PERIODIC BOUNDARY VALUE PROBLEM FOR SECOND ORDER FUNCTIONAL DIFFERENTIAL EQUATIONS

This paper investigates the periodic boundary value problems for a class of second order functional differential equations. The monotone iterative technique and the maximum principle are applied to obtain the existence of maximal and minimal solutions.     

POSITIVE SOLUTIONS OF NONLOCAL BOUNDARY VALUE PROBLEM FOR NONLINEAR RETARDED DIFFERENTIAL EQUATION

§1　IntroductionAt present,boundary value problems (BVPs) are widely investigated with variousmethods and techniques. BVPs with integral boundary conditions constitute a veryinteresting class of problems such as multipoint,three-point,four-point and nonlocalboundary value problems which are considered by many authors.And the existence ofpositive solutions for these problems becomes the subjectof many papers[1—6] .In a recentpaper[7] ,the authors have studied the existence of positive solut…     

资产组合的CVaR风险的敏感度分析

基于CVaR风险计量技术，分别给出了正态和t分布情形下资产组合的CVaR值，对一般情形下风险资产组合的CVaR风险关于头寸的敏感度进行了分析，研究了其经济意义。     

人原始生殖细胞的分离和体外培养

从4～10周龄药物流产胚胎的生殖嵴和肠系膜组织中分离原始生殖细胞(primordial germ cells,PGCs),培养在添加人重组白血病抑制因子(rh LIF)、人重组碱性成纤维细胞生长因子(rh bFGF)和Forskolin的小鼠饲养层细胞上.经过4～7 d培养,PGCs形成典型的鸟巢状集落.集落在传代过程中保持碱性磷酸酶活性,且胚胎阶段性特异抗原1(SSEA-1)、胚胎阶段性特异抗原3(SSEA-3)免疫荧光染色呈阳性.具有分化潜能的PGCs能在体外连续传代培养12代.结果表明从药物流产胚胎中分离的人类PGCs可以在体外培养成为具有分化潜能的多能性干细胞.     

饮食中微量元素砷的分布规律与人体健康关系

采用催化动力学光度法测定了六大类(共三十种)样品中的总砷含量，探讨了砷在食品中的分布规律，建立了砷在人体中的安全系效和积累系效的效学评价公式，用于评价砷与人体健康的关系，这对人们选择食物有一定的指导意义。     

Effect of dipping solution pH values on electrostatic layer-by-layer self-assembly of side-chain azo polyelectrolyte

The effect of pH value on the electrostatic layer-by-layer self-assembly and the photo-responsive behavior of Poly{2-[4-(4-ethoxyphenylazo)phenoxy]ethyl acrylate-co-acrylic acid} (PEAPE) was studied. Results show that in the studied pH value range, the lower the pH value is, the higher is the UV-vis absorbance and the larger is the thickness of the multilayer films. FTIR studies indicate that the azo polyelectrolyte exhibits a different ionization degree in solutions with different pH values. The higher absorbance and the larger thickness of the layer-by-layer films can be attributed to the low ionization degree and the shrinkage conformation of PEAPE in the solution with low pH values. FTIR analysis also confirms that the driving force for layer-by-layer self-assembly of PEAPE and PDAC is the electrostatic interaction. __________ Translated from Acta Polymerica Sinica, 2007, 5: 440–445 [译自: 高 分子学报]     

高阶微分方程允许解的存在性

本文主要目的是利用值分布理论研究复高阶微分方程(Ω(z,w)/w^k0(w’)^k1…(w^(n)^kn)^m=aw^p ∑j=0^s bj(z)w^j,(p≥m）亚纯允许解的存在性问题．证明了一个在适当的条件下，该微分方程的亚纯解一定不是允许解的结果．实例表明该文的结果是最佳的．     

Heat Kernel Asymptotics of Zaremba Boundary Value Problem

The Zaremba boundary-value problem is a boundary value problem for Laplace-type second-order partial differential operators acting on smooth sections of a vector bundle over a smooth compact Riemannian manifold with smooth boundary but with discontinuous boundary conditions, which include Dirichlet boundary conditions on one part of the boundary and Neumann boundary conditions on another part of the boundary. We study the heat kernel asymptotics of Zaremba boundary value problem. The construction of the asymptotic solution of the heat equation is described in detail and the heat kernel is computed explicitly in the leading approximation. Some of the first nontrivial coefficients of the heat kernel asymptotic expansion are computed explicitly. This revised version was published online in July 2006 with corrections to the Cover Date.     

辽河冷家油田特稠油降粘剂LJVR-1及其性能评价

采用荧光法测定了辽河冷家油田冷47-556井特稠油乳化HLB值,然后以混合型表面活性剂、非离子型表面活性剂为主剂,快速渗透剂为辅剂按一定比例制备了水基降粘剂LJVR-1.实验结果表明,该降粘剂具有良好的乳化降粘性能,开采后易于破乳脱水,是一种较为理想的特稠油降粘剂.     

氧氟沙星和左氟沙星与人血清白蛋白的相互作用研究

用光谱技术研究了水溶液中氧氟沙星(OFLX)和左氟沙星(LVFX)与人血清白蛋白相互作用的机制.荧光猝灭法测得的结果表明反应的结合常数为KOFLX＝0.482×105L@mol-1,KLVFX=0.529×105L@mol-1,结合位点数nOFLX＝0.72,nLVFX=0.74.按照Fōorster非辐射能量转移理论得到药物-蛋白之间的结合距离分别为rOFLX=2.94nm,nVFX=2.85 nm.实验结果说明OFLX与LVFX在体内与蛋白结合直到运输到受体部位这一环节基本相同.