硼氢二茂铁季铵盐的结构化学研究——Ⅰ、十硼十氢双(二茂铁甲基三甲基)铵晶体结构

本文报告了(C_5H_5FeC_5H_4CH_2N(CH_3)_3)_2B_(10)H_(10)晶体的结构。该晶体属三斜晶系、空间群为P_1~-。晶胞参数为:a=10.043(2),b=10.513(7),C=15.094(10),a=85.01(6),β=97.58(3),Υ=94.87(3)°,V=1625.7~3,Z=2。晶体在室温下用CAD-4四圆衍射仪收集衍射强度数据(MoKa),用重原子法解出铁原子坐标,综合应用E图、Fourief合成和差Fourier合成解出其他非氢原子坐标,按SDP加氢程序等求解阳离子中40个氢原子位置。各原子坐标及热振动参数经全矩阵最小二乘方修正,对于2258个独立衍射点(I≥3σI)],偏离因子R=0.043。 结构分析表明,B_(10)H_(10)~(2+)阴离子和C_5H_5FeC_5H_4CH_2N(CH_3)_3~+阳离子分别按畸变的八面体和畸变的三角形配位。两个二茂铁季铵阳离子中,两对戊二稀环平面间距为3.271(5)。阳离子中主要键长平均值为:Fe-C=2.026,C—C(环)=1.401,C—N=1.503。B_(10)H_(10)~(2+)阴离子为四方(三角)十六面体笼状结构,主要键长平均值为:B—B(顶点到正方形平面原子)1.706A,B—B(其它原子间)=1.830。     

寓教于乐在数学教学中的实践

马克思曾指出："热情就是一个人努力达到自己目标的一种积极的力量"．在数学课堂教学中，课本是剧本，学生是演员，老师是导演，寓教于乐使课堂教学始终洋溢着宽松和谐的气氛，学生在课堂中始终热情高涨、探索进取、争论质疑、反馈信息，能更好地使学生在"数学知识市场"上积极地汲取知识和发展能力．寓教于乐实践之一：教学民主教学民主是解除师生间心理障碍的有效途径，且能提高信息反馈的传递速度．而教学过程，则是双边活动的过程，是教师与学生配合的过程，也是情感交流的过程．只有在互相信任，互相尊重的前提下教师与学生才会产生积极…     

THE THREE-DIMENSIONAL STRUCTURE OF TRICHOSANTHIN MOLECULE

A model completed recently of two trichosanthin molecules in an asymmetric unit belonging to themonoclinic system is reported. It can be seen that the molecular, structure consists of two domains, onelarge and one small, and that there are some features in the secondary structure. The dissimilarity be-tween two molecules as well as their interactions in an independent unit rorrelated in a non-symmetricway has been described. moreover, the binding sites of the heavyatom position in the derivatives are alsodiscussed.     

蛋白质与钍试剂Ⅰ作用的电化学行为的研究

在pH4．8的NaAc-HAc缓冲液中，钍试剂I与蛋白质能够相互作用形成超分子复合物，使钍试剂Ⅰ在-0．58v(SCE)处的极谱还原峰峰电流下降，在最佳条件下，峰电流的下降值同牛血清白蛋白(BSA)的质量浓度在1．5～25mg／L范围内呈线性关系，其线性回归方程为△iρ=-265．4 181．2pBsa，相关系数r=0．998(n=7)，检出限为1mg／L。可应用于血清样品的测定。     

硼氢二茂铁季铵盐的结构化学研究——Ⅱ.三硼八氢N—二茂铁甲基三甲基铵的晶体构结

本文报道了C_5H_5FeC_5H4CH_4N(CH_3)_3B_3_H_8的晶体结构。晶体属正交晶系,空间群为Pnam,晶胞参数:a=13.707(6),b=13.365(4),c=9,339(9),Z=4用三维Patterson函数等方法解出全部非氢原子的坐标和B_3H_8~-中“氢桥”的2个H原子坐标,对817个独立衍射点[I≥3σ(I)]计算偏离因子,最终偏离因子R=0.071 C_5H_5FeC_5H_4CH_2N(CH_3)_3B_3H_8为离子型化合物,B_3H_8~-阴离子和C_5H_5~-FeC_5H_4CH_2N(CH_3)_3~+阳离子按四面体配位,配位数为4。二个戊二烯环平面相互平行,相距3.31,且属完全遮盖型的。二个戊二烯环平面之间夹角φ)=1.7°。平均键长:Fe—C=2.057,C—C(Cp环)=1.438,C—N=1.513。B_3H_8阴离子中“氢桥”的2个H原子和3个B原子共面。B—B(氢桥连结)=1.734;B—B(非氢桥连结)=1.779。“氢桥”是非对称的,B—H(氢桥)分别为1.460和1.209。     

