水溶液中稀土离子与甘氨酸、丝氨酸、天冬氨酸作用的13C NMR研究

测定了酸性水溶液中甘氨酸、丝氨酸和天冬氨酸稀土络合物(Ln=La、Pr、Nd、Eu、Tb、Dy、Ho、Er、Tm和Yb)的¹³C诱导位移。对位移试剂的分析指出,三种氨基酸通过α-羧基以双齿形式配位于稀土,配位键长为0.23nm~0.25nm,天冬氨酸的γ-羧基也是配位基团。由本文与文献中已报道的各种氨基酸稀土络合物的¹³C诱导位移的系统分析表明,配体¹³C超精细偶合常数A值和结构因子G值有如下规律:(1)│A(C₀)│<│A(C_α)│;A(C₀)为正,A(C_α)为负;(2)│G(C₀)│>│G(C_α)│;配体碳核的G均为负值。     

A subspace limited memory quasi-Newton algorithm for large-scale nonlinear bound constrained optimization

In this paper we propose a subspace limited memory quasi-Newton method for solving large-scale optimization with simple bounds on the variables. The limited memory quasi-Newton method is used to update the variables with indices outside of the active set, while the projected gradient method is used to update the active variables. The search direction consists of three parts: a subspace quasi-Newton direction, and two subspace gradient and modified gradient directions. Our algorithm can be applied to large-scale problems as there is no need to solve any subproblems. The global convergence of the method is proved and some numerical results are also given.

     

远达函数的可导性与远达点的存在性

该文考察Banach空间上的远达函数的可导性与远达点的存在性间的关系，指出某些Banach空间上的远达函数(对有界闭集而言)具等于1或-1的单侧方向导数蕴含远达点的存在性，并给出了Banach空间CLUR和LUR的新等价刻划．     

The dehydration behaviour of rare earth complexes ofm-nitrobenzoic acid

Rare earth complexes ofm-nitrobenzoic acid (LnL₃·2H₂O,Ln=La-Lu and Y, except Pm, HL=m-nitrobenzoic acid) were synthesized and characterized by elemental analysis, chemical analysis, IR spectroscopy and X-ray diffraction analysis. The dehydration behaviour of these complexes was studied in detail by means of TG-DTA and DSC. Dehydration occurs over the temperature range 76–215°C, and the temperature of formation of the anhydrous complexes decreases with increasing atomic number of the rare earth. The activation energies and enthalpy changes for te dehydration were obtained.     

FETV-ICP-AES直接测定高纯二氧化硅中痕量钛

以聚四氟乙烯（ＰＴＦＥ）悬浮液为氟化剂，氟化电热蒸发／（ＦＥＴＶ）－ＩＣＰ－ＡＥＳ直接分析粉末二氧化硅．在优化实验条件下，基体Ｓｉ及痕量Ｔｉ均转化为氟化物，并以氟化物形式蒸发．结果表明：高达２０ｇ·Ｌ－１的Ｓｉ对Ｔｉ的分析信号的干扰可以忽略不计；ＳｉＯ２的粒度高达１５４μｍ时，相对蒸发率仍接近１００％，对悬浮体和溶液中基体及待测元素的蒸发特性进行了比较研究，并对石墨炉内发生的热化学反应进行了初步的探索．     

发状病毒属病毒研究进展

发状病毒属(Trichovirus)是1993年建立的一个新的病毒属，现有成员4个，苹果褪绿叶斑病毒(ACLSV)为该属典型成员，近年来，该属有关病毒的分子生物学研究取得很大进展，已完全或部分揭示了各成员病毒的基因组结构与功能，同时这些研究结果促进了病毒分类的完善，并使该属成员组成也发生了较大变化．本文从分类地位的演变、基因组结构和功能、基因工程等方面概述了该属有关病毒的主要研究进展．     

Marginal productivity index policies for scheduling a multiclass delay-/loss-sensitive queue

This paper addresses the problem of scheduling a Markovian multiclass queue with a finite dedicated buffer for each class, where class-dependent linear holding and rejection cost rates model differing levels of tolerance to delay and loss. The goal is to design well-grounded and tractable scheduling policies that nearly minimize expected total discounted or long-run average cost. New dynamic index policies are introduced, awarding higher priority to classes with larger index values, where a class’ index measures the marginal productivity of work at its current state. The results are obtained by deploying the work-cost analysis approach to marginal productivity indices (MPIs) for restless bandits developed by the author, which is extended to the bias criterion. The MPI furnishes new insights: for a loss-sensitive class, it is a decreasing function of the number of empty buffer spaces, independent of the buffer size; for a delay-sensitive class, it is a decreasing function of the queue length. Such opposite orderings show that preventive work is more valuable than reactive work for the latter classes, whereas the opposite holds for the former. The results of a computational study on two-class instances are reported, shedding light on how the MPI policy’s relative performance varies with each parameter. Parameter ranges are thus identified where the MPI policy is near optimal, and substantially outperforms conventional benchmark policies. 2000 Mathematics Subject Classification 90B22 · 90B36 · 90B18 · 60K25 · 60K30 · 68M20     

Singularly Perturbed Elliptic Equations with Symmetry: Existence of Solutions Concentrating on Spheres,Part I

 We deal with the existence of positive radial solutions concentrating on spheres to a class of singularly perturbed elliptic problems like −ɛ²Δu+V(|x|)u=u ^p ,uH ¹ (ℝ ⁿ ). Under suitable assumptions on the auxiliary potential M(r)=r ⁿ⁻¹ V ^θ (r), θ(p+1)/(p−1)−1/2, we provide necessary and sufficient conditions for concentration as well as the bifurcation of non-radial solutions.     

关于—类三阶混合型方程和变系数双曲型方程的边值问题

本文先扼要介绍一类三阶双曲抛物混合型偏微分方程的边值问题，然后讨论了与之有关的一类变系数三阶双曲型方程以特征线为支柱的边值问题，得到了有唯一解时此变系数应满足的充分必要条件。