不同极性固定相上醇色谱保留指数的预测

采用拓扑指数(mQ)、定位基参数(SOX)及固定液极性值(CP)与脂肪醇在6种固定相上的气相色谱保留指数值(RI)进行了相关分析,发现RI与上述参数间存在良好的相关性,其关系可表示为:RI=158·384 57·7220Q-12·0491Q 5·720SOX 5·756CP R=0·9913继以留一法(Leave-one-out,LOO)进行交互检验,相关系数RCV=0·9909。说明所建定量结构-保留关系(QSRR)模型具有良好的稳定性和预测能力,较好地揭示了脂肪醇类物质在不同固定相上气相色谱保留指数的变化规律。     

基于贝叶斯方法的时变可靠度分析

针对现役钢筋混凝土桥梁时变可靠度分析的现状,首先根据主观经验信息确定了一个抗力统计参数退化模型,然后结合结构实际检测信息,运用贝叶斯方法综合这两类信息,并进行了推断,从而对模型参数进行了更新,并利用更新后的参数对混凝土模型和钢筋锈蚀模型进行了修正,最后结合已有的荷载效应分析理论,计算时变可靠度,给出了一个计算实例.     

类石墨相C3N4光催化剂改性研究

半导体光催化技术不仅可以将太阳能转化为化学能,还可以直接降解和矿化有机污染物,因此其在抑制环境污染和解决能源短缺方面具有广阔的应用前景。类石墨相氮化碳(g-C₃N₄)具有独特的电子能带结构、优异的热稳定性以及化学稳定性,因此g-C₃N₄作为一种廉价的无金属光催化剂被广泛应用于光解水制氢产氧、污染物降解、光催化CO₂还原、抗菌和有机官能团选择性转换等领域。然而,传统热缩聚法合成的g-C₃N₄光催化剂比表面积小、禁带宽度大、光生电子-空穴易于复合、光生载流子传输慢,抑制了其光催化活性。为了进一步提高g-C₃N₄的光催化活性,出现了多种改性方法。本文针对g-C₃N₄光催化剂的改性研究,综述了近年来国内外在g-C₃N₄光催化剂改性方面的重要研究进展,如采用模板法优化g-C₃N₄的纳米结构、元素掺杂及共聚合调控g-C₃N₄的能带结构、贵金属沉积或半导体复合提高光生载流子分离效率等。最后,本文还展望了g-C₃N₄光催化剂在改性方面的未来发展趋势。     

论教师职前教育课程的现状与改革方向

我国中小学教师的职前教育在课程理念、课程设置、课程结构等方面存在着与教师职业专业化要求不相适应的状况,因此,要培养适应基础教育课程改革需要的专业化的教师,教师职前教育需要从以下几个方面进行改革:以教师专业化为导向,转变课程理念;以教师能力提高为宗旨,改革课程内容;以教师综合素质提高为目的完善课程结构。     

Rank-one cross commutators on backward shift invariant subspaces on the bidisk

For a backward shift invariant subspace N in H^2（Г^2）, the operators Sz and Sw on N are defined by Sz = PNTz｜N and Sw, = PNTw｜N, where PN is the orthogonal projection from L^2（Г^2） onto N. We give a characterization of N satisfying rank [Sz, Sw^＊] = 1.     

Assembly of a New Cyano‐bridged 4f‐3d Dimer Sm(DMSO)4‐ (H2O)3Cr(CN)6 and Crystal Structure of [K3(18‐crown‐6)3‐(H2O)4]Cr(CN)6·3H2O

A new cyano‐bridged binuclear 4f‐3d complex Sm(DMSO)₄‐(H₂O)₃Cr(CN)₆ was synthesized and characterized by single crystal structure analysis. It crystallizes in monoclinic, space group P2₁ with a=0.9367(2) nm, b = 1.3917(3) nm, c = 1.1212(2) run, β = 99.88(3)° and Z = 2. In this binuclear complex, Sm atom is eight coordinated and linked to the Cr atom by a cyano bridge. The molecules packs to form 3D structure due to the hydrogen bonds among them. [K₃(18‐C‐6)₃(H₂O)₄]Cr(CN)₆·3H₂O (18‐C‐6 represents 18‐crown‐6‐ether) that was synthesized as a byproduct in the preparation of a Gd—Cr complex is also structurally characterized. Crystal data: triclinic, space group P‐l with a = 1.0496(7) nm, b= 1.1567(14) nm, c = 1.3530(13) nm, a = 94.15(9)°, β = 96.04(8)°, γ = 95.25(9)° and Z = l. [K₃(18‐C‐6)₃(H₂O)₄]‐Cr(CN)₆·3H₂O consists of ionic [K₃(18‐C‐6)₃(H₂O)₄]³⁺ and [Cr(CN)₆]^3‐ pairs, of which the [K₃(18‐C‐6)₃(H₂O)₄]³⁺ ion is a trinuclear duster connected by water, and K atoms are eight coordinated by eight oxygen atoms of one 18‐C‐6 and two water molecules.     

Sampling with Bessel Functions

The paper deals with sampling of σ-bandlimited functions in R^m with Clifford-valued, where bandlimitedness means that the spectrum is contained in the ball B(0, σ) that is centered at the origin and has radius σ. By comparing with the general setting, what is new in the sampling is using the explicit Bochner-type relations involving spherical harmonics and monogenics in the Clifford algebra setting. Convergence of the sampling formulas in the L² sense and in the uniform and absolute pointwise sense are studied. The study was supported by Research Grant of the University of Macau No. RG059/05- 06S/QT/FST.     

The relationship between four-dimensional θ=π Yang－Mills theory and the two-dimensional Wess－Zumino－Novikov－Witten model

Used the dimensional reduction in the sense of Parisi and Sourlas, the gauge fixing term of the four-dimensional Yang－Mills field without the theta term is reduced to a two-dimensional principal chiral model. By adding the θ term (θ=π), the two-dimensional principal chiral model changes into the two-dimensional level 1 Wess－Zumino－Novikov－Witten model. The non-trivial fixed point indicates that Yang－Mills theory at θ=π is a critical theory without mass gap and confinement.     

Palladium-catalyzed C-H activation/intramolecular amination reaction: a new route to 3-aryl/alkylindazoles

A method for the catalytic C-H activation of hydrazone compounds followed by intramolecular amination is described. It requires the use of a catalytic amount of Pd(OAc)2 in the presence of Cu(OAc)2 and AgOCOCF3, which efficiently effects the cyclization to afford variously substituted indazoles. The reactions proceed under relatively mild conditions and thus tolerate a variety of functional groups, including alkoxycarbonyl and cyano groups and halogen atoms.     

EXISTENCE AND UNIQUENESS OF THE SOLUTION FOR A CLASS OF NONLINEAR FRACTIONAL DIFFERENTIAL SYSTEM

In this paper we prove the existence and uniqueness of the solution for a class of nonlinear fractional differential system, and investigate the dependence of the solution on the orderαi.