树枝状十二酯的合成

以乙二胺和丙烯酸十二酯为原料，甲醇为溶剂，采用迈克尔加成反应合成了低代的树枝状十二酯。探讨了反应条件对树枝状十二酯收率的影响。乙二胺2mL(30mmol)，n(乙二胺)：n(丙烯酸十二酯)=1：6，甲醇占反应液总体积的50％，反应温度40℃，反应时间48h，产率54．9％。     

TEOS-MTES基SiO2溶胶微结构的SAXS研究

正硅酸乙酯(TEOS)为前驱体,在碱性条件下制备含有无定形SiO2颗粒的溶胶,以甲基三乙氧基硅烷(MTES)在酸性条件下获得聚甲基硅氧链,二者混合后应用同步辐射X射线进行混合溶胶的SAXS散射强度测定,计算了溶胶的平均回转半径、平均粒径、两相界面层厚度、散射体体积分数、两相间比表面积等参数,辅以光子相关光谱法(PCS)和透射电子显微镜(TEM)观测溶胶粒度,证实SiO2颗粒被MTES混合物连接成族团.实验发现所测混合溶胶样品均表现出对Porod定理的负偏离,说明溶胶中颗粒与溶剂之间存在很明显的两相间界面层.     

高性能计算机用热管复合制冷系统设计研究

根据高性能计算机全天候温控的需要,提出了综合应用蒸气压缩和动力型分离式热管制冷技术的复合冷源方案。在冬季及春、秋过渡的低温季节,运行热管循环不仅大幅降低环控装置的能耗,而且可以避免在低温环境运行压缩式制冷易发生的冷启动、回油润滑等问题。提出了蒸气压缩制冷、蒸气压缩/热管复合制冷和热管制冷的分区工作模式,引入复合制冷模式有效拓宽了热管运行温区,大幅提高了制冷系统的综合COP。模拟分析了在北京地区应用热管复合制冷技术的节能性能,相比常规的压缩制冷节能率高达40%。研究表明:热管复合制冷系统具有显著的节能减排优势,特别适用于全天候工作的机房、基站等高热密度电子集成系统的温控。     

导体表面的电荷分布

关于导体表面的电荷分布，部分普物教材和一些学者对此作过定量的计算和理论上的探讨，其中罗恩泽提出了导体表面电荷密度按表面曲率的分布函数理论．本文对罗恩泽的理论提出异议．笔者认为，赵凯华、戴显熹等人对此问题的论述是全面、正确的. 但他们的论述是定性的，本文对此作一些定量补充     

Synthesis and Crystal Structure of a New Pr(Ⅲ)–K(Ⅰ) Heterometallic Oxalate Coordination Polymer

A new 3D heterometallic coordination polymer, namely [K2Pr2(C2O4)4·H2O]n(1), has been successfully synthesized under hydrothermal conditions. X-ray single-crystal diffraction determination reveals that 1 crystallizes in monoclinic system, space group P21/n with a = 12.060(4), b = 8.493(3), c = 15.776(5)(A), β = 93.235(3)°, V = 1613.4(9) 3, Z = 4, Mr = 730.12, Dc = 3.006 Mg/m3, μ = 6.581 mm-1, F(000) = 1368, the final R = 0.0283 and w R = 0.0866 for 2939 observed reflections with I 2σ(I). Complex 1 features an unusual 3D heterometallic coordination framework, in which oxalates exhibit three different coordination behaviours. Moreover, powder X-ray diffraction and thermal properties for 1 have also been investigated.     

己二胺为核酯为端基的半代树枝状大分子的合成

以己二胺和丙烯酸甲酯为原料合成了以己二胺为核酯为端基的半代树枝状大分子,其结构经IR和元素分析表征。在己二胺50 mmol,n(丙烯酸甲酯)∶n(己二胺)=6∶1,于50℃反应12 h的条件下,收率99.4%。     

自组装聚酰胺-胺大分子对甲基橙相转移行为的影响

自组装聚酰胺-胺大分子对甲基橙相转移行为的影响;树枝状大分子;聚酰胺-胺;甲基橙;分子自组装     

超支化铬系催化剂的合成及乙烯齐聚性能研究

以正辛胺和十二胺为原料,分别制备了两种超支化PNP配体,通过引入金属铬活性位点的方法合成了具有不同烷基链长度的超支化PNP铬系催化剂.采用红外光谱(IR)、核磁共振磷谱(~(31)P-NMR)、核磁共振氢谱(~1H-NMR)、紫外光谱(UV)和质谱(MS)等表征方法证明合成催化剂的结构与理论结构预测相符.详细考察了催化剂用量、溶剂种类、反应条件以及配合物结构对乙烯齐聚性能的影响.实验结果显示,超支化PNP铬系催化剂在甲苯作溶剂,甲基铝氧烷(MAO)做助催化剂时表现出良好的催化乙烯齐聚性能,产物主要为低碳烯烃.在最佳条件下,催化活性最高可达到1.69×10~5 g·(mol Cr·h)~(-1),己烯和辛烯的选择性为43.3%以上.相同聚合条件下,其催化活性随着端基烷基链长度的增加而下降.     

Thermal stress reduction of GaAs epitaxial growth on V-groove patterned Si substrates

We investigate the thermal stresses for GaAs layers grown on V-groove patterned Si substrates by the finite-element method. The results show that the thermal stress distribution near the interface in a patterned substrate is nonuniform,which is far different from that in a planar substrate. Comparing with the planar substrate, the thermal stress is significantly reduced for the Ga As layer on the patterned substrate. The effects of the width of the V-groove, the thickness, and the width of the SiO₂ mask on the thermal stress are studied. It is found that the SiO₂ mask and V-groove play a crucial role in the stress of the Ga As layer on Si substrate. The results indicate that when the width of V-groove is 50 nm, the width and the thickness of the SiO₂ mask are both 100 nm, the Ga As layer is subjected to the minimum stress. Furthermore,Comparing with the planar substrate, the average stress of the Ga As epitaxial layer in the growth window region of the patterned substrate is reduced by 90%. These findings are useful in the optimal designing of growing high-quality Ga As films on patterned Si substrates.