Photoluminescence from Ge-SiO2 thin films and its mechanism

Ge-SiO₂ thin films were deposited on p-type Si substrates using the radio frequency (rf) magnetron sputtering technique with a Ge-SiO₂ composite target. Films were annealed in N₂ ambience for 30 min at 300℃—1000℃ with an interval of 100℃. Through the X-ray diffraction, the average size of Ge nanocrystals (nc-Ge) was determined. They increased from 3.9 to 6.1 nm with increasing annealing temperature in the range of 600℃—1000℃. Under ultraviolet excitation, all samples emit a strong violet band centered at 396 nm. With the formation of nc-Ge, the samples exhibit another emission of orange band with the peak at 580 nm and its intensity increases with the increasing size of nc-Ge. The peak positions of two bands do not shift obviously. Experimental data indicate that the violet band comes from GeO defect and the orange band originates mainly from the luminescence centers at the interface between the nc-Ge and SiO₂ matrix.     

汉英称呼语的语用差异

本文主要论述了汉英称呼语在不同场合的应用与差异。     

Mechanical and biochemical characterization of the contraction elicited by a calcium-independent myosin light chain kinase in chemically skinned smooth muscle

Summary The contraction induced by a Ca²⁺-independent myosin light chain kinase (MLCK-) was characterized in terms of isometric force (F_o), immediate elastic recoil (SE), unloaded shortening velocity (V_us), shortening under a constant load and ATPase activity of chemically skinned smooth muscle preparations. These parameters were compared to those measured in a Ca²⁺-induced contraction to assess the nature of cross bridge interaction in the MLCK-induced contraction. F_o developed in chicken gizzard fibers as well as SE were similar in contractions elicited by either agent. V_us in the contraction induced by MLCK-(0.36 mg/ml) was similar though averaged 39.3±8.9% less than V_us induced by Ca²⁺ (1.6x10^–6M) in the control fibers. Addition of Ca²⁺ (1.6x10^–6M) to a contraction induced by MLCK-resulted in small increases in both F_o and V_us. Shortening under a constant load was similar for both types of contractions. The contraction induced by MLCK-was accompanied by an increased rate of ATP hydrolysis. The MLCK-induced contraction is thus kinetically similar though not identical to a contraction induced by Ca²⁺. We conclude that with respect to actin-myosin interaction, MLCK- and Ca²⁺-induced contractions are similar.     

关于促进口头交流的三条建议

随着全球经济的不断发展，人与人之间的交流合作日渐增多，口头交流表达变得越来越重要．本文从交流技巧方面入手针对如何有效地促进口头交流提出了三条建议：考虑对方的观点，不要轻易放弃自己的观点和怀疑自己的感受，尊重并听取别人的感受和思想。     

Velocity and myosin phosphorylation transients in arterial smooth muscle: effects of agonist diffusion

Summary Transients in myoplasmic [Ca²⁺] and in phosphorylation of the 20,000 dalton light chain of myosin have been reported following stimulation of vascular smooth muscle by various agonists. Since these transients are rapid compared with the time required to attain a steady-state stress, agonist diffusion rates may be a significant limitation in activation. The purpose of this study was to estimate the effect of agonist diffusion rates on the time course of activation as assessed by mechanical measurements of stress development and isotonic shortening velocities and by determinations of the time course of myosin phosphorylation. The approach was to measure these parameters in K⁺-stimulated preparations of the swine carotid media of varying thicknesses and to estimate the theoretical contributions imposed by diffusion rates and the presence of a diffusion boundary layer surrounding the tissue. The results show that the time course of parameters which are tissue averages such as stiffness, active stress, and myosin phosphorylation is dominated by agonist diffusion rates. The sequence of events involved in excitation-contraction coupling including agonist actions on the cell membrane, Ca²⁺ release, activation of myosin light chain kinase, and cross-bridge phosphorylation appear to be very rapid events compared with stress development. Estimates of unloaded or lightly loaded shortening velocities which are not simple tissue averages appear to provide an imporoved estimate of activation rates.Supported by a grant from the National Institutes of Health 5-PO1-HL19242. K. E. Kamm was supported by a National Heart, Lung, and Blood Institute Research Service Award HL-05957.     

微机二级控制印染联合机同步传动系统研究

主要论述了微机两级控制系统在各种联合机同步传动中的应用.上位机为PC总线586工业控制计算机,下位机由单片机、西门子变频器等组成.     

C/1995 O1(Hale-Bopp)彗星的光变研究

汇集了上海天文台佘山观测基地自 1996年 4月 2 2日至 1997年 5月 2日期间所得的C/1995O1(Hale -Bopp)彗星的CCD观测资料 ,得出了这些资料的测光归算处理结果 ,并在此基础上对此彗星的光度变化规律进行了分析研究 .     

Novel oscillations in cell suspensions ofDictyostelium discoideum

Summary With a light-scattering technique, two novel rhythms were discovered in cell suspensions ofDictyostelium discoideum. One is a damped oscillation with a period of 2 to 2.5 min (at 23°C) induced by folate in EDTA-dissociated undifferentiated cells. The other is a sinusoidal oscillation with a period of about 12 min occasionally observed with late differentiated cells. Obviously, the repertoire of rhythms of this simple eukaryotic organism is larger than previously assumed.     

胶体的光学效应及混凝速率的测定

实验验证了Ｒａｙｌｅｉｇｈ－Ｍｉｅ光散射理论在测定胶体颗粒尺寸上的应用，并提出利用稳定胶体浊度的测定来确定该胶体颗粒尺寸的精确方法。对于直径小于１μｍ的颗粒，这种方法很可靠。结合光散射理论和Ｓｍｏｌｕｃｋｗｓｋｉ混凝速率理论建立了混凝胶体的浊度变化与混凝速率的定量关系，并提出混凝速率和胶体稳定性的精确测定方法。用这种方法对均匀胶体的混凝速率进行了测定，并验证了Ｓｍｏｌｕｃｋｗｓｋｉ混凝理论。     

电光源光通量及光效的简捷测定

给出无光通量专用测试设备情况下，用普通照度计，瓦特计测光电源光通量及光效的一种方法。