventcomposi tionhasinfluenceonnotonlythenucleationratebutalsotherelativegrowthrateofe…     

有机静电感应三级管动作特性的实验分析

1 Introduction Organic semiconductors are receiving considerableattention due to their remarkable advantages especiallyvarious manufacturing methods ,lowcost and plentifulmaterials .Ebisawa ,et al.[1]fabricated the first poly-mer-based transistor in 1983 . Since then,lots of re-search works have been done in the filed of organicmaterial-based transistors .It was reported that organicthin-fil m transistor ( OTFT) fabricated by usingorganic semiconductor material copper-phthalocyanine(CuPc)[2…     

试论艺术设计学科的设计素描

从设计素描的概念分析出发,通过对绘画素描和设计素描的比较,阐述了结构素描和装饰意味素描的造型规律及所具有的理性化和应用性的特征。     

Longitudinal effects of induction on teaching skills and attrition rates of beginning teachers

The teaching profession faces a shortage as well as a decline of teaching skills. A possible way to mitigate this is to implement evidence-based induction arrangements. Seventy-one schools with 338 beginning secondary education teachers were randomly allocated to an experimental or a control group. The experimental schools used induction arrangements; the authors measured the effects of these arrangements by using repeated lesson observations and by comparing the rates at which beginners in the control and experimental groups left the teaching profession. Three years later, 14% of the control group and 12% of the experimental group had left. Leaving the profession could be explained by a lack of certification and low initial teaching skill levels. The experimental group exhibited greater improvement in teaching skills compared to the control group. Workload reduction influenced the skill level negatively, and coaching and observing had a strong positive influence on the skill level in Year 3.     

柯西不等式证法探讨

利用配方法、构造二次三项式、二元二次型的正定性、拉格朗日恒等式、行列式性质、数学归纳法以及算术平均-几何平均不等式等7种方法给出了柯西不等式的7种证法.     

除草剂"Basta"对油菜植株和愈伤组织的生长分化的影响

通过研究除草剂“Basta”对3个油菜品种的植株和愈伤组织的生长及分化的影响,发现“Basta”对油菜植株和愈伤组织的生长及分化具有强烈的抑制作用,而且品种不同,抑制程度不同。并在此基础上找到合适的“Basta”筛选压,为以bra基因作为选择标记基因的基因转化试验莫定了基础。