阳离子表面活性剂CTAB与PVA相互作用性质研究

通过粘度、电导率、表面张力以及紫外吸收光谱等手段,研究水溶性中性聚合物聚乙烯醇(PVA)与阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)之间的相互作用。结果表明,PVA与CTAB之间有一定的相互作用,从而使体系表现出异常的粘度行为,显示出一定的电粘效应,并导致其混合溶液的最大紫外吸收峰发生了红移,未观察到PVA的加入对CTAB溶液表面张力和临界胶束浓度的影响。     

应用BP神经网络模型实现内圆磨床主要零件的快速反应设计

用数字化模型代替三维实体模型，将内圆磨床主要大件的BP神经网络模型放入数据库信息管理系统，应用较简单的使用方法实现了零件结构的再修改、灵敏度分析及优化．根据所提出的方法，通过从数据库信息管理系统中调用桥板的数据文件，对其进行结构参数修改、灵敏度分析及以第1阶扭转频率最高为目标的设计变量自动搜索寻优计算，结果表明将BP神经网络模型与数据库信息管理系统结合是实现零件快速反应设计的有效途径．     

一种基于SPIHT的分层图像压缩方法

提出一种利用SPIHT算法进行图像分层压缩的编码方法,该方法首先利用图像平滑技术将图像分解为平滑部分和轮廓部分,然后以一定的编码率分别对它们进行编码.实验结果表明,合理分配各层的编码率,能够获得视觉效果比单独采用SPIHT编码更好的编码图像.     

Effects of hyaluronic acid－chitosan－gelatin complex on the apoptosis and cell cycle of L929 cells

With the development in the field of tissue engineering, the interaction between biomaterials and cells has been deeply studied. Viewing the cells seeded on the surface of materials as an organic whole, cell cycle and apoptosis are analyzed to deepen the study of cell compatibility on biomaterials, while cell proliferation and differentiation are studied at the same time. In this paper, hyaluronic acid is incorporated into the chitosan-gelatin system. Propidium iodide (PI) was used in cell cycle analysis and the double-staining of cells with annexin-V and PI was applied in cell apoptosis analysis. The results show that incorporated hyaluronic acid shortens the adaptation period of cells on the material surface, and then cells enter the normal cell cycle quickly. In addition, added hyaluronic acid inhibits cell apoptosis triggered by the membranes. Therefore, hyaluronic acid improves the cell compatibility of chitosan-gelatin system and benefits the design of biomimetic materials.     

Evolution of the South China Sea and monsoon history revealed in deep-sea records

As the third summary report of ODP Leg 184 to the South China Sea (SCS), this paper discusses the evolution of the East Asian monsoon and the SCS basin. A multi-proxy approach, involving geochemistry, micropale-ontology, pollen and other analyses, was adopted for reconstructing the evolutionary history of the East Asian monsoon, which was characterized by a series of paleo-climate events especially at 8, 3.2, 2.2 and 0.4 Ma. The new record indicates similar stages in the development of the East and South Asian monsoons, with an enhanced winter monsoon over East Asia being the major difference. The rich spectrums of monsoon variability from the southern SCS also reveal other characteristic features of the low latitude ocean. Evidence for the evolution of the SCS includes the hemipelagic Oligocene sediments, implying the existence of deep water environments during the early seafloor spreading stage of the SCS basin. The four major unconformities and some remarkabl ediagenetic features in upper Oligocene deposits indicate the strongest tectonic events in the region. From a careful comparison of lithologies and sedimentation rates, we conclude that the prominent differences in sedimentary environments between the southern and northern SCS were established only by ～3 Ma.     

低含水率沙床的临界起沙风速

针对目前对风沙起动机制的认识有限的现状，采用量钢分析法推导出对湿沙床的起沙有影响的4个无量纲数。经分析得到起沙风速与沙床沙粒粒径和沙床粘结力间的数量关系。通过建立沙床粘结力与含水率、沙粒粒径的关系式，得到临界起沙风速和沙粒粒径，含水率间的定量关系式。认为低含水率沙床的风沙起动风速与颗粒粒径的一次方和沙床含水率的1／4次方成线性关系，此结论与前人的实验结果符合得很好。     

在Newman型结点上Lagrange插值多项式的发散性

191 8年 ,Bernstein证明了对于函数 |x|,由闭区间 [-1 ,1 ]上的等距结点所构成的 Lagrange插值多项式序列 ,除了 -1 ,0 ,1以外 ,在闭区间 [-1 ,1 ]上的其他任何点都发散 .1 995年 ,L.Brutman和 E.Passow将Bernstein的结论推广到一类 Newman型的结点上 .本文考虑了比 |x|更好性质的函数 ,它的 Lagrange插值多项式仍旧处处发散 ,进一步指出了 |x|的发散性并不是孤立的现象 .     

基于等距结点的Lagrange插值多项式在零点的收敛速度

S.M.Lozinskii指出了函数 |x|基于等距结点的 Lagrange插值多项式在零点的收敛速度 .2 0 0 0年 ,M.Revers把 S.M.Lozinskii的结果推广到 |x|α( 0 <α≤ 1 ) .在此中考虑了α>1的特殊情况 f ( x) =|x|5,对其基于等距结点 Lagrange插值多项式在零点收敛速度进行估计     

墙梁计算方法

本文通过某工程实例的计算，充分表达了新规范中墙梁计算的原理与方法。这对于广大设计人员正确计算墙梁将起到一定指导作用