高师数学教育专业概率统计课程的教学思考

讨论高师院校数学教育专业概率论与数理统计课程的教学问题.针对专业特点和课程性质,主张在教学实践中注重随机思维的培养,增强课程的示范教学作用,加强随机数学与确定数学之间的联系,并以提高学生的综合应用能力为目标组织教学.     

用于激光二极管抽运固体激光器热畸变补偿的MEMS微变形镜设计

以MEMS微变形镜驱动方式的选取为出发点,从光学特性和力学特性两方面对MEMS微变形镜进行分析.从中得出相关结构参数对微变形镜性能的影响关系.并在此基础上结合补偿激光二极管抽运固体激光器(DPL)热畸变的使用要求设计了一种新型MEMS连续面型微变形镜,并采用设计的MEMS变形镜搭建了一个闭环自适应光学实验系统,补偿了激光光束的热畸变.实验结果显示该MEMS连续面型微变形镜可对腔内畸变进行有效补偿,同时提高了激光器的输出功率及光束质量.     

Orientation dependence of electrical properties of 0.96Na<Subscript>0.5</Subscript>Bi<Subscript>0.5</Subscript>TiO<Subscript>3</Subscript>-0.04BaTiO<Subscript>3</Subscript> lead-free piezoelectric single crystal

In this paper, a single crystal of 0.96Na_0.5Bi_0.5TiO₃-0.04BaTiO₃ with dimensions of Φ 30×10 mm was grown by the top-seeded-solution growth method. X-ray powder diffraction results show that the as-grown crystal possesses the rhombohedral perovskite-type structure. The dielectric, piezoelectric and electrical conductivity properties were systematically investigated with 〈001〉, 〈110〉 and 〈111〉 oriented crystal samples. The room-temperature dielectric constants for the 〈001〉, 〈110〉 and 〈111〉 oriented crystal samples are found to be 650, 740 and 400 at 1 kHz. The (T _m, ε _m) values of the dielectric temperature spectra are almost independent of the crystal orientations; they are (306°C, 3718), (305°C, 3613) and (307°C, 3600) at 1 kHz for the 〈001〉, 〈110〉 and 〈111〉 oriented crystal. The optimum poling conditions were obtained by investigating the piezoelectric constants d ₃₃ as a function of poling temperature and poling electric field. For the 〈001〉 and 〈110〉 crystal samples, the maximum d ₃₃ values of 146 and 117 pC/N are obtained when a poling electric field of 3.5 kV/mm and a poling temperature of 80°C were applied during the poling process. The as-grown 0.96Na_0.5Bi_0.5TiO₃-0.04BaTiO₃ crystal possesses a relatively large dc electrical conductivity, especially at higher temperature, having a value of 1.98×10⁻¹¹ Ω⁻¹⋅m⁻¹ and 3.95×10⁻⁹ Ω⁻¹⋅m⁻¹ at 25°C and 150°C for the 〈001〉 oriented crystal sample.     

Fabrication of optically tunable silica nanocapsules containing Ag/Au nanostructures by confined galvanic replacement reaction

Abstract  

Silica nanocapsules containing Ag/Au alloy nanostructures (SNCAs) are fabricated by galvanic replacement (GR) reactions between silver core nanoparticles within silica shells and aqueous HAuCl₄ in a confined nano-space. The structure and morphology of the resulting SNCAs are diversified by controlling the relative amount of Ag/Au, exhibiting tunable optical absorptions in visible region. The GR reactions in a confined nano-space include alloying and de-alloying processes that determine the evolution of morphology and optical absorption of SNCAs.     

