直键与弯键的对称性判据

一穹键的提出人们认为,杂化轨道(HAO)角函数的最大值方向(亦即HAO的方向)指向与之键合的原子,这样形成的化学键称为“直键”。但环丙烷分子中的三个碳原子构成三元环,有60°的键角。而任意两个正交的S-P杂化轨道之间的夹角θ都不可能小于90°,因而形成C-C键的HAO,不可能指向键合原子,环上的C-C键不可能是直键,而是“弯键”(BentBond)。通常,人们认为张力分子环上的键是弯键,其他的键为直键。     

桥链七甲川菁的合成及光性能

菁是一种具有多功能用途的染料,除用作卤化银感光材料及有机光导材料的光谱增感剂、光记录材料中记录介质外,还可作为染料激光器中用的激光染料.我们曾合成了四甲川苯乙烯菁、五甲川(艹粦)及五甲川吡喃鎓等红外染料作为激光染料,测定了它们的光性能.本文合成了具有桥链的七甲川菁,研究了这些桥链七甲川菁的吸收光谱及荧光光谱,并以YAG激光倍频(532nm)作泵浦源,测定了它们的激光调谐范围、中心波长及激光转换效率.     

Nitriding of titanium with plasma jet under reduced pressure

The nitriding of titanium with argon-nitrogen (3%) and argon-nitrogen (3%)-hydrogen (2%) plasma jets at pressures of 190 torr was studied. The reaction kinetics obeyed mainly a parabolic law. The parabolic kinetic constants were 10^–10–10^–8 g² cm^–4 s^–1, which were 2–3 orders of magnitude larger than those in R.F. discharges. From emission spectroscopy, nitrogen atoms in the excited states were observed. The nitrogen atoms can promote the nitriding reaction. The effect of the addition of hydrogen to nitrogen is also briefly discussed.     

Diagnosis of OH Radical by Optical Emission Spectroscopy in Atmospheric Pressure Unsaturated Humid Air Corona Discharge and its Implication to Desulphurization of Flue Gas

OH radical in the corona discharge with pipe–nozzle–plate electrode has been diagnosed by optical emission spectroscopy. Spatial variations of OH radical emission in discharge gap have been measured. Relative intensity of OH radical emission spectroscopy increases with increasing water vapor flux injected into the reactor or intensity of electric field supported. In positive pulsed corona discharge, relative intensity is higher than that in positive DC corona discharge and lower than that in negative DC corona discharge. Strongest intensity of OH radical spectrum appears within the range of 5 mm near the discharge nozzle- electrode. In addition, it is proved that the efficiency of desulphurization from flue gas by pulsed corona discharge plasma processes can be improved when OH radical is produced in the reactor.     

Effect of HF addition on the microwave-assisted acid-digestion for the determination of metals in coal by inductively coupled plasma-atomic emission spectrometry

The microwave-assisted acid-digestion for the determination of metals in coal by ICP-AES was investigated, especially focusing on the necessity of adding HF. By testing five certified reference materials, BCR-180, BCR-040, NIST-1632b, NIST-1632c, and SARM-20, it was found that the two-stage digestion without HF (HNO₃ + H₂O₂ was used) was very effective for the pretreatment of ICP-AES measurement. Both major metals (Al, Ca, Fe, and Mg) and minor or trace metals (Co, Cr, Cu, Mn, Ni, Pb, and Zn) in coal gave good recoveries for their certified or reference values. The possibility of ‘HF-memory effect’ was cancelled by the use of a set of vessels which had been never contacted with HF. Twenty-four Japanese standard coals (SS coals) were analyzed by the present method, and the concentrations of major metals measured by the present method provided very high accordance with those from the authentic JIS (Japanese Industrial Standard) method.     

鲨鱼软骨质量的聚类分析法

用电感耦合等离子体原子发射光谱法（ＩＣＰ－ＡＥＳ）测定了１８个鲨鱼软骨真品中１３个元素含量，对测定结果进行分析和变量聚类分析，抽提５个特征指标，并以谱系数聚类建立了鉴别鲨鱼软骨真伪的数学模式，用３个假冒产品和一个鲨鱼软骨胶囊对其进行检验，结果表明，用无机元素所建立的数学模式不仅能鉴别鲨鱼软骨的真伪，还能区分鲨鱼软骨的部分及不同部位的混合物。     

Photophysical properties of new anthracene-ended calix[4]resorcinols

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覆氧或氧离子轰击下固体表面二次正离子发射的研究

通过对离子轰击下固体表面电离过程重新考虑认为，在固体表面覆氧或氧离子轰击下除表面原子的直接电离外，激发态双原子间电子交换和断键亦起重要作用。在此基础上修正了局部热力学平衡模型，得到了一个包含各类离子内配分函数、电离能、金属－氧原子键断键能以及表面金属原子与氧原子结合份数等参数决定的新电离几率分析表达式。应用该分析表达式解释了金属表面覆氧、氧离子轰击金属、化合物半导体表面二次离子发射中氧增强效应、充氧量对二次离子发射的影响及其基体效应等实验现象。并由此得到了元素相对灵敏度因子的分析表达式，对化合物半导体及一些陶瓷材料表面二次离子质谱分析中元素灵敏度因子随元素电离能变化曲线给予了相应的物理解释。     

7-(2-Methoxycarbonylvinyl)-3-hydroxychromones: new dyes with red shifted dual emission

7-(2-Methoxycarbonylvinyl)-3-hydroxychromones have been synthesized using Heck coupling reaction from the corresponding 7-bromo-3-hydroxychromones. Introduction of the electron acceptor (2-methoxycarbonylvinyl) group at 7-position of 3-hydroxychromone results in a 30-40 nm red shift in absorption and >50 nm red shifts of both bands in emission. This derivatization allowed us to develop dyes with absorption maxima reaching 480 nm and dual emission in the red region of the spectrum. In comparison to the parent dyes, 7-acryl-3-hydroxychromones demonstrate significantly stronger solvatochromism. This is due to the acceptor group at 7-position, which increases the transfer character of the excited state of the dyes. The new dyes are highly prospective for the development of new fluorescent probes in biological research.     

Anti-Controlling Codimension-2 Bifurcation of Discrete Dynamical Systems in 1 : 2 Resonance北大核心CSCD

从分岔反控制的角度设计了一套非线性反馈控制策略,来实现离散动力系统1∶2共振情形下余维二分岔的各种分岔解。首先,针对传统分岔准则在确定高余维分岔点时存在的局限性,建立了一个1∶2共振情形下的余维二分岔的新显式准则,基于这个显式准则通过设计线性控制增益来确保此类余维二分岔的存在性。然后,推导了1∶2共振的中心流形,并基于范式方法通过设计非线性控制增益,分析了1∶2共振情形下余维二分岔解的类型和稳定性。最后,以一个Arneodo-Coullet-Tresser映射为例,在指定的参数点处通过控制实现了具有1∶2共振分岔特性的各种分岔解,进一步验证了理论分析。