布朗马达的定向输运模型

将系统利用非平衡涨落能量做功，看作是布朗马达受到内外噪声作用的结果，并建立相应的含阻尼、双噪声的扩散模型．通过解析计算和数值模拟，在一维惯性锯齿势中，阐明了乘性噪声驱动布朗马达定向运动的机理，分析了黏滞阻力对定态流的影响．作为应用，解释了单个马达蛋白梯跳运动的实验现象． 关键词：     

MAGNETIC FIELD DISTRIBUTIONS OF A PLANAR PULSE MICROWIGGLER

Magnetic field distributions of a planar pulse microwiggler are studied analytically and numerically. An exact solution of two-dimensional magnetic field is derived in detail,and the formula shows that along the electron axis the field has a variation close enough to a sine wave. Effects of ends of the microwiggler on magnetic field are also investigated with the help of numerical methods.     

热处理温度对MgB2超导材料的超导电性及微观结构的影响

采用粉末烧结方法在不同温度(650℃,700℃,750℃,800℃,850℃,900℃)制备了MgB2超导块材.采用X射线衍射(XRD)和扫描电镜(SEM)研究了热处理温度对MgB2超导材料的成相及微结构的影响.采用磁化法测定不同温度制备MgB2超导材料的超导电性.结果显示热处理温度对MgB2超导材料的晶粒尺寸、形状和超导电性有明显影响,700℃制备的MgB2超导体具有最高的临界电流密度和最好的磁通钉扎特性,细小的晶粒尺寸是样品磁通钉扎特性改善的原因.     

中立型时滞微分方程解的零点距估计

考虑中立型时滞微分方程〔ｘ（ｔ）＋Ｐ（ｔ）ｘ（ｔ－ｒ）‘＋Ｑ（ｔ）ｘ（ｔ－σ）＝０，其中Ｐ（ｔ），Ｑ（ｔ）∈Ｃ（│ｔ０，∞），Ｒ＾＋），ｒ，σ∈Ｒ＾＋，本文对上述方程解的相邻零点间的距离作了新的估计。     

RENORMALIZATION GROUP APPROACH TO THE BOND PERCOLATION ON SIERPINSKI CARPETS

The critical behaviors of bond percolation on a family of Sierpinski carpets (SCs) are studied. We distinguish two sorts of bonds and assign them to two kinds of occupation probabilities. We develop the usual choice of cell on translationally invariant lattices and choose suitable cells to cover the fractal lattice. On this basis we construct a new real-space renormalization group (RG) transformation scheme and use it to solve the percolation problems. Phase transitions of percolation on such fractals with infinite order of ramification are found at non-trivial bond occupation probabilities. The percolation threshold values, correlation length exponents ν, and the RG flow diagrams are obtained. The flow diagrams are remarkably similar to those of Ising model and Potts model. This agrees with the correspondence between the pure bond percolation and Potts model.     

~1H-NMR测定聚醚多元醇分子量——共聚醚和混聚醚分子量测定

本文研究了用~1H-NMR测定共聚醚和混聚醚数均分子量的方法.根据测得的与酯氢峰面积对聚合段相应峰面积积分比率计算分子量,测得数据与端基化学法测量分子量对照,所获结果令人满意.     

纳米TiO2粒子浓度对HFC134a/矿物油冰箱性能影响的实验研究

本文重点考察了HFC134a/矿物冷冻油/纳米TiO2粒子工质体系中纳米粒子浓度和运行时间对冰箱性能的影响.实验结果表明:添加纳米粒子TiO2之后,冰箱制冷系统性能提高,并随着纳米粒子浓度的提高而增大;冰箱长期运行性能稳定.     

7-氨基喹唑啉的合成

7-氨基喹唑啉是合成杂环药物的重要中间体。为了寻找经济的合成7-氨基喹唑啉的方法,本文以Pd/C和Zn粉共同作用还原4-氯-7-硝基喹唑啉制备7-氨基喹唑啉,产率达到52%。比文献报道的产率略高,最关键的是与文献报道的直接用Pd/C还原的方法相比较,此法更经济。     

The synthesis and thermotropic behaviour of an ethyl cellulose derivative containing azobenzene-based mesogenic moieties

An ethyl cellulose derivative containing azobenzene-based mesogenic moieties was prepared by the reaction of 4-methoxyazobenzene-4′-oxyacetic acid and ethyl cellulose by esterification in the presence of N,N′ -dicylcohexylcarbodiimide and 4-dimethylaminopyridine. Its chemical structure and liquid crystalline properties were characterized by FTIR, ¹H NMR, POM, DSC and WAXD. The degree of substitution of the cellulose backbone by the azobenzene-based mesogenic moieties is 0.9. The polymer is thermotropic and exhibits liquid crystalline behaviour over the temperature range 125–172°C.     

掺铒氢化非晶氧化硅1.54μm发光性质的研究

采用等离子体增强化学汽相沉积技术生长不同氧含量的氢化非晶氧化硅薄膜(a-SiOx:H),离子注入铒及退火后在室温观察到很强的光致发光.当材料中氧硅含量比约为1和1.76时,分别对应77K和室温测量时最强的1.54μm光致发光.从15到250K的变温实验显示出三个不同的强度与温度变化关系,表明氢化非晶氧化硅中铒离子的能量激发和发光是一个复杂的过程.提出氢化非晶氧化硅薄膜中发光铒离子来自于富氧区,并对实验现象进行了解释.氢化非晶氧化硅中铒发光的温度淬灭效应很弱.从15到250K,光致发光强度减弱约1/2.