大学物理实验的简化与深化

以复摆实验、地磁实验和衍射光栅实验为例,说明在大学物理实验中,通过提供简单的实验器材,就可以将实验内容延伸扩展,将原来内容单一的实验扩展为多层次、多目的的实验项目,实现大学物理实验的简化与深化.     

LD泵浦腔外倍频高转换效率Nd3+∶GdVO4固体激光器

通过合理设计精密调控各元件和温控电流，得到了平均功率为70 mW，脉冲宽度为22 ns，重复频率为14 kHz，峰值功率高达230 W的Nd3+∶GdVO4/Cr4+YAG红外脉冲激光器.先采用双凸透镜组合成的望远镜系统对1 063 nm的红外激光进行扩束，再对该光束聚焦，最后经双轴晶体LBO倍频后，得到了平均功率为40.6 mW，脉冲宽度为16 ns，重复频率为14 kHz，峰值功率高达181 W的绿光激光输出，1063 nm→532 nm的转换效率高达58%.测量了532 nm的光谱线宽曲线.解释了该聚焦方法比单一薄透镜效果明显好的原因，并指出了这种聚焦方法的使用对象.     

Thomas rotation and Foucault pendulum under a simple unifying geometrical point of view

In this paper we show that there is a complete parallelism between the Foucault pendulum and the Thomas rotation phenomena by using the concept of parallel transport in a surface. In the case of the Foucault pendulum the surface is the ordinary sphere corresponding to the Earth sphere, whereas in the case of the Thomas rotation the surface is the pseudosphere corresponding to the space of relativistic velocities. Moreover, in both cases we use a simple method that reduces the problem to the parallel transport in a conical surface, and so, to the plane.     

单摆周期的数值计算

本文从理论上分析了单摆周期随角振幅变化的规律，并给出了数值计算结果     

复合冷凝空调机组的分析

以家用分体式空调作为节能改造对象,将传统单一冷凝改进为复合冷凝,即在压缩机排气管路上串联一个水冷冷凝器,吸收部分冷凝热制备生活热水。并在此基础上建立了分析模型。模拟计算结果表明,复合冷凝空调的目的效率得到了大大的提高,当空调的蒸发温度为0℃、冷凝温度为30℃时,空调目的效率由单一冷凝时的52%上升到70%。     

Effect of polarization on two-dimensional carrier distribution in nitride quantum wells

Wide band-gap group-III nitrides are important for the design of optical devices in the blue and blue–green region. Owing to their wurtzite structure, these materials have a strong inherent polarization field that affects carrier distribution, exciton stability and hence influences the optical properties of the devices. So far, carriers have been assumed to have a sheet-like character. In this paper a non sheet-like distribution function for these quasi two-dimensional carriers is proposed that incorporates the effect of the polarization field. Here GaN/InGaN/GaN and AlGaN/GaN/AlGaN quantum wells have been studied. The polarization field causes the electron and hole wave functions to separate out, thus causing decrease of emission strength and strong reduction of exciton binding energy. This treatment explains well the qualitative nature of carrier distribution in the well. The polarization field changes with GaN mole fraction present in the tertiary nitride layer. The effect of mole fraction on carrier distribution has also been studied. It is found that, inside the well, the hole distribution changes a little more with change in mole fraction than the electron distribution, but for all practical purposes the net change in the distribution pattern is negligible.     

GC-MS技术在舰船复合板毒性评价中的应用

海军舰船舱室多为密闭环境,其舱室狭小,设备庞杂,人员密集。舱室内部的防护装饰多系非金属材料,随着现代各种复合、聚合材料的迅速发展和广泛使用,周围环境特别是密闭舱室空气污染的问题也更为突出。本文根据有关军用标准和规程[1],应用GC-MS技术对2种舰船复合板常温释放物和高     

An efficient microwave assisted synthesis of N′-aryl/(alkyl)-substituted N-(4-hydroxy-6-phenylpyrimidin-2-yl)guanidines: Scope and limitations

