介孔硅与大孔硅的结构、电学和气敏特性

采用双槽电化学腐蚀法在P型单晶硅表面制备两种多孔硅.根据它们的孔径将它们分为介孔硅和大孔硅.使用扫描电子显微镜(SEM)观察两种多孔硅表面和断面形貌,介孔硅和大孔硅的表面化学键用傅里叶变换红外(FTIR)光谱仪来研究,通过I-V特性测试表征两种多孔硅电学特性,随后在室温下测试其气敏特性.结果表明:介孔硅具有较高的气体灵敏度,大孔硅具有较好的气体响应恢复特性.介孔硅对NO2气体具有较好的选择性,大孔硅对NH3气体具有较好的选择性.     

从零维硅量子点到二维硅烯:纳米硅单质的发现历程

20世纪90年代,多孔硅发光现象的发现,掀起了硅的低维材料的研究热潮。从零维硅量子点,到一维硅纳米线、硅纳米管,再到二维硅烯,不同形态的纳米硅逐步被发现。这些发现从理论预测到实验合成,从宏观尺度到界观尺度,丰富发展了对于硅的原有认识。随着理论研究的深入和技术手段的进步,纳米硅的种类、性质、合成方法等在不断地更新完善。纳米硅作为重要的半导体纳米材料,其发现历程中所蕴涵的新理论、新方法,对纳米材料的研究具有启示作用。     

硅改性密封剂的进展

简要地回顾了硅改性聚醚和硅改性聚氨酯密封剂的出现和发展 ,对硅改性聚醚和硅改性聚氨酯的制备作了简要的介绍 ,并对硅改性密封剂的配方、性能和应用作了进一步阐述。     

硅杂六元环化合物的合成

本文综述了环上只含有一个硅原子的硅杂六元环化合物在有机合成方法学方面的进展。介绍了通过α,ω-双金属试剂的关环反应、硅烯参与的[4+2]环加成反应、生成C—Si键的关环反应、生成C—C键的关环反应、硅杂环扩环反应等来合成硅杂六元环化合物,总结了硅杂环己烷、硅杂环己烯以及硅杂环己二烯等不同结构化合物的常见合成方法,为促进硅杂六元环化合物在有机合成化学和材料科学方面的进一步应用提供了基础。     

硅纳米晶的制备及其在太阳电池中的应用研究

硅纳米晶由于量子限域效应的作用而产生了多种不同于体硅材料的新特性,如荧光效应显著、光学带隙可调等,因而在微电子、光伏、生物医学等领域受到极大的重视。本文介绍了分立的硅纳米晶颗粒和硅纳米晶薄膜的制备方法,并对比了不同方法制备硅纳米晶体的优缺点。着重介绍了硅纳米晶体在太阳电池中应用的几种方式,包括利用纯硅纳米晶薄膜制备太阳电池、硅纳米晶体与有机薄膜基质结合形成复合结构太阳电池、含有硅纳米晶颗粒的硅墨水在太阳电池中的应用等。     

锰硅合金中硅的测定

锰硅合金可作为炼钢脱氧剂。根据合金中含锰和含硅量不同 ,分为各种牌号的合金 ,所以合金中含硅量的数据也要求准确。锰硅合金中硅的测定 ,原采用锰铁合金中硅的分析方法进行测定 ,因锰硅合金中硅含量较锰铁合金中硅含量高 ,试样不易溶解完全 ,锰与铁也不易分离完全 ,至使分析结果偏高。后又采用铁 (镍 )坩埚碱熔 ,试样虽溶解完全 ,但在溶样过程中试样易溅出 ,造成损失 ,且碱熔时易将铁 (镍 )坩埚腐蚀而转入试液中 ,洗二氧化硅沉淀时难于洗净 ,至使结果偏高。为此 ,经试验 ,采用盐酸 -过氧化氢溶样 ,动物胶重量法测定锰硅合金中的硅 ,经试验…     

差示分光光度法测定硅铝铁合金中高硅

差示分光光度法测定硅铝铁合金中高硅李树伟，李凤丽（四川师范大学化学系成都，６１００６８）（成都航空发动机公司成都，６１００６６）关键词硅，合金，差示分光光度法硅铝铁合金在航空工业、机械工业领域有着广泛的应用。该合金中硅含量较高（硅含量１５－２０％），...     

