新型磷钨酸盐的合成、表征及其抑菌性能研究

甲壳低聚糖具有广谱抗菌性,对日常生活中特别是食品中一些常见的细菌、霉菌、酵母菌具有抑制作用,在抗菌抑菌方面具有很好前景[1]。杂多化合物是一类以氧原子桥联的多核配合物,由杂多阴离子、反荷阳离子及结晶水构成。一般具有大的分子体积、高分子量、好的电子和质子的传输作用和贮备能力、高的热稳定性等方面的独特性质[2]。20世纪80年代末,Yamase等[3]报道了Keggin结构钨系杂多化合物具有抗艾滋病毒活性,从而掀起了多酸化合物药物化学应用研究的高潮[4-8]。本文采用液相法将磷钨酸引入甲壳低聚糖中,合成了新型磷钨酸盐。对该盐进行红外…     

具有纳米孔结构的配位聚合物[Co2(HO-BDC)2(bpe)2(H2O)2]n·n(py)·nH2O的合成、晶体结构与热稳定性

在水-吡啶混合体系中, 以5-羟基-1,3-苯二甲酸(简作HO-H2BDC )、1,2-二(4-吡啶)乙烷(简作bpe)为配体与Co(NO3)2·6H2O反应, 培养出[Co2(HO-BDC)2(bpe)2(H2O)2]n·n(py)·nH2O(py=pyridine)的紫色单晶, 该晶体属三斜晶系, P1空间群, 晶胞参数a=1.0245(3) nm, b=1.1467(3) nm, c=1.2430(4) nm, α=68.915(5)°, β=67.163(4)°, γ=71.373(4)°, V=1.2279(6) nm3, Z=1, Mr=979.70, Dc=1.325 Mg/m3, F(000)=506, μ=0.740 mm-1, R1=0.0515, wR2=0.1058. 该配位聚合物中在ac平面上具有规则平行四边形纳米尺寸的孔, 其孔径大小约为1.025 nm×1.354 nm, 而且通过氢键相互作用连成具有双层结构的2D网络结构. TGA曲线表明, 配位聚合物的失重发生在110~150 ℃之间, 总失重约为80.1%, 最终产物为Co2O3.     

Simple estimation of electron correlation energy for multi-atomic strong ionic compounds KX and (KX)2 (X = OH, NC)

On the basis of the calculations and analyses of the intrapair and interpair correlation energy of KX (X = OH, NC) molecules and the results of the transferability of both the innermost intrapair correlation energy and the inner core effect of K and X in KX molecules, we defined and calculated the Kδ- and Xδ-correlation contributions to the total correlation energy of KX molecules. With the comparison of the pair correlation energy of K+, X- and KX systems, we present a simple estimation method to estimate the electron correlation energy of strong ionic compound by summarizing the correlation energy of its constituent ion and ionic group. By using this simple method, the reasonable estimation results of the correlation energy of (KOH)2 and (KNC)2 have been obtained at mp2/6-311++G(d) level with Gaussian98 program, and the deviations are very small. Applying the scheme of "Separate Large System into Smaller Ones" to the calculation of electron correlation energy of large ionic compounds, it can not only     

CHEMOTHERAPEUTIC POLYMERS ⅩⅩⅢ SYNTHESIS AND ANTITUMOR ACTIVITY OF POLYPHOSPHATES CONTAINING BOTH NUCLEIC ACID BASE AND PHOSPHONOACETIC ACID ETHYL ESTER

Eight new polyphosphates containing both nucleic acid base and phosphonoacetic acid ethyl ester were synthesized by the polycondensation of P, P-dichloride of phosphonoacetic acid ethyl ester with 1, 3-dihydroxyalkyl-5-fluorouracil, 1,3-dihydroxyalkyl-uracil and 1,3-dihydroxyalkylthymine. These polyphosphates were tested against Ehrlich Ascites Carcinoma in mice. Polymer IIa and IIc exhibited excellent antitumor activity. IIc also showed lower toxicity.     

DENATURATION AND PROPAGATION OF THE LOCALIZED EXCITATION IN DNA

The thermal denaturation and propagation of the localized excitation in desoxyribonucleic acid (DNA) molecules are studied in the unified way under a new Hamiltonian proposed in this work and the large amplitude motion of the DNA molecules is investigated during the propagation of the localized excitation. We discussed the nonlinear effect on the formation of the localized excitation, and showed that our model not only can reproduce the experimental results of the DNA thermal denaturation, but also can describe the process of the nonlinear localized excitation of fluctuational opening in DNA molecules.     

高原多年冻土地区遥感图像工程地质分区的探讨

简要叙述了利用遥感图像进行高原多年冻土工程地质分区的优越性,将高原多年冻土工程地质分区分为 3个大区和 10个亚区,着重叙述高原多年冻土工程地质分区判释特征,对判释特征进行了较系统的归纳,并以实例说明遥感工程地质分区判释在青藏铁路线方案比选中的作用。     

基于分子动力学的结合材料界面破坏准则

结合材料的破坏通常都是从界面或其附近发生的,但界面破坏的机理及其评价准则尚未十分清楚.采用分子动力学模拟方法,可以对结合材料的界面破坏过程进行模拟,从而获得结合材料的界面应力和界面破坏之间的关系.界面破坏可以分为奇异应力场作用下的破坏,和界面应力集中引起的破坏两种.虽然在分子动力学模拟中采用了高度简化的界面模型,但对界面破坏过程的模拟,仍可以帮助人们获得结合材料界面破坏过程的规律性认识.分别模拟远场作用下界面上存在初始裂纹和界面附近存在初始裂纹两种情况下的界面破坏,根据分子动力学模拟结果,提出了一个结合材料界面破坏的准则.     

纳米金修饰玻碳电极对儿茶酚的催化氧化

研究了电沉积纳米金修饰玻碳电极对儿茶酚的催化氧化,发现该修饰电极使儿茶酚的氧化电位大大降低,峰电流显著增大并且线性范围较宽;讨论了酸度、沉积量、扫速等条件对儿茶酚在纳米金修饰玻碳电极上催化氧化的影响。该电极制备简单,重现性好,用于儿茶酚的定量分析,发现儿茶酚氧化峰电流与浓度在2.0×10-6~1.2×10-2mol/L范围内呈良好的线性关系,相关系数为0.9965,检出限(3σ)为3.2×10-7mol/L;用于样品检测,效果较好。     

离子强度对P(HEMA-co-MMA)水凝胶溶胀性能及水的状态的影响

对甲基丙烯酸-β-羟乙酯(HEMA)与甲基丙烯酸甲酯(MMA)共聚水凝胶扩散行为、聚合物-溶剂相互作用及水的状态进行了研究。考察了不同NaCl离子强度下水凝胶平衡含水率、扩散系数及聚合物-溶剂相互作用参数的变化关系。研究结果表明,随着NaCl离子强度增大,平衡含水率降低,扩散系数下降,聚合物-溶剂相互作用参数升高。通过DSC测定了水凝胶中冻结水和非冻结水的组成。     

非磁性元素掺杂ZnO稀磁半导体研究进展

ZnO基稀磁半导体的磁性来源和机理一直是研究的热点和难点.传统的磁性3d过渡族元素掺杂ZnO容易形成铁磁性的第二相,而非磁性元素掺杂可以很好的避免这一弊端,是研究稀磁半导体磁性来源和机理的理想体系.而且理论计算和实验方面已经报道了室温以上的铁磁性.本文从实验上和理论上综述了非磁性元素掺杂ZnO基稀磁半导体最近的研究进展.