HIRFL-CSR前端总线控制器的改进设计

论述了用于兰州重离子加速器冷却存储环(HIRFL-CSR)控制系统的前端总线系统控制器的改进。改进了控制器的嵌入式操作系统和应用程序,开发了控制器和数据库交换数据的应用程序。该控制器基于BGA封装的ARM920T(ARM9)处理器和嵌入式的LINUX操作系统,可以连接标准的VGA显示器、键盘、鼠标,采用了现场可编程的FPGA器件进行背板接口设计,并具有64mA高驱动能力的总线驱动器,以及拥有灵活的接口信号定义可编程能力,是HIRFL-CSR控制系统的关键部件。

基于MCGS的CSR真空连锁控制系统设计

介绍了MCGS工控组态软件,并以之构建了CSR真空连锁控制系统和系统的总体结构,相关软硬件和MCGS下设备驱动程序设计,实践证明该系统开发周期短,可靠性高,具有较好的可移植性和可扩充性。

HIRFL-CSRm内靶实验终端CsI(Tl)电磁量能器性能模拟

基于GEANT4模拟了HIRFL CSRm内靶实验终端的CsI(Tl)电磁量能器系统,给出了CsI电磁量能器的最佳设计参数及可能达到的性能.结果表明,设计的CsI(Tl)电磁量能器系统能够满足所研究的物理要求.

氮化碳薄膜的制备及研究现状

氮化碳具有良好的物理、化学性质和广泛的应用前景。目前主要采用化学气相沉积法、离子束溅射法、激光等离子体沉积和激光烧蚀、离子镀、离子注入法等制备方法。文中对氮化碳的结构、性质、制备、性能表征以及研究现状进行了比较详细的介绍。

多重示踪技术在植物学研究中的应用

简要阐述了多重示踪技术在植物学研究中的应用,主要内容有多重示踪剂的制备和分离,检测植物对金属离子的吸收和在体内的分布状况,以及在植物体细胞胚发生中对金属离子吸收的动态变化。

重离子辐照春麦稳定后代品质和贮藏蛋白的变化

低能重离子辐照春麦定西 2 4,经过多年选择获得了稳定的两个后代 1 1 8和1 1 9。品质测定和种子贮藏蛋白分析表明 :1 )同定西 2 4相比 ,1 1 8的蛋白质含量提高了 1个百分点 ,1 1 8和 1 1 9的SDS沉降值都有所升高 ;2 )在和面仪曲线分析中 ,两个品质的和面时间和 7分钟带宽均有所下降 ,而峰高和 7分钟尾高 ,1 1 8增加 ,1 1 9降低 ;3 )辐照后代的高分子量麦谷蛋白亚基类型没有改变 ,但其相对含量发生了很大变化 ;4)低分子量麦谷蛋白和醇溶蛋白区表现了新带产生和旧带消失的较大改变。品质性状及贮藏蛋白的变化为重离子辐照小麦材料实现高产、优质的结合提供了机会

Geometries of the Halocarbene anions HCF- and CF2-: ab initio calculation and Franck-Condon analysis

A theoretical method to calculate multidimensional Franck-Condon factors including Duschinsky effects is described and used to simulate the photoelectron spectra of HCF- and CF2- radicals. Geometry optimization and harmonic vibrational frequency calculations have been performed on the (X) over tilde (1)A' state of HCF and (X) over tilde (2)A" state of HCF-, and (X) over tilde (1)A(1) state of CF2 and (X) over tilde B-2(1) state of CF2-. Franck-Condon analyses and spectral simulation were carried out on the first photoelectron band of HCF- and CF2- respectively. The theoretical spectra obtained by employing B3LYP/6-311 + G(2d,p) values are in excellent agreement with the observed ones. In addition, the equilibrium geometry parameters, R(CF) = 0.1475 +/- 0.0005 nm, of the (X) over tilde (2)A" state of HCF-, and r(FC) = 0.1425 +/- 0.0005 nm and angle(FCF) = 100.5 +/- 0.5degrees, of the (X) over tilde B-2(i) state of CF2-, are derived by employing an iterative Franck-Condon analysis procedure in the spectral simulation. (C) 2003 Elsevier B.V. All rights reserved.

CO_2浓度升高对森林土壤微生物呼吸与根(际)呼吸的影响

根呼吸与微生物呼吸的作用底物不同,二者对高浓度CO2的响应机理及敏感程度亦不同。在大气CO2浓度升高的背景下,精确区分根呼吸与微生物呼吸是构建森林生态系统碳循环模型和预测森林生态系统碳源/汇关系所必需的。根(际)呼吸与微生物呼吸对高浓度CO2的响应呈增加、降低或无明显变化等不同趋势,根(际)呼吸变化主要与根生物量明显相关,细根的作用大于粗根;土壤微生物呼吸变化存在较大的不确定性,微生物量和微生物活性与土壤微生物呼吸相关或不相关。根系统对高浓度CO2的响应会潜在地影响微生物的代谢底物,进而影响微生物呼吸强度。凡影响土壤总呼吸的生物与非生物因子都会直接或间接地影响根呼吸与土壤微生物呼吸。

Double proton transfer and one-electron oxidation behaviors in double H-bonded glycinamide-formamidine complex and comparison with biological base pair

The behaviors of double proton transfer (DPT) occurring in a representative glycinamide-formamidine complex have been investigated employing the B3LYP/6-311++G** level of theory. Computational results suggest that the participation of a formamidine molecule favors the proceeding of the proton transfer (PT) for glycinamide compared with that without mediator-assisted case. The DPT process proceeds with a concerted mechanism rather than a stepwise one since no zwitterionic complexes have been located during the DPT process. The barrier heights are 14.4 and 3.9 kcal/mol for the forward and reverse directions, respectively. However, both of them have been reduced by 3.1 and 2.9 kcal/mol to 11.3 and 1.0 kcal/mol with further inclusion of zero-point vibrational energy (ZPVE) corrections, where the lower reverse barrier height implies that the reverse reaction should proceed easily at any temperature of biological importance. Additionally, the one-electron oxidation process for the double H-bonded glycinamide-formamidine complex has also been investigated. The oxidated product is characterized by a distonic radical cation due to the fact that one-electron oxidation takes place on glycinamide fragment and a proton has been transferred from glycinamide to formamidine fragment spontaneously. As a result, the vertical and adiabatic ionization potentials for the neutral double H-bonded complex have been determined to be about 8.46 and 7.73 eV, respectively, where both of them have been reduced by about 0.79 and 0.87 eV relative to those of isolated glycinamide due to the formation of the intermolecular H-bond with formamidine. Finally, the differences between model system and adenine-thymine base pair have been discussed briefly.

Theoretical study on analytical potential function and spectroscopic parameters for CaF molecule

The equilibrium properties and potential energy curves of the ground electronic state of CaF have been calculated using the Brueckner Doubles calculation with a triples contribution added [BD(T)] and the gradient-corrected density functional theory with three-parameter exact exchange mixing (B3LY-P) method, with 6-311 + G*,6-311 + G(2df,2pd) and 6-311 + G(3df,3pd) basis sets. All the computational PECs are fitted to analytical potential energy functions using Murrell-Sorbie, Huxley and Tang-Toennies potentials. Based on this, the spectroscopic parameters are calculated, and then compared with some other theoretical and experimental data. (C) 2004 Elsevier B.V. All rights reserved.