D→Klv～l衰变过程的研究

用光锥QCD求和规则研究D→Klv～_l衰变过程，首先计算D→K跃迁形状因子，通过构造新的关联函数，消除了twist-3波函数的不确定性给计算结果所带来的影响，从而使计算结果更加精确. 计算得到的分支比与最近的实验数据相一致. 关键词： QCD光锥求和规则 D介子半轻衰变 分支比 形状因子     

Fabrication of isotype (p-p) selenium-polyaniline heterojunction diode by electrochemical method

In the present work, for the first time, heterojunction has been fabricated using electrochemically deposited isotype p-selenium-p-polyaniline from a single solution bath. The structural characterization of selenium and polyaniline thin film was carried out using XRD technique. Polyaniline exhibited amorphous structure while selenium offered monoclinic (β) phase. The junction was formed by electrodepositing polyaniline over selenium film and heating at 423 K. The current density versus voltage (J-V) plot showed the formation of a junction with ideality factor of 1.16. From J-V characteristics at different temperatures, static resistance (R_s), dynamic resistance (R_d), and rectification ratio of diodes were determined. Heat treatment above 448 K caused junction breakdown.     

Effect of reaction conditions on the molecular weight and polydispersity of linear poly(arylene ether phosphine oxide)s prepared from an AB monomer

A thorough study of the polymerization behavior of 4‐fluoro‐4′‐hydroxytriphenyl‐phosphine oxide, 2 , under nucleophilic aromatic substitution reactions has been carried out. The synthesis of 2 was achieved in excellent yields by the reaction of bis(4‐fluorophenyl)phenylphosphine oxide, 1 , with one equivalent of potassium hydroxide in DMSO/water. The structure and purity of 2 were confirmed via ¹H, ¹³C, and ³¹P NMR spectroscopy along with elemental analysis. Polymerization reactions of 2 in NMP or DMSO at 180 °C provided the corresponding linear poly(arylene ether phosphine oxide)s, PAEPOs, with number average molecular weights, M_n, ranging from 11,700 to 36,500 Da. All of the polymer samples were completely soluble in chloroform, tetrahydrofuran, DMSO, NMP, and DMAc. The polymerization reactions were accompanied by a competing intramolecular process that resulted in the formation of cyclic oligomeric species that were removed via a final precipitation from methanol. Analysis using ³¹P NMR spectroscopy and size exclusion chromatography (SEC) confirmed that the majority of the lower molecular weight cyclic species were removed via this process. The polymer samples formed tough films when chloroform solutions were slowly evaporated on a glass slide. The PAEPO samples prepared in this study exhibited excellent thermal stability with T_d (5%) values between 503 and 542 in air while the glass transition temperatures ranged from 223 to 237 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2099–2106, 2006     

Synthesis of polyacrylonitrile via reverse atom transfer radical polymerization catalyzed by FeCl3/isophthalic acid

FeCl₃ coordinated by isophthalic acid was first used as a catalyst in the azobisisobutyronitrile‐initiated reverse atom transfer radical polymerization of acrylonitrile. N,N‐Dimethylformamide was used as a solvent to improve the solubility of the ligand. An FeCl₃‐to‐isophthalic acid ratio of 0.5 not only gave the best control of the molecular weight and its distribution but also provided rather a rapid reaction rate. The effects of different solvents on the polymerization of acrylonitrile were also investigated. The rate of the polymerization in N,N‐dimethylformamide was faster than that in propylene carbonate and toluene. The molecular weight of polyacrylonitrile agreed reasonably well with the theoretical molecular weight in N,N‐dimethylformamide. The rate of polymerization increased with increasing polymerization temperature, and the apparent activation energy was calculated to be 59.9 kJ mol^?1. Reverse atom transfer radical polymerization was first used to successfully synthesize acrylonitrile polymers with a molecular weight higher than 80,000 and a narrow polydispersity as low as 1.22. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 219–225, 2006     

Mathematical modeling of crystallization analysis fractionation (Crystaf) of polyethylene

