基于Internet的远程教育系统模型研究

随着计算机网络技术的发展，远程教学系统的结构发生了重大的变化，逐步由原来的客户机／服务器(C／S)结构转变为基于Internet的浏览器／服务器(B／S)结构。本文提出了基于CORBA技术的B／S结构系统模型。分析了其运行过程，并与传统的结构进行了比较，指明了其优越性。在本文的结尾。指出了使用这种技术的一个具体例子。     

Failure mode transition and energy dissipation in naturally occurring composites

The microstructural aspects of compressive inelastic deformation in balsa wood are investigated with emphasis on the failure mode transition and its effects on energy dissipation characteristics. The architectural features as well as the composite character of cell wall ultrastructure are discussed in a framework to understand the complex interrelationship between microstructure and macroscopic behavior in this extremely lightweight cellular biocomposite. Based on this discussion and experimental results, it is concluded that the biomimetic approach may prove to be a viable strategy in designing composite structures with high specific energy absorption capacity.     

石墨炉原子吸收光谱(GFAAS)法测定石英玻璃中硼的研究

试样经氢氟酸分解，通过加入化学改进剂和多次注射浓缩样品及低温、长时间灰化的方法，在硝酸介质中用石墨炉原子吸收光谱法(GFAAS)测定石英玻璃中硼的含量。该方法解决了GFAAS法分析石英玻璃中硼灵敏度低和准确度低的问题。     

Gamma-irradiation-induced Ag/SiO2 composite films and their optical absorption properties

Small Ag particles or clusters dispersed mesoporous SiO₂ composite films were prepared by a new method: First the matrix SiO₂ films were prepared by sol-gel process combined with the dip-coating technique, then they were soaked in AgNO₃ solutions followed by irradiation of γ-ray at room temperature and in ambient pressure. The structures of these films were examined by X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), and optical absorption spectroscopy. It has been shown that the Ag particles grown within the porous SiO₂ films are very small, and they are isolated and dispersed from each other with very narrow size distributions. With increasing the soaking concentration and an additional annealing, an opposite peakshift effect of the surface plasmon resonance (SPR) was observed in the optical absorption measurements.     

数字下变频器GC1012B原理及配置方法

数字下变频技术是软件无线电的一项核心技术,其性能的好坏直接影响数字接收机的精度。GC1012B是美国TI公司推出的新型数字下变频器。文中从GC1012B的结构特点和内部功能框图出发,分析其工作原理,并介绍GC1012B几个主要寄存器的配置方法,从而实现对频率、滤波模式、增益大小等参数的设置。最后给出了一个具体配置实例作为参考。     

NSA-500-1型氩弧焊机VD9不同接法对引弧和稳弧的影响

从一起NSA－500－1型氩弧焊机故障，分析其高压脉冲旁路二极管VD9不同接法对引弧、稳弧及设备安全的影响。     

Étude du refroidissement avec solidification d'un fluide pseudoplastique thermodépendant

Heat transfer of highly consistent shear-thinning fluids flowing in a horizontal cylindrical channel has been investigated numerically and experimentally when the outer channel wall is subjected to a constant convective heat exchange. The case considered being cooling, a possible ice deposit must be taken into account. The variation of the rheological properties with temperature must be considered as well.     

自动力套管补贴加固技术及其在B125井的应用

随着油田开发时间的延长，油水井井下套管的损坏将越来越严重，套管故障井将越来越多，为了恢复套损井生产，将套管损坏所造成的损失降到最低，在配套波纹管补贴，水动力补贴，爆炸补贴等专门修套技术的基础上，通过认真调查研究，又配套了操作方便简单，适用套管损坏类型广的自动力套管补贴加固技术，使各种套管变形，套管断错（错开没有位移或位移量不大时）、套管破裂，误射孔井段封堵，已射开水层封堵等修井作业的难度进一步降低，从而进一步提高了修复井综合开发经济效益。     

Effect of Tongmai Decoction on expression of NF-κB in ox-LDL injured endothelial cells

Objective Study on the effect of NF-κB in ox-LDL injured HUVEC-304 and the intervention with the serum of Tongmai Decoction. Methods Tongmai Decoction herbage-contained serum was made by the serum pharmacology methods, then the HUVEC-304 cells were divided into 5 groups and incubated for 24 h: 1) normal group;2) fetal calf serum group; 3) ox-LDL group; 4) simvastatin group; 5) Tongmai Decoction group. RT-PCR was used to determine the mRNA of NF-κB in the cells, Western Blot Assay was used to determine the protein content of NF-κB in the cells. Results 1) Compared with the cells in normal group and serum control group , the endothelial cells in ox-LDL group are seriously injured, while those in Tongmai Decoction group grow better; 2) Compared with the cells in normal group and fetal calf serum group, the expressions of NF-κB gene and protein are up-regulated in ox-LDL group(P＜0.05, P＜0.01); 3) Compared with the cells in ox-LDL group, the expression of NF-κB gene and protein in Tongmai Decoction group are significantly down-regulated, there is no difference between Tongmai Decoction group and simvastatin group(P＞0.05). Conclusion Tongmai Decoction can protect the injured endothelial cells, up-regulate the expressions of NF-κB gene and protein content.