BaCe0.8Ho0.2O3-a陶瓷的性质与应用

Ceramic BaCe0.8Ho0.2O3-α with orthorhombic perovskite structure was prepared by conventional solid state reaction, and its conductivity and ionic transport number were measured by ac impedance spectroscopy and gas concentration cell methods in the temperature range of 600-1000 ℃ in wet hydrogen and wet air, respectively. Using the ceramics as solid electrolyte and porous platinum as electrodes, the hydrogen-air fuel cell was constructed, and the cell performance at temperature from 600-1000 ℃ was examined. The results indicate that the specimen was a pure protonic conductor with the protonic transport number of 1 at temperature from 600-900 ℃ in wet hydrogen, a mixed conductor of proton and electron with the protonic transport number of 0.99 at 1000 ℃. The electronic conduction could be neglected in this case, thus the total conductivity in wet hydrogen was approximately regarded as protonic conductivity. In wet air, the specimen was a mixed conductor of proton, oxide ion and electron hole. The protonic transport numbers were 0.01-0.09, and the oxide-ionic transport numbers were 0.27-0.32. The oxide ionic conductivity was increased with the increase of temperature, but the protonic conductivity displayed a maximum at 900 ℃, due to the combined increase in mobility and depletion of the carriers. The fuel cell could work stably. At 1000 ℃, the maximum short-circuit current density and power output density were 346 mA/cm^2 and 80 mW/cm^2, respectively.     

体温计模型的临界行为

提出一个可用离散朗之万方程描述的体温计模型.该体温计的特点是其温度示数只能随外界温度的升高而上升,当外界温度降低时,其示数却不能下降.根据体温计示数这种只升不降的特点,定义了“停顿”事件.用随机行走的理论解析地推导了停顿时间分布函数数值模拟和解析结果都显示这种分布函数呈幂律形式D(s)∝s^-ξ,揭示出在这一过程中所表现出的临界性. 关键词：     

中国南部二叠纪末和三叠纪初的沉积分区及其相型

本文论述了中国南部二叠纪末、三叠纪初的沉积岩相和生物相类型,并划分了若干性质不同的沉积区和相区。晚二叠世晚期有2个沉积区和8个相区;三叠纪初则演变为2个沉积区和斗个相区。文中还探讨了古生代与中生代之交沉积环境、气候以及生物群的演替等问题,认为中国南部大部分地区二叠系与三叠系之间无论岩相或生物相都显示了过渡性质。     

碱性介质中二过碲酸合铜(III)氧化乙二醇的反应动力学及机理

本文采用分光光度法研究了碱性介质中二过碲酸合铜(III)(DTC)氧化乙二醇(Glgcol)在291.2-303.2K的反应动力学机理。结果表明, 反应对氧化剂(DTC)是一级, 对乙二醇也是一级, 准一级([Glycol]0>>[DTC]0)速率常数Kobs随着[OH^-]增加而增加, 随着[TeO4^2^-]增加而降低, 并且有负盐效应, 提出了一种含有前期平衡的反应机理。据此导出了一个能够解释全部实验事实的速率方程, 求出平衡常数、速控步骤的速率常数及298.2K时的活化参数。     

应用新型立式逆流色谱制备分离南蛇藤中的南蛇藤素

A versatile countercurrent chromatography with upright multilayer coil planet centrifuge, named upright countercurrent chromatography (UCCC), was applied to the isolation and purification of celastrol from the roots of Celastrus orbiculatus Thunb. The crude celastrol was obtained by elution with petroleum ether from ethanol extracts using a 15 cm length and 5 cm I.D. of silica gel flash chromatography. Preparative UCCC (Fig. 1) with a two-phase system composed of petroleum ether (b. p. 60 ～ 90 ℃ )-ethyl acetate-tetrachloromethanemethanol-water ( 1:1:8:6: 1, v/v) was successfully performed, yielding 705 mg celastrol at 99.5 % purity from 1020 rng of the crude extract in one step separation.     

次甲基硅SiH与H2X(X=O,S)反应的热力学及动力学性质研究

在量子化学对SiH与H₂O和H₂S反应计算的基础上,运用统计热力学和Wigner校正的Eyring过渡态理论,计算了上述两反应在200～2000 K温度范围内的热力学函数、平衡常数、频率因子A和速率常数随温度的变化。计算结果表明,两反应在低温下具有热力学优势,而在高温下具有动力学优势。比较两反应的计算结果发现,在相同的温度下,SiH与H₂O反应比SiH与H₂S反应放热较多,但速率常数却较小。SiH与H₂O反应和前文报道的SiH与HF反应的比较表明,SiH与H₂O反应放热较少,而且在相同温度下,速率常数也较小。     

丹宁纤维素富集-氢化物发生ICP-AES同时测定水中痕量锗

研究了丹宁纤维素富集10~(-11)g/ml级锗的条件,并考察了地下水中36种共存离子对磷酸介质中氢化物发生ICP-AES测定锗的干扰和消除,应用于测定地下水中的超痕量锗,结果满意,检出限为15ng/L。     

具有小Knudsen数的Boltzmann方程的奇异扰动解法

本文提出一种解小Knudsen数的Boltzmann方程的方法,它可以消去Hilbert展开和Enskog展开中的久期项改进正规解,消去Grad展开中的久期项改进初始层解,并把求边界层解归结为求解线性代数方程组。 关键词：     

一系列新型三环二萜的合成与抗肿瘤活性研究

对活性天然产物(+)-7-deoxynimbidiol非对映异构体的外消旋体cis-(±)-7-deoxynimbidiol进行了合成和衍生, 共得到了8个新型三环二萜化合物; 对合成的新化合物进行了抗肿瘤活性的实验研究, 其中化合物5d对人体乳腺癌瘤株MCF7表现出了较强的抑制作用(IC50=7.49 μg/mL), 可能作为新型抗肿瘤药物先导化合物.     

新型微填充柱－毛细管柱二维色谱系统过程的动力学研究

从色谱动力学角度对新型微填充柱－毛细管柱二维色谱系统过程中双柱条件与流出曲线及柱效之间的依赖关系加以系统研究。结果表明：由于双柱条件之间存在关联，双柱系统流出曲线特征与单柱系统存在一定的差异，流出曲线一阶矩和二、三阶中心矩以及双柱系统的柱效皆由预柱和主柱条件综合确定。