Four polyethylene samples (PE) with different molecular weight distributions (MWD) were analyzed by crystallization analysis fractionation (Crystaf) at several cooling rates to investigate the effect of MWD and cooling rate on their Crystaf profiles. Using these results, we developed a mathematical model for Crystaf that considers crystallization kinetic effects, which are ignored in all previous Crystaf models. The Crystaf model we proposed can fit the experimental Crystaf profiles of the 4 polyethylene resins very well. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2749–2759, 2006     

Electrical properties of polypyrrole/p‐InP structure

The polypyrrole/p‐InP structure has been fabricated by the electrochemical polymerization of the organic polypyrrole onto the p‐InP substrate. The current–voltage (I–V), capacitance–voltage (C–V), and capacitance–frequency (C–f) characteristics of the PPy/p‐InP structure have been determined at room temperature. The structure showed nonideal I–V behavior with the ideality factor and the barrier height 1.48 and 0.69 eV respectively. C–f measurements of the structure have been carried out using the Schottky capacitance spectroscopy technique and it has been seen that there is a good agreement between the experimental and theoretical values. Also, it has been seen that capacitance almost show a plateau up to a certain value of frequency, after which, the capacitance decreases. The higher values of capacitance at low frequencies were attributed to the excess capacitance resulting from the interface states in equilibrium with the p‐InP that can follow the a.c. signal. The interface state density N_ss and relaxation time τ of the structure were determined from C–f characteristics. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1572–1579, 2006     

环境因素对跳远踏板准确性的分析研究

采用实验法、数理统计法对江西省不同等级男子跳远运动员踏板准确性受环境因素影响进行研究.结果表明:塑胶跑道与煤渣跑道,顺风跑,逆风跑,阴天,大量观众,噪音对跳远踏板准确性都具有较明显的影响.跳远运动员踏板的准确性一般不受运动员等级水平的影响.     

Gas transport through homogeneous and asymmetric polyethersulfone membranes

Both homogeneous and asymmetric polyethersulfone (PES) membranes were prepared by solvent casting. The sorption and permeation behavior of CO₂, O₂, and N₂ using these two kinds of cast PES membranes and commercially available homogeneous PES film was investigated to extract the pressure dependence of gas permeability and the permselectivity for CO₂ relative to N₂, and to confirm the validity of the working assumption that a skin layer in an asymmetric membrane can be essentially replaced by a thick homogeneous dense membrane. The pressure dependence of the mean permeability coefficient to CO₂ in homogeneous membranes obeys the dual-mode mobility model. The ideal separation factor for CO₂ relative to N₂ at an upstream pressure of 0.5 MPa attains ca. 40, while the permeability to CO₂ is about 2.7 Barrer at the same upstream pressure. The same separation factor in asymmetric membranes amounts to 35. The diffusion behavior for the skin layer in an asymmetric membrane with a thin skin layer can be simulated approximately by that in a homogeneous dense membrane. © 1993 John Wiley & Sons, Inc.     

华佗再造丸治疗脑血管病疗效评估

用华佗再造丸治疗脑血栓、脑出血及其后遗症52例,其有效率达90.5％,对照组20例,10例脑出血用20％Mannitol及止血剂治疗,10例脑血栓用低分子右旋糖酐及脑络通治疗,有效率为70％,有高度显著性差异,P<0.001,笔者认为该药是治疗脑血管病较理想的中成药,具有镇静神经,滋阴强心,舒经活络,活血化瘀等作用。对病程短的年纪青的病人的疗效更为显著,脑出血性与脑缺血性疾病均有疗效,正是中药一药多用、一药多治的微妙体现。推测对脑血管病后遗症有效可能与该药能促进神经再生因子(NGF)的合成和利用有关。     

粘结平面对称分叉裂纹的奇异积分方程数值解

本文对一个含分叉裂纹的弹性半平面与另一不同材料的半平面粘结的问题用复势方法化为一组三个复Caucby型奇异积分方程。采用修正的Gauss-Legendre和修正的Lobatto-Legendre数值求积法则化成一代数方程组,裂纹尖端的应力强度因子值可从代数方程组的解求得。本文计算得到了弹性半平面、刚体与弹性半平面相粘结、两种不同材料的弹性半平面相粘结的三种问题的几种几何形状的对称分叉裂纹的应力强度因子。本文的结果扩充了“应力强度因子手册”的内容。