Synthesis of β-（ 1→6）-Branched （ 1→3）-Glucononaoside with Alter-nate β- and α-Bonds in the Backbone

Lauryl glycoside of β-D-Glcp-(1→3)-[β-D-Glcp-(1→6)-]α-D-Glcp-(1→3)-β-D-Glcp-(1→3)-[β-D-Glcp-(1→6)-]α-D-Glcp-(1→3)-β-D-Glcp-(1→3)-[β-D-Glcp-(1→6)-]β-D-Glcp was synthesized through 3 3 3 strategy. 3-O-Allyl-2,4,6-tri-O-benzoyl-β-D-glucopyranosyl-(1→3)- -[2, 3, 4, 6-tetra-O-benzoyl-β-D-glucopyranosyl-(1→6)-] 1,2-O-isopropylidene-α-D-glucofuranose was used as the key intermediate which was converted to the corresponding trisaccharide donor and acceptor readily.     

用内耗方法研究铜的蠕变断裂过程

在文献[1]关于工业纯铝研究的基础上,研究了工业纯铜在不同条件下蠕变过程中晶界内耗峰的变化,蠕变条件分为三类:(a)较高温度、较低应力;(b)中等温度、中等应力;(c)较低温度、较高应力;使试样分别发生晶间型、混合型和穿晶型的断裂。由晶界内耗峰的变化可以推知:在较高温度、较低应力的蠕变过程中,晶界强度变化不大;在中等温度、中等应力的蠕变过程中,晶界强度有一定程度的提高;在较低温度、较高应力的蠕变过程中,晶界强度则有比较显著的提高。这说明,在蠕变过程中,晶界强度是变化着的,在不同的蠕变条件下,晶界强化的程度不同,最终导致了不同类型的蠕变断裂。这对于“等强温度”概念是一个修正和补充。 关键词：     

CHEMICAL SPECIES OF IRIDIUM AND OTHER TRACE ELEMENTS AT K-T BOUNDARY CLAY LAYER, STEVNS KLINT, DENMARK, AND ITS IMPLICATION

The chemical species of anomalous Ir in the Fish Clay K-T boundary at Stevns Klint, Denmark, was studied by using a newly-developed chemical stepwise dissolution procedure and neutron activation analysis. The experimental results indicate that the anomalous Ir mostly exists in the acid-insoluble residue phase. The Ir pattern of the K-T boundary resembles that of the Ningqiang carbonaceous chondrite, while remarkably different from those of the ultrabasic rock and volcanic lava. Thus, we deduce that the Ir anomaly at K-T boundary is mainly extraterrestrial, instead of volcanogenic or geochemical enrichment origin. The patterns of other trace elements in various phases also confirm the above conclusion.     

Multiphoton Ionization of Monosilane

The (3 + 1) photon ionization spectra of SiH_4 have been measured. A basically continuous spectrum was recorded in laser wavelengths from 428 to 458 nm.Two vibrational progressions were found in the UV laser region of 347-392 nm, anda fine structure of the band at 363.5 nm was assigned.The fragment ions were detected by a time-offlight mass spectrometer. No parent ion SiH_4~+ was observed whereas SiH_2~+ and SiH_3~+ were the major products. The ratio of SiH_2~+/SiH_3~+ was approximately equal to that of single photon ionization at the same energy, but the fraction of Si~+ was increased. Some additional bands appeared in Si~+ spectrum in the range of 384-390 nm implicating that the increased Si~+ might be generated from SiH_2~+ and SiH~+ ions.     

双[1,3-二(三甲硅基)环戊二烯基]四羰基二铁的反应性

题示化合物分子中的铁铁键被钠汞齐还原断裂, 生成相应的单核铁负离子, 后者分别与PhCOCl, PhCH~2Cl,ClCH~2COOC~2H~5, Ph~3SnCl 及Ph~2SnCl~2进行亲核取代反应,生成在铁原子上引入相应取代基的产物。题示化合物分别与卤素和二氯化汞反应, 生成铁铁键断裂的铁卤化物和铁氯汞化物。用X-射线测定了题示化合物与Ph~3SnCl反应生成产物的晶体和分子结构。     

溶胶插入法制备高比表面TiO2柱层状铌酸

采用溶胶插入法合成了氧化钛柱层状铌酸，并用XRD、IR、BET和TEM等技术进行了表征。所得层柱材料是多孔性的，包含大量的中孔，其BET比表面积高达131.3m²·g^-1(450℃)。另外，材料具有较好的热稳定性，经450℃焙烧后其层间距为1.26nm，经550℃焙烧2h后其层柱结构仍然保持。     

水杨醛缩对氨基苯磺酸Ca(Ⅱ)配合物的合成和晶体结构

The title complex Ca(L)₂(H₂O)₅ [HL=salicylaldehyde-4-aminobenzene sulfonic acid] was synthesized by the reaction of calcium perchlorate with salicylaldehyde-4-aminobenzene sulfonic acid in the CH₃CH₂OH/H₂O. It was characterized by elemental analysis， IR and X-ray diffraction single crystal structure analysis. The crystal of the title complex [Ca(H₂O)₅(C₁₃H₁₀NO₄S)₂] belongs to orthorhombic， space group Pca2₁ with a=1.162 47(18) nm， b=0.725 91(10) nm， c=3.516 3(3) nm， V=2.967 3(7) nm³， Z=4， D_c=1.528 Mg·m^-3， μ=4.22 mm^-1， F(000)=1 424， and final R₁=0.044 2， wR₂=0.098 3. The complex comprises a seven-coordinated calcium(Ⅱ) center， with a O₇ distorted pengonal bipyramidal coordination environment. The molecules are connected by hydrogen bonds to form two dimensional layered structure. CCDC: 658852.     

核磁共振氢谱法鉴定油性圆珠笔文书的书写时间

油性圆珠笔文书书写时间的鉴定是司法鉴定工作中的热点.该文采用核磁共振氢谱法(~1H NMR)对所购6种不同型号油性圆珠笔的油墨进行了表征,研究了圆珠笔油墨中的溶剂——苯氧基乙醇在文书老化过程中的变化,并建立了MG-115书写文书的自然老化标准曲线.该标准曲线能够准确鉴定MG-115圆珠笔4个月内的文书书写时间,重现性良好;同时,该文探究了人工老化与自然老化的关系,为文书书写时间的鉴定提供了依据.     

碳氧化反应速率常数与温度特殊关系的理论解释

对于碳氧化反应,在不同温度范围内,温度对反应速率常数的影响呈现不同规律的现象进行了讨论。指出第一阶段主要由氧气在碳表面化学吸附平衡受温度的影响决定。第二阶段则由碳在二氧化碳中发生气化反应,特别是其中的酮基脱附步骤决定。对已有的反应机理进行了比较,提出了新的简化机理,并采用速率控制步骤近似和平衡近似对机理进行了近似处理,得出的第二阶段动力学方程可以较好地解释相关实验规律。     

关于表面张力和表面自由能的讨论

简要地回顾了表面物理化学中表面张力和表面吉布斯自由能(以下简称为表面自由能)两个基本概念的发展历史,讨论了表面张力和表面自由能形成的机制,以及键能与表面张力的关系,最后指出了尽管表面相可以在理论上抽象为几何面,但它是真实存在的独立相,而且由于表面自由能的原因它始终处于亚稳定状态.