BONDED TABLEAU AND UNITARY GROUP APPROACH FOR MANY-ELECTRON PROBLEMS

A unitary group approach based on the so-called bonded tableaux (VB) states is described. Several different realizations of the bonded tableaux are discussed and their relations are pointed out. From a viewpoint of the symmetric group we reveal a simple structure of the matrix elements of unitary group generators and generator products. This structure makes an efficient approach to the matrix element evaluation.     

盐中水不溶物测定中的问题及解决办法

分析盐中水不溶物含量测定时过滤、洗涤、称量等操作过程中存在的一些问题，提出了相应的解决办法。     

HV-21型碳硫自动分析仪测定碳、硫常见问题及解决办法

采用HV－21型碳硫自动分析仪测定碳、硫时，经常出现空白值偏高，碳含量突然偏低或无检测信号等现象，对这些现象进行了分析并提出了解决办法。     

MOLECULAR PHOTOELECTRON SPECTROSCOPIC STUDIES OF BONDING AND STEREOCHEMICAL PROBLEMS IN PHOSPHORUS CHEMISTRY

Abstract

This article is concerned with the application of the relatively new technique of molecular photoelectron spectroscopy (pes)^1,2 to some bonding and stereochemical problems in phosphorus chemistry. No attempt will be made to infer that pes is a deus ex machina capable of functioning as the final arbiter on all controversial bonding problems; rather the general tenor will be one of unbiased examination of a selection of currently unresolved questions with a recently developed tool. In essence the pes method involves the measurement of the various first ionization potentials (IP_x) of a neutral molecule in the vapor phase. In the photoionization process the molecule M is ionized to its radical cation M⁺ by means of a photon of energy hv     

乙醇气体标准物质研制过程中出现的一些问题

在研制乙醇气体标准物质的过程中,发现高浓度和低浓度乙醇气体标准物质的一致性、重现性和稳定性都很好.但通过对高浓度和低浓度的乙醇气体进行分装实验后发现,低浓度的乙醇在分装后子气与母气之间有明显的变化;经过分析发现乙醇在制备过程中,会在气瓶上出现一定的吸附,但吸附过程在很短时间就会完成.     

ORGANYL (CHLOROETHYNYL) SULPHIDES,ORGANYL (CHLOROVINYL) SULPHIDES AND RELATED PROBLEMS

Abstract

Organyl(β,β-dichlorovinyl)- and organyl(α,β,β-trichlorovinyl) sulphides, CCl₂=CHSR, CCl₂=CClSR, (CCl₂=CHS)₂R, have been obtained by dechlorination and dehydrochlorination of α,β,β,β-tetrachloroethylorganylsulphides and by reactions of tri- and tetrachloroethylenes with mono- and dithiols of the aliphatic and aromatic series in the presence of radical initiators.     

标准物质及其作用

介绍了标准物质的特点、分类及作用。     

甲醇-正己烷和甲醇-环己烷溶液构型的分子模拟

用Ｍｏｎｔｅ Ｃａｒｌｏ分子模拟方法研究了不同温度条件下甲醇－正已烷、甲醇－环已烷溶液体系微观结构的变化情况。模拟表明，无论是甲醇－正已烷体系，还是甲醇－环已体系，在其溶液的近临界区，甲醇周围溶剂介质的密度最小，而甲醇分子之间的积聚最为明显。通过对氢健分析的结果表明，在溶液临界区，氢键作用与非氢键作用的距离不可区分。     

锡原子簇的结构和相对稳定性

基于从固体锡确立的多体展开势能函数, 采用座标直接优化方法预测了锡原子簇分子(Sn_2-Sn_(300))的结构和相对稳定性, 并用蒙特卡罗方法验证了有关小的原子簇(Sn_2-Sn_(15))的所有结果. 优化结果表明: (1)小的锡原子簇分子(Sn_2-Sn_(15))倾向于密堆积结构, 与锡晶体结构无关; (2)中等大小的簇分子, 如Sn_(47), Sn_(71), Sn_(87)及Sn_(147)等, 则呈α-Sn晶体的畸变结构, 其外围各层原子到中心原子的距离受到压缩, 且某些层被劈裂为两层或多层; (3)随着原子簇尺寸的进一步增大, 结构畸变逐渐减弱, 簇分子的单原子平均结合能缓慢增大, 其外椎值大约在Sn_(740)处趋近于α-Sn的结合能.     

