烷基镁对杯芳烃钕催化苯乙烯聚合反应的影响

用助催化剂二正丁基镁和催化剂P204Nd及第三组分六甲基磷酰胺(HMPA)组成的催化体系是苯乙烯聚合的优良催化体系,能以很高的转化率得到高分子量的聚苯乙烯[1],用杯芳烃钕配合物代替P204Nd作为催化剂也能得到很好结果[2].为了提高其助催化作用,丁基镁是用镁粉和氯代正丁烷在弱极性溶剂甲苯中制备的.丁基镁在甲苯中的溶解度比较小,要加入少量的三乙基铝,以增加其在甲苯中的溶解度.镁粉和氯代正丁烷在甲苯中的反应没有在四氢呋喃中容易进行,每次制备出的丁基镁的浓度和Mg/Al的物质的量比都有较大的差别,对苯乙烯的聚合产生明显影响.为此我们…     

Secure Direct Communication Using Ensembles with the Same Compressed Density Matrix

In this paper, a quantum secure direct communication protocol using ensembles with the same density matrix is proposed. The two communication parties can realize the message transmission using this method through a quantum channel, each bit of information can be transmitted using an ensemble and read out through global measurement. The eavesdropping behavior can be detected through the channel diagnoses.     

Relativistic Consistent Angular-Momentum Projected Shell-Model:Angular-Momentum Projection

The angular-momentum projection part of RECAPS is presented. Application of RECAPS to some deformed nuclei is also presented.     

Secure Direct Communication Using Ensembles with the Same Compressed Density Matrix

In this paper, a quantum secure direct communication protocol using ensembles with the same density matrix is proposed. The two communication parties can realize the message transmission using this method through a quantum channel, each bit of information can be transmitted using an ensemble and read out through global measurement.The eavesdropping behavior can be detected through the channel diagnoses.     

超临界CO2-DME混合物竖直圆管内传热特性数值研究

本文采用RNG k-ε湍流模型对超临界CO₂/DME(二甲醚)二元混合工质在竖直圆管内的传热特性进行了数值模拟研究。管径4 mm,管长为1000 mm;CO₂/DME浓度配比分别为97/3、95/5、92/8、90/10、85/15、以及70/30;质量流速为125~200 kg·m^-2.s^-1;热流密度为15~30 kW.m^-2,入口温度295~308 K,入口压力8~15 MPa。不同浓度配比的混合工质在各自临界压力下应用时,随着DME浓度的增加,换热系数的峰值逐渐减低,但在温度大于310 K时混合工质的换热系数会高于纯CO₂。压力相同时,随着DME浓度的增大,拟临界温度升高,换热系数峰值点也随之向温度升高的方向移动。混合工质的换热系数随质量流速的增大而增大。在拟临界点前,增大热流密度及降低压力对管内传热有利,而在拟临界点之后,换热系数随热流密度的升高以及压力的降低而降低。     

A Characterization on the Spectra of Self-Affine Measures

Journal of Fourier Analysis and Applications - A discrete set $$\Lambda \subseteq {\mathbb {R}}^d$$ is called a spectrum for the probability measure $$\mu $$ if the family of functions $$\{e^{2 \pi...     

One-step synthesis of some polyfluoroalkylated 1,3-benzodioxoles, 4H-1,3-benzodioxins and dibenzo[d,f] [1,3]dioxepins

Several polyfluoroalkylated heterocyclic compounds containing methylenedioxy group such as 2-(F-alkyl) substituted 1,3-benzodioxole, piperonal, 4H-1,3-benzodioxin, 1,3-dioxolane and 6-(F-alkyl) substituted dibenzo[d, f][1,3]dioxepin have been prepared through double Michael-addition reactions of 2,2-dihydropolyfluoroalkanoates with the corresponding diphenols or diols in high yields.     

油田增产措施合理规划的优化模型研究

在考虑均衡使用增产措施的前提下,以油田规划期内增产措施5年的产油量最大为目标,以增产措施的产油量下限、产水量和费用的上限、增产措施的工作量上限为约束条件建立了规划期内增产措施产油量最大的整数线性优化模型,并运用LINDO6.1对模型编程求解和分析,给油田规划提供一个很好的参照.     

High-Dimensional Multi-particle Cat-Like State Teleportation

Two kinds of M-particle d-dimensional Schmidt-form entangled state teleportation protocols are presented.In the first protocol, the teleportation is achieved by d-dimensional Bell-basis measurements, while in the second protocolit is realized by d-dimensional GHZ-basis measurement.