硅钙合金中非合金相态硅的分析

硅钙合金是一种炼钢脱氧剂,其中若存在游离硅、二氧化硅杂质会影响炼钢脱氧效果,目前国家标准无硅钙合金中游离硅分析方法。研究了氢氧化钠溶液提取非合金相硅的条件,用硅钼蓝光度法分析硅含量,分析方法回收率达95.9%,可用于硅钙合金中非合金相硅测定。     

由硅醚经脱保护-氧化-Wittig反应一锅法合成α,β-不饱和酯

在1摩尔醋酸和稳定的Wittig试剂存在下,活性MnO2作为氧化剂时,硅醚发生脱保护-氧化-Wittig反应.考查了各种硅醚,诸如苄基硅醚、炔丙基硅醚、烯丙基硅醚和烷基硅醚等作底物在反应性能方面的差异.该反应使硅醚直接形成碳碳双键而得到α,β-不饱和酯.产物的结构经红外光谱、核磁共振谱表征.     

过氧化氢氧化硫酸耐尔蓝催化褪色光度法测定痕量硅

测定痕量硅的方法有硅钼蓝光度法、间接原子吸收光谱法、硅钼蓝杂多酸极谱法、流动注射示差动力学化学发光法、硅钼蓝．罗丹明B离子缔合物分光光度法、阻抑．褪色光度法、硅锑钼杂多酸．罗丹明B四元络合体系光度法、乙基罗丹明B-硅钼杂多酸．PVA光度法、乙基罗丹明B-硅钼杂多酸．阿拉伯树胶体系分光光度法及停流流动注射化学发光法,未见     

Tautomerism and conformational isomerism of mercaptoacetylhydrazones of aliphatic and aromatic aldehydes

Mercaptoacetylhydrazones of aliphatic and aromatic aldehydes exist in the solutions as tautomeric mixtures of open-chain and cyclic 1,3,4-thiadiazine forms. The linear hydrazone form consists of a set of isomers due to the configurational and conformational isomerism. At growing bulk of the alkyl substituent at the C=N bond of the aliphatic aldehydes derivatives decreases the fraction of the cyclic tautomer; therewith the logarithms of the constants of the chain-ring tautomeric equilibrium correlate with the steric constants of the alkyl substituents. In the series of the aromatic aldehydes mercaptoacetylhydrazones the linear tautomer prevails, and the equilibrium position is insignificantlyt affected at variation of the electronic characteristics of the substituents in the aromatic ring.     

取代基物化参数及其在药物定量构效关系中的应用

把取代基电性、立体及疏水性物化参数组合建立一种新取代基描述方法, 对环尿素类和N,N-二甲基-2-溴苯乙胺类衍生物进行结构表征. 对训练样本集通过逐步回归筛选变量, 所建多元线性回归方程R2分别为0.853和0.960, 留一法交互检验Rcv2分别为0.723和0.901；用预测集样本作外部预测, 所得Qext2分别为0.7617和0.7653. 结果显示：环尿素类化合物结构中苯环邻位立体、间位疏水、对位疏水及立体因素对该类药物抗HIV活性产生阻抑作用； N,N-二甲基-2-溴苯乙胺类苯环上取代基立体因素及对位给电子效应有利于提高肾上腺素能阻断活性.     

Changes in Electron Structure of the Triple Bond in Substituted Acetylene and Diacetylene Derivatives

The substituent effect is usually considered by means of various Hammett-like substituent constants and is most often related to aromatic systems. Unlike this, we present results of our research on the influence of 27 substituents spanning a wide range of electronic properties, from strongly electron-withdrawing to strongly electron-donating, on the electron structure of X-substituted acetylenes and diacetylenes – thus the systems which until now have practically not been subject of any deeper studies. It is shown that the interaction through triple bond(s) is associated with a significant advantage of resonance effects and that the substituent effect transmitted by the C≡C−C≡C unit is about half of that transmitted by the C≡C unit alone. Substituent X mainly affects the closest carbon atom by means of proximity effect, hence changes of charge on this atom do not follow any substituent constants. The effect on further carbon atoms is much smaller. The presence of the C≡C−C≡C unit withdraws more charge from X than a triple bond alone, and hinders communication between X and the terminal H atom. Comparison of substituent effects to those present in X-substituted benzene derivatives shows that the electronic properties of the terminal hydrogen atom in acetylenes and diacetylenes are most similar to the electronic properties of ortho and para hydrogen atoms in X-substituted benzene derivatives.     