Treatment of N-[(4-hydroxy-6-phenyl)pyrimidin-2-yl]cyanamide with 1° alkyl or arylamines in isopropyl alcohol for only 10 min at 110–120 °C under microwave conditions gave the corresponding N′-alkyl(aryl)guanidine derivatives in excellent yields (65–84%). Isolated yields were greatest when >1.0 equiv. of amines were employed, but excellent results were also obtained when aryl and alkylamines were reacted with a more atom-economical loading (1.0 equiv.; 70% and 72% ave. yields, respectively). Arylamines with either highly electron withdrawing substituents (e.g. CO₂H) or pi-deficient heterocycles (e.g. variously substituted aminopyridines) did not work well under these conditions, and reaction with ureas and/or amino acids did not give detectable products. Work-up was exceedingly simple, and involved simple collection and washing of product on a sintered glass funnel. Products were obtained in analytically pure form and required approximately 1 h to prepare, start to finish.     

Beschreibung des visko-elastischen Verhaltens des polymeren Mischsystems Phenolnovolakharz-Nitrilkautschuk (PF/NBR) mit Hilfe der Van-der-Poel-Gleichung

Zusammenfassung Morphologische Untersuchungen an dem polymeren Mischsystem Phenolnovolakharz-Nitrilkautschuk haben gezeigt, daß diese Mischungen eine Struktur aufweisen, in der harte kugelige PF-Teilchen in einer Kautschukmatrix bzw. weiche Kautschukteilchen in einer Harzmatrix eingebettet sind. Mit Hilfe der morphologischen und mechanisch-dynamischen Untersuchungen wird versucht, das viskoelastische Verhalten von Polyblends mit der Van-der-Poel-Gleichung zu beschreiben. Es konnte gezeigt werden, daß bis zu ModulwertenGhart/Gweich ~ 100 eine gute Übereinstimmung mit der Van-der-Poel-Gleichung gefunden wird. Hohe Modulverhältnisse der harten Einlagerungskomponente zur weichen KomponentenGhart/Gweich ~ 1000, wie sie im kautschukelastischen Bereich auftreten, zeigen eine Übereinstimmung mit der Van-der-Poel-Gleichung nur bei einer Volumenkonzentration der harten EinlagerungskomponenteV _f < 0,3. Diese Ergebnisse werden mit anderen bekannten theoretischen Überlegungen über den Zusammenhang zwischen Elastizitätsmodul und Zusammensetzung von Verbundwerkstoffen verglichen.Schlüsselwörter Phenolnovolakharz-Nitrilkautschuk-System, viskoelastisches Verhalten, Torsionspendel, Van-der-Poel-Gleichung

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Summary Morphological investigations of the polymer compound-system novolak resin-nitril rubber (PF/NBR) have shown, that these mixtures exhibit structures, in which hard spherical particles are embedded in a rubber matrix, respectively soft rubber particles in a resin matrix.An attempt was made to describe the viscoelastic behaviour of these polyblends by means of morphological and dynamic-mechanical investigations with the relation given by Van der Poel.Up to ratios of the moduliGhard/Gsoft ~ 100 a good agreement with the Van-der-Poel equation was found. In the rubber elastic region at ratiosG hard/G soft ~ 1000 this agreement was found for volume concentrations of the phenolic componentV _f ~ 0.3 only.The results are compared with other existing theories on the correlation between elastic modulus and composition of compound materials.

Mit 7 Abbildungen und 6 Tabellen     

11-钨锌三元杂多阴离子层状化合物的合成、表征及催化活性

用离子交换法将具有K egg in结构11-钨锌三元杂多化合物K8[M ZnW11（H2O）O39]（M=Co2＋、N i2＋、Cu2＋、Cd2＋）嵌入到Zn2A l类水滑石中,得到层状化合物：Zn2A l-[M ZnW11（H2O）O39]（M=Co2＋、N i2＋、Cu2＋、Cd2＋）,并用XRD、IR、UV对其进行了表征。结果表明,杂多阴离子进入水滑石层间后,仍保留了其K egg in结构。利用层状化合物催化合成乙酸正丁酯考察其催化活性,结果表明,层状化合物在酯化反应中显示优良的催化性能。