陆地棉体细胞胚胎的发生和遗传转化条件初探

以陆地棉（冀棉20）下胚轴为外植体，在含KT0．3mg／L和2，4－D0．08mg／L的MS培养基上，诱导产生了胚性愈伤组织，继代培养不需要添加激素，胚性愈伤组织即分化为胚状体，并萌发出小芽，胚状体萌发过程与合子胚相似，但出现了一些畸形胚，解剖学方法观察发现，这些畸形胚的维管束系统不明显或形态异常，以农杆菌介导法对冀棉20胚状体及胚性愈伤组织进行了雪花莲凝集素（GNA）基因的遗传转化条件探索，并以GUS基域瞬间进行检测加以证实，得出农杆菌的浓度为O．D600＝0．8时，浸染时间为5min，共培养时间为3d，筛选培养基中卡那霉素浓度为75mg／L，对冀棉20胚状体及胚性愈伤组织转化是较为适合的。     

A molecular network model to describe the nonlinear viscoelastic behavior of polymers

A transient molecular network model is built to describe the nonlinear viscoelasticity of polymers by considering the effect of entanglement loss and regeneration on the relaxation of molecular strands. It is an extension of previous network theories. The experimental data on three thermoplastic polymers (ABS, PVC and PA6) obtained under various loading conditions are used to test the model. Agreement between the theoretical and experimental curves shows that the suggested model can describe successfully the relaxation behavior of the thermoplastic polymers under different loading rates by using relatively few relaxation modes. Thus the micromechanism responsible for strain-rate dependence of relaxation process and the origin of nonlinear viscoelasticity may be disclosed. The project supported by the National Natural Science Foundation of China and Doctorial Fund     

Activity coefficients for NaBr in aqueous ternary solutions with sodium propionate and butyrate from EMF measurements

The activity coefficients of NaBr in the NaBr–NaPropionate–H₂O and NaBr–NaButyrate–H₂O systems were determined from EMF measurements at constant total ionic strength of 0.1 0.5 1.0 1.5 2.0 and 2.5 mol-kg^–1 and at 25° C. The activity coefficients were fitted using Scatchard, Pitzer and Lim equations. Finally the excess Gibbs free energy of these mixtures were also calculated.     

Complexes in polymers IV. FTIR microscopic characterization of thin organic polymer films containing embedded transition-metal carbonyl complexes

Thin films of polystyrene (PS), poly(methyl methacrylate) (PMMA) and polystyrene-polyacrylonitrile copolymer (PS-AN), containing various embedded transition-metal complexes, have been studied by FTIR microscopy. The spatial distributions of the transition-metal carbonyl complexes throughout the thin organic polymer films have been determined by a two-dimensional IR mapping procedure. The spectral variations observed in the distribution of the metal carbonyls throughout the different polymer films are discussed. The IR data show that the technique used to prepare the organometallic-embedded thin films (viz. freeze-drying of solutions followed by hot mechanical pressing of the residues) does in general lead to homogeneous films which may eventually find industrial application, e.g. as membrane sensors for small molecules.     

Physico-Chemical Characterization of Yu Guo Beads(1100-771 B. C. ) in China

When was the earliest glass produced in China? This has still been a question so far. Some archaeologists have thought that Yu Guo beads are real glass, the earliest glass(1100-771 B. C. ) in China. However, more details of scientific investigations in this paper show that Yu Guo beads are mainly made of clastic quartz (>95%) with a small amount of clay and sintered under the low temperature(500-600℃). It is not a glassy body, but a kind of polycrystal ornaments.     

A posteriori error analysis for linearization of nonlinear elliptic problems and their discretizations

The paper is devoted to a posteriori quantitative analysis for errors caused by linearization of non-linear elliptic boundary value problems and their finite element realizations. We employ duality theory in convex analysis to derive computable bounds on the difference between the solution of a non-linear problem and the solution of the linearized problem, by using the solution of the linearized problem only. We also derive computable bounds on differences between finite element solutions of the nonlinear problem and finite element solutions of the linearized problem, by using finite element solutions of the linearized problem only. Numerical experiments show that our a posteriori error bounds are efficient.     

2+1维SU(2)格点规范场胶球质量的七阶RPA近似

采用无规相近似(RPA)方法,用空心图作为试探波函数,利用Feymann?Hellman定理计算七阶2?+?1维SU(2?)格点规范场的胶球质量,在弱耦合区1/g2?=1.0?–?1.8胶球质量表现出良好的标度行为,基本趋于常数(m/e2?≈1.2?0±0?.0?1)?.     

排球比赛中的二传最优过程

为了研究排球比赛中的二传最优过程 ,本文基于决策论的理论和方法建立了排球二传最优过程的数学模型 .通过对模型的分析研究分别给出了最大概率准则和最大期望准则下的最优传球方式 .本文所得到的结果对排球队的训练和比赛有一定的指导意义 .     

微腔激光器的发展与应用

本文探讨了微腔激光器的分类、基本原理及特点，并简单介绍了目前几种微型激光器的发展及应用。     

Riemann Zeta函数的六阶和

利用概率论与组合数学的方法,研究了与Riemann-zeta函数ξ(k)的部分和ξ_n(k)有关的一些级数,计算出了一些重要的和式．特别的,Euler的著名结果5ξ(4)= 2ξ~2(2)能够从四阶和式直接推出．因此,通过计算全部的11个六阶和式,研究它们之间的非平凡关系,就有可能得到ξ(3)的数值．