η3:η1⇌η2-tautomerism in carbonyliron complexes. Influence of substituents

A number of chelate η³-allylcarbamoyl iron complexes (I) with different substituents (R in the allyl ligand and R′ at the nitrogen atom) were synthesized. The influence of structural features on the equilibrium between the complexes I and their η²-azadiene tautomers (II) was studied by IR spectroscopy. It was established that the equilibrium position is determined in the first place by steric factors. When R is a bulky substituent the equilibrium is shifted towards the cyclic form I, whereas the branching of the alkyl substituent R′ at the nitrogen atom favours the open olefinic form II. Furthermore π-σ-(N) rearrangement of complexes II to σ-(N) derivatives (III), and the conversion of III into η⁴-azadiene complexes (IV) also depend on the steric requirements of the substituents R and R′.     

Stereoelectronic effects on type I 1,2-dyotropic rearrangements in vicinal dibromides

The effects of different substituents on type I-dyotropic rearrangements of open-chain and cyclic 1,2-dibromo hydrocarbons have been studied by means of DFT calculations. The activation energy (E(a)) of this transformation decreases with the pi-donor ability of the substituent attached to the reacting ethylenic system. This is due to donation of electronic density by conjugation or hyperconjugation. This donation leads to longer C--C and C--Br bond lengths in the corresponding four-membered transition states (TSs). Linear relationships between the E(a) and either the sigma(p) Hammett substituent constants and the C--C bond length of the TSs were also found. In all cases, the processes have a high value of synchronicity, which is mainly independent on the substituents. A model based on the second-order perturbational analysis for one ethylene unit with two apical bromine radicals accounts for all the computed results.     

1-烃基-1-硅杂环丁烷的合成及其Si—H键伸缩振动频率与结构关系的研究

硅杂环丁烷在有机硅化学中是一类非常重要的小分子环系化合物。由于硅杂环丁烷和环丁烷的环张力相似,因而显示出较高的反应活性。例如能与某些试剂作用,生成开环产物;在光解或热解条件下,产生具有Si=C结构的高活性中间体,可用以合成多种有机硅化合物。     

IR studies in the substituted benzaldehyde series provide a new definition of sigma-plus constants of ionic substituents

Fourier-transform IR frequencies nu(C=O) and integrated intensities A(C=O) of the carbonyl groups of a series of benzaldehydes (53 compounds) have been measured in dimethyl sulphoxide. Excellent and satisfactory correlations have been found between nu(C=O) and sigma(+) substituent constants of the m- and p-substituted compounds. Diortho-substituted compounds deviate strongly from the correlation lines because of the steric ortho-effects mainly. sigma(+) constants of ionic substituents (10 examples) have proved satisfactorily valid in the series studied.     

Nitrogen-containing organosilicon compounds. 150. Synthesis and chromatographic and 1H, 13C, 15N,and 29Si NMR spectroscopic investigation of substituted (piperidinoalkyl)silanes

Substituted (piperidinoalkyl)silanes were synthesized and investigated by means of multinuclear NMR spectroscopy and GLC. The data obtained indicate an additional N-Si interaction in -aminomethylsilanes that depends substantially on the properties of the substituents attached to the silicon atom. The effect of the R¹R²R³Si substituent on the capacity of the nitrogen atom for intermolecular interactions is not restricted to steric effects but also has electronic character.See [1] for communication 149.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1644–1652, December, 1991.     

Pd—SnO_2/D3520催化剂上碳碳双键化合物催化加氢活性与取代基性质的相关性

本文研究了Pd－SnO2／D3520系列催化剂催化碳碳双键化合物加氢活性与取代基性质的关系，结果表明：催化加氢活性（logR0）与F（诱导效应和场效应）、R（共轭效应）和Es（位阻效应）均有良好的线性关系，并且，线性关系与Sn的含量有关。     

Correlation of the nuclear quadrupole resonance frequencies of Cl35 of dihydrochlorides of certain phosphorus acids with the σφ constants of substituents on the phosphorus atom

Conclusions Two linear relationships exist between the nuclear quadrupole resonance frequencies of Cl³⁵ in dichlorides of certain phosphorus acids and the constants of substituents at the phosphorus atom; one of them is formed by alkyldichlorophosphonates, while the other is given by compounds in which conjugation is possible between the substituent and the d-orbitals of phosphorus-alkyldichlorophosphates, aryl- and vinyldichlorophosphonates.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2375–2378, November, 1967.Some of the substances were synthesized by G. P. Kharitonova, whom the authors would like to thank.