2,3,4- or 2,3,5-trisubstituted furans: catalyst-controlled highly regioselective ring-opening cycloisomerization reaction of cyclopropenyl ketones

2,3,4- or 2,3,5-trisubstituted furans were highly regioselectively formed from the cycloisomerization reaction of the same starting cyclopropenes 1 via the subtle choice of the transition metal halides. Under the catalysis of 5 mol % PdCl2(CH3CN)2, 2,3,5-trisubstituted furans 2 were given in 50-88% yields with 95-99% regioselectivities, while 2,3,4-trisubstituted furans 3 were formed in 78-96% yields with 99% regioselectivities under the catalysis of 5 mol % CuI.     

Hydrothermal Synthesis of Acicular Lead Titanate Fine Powders

A pure, acicular lead titanate (PbTiO₃) fine powder with a white color has been prepared by hydrothermal synthesis. It is a new phase of PbTiO₃ with I 4 symmetry, cell parameters of a = 12.358 Å and b = 14.541 Å, and a density of 6.80 g.cm⁻³. The influences of pH (12.5 to 14.4), Pb/Ti ratio (1.0 to 1.6) in the feedstock, reaction temperature (130° to 230°C), time (0.25 to 4 h), starting materials, and additives on the formation of acicular PbTiO₃ under hydrothermal conditions have been investigated. The acicular PbTiO₃ with I 4 symmetry, referred to as the PX phase, can be converted to the perovskite-type (PE phase) of PbTiO₃ at about 605°C while its acicular morphology is essentially unchanged. The preferable conditions for preparing pure acicular PX-phase PbTiO₃ are that the pH is 13.0 to 14.0, Pb/Ti ratio is >1.3, reaction temperature is 170° to 200°C, time is 0.5 to 1.0 h, titanium butoxide (Ti[O(CH₂)₃CH₃]₄) is the starting material, and poly(vinyl alcohol) is an additive. The acicular grain of the PX phase is usually less than 100 nm in diameter and more than 1000 nm in length.     

自发参量下转换光场的实验研究进展综述

自发参量下转换(spontaneous parametric down-conversion,SPDC)光场是基于单色泵浦光子流和量子真空噪声对非线性晶体的综合作用而产生的,它固有的量子起源决定了在非经典光场研究中的重要地位和作用.对SPDC光场的相干特性和它在绝对测量光电探测器量子效率中的应用进行了深入而细致的研究和探讨.     

Continuous Separation of Inclusions from Aluminum Melt Flowing in a Circular Pipe using a High Frequency Magnetic Field

The continuous separation of inclusions from aluminum melt flowing in a circular pipe using a high frequency magneticfield was investigated both theoretically and experimentally The separation efficiency was calculated based on thetrajectory method and compared with experimental results. It is found that the separation efficiency is a functilnondimensional parameters t_i·d_p~2B_e~2/μ_fμ_eα~2 and α/δ.The effective way to improve the separation efficiency is to increasethe effective magnetic flux density and decrease the pipe radius. and the value of α/δ should be kept about 2 in orderto obtain the optimum separation efficiency.     

HYQ-965-Ⅲ解堵剂的研制及现场应用

针对涠洲11-4油田W11-4D-A1井返吐油基泥浆堵塞油管问题,以渗透剂、乳化剂、分散剂、互溶剂为原料,制备了HYQ-965-Ⅲ解堵剂.考察了不同配方解堵剂中原料间的配伍性和溶垢效果,研究了最佳配方:渗透剂Ⅰ20%、乳化剂Ⅰ10%、分散剂10%、互溶剂10%、海水50%.将该解堵剂在W11-4D-A1井进行应用,从现场使用情况看,HYQ-965-Ⅲ对油基泥浆、原油具有很好的分散能力,成功解除了油管堵塞,达到预期设计要求.     

氮气氛下LTCC基板Cu共烧金属化研究

从PMMA型LTCC素坯膜的制备和PMMA的排胶机理两方面，研究了LTCC基板Cu共烧金属化。结果表明，采用PMMA作为粘结剂的流延浆料具有剪切变稀行为，所得的流延坯膜微观组织均匀，叠压后坯体内部无分层现象。热失重、差热和傅立叶红外光谱联用分析结果表明高纯N2气氛中PMMA以解聚机理热解，热解后释放的主要产物为丙烯酸甲酯。在高纯N2气氛中LTCC与Cu共烧后Cu金属化膜平整、致密，连通良好。经测试，基板表面Cu导体方阻小于5mΩ/□。     

Dynamics of the uptake of free amino acids in the blood serum of the portal vein during the digestion of isolated krill protein

The rate of absorption of amino acids obtained from isolated krill protein administered to rat stomach was studied. Absorption of casein amino acids was determined for reference purposes. Rats subjected to 48-hour fasting were administered krill isolate and casein in the form of homogenates at a rate 540 mg protein per 100 g bw in 6 ml of distilled water. The concentration of free amino acids in the portal vein was measured after 30 minutes, 1, 3 and 6 hours. The content of amino acids was measured by ion-exchange chromatography with the use of an automatic analyzer of amino acids. The digestion of krill protein proceeds at a high rate. This ensures the maximal augmentation of the concentration of most amino acids in the blood of the portal vein 30 min after isolate administration to the stomach.     

攀钢1号和2号方坯连铸工艺及设备

介绍了攀钢提钒炼钢厂1号和2号方坯连铸机的性能参数、工艺布置及流程、设计特点、装备水平,及攀钢通过技术改造新建1号和2号方坯连铸机,彻底淘汰模铸实现全连铸的实践经验.     

从文化变迁谈民族服饰的演变

随着国际交流的日益加深，人们讨论的重点多是跨文化的接触以及频繁接触中的文化认同问题。西方许多领域的学者已把“西方中的东方”（the East in the west）纳入他们的研究领域中。因此，我们随处可以读到西方人有关中国文化的评论。服饰文化研究者也应学会认识异域文化（the West in the East），本文通过对民族服饰变异实例的研究，探索促成民族服饰变异的文化因素和历史根源，从而揭示文化变迁与服饰变异的关系。