脂肪酶不对称水解含酯基的异核金属簇合物

对脂肪酶催化含酯基的异核金属簇合物的水解反应进行了初步研究. 发现脂肪酶对簇合物的酯基进行水解时确有不对称效应, 同时簇骨架中的重金属使酶失活. 尽管不知道水解产物的e.e.值,但从旋光结果可以看出, 酶催化确是一条拆分手性簇合物的途径.     

一种低功耗的混合谐振时钟分布机制

提出了一种低功耗的混合谐振时钟分布机制,通过改进的旋转行波振荡器产生和分布方波形全局时钟信号,采用基于片上变压器的谐振电路产生局部谐振时钟信号.在SMIC 0.13μm CMOS工艺下,对目标频率为1 91GHz的混合时钟网络进行了设计和仿真,能够显著降低时钟系统功耗.     

Determination of the stellar reaction rate for 12C（α,γ）16O： using a new expression with the reaction mechanism

The astrophysical reaction rate of 12C(α, γ)16O plays a key role in massive star evolution. However, this reaction rate and its uncertainties have not been well determined yet, especially at T9=0.2. The existing results even disagree with each other to a certain extent. In this paper, the E1, E2 and total (E1+E2) 12C(α, γ)16O reaction rates are calculated in the temperature range from T9=0.3 to 2 according to all the available cross section data. A new analytic expression of the 12 C(α, γ)16 O reaction rate is brought forward based on the reaction mechanism. In this expression, each part embodies the underlying physics of the reaction. Unlike previous works, some physical parameters are chosen from experimental results directly, instead of all the parameters obtained from fitting. These parameters in the new expression, with their 3σ fit errors, are obtained from fit to our calculated reaction rate from T9=0.3 to 2. Using the fit results, the analytic expression of 12C(α, γ)16O reaction rate is extrapolated down to T9=0.05 based on the underlying physics. The 12C(α, γ)16 O reaction rate at T9=0.2 is (8.78 ± 1.52) × 1015 cm3s-1mol-1. Some comparisons and discussions about our new 12 C(α, γ)16 O reaction rate are presented, and the contributions of the reaction rate correspond to the different part of reaction mechanism are given. The agreements of the reaction rate below T9=2 between our results and previous works indicate that our results are reliable, and they could be included in the astrophysical reaction rate network. Furthermore, we believe our method to investigate the 12C(α, γ)16O reaction rate is reasonable, and this method can also be employed to study the reaction rate of other astrophysical reactions. Finally, a new constraint of the supernovae production factor of some isotopes are illustrated according to our 12C(α, γ)16O reaction rates.     

激光偏振实验装置研制

本文介绍自制激光偏振实验装置的结构和实验原理。     

回旋辐射的半经典量子理论

基于半经典量子理论讨论了强磁场中非相对论性热电子的回旋辐射过程,在四极近似下导出回旋共振吸收系数k_ν、回旋共振吸收截面σν及回旋共振微分散射截面的表达式.结果表明,强磁场中电子回旋共振吸收截面远大于自由电子的Thomson散射截面.     

NBUE分布类应力-强度模型的概率上界

研究应力-强度模型的结构的可靠性分析,当元件应力变量分布属于NBUE类,强度变量服从指数分布,给出了应力-强度模型中概率的上界,由此讨论了n个元件组成系统的应力-强度模型概率上界.     

快速测定酶法动力学拆分中转化率和ee值的新方法

在动力学拆分反应中 ,转化率和对映体过量值( ee值 )是经常需要测量的两个重要参数 .传统的测定转化率的方法包括色谱法、分光光度法和滴定法等 .而测定 ee值主要应用手性色谱柱、手性毛细管电泳、核磁以及旋光法等 .在动力学拆分过程中 ,需要对反应进程进行监测 ,而应用传统的方法进行监测需要同时测定两个量 (转化率和 ee值 ) ,工作量较大 ,且使用手性色谱柱进行监测成本也较高 ,不适合大量实验数据的常规分析 .为此 ,需要发展一种快速、灵活、经济的测量方法 ,用以实验前期筛选条件时的常规分析 .基于此思路 ,我们借助于自己编制的计算机…     

我国光纤无源器件的现状及其前景展望

本文介绍了光纤无源器件概况,重点阐述了其在我国的发展现状以及对其未来发展趋势的展望。     

漫话光纤通信

1996年，高锟(C.K.Kao)博士首先提出玻璃     

动量矩守恒定律的定量验证

通常验证动量矩守恒的教学实验多是定性的,本文介绍一种定量验证动量矩守恒定律的教学实验。一、实验原理本实验通过可变转动惯量圆盘在水平转动过程中,在∑M外=0条件下,自行改变其转动惯量,并由光电门测速系统分别测