Effect of Intersubband Coulomb Interaction on Hot-Electron Transport in Two-and One-Dimensional Electron Systems

We study the hot-electron transport properties of model GaAs-based quasi-two-dimensional(-quantum-well) and quasi-one-dimensional'(quantum wire) systems having two occupied subbands by using the Lei-Ting balance-equations for two types of carriers. Both the intersubband electron-phonon interaction and intersubband Coulomb interaction are taken into account. Our numerical results show that when the electron density is high enough, the intersubband Coulomb interaction is substantially strong in thermalizing the electrons between the different subbands. As a consequence, the one-type-of-carriers model (OTCM) is a good approximation for electron transport. However, in the cases of the lower electron densities, the intersubband Coulomb interaction is not strong enough to fire the electrons in differents-ubbands to share a common electron temperature and a more accurate two-types-of-carriers model (TTCM) must be used for analysis.     

Heterolytic and homolytic bond dissociation energies of the N-NO bonds in N-nitroso diethyl phosphoramidates

Interest in nitric oxide(NO) as a biological radical in affecting human life has increased dramatically over the last twenty years.^[1] It has been implicated in diverse physiological process, including vasodilatory and antiplatelet effects, macrophage-induced cytotoxicity, and neurotransmission.     

Five Coniferyl Alcohol Derivatives from Ligularia Duciformis

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奇点处分岔解支的数目问题*

本文在孤立奇点的假设下证明了带参数非线性方程组解的孤立性,同时指出在分岔点处必有而且仅有有限条解支分岔出来．这一结论是分岔问题数值方法的一个理论基础．     

Anticancer Drugs (VI)——Synthesis and Activity of Spin Labeled Derivatives of 4-Amino-4-deoxy-4′-demethylepipodophyllotoxin

Some derivatives of podophyllotoxin(1), such as etoposide(12), possess antitumor activity and have been extensively used clinically^[1]. Because etoposide has a less solubility in water and higher toxicity, many chemists have an interest in further studies on the modification of the C-4 substituent of 1 for its better antitumor activity. Lee Kuo-hsing, Wang Zhe-qing et al. have synthesized a series of derivatives of CA (substituted anilino)-4-deoxypodophllotoxin. The pharmaceutical tests have shown that a number of 4β-(arylamino )-4'-demethylepi-podophyllotoxin are as potent as or more potent than etoposide(12) in inhibiting the human DNA topoisomerase Ⅱ.     

均匀Fe~3O~4胶体粒子形成机理II. 低温Mossbauer谱研究

在液氮温度下, 测定了均匀Fe~3O~4胶体粒子制备过程中陈化时间为1小时内的不同时间所得样品的Mossbauer谱。结果表明, γ-FeOOH为Fe~3O~4均匀胶粒形成过程的中间产物, 并提出均匀Fe~3O~4胶粒的形成机理。     

p-(N,N-二甲氨基)肉桂酸乙酯在分子聚集体中的光化学行为

本文报道了p(N,N-二甲氨基)肉桂酸乙酯(DMAC)在十二酸(LA)聚集体中的光谱和光化学性质。这种肉桂酸衍生物的吸收和发射光谱表现出典型的分子内电荷转移的特征,在十二酸存在下,观察到DMAC激基缔合物荧光,荧光强度随DMAC浓度增加而增加,与普通溶液中的反应相比,十二酸聚集体中的DMAC具有较大的光二聚反应速度。用荧光光谱跟踪反应的结果表明,DMAC激基缔合物具有较DMAC单体更高的光化学活性。     

过渡金属卡宾配合物V.铼的阳离子卡拜配合物与邻-碳硼烷双锂盐的反应及其产物π-环戊二烯基二羰基[(1-碳硼烷基)(苯基)卡宾]铼的晶体结构

铼的阳离子卡拜配合物,[π-C5H5(CO)2ReCC6H5]BBr4(1),在THF中低温下与1,2-碳硼烷双锂盐反应,生成π-环戊二烯基二羰基[(1-碳硼烷基)(苯基)卡宾]铼[π-C5H5(CO)2ReC(C2HB10H10)-C6H5](2)及π-环戊二烯羧基[(1-碳硼烷基甲酰基)(苯基卡拜)铼[π-C5H5(CO)(COC2HB10H10)-ReCC6H5](3),和1与邻-碳硼烷单锂盐反应所生成的产物完全相同.2的分子结构已由单晶X-射线结构分析证实.属于单斜晶系,空间群为P21/n,晶胞参数:a=14.043(8)埃,b=8.302(6)埃,c=17.926(11)埃,β=93.96(5).晶胞中有四个分子.其结构已用重原子法解出并用块矩阵最小二乘法修正,最后的偏离因子R=0.076.同时也讨论了可能的反应机制.     

A NEW KIND OF POCKET GAMMA-NEUTRON DOSERATE CHIRPER

In order to avoid unnecessary or unallowable exposure in the gamma-neutron mixed field, the radioactive-contact person should know the radiation environment at any time by himself when he is working. A new kind of pocket radiation doserate monitor (chirper) based on silicon PIN photodiode as detector is designed. It can be used to monitor the gamma doserate in the order of 1 mrem/h and the neutron doserate in the order of 10 mrem/h simultaneously. In this paper, the detector selection, the circuit design, the construction and the performance of the chirper prototype are described.     

脂族酰基过氧化物分解动力学的研究VI.过氧化月桂酰和过氧化3,5,5-三甲基己酰热分解产物的化学诱导动态核极化(CIDNP)

过氧化月桂酰(1),过氧化3,5,5-三甲基己酰(2)在2-碘丙烷存在下,于邻二氯苯中热分解的1H NMR谱表现出典型的自由基产物的增强吸收和发射的多重效应,对1分解产物的1H CIDNP谱图的定量处理,得到了主要极化产物的相对浓度与时间的关系,测定了1-碘十一烷α-CH~2和1-十一烯双键CH~2质子的自旋晶格弛豫时间T~1,并求得增强因子和一级速率分解常数。