结构静动力屈曲问题研究进展

近几十年来，结构的静动力屈曲问题一直是力学工作者极为关注的一个前沿课题．本文总结和综述了这一研究领域的几个基本问题：屈曲问题的分类、动态屈曲问题的特点及其特征量；介绍了屈曲问题的处理方法和目前已取得的成果；总结评述了人们关心的热点问题；屈曲问题的模型分析和实验技术、动态屈曲判别准则．     

Synthesis of New Flavanone Derivatives of Farrerol and Preliminary SAR Studies on Anti-VSMCs Vegetation Activity

A series of new flavanone derivatives of farrerol was designed and synthesized as a potent inhibitor of vascular smooth muscle cells(VSMCs) vegetation according to a convenient method. The structures of all the synthesized compounds were confirmed by 1H NMR, 13C NMR and EIHR-MS. The biological activities of these compounds against VSMCs in vitro were evaluated. The assay results indicate that two compounds, 5,7-dihydroxy-6,8-dimethyl- 2-(2-nitrophenyl)chroman-4-one(7f) and 2,3-dibromo-4,5-dihydroxydiphenylm...     

A DFT theoretical study of CH_4 dissociation on gold-alloyed Ni(111)surface

A density-functional theory(DFT)method has been conducted to systematically investigate the adsorption of CHx(x=0～4)as well as the dissociation of CHx(x=1～4)on(111)facets of gold-alloyed Ni surface.The results have been compared with those obtained on pure Ni(111)surface.It shows that the adsorption energies of CHx(x=1～3)are lower,and the reaction barriers of CH4 dissociation are higher in the first and the fourth steps on gold-alloyed Ni(111)compared with those on pure Ni(111).In particular,the rate-determining step for CH4 dissociation is considered as the first step of dehydrogenation on gold-alloyed Ni(111),while it is the fourth step of dehydrogenation on pure Ni(111).Furthermore,the activation barrier in rate-determining step is higher by 0.41 eV on gold-alloyed Ni(111)than that on pure Ni(111).From above results,it can be concluded that carbon is not easy to form on gold-alloyed Ni(111)compared with that on pure Ni(111).     

Investigation of Microemulsion System for Transdermal Drug Delivery of Amphotericin B

In order to solve the drawback of poor bioavailability by the oral route and infusion-related side effect for Amphotericin B(AmB), microemulsion vehicles composed of isopropyl myristate(IPM), Tween 80, isopropyl alcohol and water for transdermal delivery of AmB were designed. The pseudo-ternary phase diagrams were constructed by the H2O titration method and the structures of the microemulsion were determined by measuring electrical conducti-vities(σ). The diffusion studies of AmB microemulsion were performed via excised rabbit skin on a drug diffusion apparatus. To obtain a high solubization of AmB, three different methods were tested to incorporate AmB into mi-croemulsion. The result suggests adding AmB in the shape of NaOH solution to the O/W blank microemulsion over the phase inversion temperature(PIT) of the emulsifier obtains the maximum drug content(2.96 mg/mL). The pH value of the system could be adjusted to pH8.5 or pH<5.2, in this range AmB molecules converts from aqueous to the hydrophilic shell of the microemulsion droplets, drug precipitate is no more than 5%, and the formulations were corresponding to the characterizations of microemulsion. At pH 5.14, AmB microemulsion with Km 1:1, O/SC 1:9(mass ratio ofoil phase to surfactant/cosurfactant blend), water content 64.6%, drug content (2.93±0.08) mg/mL,showed the maximum permeation rate(3.255±0.64)μg·cm-2·h-1,which is stable for a long time.     

吩噻嗪卤代衍生物的荧光研究

本文主要研究了3-溴-N-乙基吩噻嗪(Br-P)在各种酸度、增敏溶剂、感光效应等条件下的荧光变换现象，并确定了最佳的发光体系。方法简单、准确可靠，其线性范围为1×10     

Study on mode-filtered light sensor for methane detection

A novel mode-filtered light gas sensor has been reported.It was constructed by inserting an optical fiber deposited by a thin silicone cladding of cryptophane A into a fused-silica capillary.When different concentration of methane gas was introduced to the sensor,the phenomenon that mode-filtered light intensity decreased with the increasing concentration of methane was observed. And a linear relationship was obtained within the methane concentration range of 0.0-16.0%(v/v).The detection limit was 0.06% ...     

双组分玻色-爱因斯坦凝聚体中亚稳态存在条件及其寿命

本文对双势阱中凝聚的冷原子通过约瑟夫森结隧穿时所形成的亚稳态进行研究.通过介观自旋算符建立了体系的精确量子相位模型,利用对量子自旋的势场描述给出了在两阱中振荡的原子之间相位差为时,即亚稳态时所要满足的物理条件,并用瞬子方法计算了该亚稳态存在的寿命.     

磷光光度法在药物分析中的应用

本文评述了固体基质室温磷光，流体介质室温磷光，低温磷光和室温磷光传感器在药物分析中的应用，涉及到的药物有生物碱，中草药有效成分，四环素类，喹喏酮类，维生素B2，抗癌药物，萘唑啉，萘普生和血管扩张剂潘生丁双嘧哌胺醇等，在药物分析中，固体基质室温磷光取样量只有微升级，操作快，成本低，流体室温磷光结合流动注射和化学传感技术，在药物的快速连续在线监测方面优势明显，而经过改善的低温磷体室温磷光结合流动注射和化学传感技术，在药物的快速连续在线监测方面优势明显，而经过改善的低温磷光方法，除了克服操作方面的某些弱点外，仍然保持高灵敏度的特点，随着敏化和猝死发光，能量转移，衍生发光和免疫发光等技术的发展，磷光方法在药物分析中的应用将会更加广泛。     

原子吸收法直接测定食用L-赖氨酸盐酸盐中的铜和铅

本文报道了用石墨炉-原子吸收分析法，将食用L-赖氨酸盐样品经稀酸溶解后，直接进样测定。该方法省去了通常必需的干灰化或湿消解过程，充分利用石墨炉本身所具的对样品进行部分预处理的功能，在无基体改进剂的条件下，快速测定样品中的Cu和Pb的含量。方法简便，快速，准确，实用，Cu和Pb的精密度试验的相对标准偏差分别为4.8%和5.3%；回收率分别为100%-110%和102%-105%。     

REACTION KINETICS OVER PRECIPITATED Fe/Mn/K CATALYST FOR THE FISCHER-TROPSCH SYNTHESIS

The kinetics of the Fischer-Tropsch Synthesis reaction is studied in an internally recycled reactor (CSTR) over a commercial, precipitated Fe/Mn/K catalyst. Kinetic data are obtained with 1 47-4.04 H2/CO feed gas over a temperature range of 265-320℃, a pressure range of 1.0-2.6 MPa, and a space velocity range of 300-800 h-1 . The kinetic model which fits the experimental data well is the same as that of the intrinsic kinetics, i.e. -RH2 CO=kPH2PCO/(PCO bPH2O, where k is the kinetic constant for the rate-determining step and b is a function of temperature only. This model may be derived by assuming that the rate-determining step is the hydrogenation of adsorbed CO according to the enol mechanism. It is found that the CO usage ratio is probably independent of synthesis gas conversion and total pressure, and the catalyst shows high water-gas-shift activity.