混合稀土对ZA27合金阻尼性能的影响

研究了ＺＡ２７合金的稀土变质机制及阻尼性能,利用悬臂梁测试了阻尼能力。结果表明,合金中加入Ａｌ－１０％ＲＥ中间合金可以细化组织和提高阻尼能力,稀土添加量为０．３％时有最佳的变质效果和最佳高的阻尼能力。     

稀土化合物增强ZA—27合金耐磨性的研究

对稀土化合物增强ＺＡ－２７合金的组织及耐磨性做了研究。试验发现,由于在ＺＡ－２７合金中加入一定量的ＥＲ和Ｓｉ元素,组织中出现一些颗粒状第二相;这些物相分布在晶界及枝晶间,阻止了晶粒长大。通过航向电镜能谱分析发现,该物相是一种含有Ｚｎ、Ａｌ、Ｓｉ及ＲＥ元素的复杂化合物。经测试,这种物相的显微硬度要比基体高得多。耐磨性等性能试验结果表明,这种合金的耐磨性要比ＺＡ－２７合金高４倍,比Ｓｉ相增强合金也高,     

稀土化合物增强ZA—27合金耐磨性的研究

对稀土化合物增强ＺＡ－２７合金的组织及耐磨性做了研究。试验发现,由于在ＺＡ－２７合金中加入一定量的ＥＲ和Ｓｉ元素,组织中出现一些颗粒状第二相;这些物相分布在晶界及枝晶间,阻止了晶粒长大。通过航向电镜能谱分析发现,该物相是一种含有Ｚｎ、Ａｌ、Ｓｉ及ＲＥ元素的复杂化合物。经测试,这种物相的显微硬度要比基体高得多。耐磨性等性能试验结果表明,这种合金的耐磨性要比ＺＡ－２７合金高４倍,比Ｓｉ相增强合金也高,     

稀土对高强锌合金耐磨性和耐蚀性的影响

ＺＡ２７合金中加入稀土，由于合金化，变质等作用使合金微观组织发生变化，强化了合金，因此提高了合金的综合性能和耐磨性，又因稀土加入能净化晶界，对电化学性产生有利影响，所以合金的耐蚀性也得到改善。     

混合稀土与铈对铝-镁合金凝固组织及光泽度的影响

研究了混合稀土及铈对铝-镁合金凝固组织、硬度、表面光泽度的影响。稀土加入Al-1.0％Mg-0.5％Si合金中能明显细化合金的凝固组织,且随稀土加入量增加,合金的二次枝晶间距减小。在<6％范围内,随着稀土加入量的增加,合金的硬度明显提高。当加入0.1～0.3％RE时,合金的最大反射率可达89％,并能提高光泽度持久性,当超过0.3％时,光泽度逐渐下降。金属型铸造试样的光泽度比砂型铸造的要高。     

铈对Zn-22%Al减振合金组织和力学性能的影响

借助于光学显微镜、透射电镜及扫描电镜,采用自然时效、人工时效等热处理工艺,研究了微量Ｃｅ对Ｚｎ－２２％Ａｌ减振合金显微组织和力学性能的影响,Ｃｅ具有细化Ｚｎ－２２％Ａｌ合金组织并障碍时效时晶粒长大和等轴程度降低的作用,在低于８０℃的温轧温度下效时,加Ｃｅ和不加Ｃｅ的Ｚｎ－２２％Ａｌ合金的强度不随时间的推移而变化。Ｃｅ还提高了Ｚｎ－２２％Ａｌ合金的强度和时效时力学性能的稳定性。     

稀土对ZA27合金底缩影响的机制

研究了金属镧和铈基混合稀土对凝固速率为３２℃／ｍｉｎ的ＺＡ２７底缩的影响。结果表明，Ｌａ和混合稀土均使ＺＡ２７底缩体积和总缩孔体积减小；二者加入量大于０３％时，底部缩孔封闭，内部缩孔位置逐渐上移。稀土化合物下沉富集在试样底部，是造成底部缩孔封闭的原因。由于稀土的加入不能有效地阻止α初生相的上浮，内部缩孔位置仍靠近试样底部。     

Fe—15Cr—4Al—Y合金中的Y—Fe相及其作用

在含０．２％－１．４％Ｙ的Ｆｅ－１５Ｃｒ－４Ａｌ－Ｙ合金中，１－１０μｍ的Ｙ－Ｆｅ相质点弥散分布，其硬度高于ａ相的２倍，组成可用Ｙ２（Ｆｅ７６Ｃｒ１２Ａｌ１１Ｓｉ）１７表示。Ｙ－Ｆｅ相强烈俘获ａ相中的碳原子，使合金在固溶处理状态下的Ｓｎｏｅｋ内耗峰消失，在７００℃下析出碳化物。Ｙ－Ｆｅ相南点通过阻止闰长大而抑制合金的高温脆化，通过俘获碳原子而延缓４７５℃脆性发展。此外，它们还有提高热强性和抗氧化性     

稀土7075铝合金中块状化合物的结构和形成规律

用分析电镜、扫描电镜等手段研究了稀土７０７５铝合金中粗大块状化合物的成分、结构和形成规律。研究表明，在铸态稀土７０７５合金中出现的粗大块状化合物是一种（Ｃｒ，Ｔｉ）２ＲＥ（Ａｌ，Ｘ）２０型稀土化合物，其中Ｘ为Ｍｇ，Ｃｕ，Ｚｎ等元素。该化合物具有体心立方结构，晶体常数为１．４５３－１．４５８ｎｍ，显微硬度为４０００－５６００ＭＰａ，计算密度为３．４ｇ／ｃｍ＾３。合金中（Ｔｉ＋Ｃｒ）含量的减少和凝固时     

稀土对钨钴钛类硬质合金性能及组织结构的影响

研究了在钨钴钛类硬质合金中的添加稀土元素对合金性能和组织结构的影响，以及稀土在硬质合金中的存在形貌和分布状态。结果表明，添加稀土后合金性能如抗弯强度和抗冲击性都有明显提高，并着重阐述了稀土对ＷＣ－１４ＴｉＣ－８Ｃｏ合金的强化机理。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.