天花粉蛋白2.6A分辨率的晶体和分子结构

天花粉蛋白晶体已经在2.6A分辨率进行晶体学修正,本文将详细描述天花粉蛋白的晶体和分子结构,在总结8种核糖体失活蛋白氨基酸顺序规律的基础上,结合天花粉蛋白晶体和分子结构对15个最保守的氨基酸残基进行分析,发现Gin 156,Glul60,Arg 163和Glu189 4个最保守的极性氨基酸残基聚集在大小结构域交界处的分子表面上,构成了蛋白分子的活性中心。     

Frontier orbital interactions of electron pushing and drawing substituents with ferrocenyl group

The frontier orbital interactions of electron pushing and drawing substituents with ferrocenyl group were analyzed based on the electrochemical,UV visible spectral and spectroelectrochemical results of five ferrocene derivatives,R-Fc-A1(PⅠ),A1-Fc-A1(PⅡ),D-Fc-R (PⅢ),D-Kc-A1(PIV) and D-Fc-A2(PV)(R,CH2OH;A1 CHO;A2,CH=C(CN)2 and D,(C18H37)2N-C6H4-CH=CH) It was found that there are strong interactions of the LUMO (πA) of electron drawing substituents with le2g(dxy,dx2 y2)and e2u of the ferroeenyl group because the energy levels of πA and e2g,C2U of (Cp )2 are close,which lower not only the energy levels of bonded orbits,πA+ and dx2-y2+[πA] of PⅠ,PⅡ,PⅣ and PⅤobviously,but also those of their non-bonded orbu dxy For PⅢ,PⅣ and PⅤ,there are strong interactions of HOMO(πD) of the electron pushing substituent with le of the ferrocenyl group because the levels of πD and e of (Cp)2 are close,which result in the formation of anti-bonded orbit,πD- and bonded orbit     

粘弹性减阻流动的雷诺应力模型研究

针对由Giesekus本构方程描述的粘弹性槽道减阻流动,建立了低Re数雷诺应力模型.通过与DNS数据的比较,该模型对平均速度、平均变形、减阻率和应力的预测较准确,而对时均速度剖面和脉动速度强度的预测精度有待提高.另外,对雷诺应力再分配项(压强变形率相关项)的模化有待改进.     

Comments on <Emphasis Type="Italic">Three-point explicit compact difference scheme with arbitrary order of accuracy and its application in CFD</Emphasis>

The explicit compact difference scheme, proposed in Three-point explicit compact difference scheme with arbitrary order of accuracy and its application in CFD by Lin et al., published in Applied Mathematics and Mechanics （English Edition）, 2007, 28（7）, 943-953, has the same performance as the conventional finite difference schemes. It is just another expression of the conventional finite difference schemes. The proposed expression does not have the advantages of a compact difference scheme. Nonetheless, we can more easily obtain and implement compared with the conventional expression in which the coefficients can only be obtained by solving equations, especially for higher accurate schemes.     

Enhancement of next-nearest-neighbouring entanglement in quantum Ising spin chain

Using the method of the Jordan--Wigner transformation for solving different spin--spin correlation functions, we have investigated the generation of next-nearest-neighbouring entanglement in a one-dimensional quantum Ising spin chain with the Gaussian distribution impurities of exchange couplings and external magnetic fields taken into account. The maximal value of entanglement between the next-nearest-neighbouring qubits in the transverse Ising model was analysed in detail by varying the effectively controlled parameters such as interchange coupling, magnetic field and the system impurity. For such systems, where both exchange couplings and external magnetic field disorder appear, we show that it is possible to achieve next-nearest-neighbouring entanglement better than the previously discussed pure Ising spin chain case. We also show that the Gaussian distribution impurity can induce next-nearest-neighbouring entanglement, which can be used as a means to characterize quantum phase transition.