纳米稀土复合超强酸SO42-/ZrO2-La2O3催化合成乙酸冰片酯及其动力学初探

采用纳米稀土复合固体超强酸SO4^2-／ZrO2-La2O3催化合成乙酸冰片酯，并对反应条件和该反应的动力学进行了探究。结果表明，在反应温度为120℃，催化剂用量为天然冰片质量的6％．天然冰片与乙酸的摩尔比为1：6，反应时间为8h时，反应的酯化率和选择性可达到93．14％和99．8％．研究发现，该催化剂可重复使用，并能活化再生。给出了反应速率方程，测出了反应的活化能。     

IPv6过渡机制讨论

本文在简要地介绍Ngtrans工作组提出的大多数过渡机制的基础上，尝试对它们进行区分、分类，并对每一种过渡机制的优缺点进行分析。另外．还对这些机制的布置以及一部分支持这些机制的产品平台进行讨论。     

WCDMA的软切换算法和TD-SCDMA的接力切换算法的分析与比较

本文概述了WCDMA的软切换算法和TD-SCDMA中的接力切换算法,分析和比较了这两种算法的各自得特点.     

Formation of composites fabricated by exothermic dispersion reaction in A1-TiO2-B2O3 system

The formation of aluminum matrix composites fabricated by exothermic dispersion reaction in A1-TiO2-B2O3 system was investigated. The thermal analysis results show that the reactions are spontaneous and exothermic. The Gibbs free energy of α-Al2O3 is the lowest among all the combustion products, followed by TiB2 and Al3Ti. It is noted that when the B2O3/TiO2 mole ratio is below 1, the reaction products are composed of particle-like α-Al2O3, TiB2 and rod-like Al3Ti. The α-Al2O3 crystallites, resulting from the reaction between A1 and TiO2 or B2O3, are segregated at the grain boundaries due to a lower wettability with the matrix. SEM micrographs show that rod-like Al3Ti phase distributes uniformly in the matrix. When the BEO3/TiO2 mole ratio is around 1, the Al3Ti phase almost disappears in the composites, and the distribution of α-Al2O3 particulates is improved evidently.     

非标准棱体体积计算公式介绍

阐述了非标准四棱台体和畚箕形体的体积计算公式及其用法,在水利工程建设中具有一定的参考和使用价值.     

Dynamic external fixation for distal radius fractures

Thirty adult patients with closed comminuted and mostly intraarticular fractures of the distal radius were treated by closed reduction and immobilization with a dynamic external wrist fixator during a 2-year period. In 13 patients with severely comminuted and unstable fractures, additional Kirschner wires were used. After 10 to 14 days of rigid fixation in neutral position, the motion element was unlocked to allow up to 30 degrees flexion. Six weeks later, the fixator was removed. The patients then were observed for an average of 24 weeks. An excellent functional outcome was seen in 6 patients (20%), a good outcome in 20 patients (67%), and a fair outcome in 4 patients (13%). Anatomically, 15 patients (50%) had an excellent result, 14 (47%) a good outcome, and 1 (3%) a fair outcome. Only minimal loss of reduction averaging 1 degree palmar tilt was seen during mobilization. There were 2 major complications: 1 deep Kirschner wire tract infection and 1 index metacarpal fracture. Minor complications such as sensory disturbances and pin tenderness were present but recovered completely after removal of the fixator. This study provides promising data and offers an alternative method in the treatment of distal radius fractures with severe comminution. In cases with postreductive unstable fragments, additional Kirschner wires should be used to allow early mobilization of the wrist.     

The Nicolas Andry Award-1995. Fracture healing. Radiation induced alterations

This study investigated the effects of radiation on fractures in a rat femur model. Two different radiation dosage fractionation schemes (1100 rads given in one dose and 2500 rads given in 10 divided doses over 12 days) and three different times of initiation of radiation (1 day before fracture, 3 or 10 days after fracture) were studied. Fractures exposed to these levels of radiation all appeared to heal during the course of this experiment, although with varying degrees of delay, with the exception of those exposed to a single dose of 1100 rads 3 days after fracture. These animals remained at a more immature level of repair histologically compared with the control group, throughout the entire time evaluated. The strength of the final repair remained less than the control for all the groups receiving treatment. These results may offer some explanation for the clinical observations of an increased incidence of delayed union and nonunion of fractures, an increased incidence of fracture and refracture in irradiated bone, and an increased incidence of fracture and nonunion in constructs using radiation in conjunction with allogeneic bone. Furthermore, the observed effects were generally no different in the animals treated with the two clinically relevant dose fractionation schemes chosen for this study.     

LP-BM5 virus causes changes in lactic dehydrogenase and oxygen radical production in splenocytes of C57BL/6J mice

The LP-BM5 murine leukemia virus causes acquired immunodeficiency syndrome in C57BL/6J mice (MAIDS), similar to that of AIDS in humans. The objective of this study was to determine the effect of LP-BM5 viral infection on cellular activation and membrane integrity of splenocytes. Oxidative burst in splenocytes in response to exposure to PMA (20 microg/ml) was significantly higher (p<.02) in infected than in control mice at two weeks post-infection using luminol-enhanced chemiluminescence. By 13 weeks post-infection superoxide anion production in infected mice was significantly lower when compared to controls coinciding with decreased proliferative response to mitogens. The extent of cell membrane damage as indicated by lactic dehydrogenase (LDH) activity in serum was significantly higher in infected than in control mice (p<.001). The results from this study suggests that LP-BM5 virus causes an initial stimulation of cellular activity followed by a decreased cell activation characterized by decreased proliferation of splenocytes and decreased oxygen radical production. Decreased cell membrane integrity indicated by increased LDH activity may partly be responsible for these changes.     

跟踪系统中跟踪器延迟的自适应预测补偿方法

跟踪系统中跟踪器的延迟会对系统的稳定性和跟踪精度产生不利影响。为此以典型Ⅱ型系统为例，理论上定理地分析了跟踪器延迟对跟踪系统的影响，并提出了将采用LMS算法和横向滤波器结构的自适应滤波器用于延迟预测补偿的方法。仿真结果验证了方法的有效性。     

ERCM与数据库设计

本文介绍了一种实用的数据库设计方法，它以实体分析法为理论基础，通过对我们日常使用的表进行聚集和归类，完成数据库的逻辑设计，所设计的数据库满足ＢＮＯＦ范式。同时该方法可操作性较强，本文还介绍了自行设计的ＥＲＣＭ数据库辅助设计工具。