二元合金Ag_(50)Rh_(50)从液态到非晶的分子动力学计算

本文对贵重金属银铑合金Ag50Rh50的液态结构和激冷过程进行了分子动力学模拟研究原子间作用势采用紧束缚势模拟在施加了周期性边界条件的常压状态下进行。采用了偶关联函数、键对分析技术和键取向序参数以分子动力学模拟计算方法揭示了Ag50Rh50的液态结构存在原子偏聚特征以及在快速凝固过程形成原子偏聚的不均匀非晶并与同族过渡金属进行了非晶形成能力的比较。     

Direct Observation of Various Al Sites in SAPO-34by ^27Al Multiquantum(MQ) Magic Angle Spinning (MAS)NMR

The elegant 2D multiquantum (MQ) MAS NMR has been applied to investigate the coordination of Al atoms in SAPO-34.The results show that the effects of the template and /or water on the coordination of Al atoms are significant,which lead to the formation of various Al species.Up to four kinds of Al species are distinctly resolved.     

后处理对TiO_2纳米薄膜的表面结构和光催化活性的影响

半导体TiO2光催化材料对环境中各种污染物的明显去除效果已引起人们的广泛关注犤1～6犦。在普通钠钙玻璃表面涂制高光催化活性的TiO2纳米薄膜,制成环保建筑材料,不仅可以自洁玻璃表面,而且可以用于净化空气、处理废水等。但由于在热处理过程中玻璃基体内的Na+离子扩散到薄膜表面,形成光生电子和空穴的复合中心,使TiO2纳米薄膜的光催化活性大大降低犤7～10犦。为了减少玻璃中Na+离子对TiO2薄膜光催化活性的有害影响,Paz等犤8犦研究了将钠钙玻璃浸入酸溶液中,使玻璃表面的钠离子被酸中的氢离子置换出来;在玻璃表面形成SiO2凝胶层,以便阻…     

Facile Synthesis of 1, 2-Diazepine Derivatives under Microwave Irradiation

An efficient and convenient synthesis of 3, 5, 7-triaryl-4H-1, 2-diazepine from 2, 4,6-triarylpyrylium salts and hydrazine in water under microwave irradiation is reported. The same reaction can be conducted using 2, 4, 6-triarylthiopyrylium salts and hydrazine.     

两个含有平行交替链的新型二氰胺配位高聚物: {Mn(dmpz)[N(CN)2]2}2和{Cu(dmpz)[N(CN)2]2}2

Two new dicyanamide coordination polymers, {Mn(dmpz)[N(CN)2]2}2 (1) and {Cu(dmpz)[N(CN)2]2}2 (2)(dmpz=3,5-dimethylpyrazole), were synthesized and characterized by single crystal X-ray diffraction analysis and IR spectroscopy. In 1 and 2 the metal ions have two different coordination modes, where one is coordinated to four dicyanamide anions and two monodentate dmpz molecules to form a slightly distorted octahedral geometry, while the other adopts octahedral geometry, surrounded by four nitrile N atoms and two amide N atoms of the dicyanamide anions. Both complexes contain two alternating chains that are parallel to each other.     

茂金属化合物对苯乙烯丁二烯嵌段共聚物SBS催化加氢的研究

合成了一系列茂金属催化剂（C5H4R)2TiCl2[R=H(1),Me(2),C6H11(3)]和（C5H4R)2TiAr2[R=H,Ar=C6H5(4),p-MeC6H4(5),m-MeC6H4(6);R=Me,Ar=C6H5(7),p-MeC6H4(8);R=C6H11,Ar=C6H5(9),p-MeC6H4(10)],研究了这些催化剂对苯乙烯丁二烯嵌段共聚物SBS的催化加氢,考察了催化剂种类、用量及催化剂各组分之间的比例对加氢效果的影响,得到了较佳的条件,可使聚合物加氢度达到98%以上,钛催化剂用量为0.001-0.003mmol/g聚合物。     

ααTwo new eudesmane sesquiterpenes from Lactuca sativa var. anagustata L

Two new eudesmane sesquiterpene lactones were isolated from the stalk of Lactuca sativa var.anagustata L and their structureswere elucidated by means of spectroscopic methods,including 2D NMR(~1H-~1H COSY,HMBC and NOESY) as 1β-O-β-D-glucopyranosyl-4α-hydroxyl-5α,6β,11βH-eudesma-12,6α-olide(1) and 1β-hydroxyl-15-O-(p-methoxyphenylacetyl)-5α,6β,11βH-eudesma-3-en-12,6α-olide(2).     

溶胶-凝胶法合成超细Li_(2 x)RE_xSi_(1-x)O_3及其离子导电性

用溶胶 凝胶法合成了Li2 xRExSi1 -xO3(RE =Pr ,Nd ,Sm ,Gd ;x =0～ 0 15 ) ,用DTA TG ,XRD ,TEM及交流阻抗等技术对样品的结构、形貌、粒径及离子导电性等进行了观察和测试。其固溶体形成范围是 0 相似文献   

α-可分解4-圈系统

An m-cycle system of order ν and index λ, denoted by rn-CS(ν, λ), is a collection of cycles of length m whose edges partition the edges of λκ_v. An m-CS(ν, λ) is α-resolvable if its cycles can be partitioned into classes such that each point of the design occurs in precisely α cycles in each class. The necessary conditions for the existence of such a design are m|λν(ν-1)/2,2|λ(ν-1), m|αν,α|λ(ν-1)/2 It is shown in this paper that these conditions are also sufficient when m = 4.     

两束啁啾脉冲控制下的H+D+光缔合反应研究

从理论上研究了两束啁啾脉冲控制H+D⁺的光缔合反应. 第一束脉冲用来加速碰撞伴的碰撞速度,第二束脉冲用来增加产物HD⁺的产率. 结果表明:第一束脉冲的参数决定了第二束脉冲的优化参数以及产物HD⁺的布居. 产物的布居可以通过调节两束脉冲的延迟时间得到控制. 关键词： 光缔合 +分子')" href="#">HD⁺分子 啁啾脉冲 波包