我国标准工作中存在的问题

简述了我国国家标准的制定水平、采用国际标准的程度、国家标准的更新，以及参与国际标准制定等现状，指出了存在的不足，并提出了提高国家标准的起点水平，积极参与国际标准制定等建议。     

PSEUDO-SOLUTION ON GEODETIC OVERDETERMINED BOUNDARY VALUE PROBLEMS

A higher step of study on the GOBVPs (geodetic overdetermined boundary value problems) is reached in this paper, which covers the proposal of new concept of pseudo-solutionon the GOBVPs, its strict definition of mathematics and solving principle. The so-called pseudosolution is a harmonical function having the property of optimum approximating the given boundary values in the sense of a relevant norm. Analytical expressions of the pseudo-solutions of two typical OBVPs for biboundary surfaces in physical geodesy, the problems S—D and S—N, are obtained, which is elegant and concise in form and convenient for practice, by using the derived formulas of norms of fractional exponential Sobolev's spaces in the case of spherical biboundary. The pseudo-solution is composed of two parts: the major is the solution of classical Stokes' problem, playing control role in field representation; the minor is correction term, serving the function of synergist and precision of the gravity field. Besides, a general case o     

针对欧盟禁用APEO想到的几个问题

针对欧盟禁用APEO类表面活性荆问题,对APEO及各国关于APEO的政策法规进行了介绍,简述了APEO的毒性、生产和使用现状,APEO替代品的研究及检测状况;结合欧盟化学品新法规REACH制度,展望了我国APEO方面的工作.     

关于气相色谱仪检定的几个问题

在对气相色谱仪进行检定的过程中,遇到了有关色谱柱,标准样品,积分仪和色谱数据工作站数据采集等实际问题,为了既不影响生产工艺分析任务的进行,又能及时完成对仪器性能的检定工作,采取了相应的措施和办法,较快地完成了对气相色谱仪的检定,并对某些测试数据进行了比较和讨论。     

碱金属原子簇的结构和稳定性

基于从体心立方碱金属晶体优化确立的多体展开势能函数，本文通过坐标优化研究了碱金属原子簇Ｘｎ（Ｘ＝Ｌｉ，Ｎａ，Ｋ，Ｒｂ，Ｃｓ）的结构和稳定性。发现：（１）Ｘｎ原子簇（ｎ＝４－２１）倾向于形成畸变四面体结构单元，（Ｔｄ）的密堆积，分子表面被三元环（Ｄ３ｈ）所覆盖，其中Ｘ７－Ｘ１５最优化结构中包含五角双锥Ｘ７（Ｄ５ｈ）结构单元，具有区域五重对称轴；（２）“微观晶体碎片”的分层优化结果表明，体心立方、面心     

Large-Scale Chirality Measures and General Symmetry Deficiency Measures for Functional Group Polyhedra of Proteins

Functional Group Polyhedra provide a simplified representation of the most essential spatial features of macromolecules, especially, of globular proteins. Since the functional group polyhedron model focuses on large scale features, the chirality and other symmetry deficiency measures of these molecules, when adapted to these polyhedra, should also be based on the characterization of large scale shape features. Two new approaches for the evaluation of such symmetry deficiency and chirality measures are presented.     

EXTENDED GABOR FUNCTION MODEL AND SIMULATION OF SOME CHARACTERISTIC CURVES OF RECEPTIVE FIELD

In this paper we propose a family of extended Gabor functions as weight functions of the primary information processing in the visual system. The orientation tuning curve, the length tuning curve and spatial frequency tuning characteristics of simple cells, complex cells and some hypercomplex cells were simulated by means of our model. The results calculated by this model coincide closely with the experimental data. It has been shown that the extended Gabor function model can reasonably describe the main properties of receptive fields several levels of the visual system.     

高分子混合体系相分离过程相结构的自相似与分形

本工作用激光光散射和光学显微镜手段研究了聚甲基丙烯酸甲醋(PMMA)和聚醋酸乙烯酯[PVAc]共混体系相分离过程。结果表明系统的相态结构呈现较强的自相似,结构函数在大波矢处具有q~(-6)的渐近行为,相结构具有分形特征,其分形维数[Fractal Dimension]D约为1,64,初步认为结构函数的标度[Scaling]行为是由于相结构的分形特征所致。     

南昌市城区416名儿童锌缺乏状况调查

为了解南昌市城区儿童锌缺乏状况，采集手指尖末梢血20μL用石墨炉原子吸收分光光度法测定全血锌浓度。以血锌值5.00μg/mL为正常下限。结果表明，该儿童人群血锌值呈非正态分布，样本中位数为5.659μg/mL，四分位数间距为Q3－Q1＝1．927。416名2－8岁儿童中男240人，女176人。锌缺乏人数134人，锌缺乏患病率35．80％。不同性别间血锌值无显著差异，而不同年龄间血锌值有显著差异，但未表现出与年龄呈正相关关系。提示南昌市城区儿童锌缺乏的发生率较高，应引起人们足够的重视。     

FUNDAMENTAL PROBLEMS IN FINITE ELEMENT SIMULATION OF WAVE MOTION

The transmitting boundary condition is written in a compact form, which can be direct-ly incorporated into finite elements. Basic characteristics of discretization are analyzed throughstudies on wave motion in a one-dimensional discrete model and their differences from those in thecorresponding continuum. Tbe analysis leads to identifying a frequency band within which thesimulation is possible, and to a suggestion of using the lumped-mass finite element model forthe simulation. Mechanism of the oscillation instability is then illuminated in the frequencydomain by amplification at the artificial boundary and multi-reflection of wave motion in afinite discrete model. Based on understanding of the mechanism, a modified transmittingboundary condition is devised for eliminating the instability. The special stability criterion forthe modified boundary is finally presented for the one-dimensional model.