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1.
In a view to balancing cost and lithium ion conductivity, Li6BaLa2Nb x Ta2???x O12 (x?=?0–2) was prepared by solid-state reaction, and its corresponding AC impedances were tested at temperatures ranging from 20 to 250 °C in air. Li6BaLa2Ta2O12 exhibits the highest conductivity, 8.77?×?10?6?S/cm, and the second highest is Li6BaLa2Nb2O12 with 6.69?×?10?6?S/cm. Partial replacement of Ta with Nb cannot bestow the advantages of cost saving or the enhancement of lithium ion conductivity. X-ray diffraction patterns revealed a gradual change as an increasing amount of Nb replaces Ta in Li6BaLa2Nb x Ta2???x O12 (x?=?0–2), and it is thought that the trending of Nb and Ta to rest on the crystallographic planes is different.  相似文献   
2.
刘淑娥 《物理通报》2013,(9):124-127
根据已有的微波对眼睛伤害的实例,结合人的眼睛结构,从理论上分析微波对眼睛危害产生的原因.同时,指出了在微波操作和使用过程中,如何保护好自己的眼睛.  相似文献   
3.
Dispersion compensation up to the third order is experimentally demonstrated by using a dual-fibre stretcher combined with the coma of an imaging lens, in a fibre-based scan-free time domain optical coherence tomography system, leading to an axial resolution of less than 3 μm.  相似文献   
4.
韩彩芹  段培同  刘莹  骆晓森  倪晓武 《光学学报》2012,32(4):430005-314
实验获得了激光照射红细胞悬液的荧光光谱,并分别监测不同荧光峰值波长处强度随时间的衰变过程,测试了其相应的荧光寿命.结果表明,在波长为407 nm的激光照射下,红细胞悬液向外发射中心波长分别位于596,628,692 nm的荧光光谱,各荧光峰对应衰变过程的平均荧光寿命分别为1.97,13.31,14.58 ns.利用荧光强度和吸收率的加和性表示了混合物的总吸收率和总荧光发射强度,通过理论计算获得了红细胞悬液中锌卟啉、原卟啉和其他游离物参与荧光发射的相对含量和相对强度在不同荧光峰位的变化关系,进一步解释了不同峰位处荧光发射强度和平均荧光寿命的变化原因.  相似文献   
5.
    
Single-atom catalysts have drawn great attention, especially in electrocatalysis. However, most of previous works focus on the enhanced catalytic properties via improving metal loading. Engineering morphologies of catalysts to facilitate mass transport through catalyst layers, thus increasing the utilization of each active site, is regarded as an appealing way for enhanced performance. Herein, we design an overhang-eave structure decorated with isolated single-atom iron sites via a silica-mediated MOF-templated approach for oxygen reduction reaction (ORR) catalysis. This catalyst demonstrates superior ORR performance in both alkaline and acidic electrolytes, comparable to the state-of-the-art Pt/C catalyst and superior to most precious-metal-free catalysts reported to date. This activity originates from its edge-rich structure, having more three-phase boundaries with enhanced mass transport of reactants to accessible single-atom iron sites (increasing the utilization of active sites), which verifies the practicability of such a synthetic approach.  相似文献   
6.
    
Understanding the thermal aggregation behavior of metal atoms is important for the synthesis of supported metal clusters. Here, derived from a metal–organic framework encapsulating a trinuclear FeIII2FeII complex (denoted as Fe3) within the channels, a well-defined nitrogen-doped carbon layer is fabricated as an ideal support for stabilizing the generated iron nanoclusters. Atomic replacement of FeII by other metal(II) ions (e.g., ZnII/CoII) via synthesizing isostructural trinuclear-complex precursors (Fe2Zn/Fe2Co), namely the “heteroatom modulator approach”, is inhibiting the aggregation of Fe atoms toward nanoclusters with formation of a stable iron dimer in an optimal metal–nitrogen moiety, clearly identified by direct transmission electron microscopy and X-ray absorption fine structure analysis. The supported iron dimer, serving as cooperative metal–metal site, acts as efficient oxygen evolution catalyst. Our findings offer an atomic insight to guide the future design of ultrasmall metal clusters bearing outstanding catalytic capabilities.  相似文献   
7.
《Solid State Sciences》1999,1(6):449-460
The new compound BiCoPO5, monoclinic, P21/n, a = 7.2470(1) A, b = 11.2851(2) A, c = 5.2260(1) A and β = 107.843(1) °, Z = 4, was synthesised and structurally characterised by powder X- ray diffraction and infrared spectroscopy. It is isostructural with bismuth nickel oxyphosphate BiNiOPO4. The crystal structure is built from a complex tridimensional assembly of (Co/Ni)2O10 dimers linked by PO4 groups. This forms large tunnels running along c which host Bi3+ cations. Smaller tunnels running along a and crossing the latter were also evidenced. It is noteworthy that the original BiNiPO5 lattice is appreciably increased with Co2+ cations as the transition metal. This feature is essentially pointed out by the Co-O longer distances. The Bi3+ cation is surrounded by a strongly distorted oxygen octahedron. Reducing the BiO bonds to the three shortest, Bi environment can be considered as tetrahedral considering the BiO3Lp polyhedron, Lp = 6s2 lone pair (Lp). The lone pair localisation was performed from electrostatic interactions and revealed Lp - Bi distance of 0.68 A and 0.58 A, for Co2+ and Ni2+ compounds respectively. The infrared spectra of the two compounds are essentially the same and only show slight shifts of the significant bands.  相似文献   
8.
A novel method for the synthesis of dibenzo[b,f]imidazo[1,2-d][1,4]oxazepine derivatives was described via cascade Csp2 N and Csp2 O bond constructions. It was a crossed double Ullmann reactions using 4,5-diaryl-2-(2-hydroxylphenyl)-1H-imidazole as the double nucleophilic centers in the presence of Cs2CO3, while 1-bromo-2-iodobenzene was used as a substrate catalyzed by CuI and o-phenanthroline in good yields.  相似文献   
9.
10.
研究了1,4-烯炔衍生物与二芳基膦氧化物在银介导下发生的炔酰化反应.该反应利用自由基引发的1,2-炔基迁移策略合成了一系列γ-酮膦氧化物,产率适中.该反应机理可能涉及膦中心自由基与乙烯基的加成、3-exo-dig环化和1,2-炔基迁移等连续的过程,一步形成了C-P、C-C键等化学键,实现了非活性烯烃的双官能化.  相似文献   
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