外场下二甲基硅酮双自由基的从头计算研究

本文首先采用密度泛函(DFT)方法在6-311+g(2d,p)基组水平上计算研究了二甲基硅酮双自由基的红外振动光谱和核磁共振化学位移,而后在同样的基组水平上采用含时密度泛函(TDDFT)方法研究了外电场对二甲基硅酮双自由基的激发态、偶极矩和分子能量的影响,结果表明,不同方向的外加电场对他们的影响情况各不相同,沿X、Y方向的电场对激发态的激发能、振子强度影响在外加电场为0.005～0.010 a.u.是转折点,沿Z方向的电场在电场强度为0.015 a.u.是转折点.沿Y方向的外电场对分子的偶极矩、分子能量影响最大,沿X方向的外电场次之,沿Z方向的外电场对偶极矩和分子能量影响最小.     

64位技术重塑PC产业链

新兴的64位市场,正悄然地影响着整个产业链,昔日固若金汤的英特尔联盟如今正悄然松动2004年4月前后,台湾笔记本厂商宏荟、华硕和明基相继推出基于64位AMD处理器的笔记本电脑产品;国产PC老二方正也接受了AMD投来的64位橄榄枝;英特尔也一改常态,开始大力宣扬自己的64位计划。     

Continual auxiliary leakage-resilient attribute-based broadcast encryption with constant size ciphertexts

Attribute-based broadcast encryption ( ABBE) under continual auxiliary leakage-resilient ( CALR) model can enhance the security of the shared data in broadcasting system since CALR model brings the possibility of new leakage-resilient (LR) guarantees. However, there are many shortcomings in the existing works, such as relying on the strong assumptions, low computational efficiency and large size of ciphertexts, etc. How to solve the trade-off between security and efficiency is a challenging problem at present. To solve these problems, this paper gives an ABBE scheme resisting continual auxiliary leakage ( CAL ) attack. ABBE scheme achieves constant size ciphertexts, and the computational complexity of decryption only depends on the number of receivers instead of the maximum number of receivers of the system. Additionally, it achieves adaptive security in the standard model where the security is reduced to the general subgroup decision (GSD) assumptions (or called static assumptions in the subgroup). Furthermore, it can tolerate leakage on the master secret key and private key with continual auxiliary inputs. Performance analysis shows that the proposed scheme is more efficient and practical than the available schemes.     

千赫兹亚纳秒径向偏振光北大核心CSCD

利用Nd…YAG/Cr4+…YAG键合晶体被动调Q和S波片得到亚纳秒径向偏振光。采用峰值功率为30 W、脉宽为120μs、重复频率为1kHz的脉冲半导体激光端面抽运方式,得到了脉冲宽度为878ps、单脉冲能量为76.8μJ的调Q激光脉冲输出,其重频不稳定性小于±0.003%,幅值不稳定性小于±3%。然后通过在键合晶体后插入偏振片和S波片的方式,得到纯度大于96%、单脉冲能量为27.5μJ的亚纳秒径向偏振光。     

顶空气相色谱法测定食品添加剂中15种有机溶剂残留量

建立了顶空气相色谱法同时测定食品添加剂中甲苯、甲醇、正己烷等15种有机溶剂残留量的分析方法。选择N,N-二甲基甲酰胺对不同食品添加剂中的有机溶剂进行提取,将样液转移至顶空瓶中密封,顶空进样测定。对提取溶剂、提取方式、平衡时间和平衡温度等进行了优化。结果表明,15种有机溶剂分离良好,各残留溶剂在相应浓度范围内呈良好的线性关系,相关系数不小于0.999 8,定量下限为10.0 mg/kg(三氯甲烷和吡啶为20.0 mg/kg),回收率为90.6%~109.1%,相对标准偏差为0.1%~7.2%。该方法灵敏度高,重现性好,适用于食品添加剂中甲苯、甲醇、正己烷等15种残留溶剂的检测分析。     

从德国实验仪器谈现代技术与物理教学

1 德国实验仪器简介 Phywe公司从事物理、化学、生物等的科学实验设备教学和研究.它的产品在德国制造,在世界各地小学到大学的教育和研究领域广泛使用.     

EGCG在Tween80胶束体系中的性质(英文)

通过离子萃取技术,从黄山绿茶中提取高纯度儿茶素没食子酸酯(EGCG).在Tween 80/EGCG/H2O体系中,随着EGCG浓度增加,Tween 80临界胶束浓度和胶束动力学半径增大;随着Tween 80浓度增加,EGCG和Tween 80扩散系数减小,而EGCG的紫外-可见吸收光强度和荧光强度增加.对EGCG在Tween 80胶束中的定位也进行了讨论.     

STUDIES ON ELECTROANALYTICAL CHEMISTRY OF RARE EARTH ELEMENTS——POLAROGRAPHIC INVESTIGATION OF CARBOXYNITRAZO (CNA) AS A LIGAND OF RE-CNA COMPLEXES

The polarographic behaviour of carboxynitrazo (CNA) has been investigated in detail by means of single-sweep, DC, AC polarography and cyclic voltammetry. It has been shown that CNA has different reduction mechanisms in acidic and basic solutions. In acidic solution, the first wave is reversible and the second involves the disproportionation mechanism with acid catalysis, while in basic solution the first wave splits into two and the second wave has no disproportionation characteristics. The third wave is the reduction of nitro-group in the molecule.     

STUDIES ON THE ELECTROANALYTICAL CHEMISTRY OF RARE EARTHS——THE ADSORPTIVE-COMPLEX WAVE OF THE COMPLEXES OF N, N'-DI-(2-HYDROXY-5-SULPHOPHENYL)-C-CYANFORMAZAN (DSPCF) AND LIGHT RARE EARTH ELEMENTS

The sensitive adsorptive-complex wave of the complexes formed by light rare earth elements and DSPCF is studied in this paper. The electroactivities of the complexes of light (La-Eu) and heavy rare earth elements (Gd-Lu), are quite different, so we can determine a certain light rare earth element or the total amounts of light rare earths without separating them from heavy rare earths. The mechanism of the adsorptive-complex wave and the reason why heavy rare earths could not form the electroactive complexes have been studied as well.