SMC 15MN液压机上横梁刚度分析试验

本试验采用“冻结”刚度这一新测试方法,测试了 SMC 15MN 液压机上横梁的刚度分布,并抽样验证了此种方法的可靠性。试验结果表明 SMC 压机结构在刚度分布上比较合理,刚性较好,同以往箱型焊接结构相比有较大优越性。     

一堂物理课

 我是一位中学教师,我深爱《现代物理知识》,在讲授《卢瑟福核式结构》一课时,我向同学们言简意赅地介绍了那上面的一篇文章:《原子核壳模型发现前后》.当我讲述卢瑟福提出有效模型是怎样成功地解释盖革与马斯顿的实验结果时,同学们顿时活跃起来,纷纷想一展身手,体验一次科学发明的过程.然而,物理上的每一个发现,都是科学家凭借坚实的理论基础和实验事实而获得的.在教师的指导下,同学们通过阅读教材,得出了如下结论:“如果是枣糕式模型,α粒子穿过原子内部时,它受到原子内两侧的斥力相互抵消,使α粒子偏转不会很大”.     

Synthesis,X-Ray Structure and Characterization of a Triruthenium Cluster Complex Ru_3~Ⅲ(μ_3-O)(μ-CH_3COO)_6(py)_2Cl with Four Steps One-electron Redox Processes

Great attention is currently paid to the synthesis of polynuclear transition metal complexes as well as their photochemical, photophysical, and electrochemical properties. The design of multicomponent systems capable of performing useful light- and/or redox-induced function is of special interest1. The oxo-centered carboxylate-bridge trinuclear ruthenium clusters have been investigated extensively during recent decades because they have remarkable electron-transfer properties, intense visibl…     

A Novel Organic—Inorganic Complex：Synthesis and Crystal Structure of [Ca（DMSO）5（H2O）]2 SiMo12O40

It is becoming a focus to synthesize and assemble organic-inorganic materials, especially, to synthesize charge-transfer complexes formed by polyoxometalate and organic donors. They have attracted much attention because such complexes are active in their electric, magnetic and optic properties1-4, many investigations about them have been done and some crystal structures of them were reported5-6. But, the disadvantage of these crystals is instability at room temperature. According to the view…     

Dioxygen Affinities and Catalytic Oxidation Performance of Cobalt (II)Complexes with N-Aryl Hydroxamic Acid

It is well known that the study on biomimetic oxygen carriers not only has important theoretic significance to discover the mechanism of reversible bonding, activating oxygen as well as the oxidation reaction in organism, but also has potential application in separating oxygen from air and realizing the high efficiency and selectivity of catalytic oxidation reaction under a mild condition1. Metal- porphyrin and metal- phthalol- gaunine have been extensively used as biomimetic oxygen carriers u…     

Dendritic Macroinitiator for the Ring—Opening Polymerization of γ—Benzyl L—Glutamate N—Carboxyanhydride

Much effort has been dedicated to the molecular design and synthesis of model proteins to define protein folding interactions and to develop protein-based materials. Among them, the ring-opening polymerization of -amino acid-N-carboxyanhy- drides (NCAs) has drawn much attention because the resulting artificial polypeptides have wide applications in biotechnology, biomineralization and diagnostics1, 2. It is well known that dendrimers are hyperbranched macromolecules possessing a very high co…     

Indium (III) Tribromide : An Excellent Catalyst for Biginelli Reaction

A highly efficient catalyst indium (III) tribromide is used to synthesize 5-alkoxy- carbonyl-4-hydrocarbyl-3,4-dihydropyrimidin-2(1H)-ones by a three-component coupling of β-keto ester, aldehydes and urea through improved Biginelli reaction.     

Spacial Structure of Cationic Phosphorus Ligand–Ru (II) Halide Complexes—by DFT Study

The increasing demand to produce enantio-pure pharmaceuticals, flavors, and other fine chemicals has advanced the field of asymmetry catalytic technologies. Among all asymmetry catalytic methods, catalytic enantioselective hydrogenation of unsaturated bonds such as olefins, ketones, and imines, which employs dihydrogen and small amounts of transition-metal complexes modified intrinsically by chiral ligands, is now recognized as being the most promising strategy for the synthesis of large amount…     

The Purification of Glucose Type Glycosyl Nitrate and the Synthesis of Spacer—armed N—Acetyllactosamines and Their Dimers

Our previous paper1,2reported the results of selective synthesis of mannose type glycosides and their dimers in our attempt to synthesize derivatives of N-acetyllacto- samine, which could have potential activity of anti-metastasis3. Further studies on the glycosylation of the accepters exploiting glycosyl nitrate instead of the acetate as donor showed interesting chemoselectivity between the two kinds of donor, namely, the glucose type and the mannose type. The reactivity difference of the t…     

Ag+、Hf2+与Tl3+对Belousov-Zhabotinskii反应影响的初步研究

本文初步研究TAg＋、Hg’十与T13十对以Mh‘十为催化剂的B－Z反应的影响，观察这些Br’去除离子存在下的极投环行为，并对其机理进行初步研讨．按照FKN机理同，B－Z反应是受Br一控制的．1979年N。SZtiCZills将适量的Ag十加入B·Z反应系统，澳离子选择电极上振荡虽被抑制了，但拍电极上却出现频率更高的振荡问．由于Ag十与Bt一生成了AgBr沉淀，使系统的［Br则降至其临界值以下，因此，Noszticzius认为不可能是Br控制的，FKN机理不再适用．1981年K5rs。等人报导了能与Br一形成稳定配合物的Hg‘十与T户十对B－Z反应的影响［3］…