不同冻结对大黄鱼冻藏期间品质的影响

为研究冻结速率对大黄鱼冻藏期间品质的影响, 采用冰箱慢速冻结、酒精浸渍速冻、液氮浸渍速冻方法处理新鲜大黄鱼, 以pH值、汁液损失率、TVB-N值、盐溶性蛋白提取率、质构等指标研究鱼肉冻藏过程中的理化特性变化, 并通过扫描电镜研究其组织微结构的变化. 结果显示, 随着冻藏时间的延长, 慢冻组和酒精速冻组样品pH值先下降后上升, 液氮速冻组样品的pH值趋于平缓; 3组样品TVB-N值均逐渐上升, 但液氮速冻组的TVB-N值较小, 且上升速率最缓慢, 冻藏210d时, 慢冻组、酒精速冻组、液氮速冻组的TVB-N值分别达到27.79, 25.024, 21.57 mg?dg-1; 盐溶性蛋白提取率和硬度、弹性、胶黏性、凝聚性、回复性降低, 液氮速冻组的值下降程度较小; 扫描电镜观察发现贮藏过程中大黄鱼的肌肉纤维损伤程度逐渐增大, 而液氮浸渍速冻对大黄鱼肌肉纤维的损伤最小. 与慢速冻结样品相比, 虽然速冻组样品(液氮速冻组、酒精速冻组)有较大的汁液损失率, 但其更有利于延缓大黄鱼蛋白质变性和降解, 保持样品质构特性, 且液氮浸渍速冻优于酒精浸渍速冻. 本研究可为进一步改进水产品的速冻技术提供参考依据.     

生物医用类环糊精/聚合物(准)聚轮烷

环糊精及其衍生物具有“内疏水、外亲水”的特殊分子结构,可与许多客体分子包结形成包合物。利用环糊精与聚合物的包结作用构建稳定、结构可控并具有广泛应用前景的生物医用材料是材料及医学界研究的焦点之一。本文介绍了环糊精基(准)聚轮烷的概念及其组装驱动力,同时围绕由环糊精和聚合物组装形成的(准)聚轮烷在生物医用方面的研究包括药物载体(如超分子凝胶、超分子胶束、超分子纳米囊泡、药物键合(准)聚轮烷、刺激响应型(准)聚轮烷等)、基因载体、多重识别与靶向、形状记忆材料及其它相关领域工作进展作一概述。     

生物医用类壳层可脱落纳米粒子

长循环纳米粒子的亲水壳层虽能有效延长纳米粒子在体内的循环时间,但到达靶向部位后壳层会大大制约其与细胞膜的作用,并延缓药物的释放。壳层可脱落纳米粒子可很好地解决长循环纳米粒子壳层这一问题,提高药物的生物利用度,其设计与制备具有很大的研究意义。本文介绍了不同类型的壳层可脱落纳米粒子,包括pH敏感型、氧化还原敏感型、酶解型等,着重阐述了壳层可脱落纳米粒子的设计机理和应用优势,并综述了国内外生物医用类壳层可脱落纳米粒子的研究进展与发展方向。     

轮换矩阵密码学性质

从AES中的列混淆出发,研究了有限域上轮换矩阵的一些性质,给出了轮换矩阵求逆算法和生成分支数最大的四阶轮换矩阵算法;讨论了轮换正形矩阵及轮换对合矩阵的一些性质,给出生成分支数达最大的四阶轮换正形矩阵的算法,得到了分支数最大的轮换对合矩阵不存在的结论.     

Interfacial structure and properties of polyurethane/poly(methylacrylate-co-styrene) coating to regenerated cellulose film

A semiinterpenetrating polymer network (IPN) containing 72 wt % polyurethane (PU) and 6 wt % poly(methylacrylate-co-styrene) [P(MA-St)] was coated onto surfaces of regenerated cellulose (RC) film, which was prepared by coagulating a cellulose cuoxam from bagasse pulp. The interfacial structures, bonding manner, and the strength of the coated film were studied by infrared (IR),¹³C nuclear magnetic resonance (NMR), differential thermal analysis (DTA), transmission electron microscopy (TEM), and electron probe microscopy analysis (EPMA). It was shown that the RC film coated with PU/P(MA-St) has strong interfacial interactions, where covalent and hydrogen bonds are formed across the interface between cellulose and the PU/P(MA-St) coating. The interfacial structure of the coated film is regarded as a shared PU network crosslinked simultaneously with P(MA-St) and cellulose film. The tensile strength, water resistivity, and optical transmission of the coated films were considerably higher than that of the uncoated films. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 2495–2501, 1997