排序方式: 共有89条查询结果,搜索用时 15 毫秒
51.
Nilesh P. Tale Amol V. Shelke Girdharilal B. Tiwari Prerana B. Thorat Nandkishor N. Karade 《Helvetica chimica acta》2012,95(5):852-857
A short total synthesis of rubrolides C and E has been achieved in four steps, using readily available 4‐methoxyacetophenone, 2‐bromoacetic acid, and the appropriate aromatic aldehyde, in 46 and 45% yield, respectively. Key reactions involved are α‐tosyloxylation of the aryl methyl ketone, intramolecular Wittig reaction, Knoevenagel condensation, and demethylation. 相似文献
52.
This paper outlines the benefits of computational steering for high performance computing applications. Lattice-Boltzmann mesoscale fluid simulations of binary and ternary amphiphilic fluids in two and three dimensions are used to illustrate the substantial improvements which computational steering offers in terms of resource efficiency and time to discover new physics. We discuss details of our current steering implementations and describe their future outlook with the advent of computational grids. 相似文献
53.
An efficient microwave-assisted copper triflate-catalyzed reaction for the hydration of terminal aryl acetylenes to prepare substituted acetophenones has been developed. Significantly shorter reaction time, low catalyst loading, and wide range of functional group tolerance are salient features of this methodology. 相似文献
54.
Vilas Shelke H. S. Tewari N. K. Gaur R. K. Singh 《Physica C: Superconductivity and its Applications》1998,300(3-4):217-224
We have investigated the effect of Hg addition on the superconducting properties of BiSrCaCuO system. Polycrystalline samples with nominal composition Bi2Sr2−xHgxCa1Cu2Oy and Bi2Sr2−xHgxCa2Cu3Oy (x=0.3) were synthesized and used to investigate the phase evolution by XRD, superconducting behaviour by R–T measurement and the structural grain boundary effects by SEM. From these measurements, it has been noticed that the phases obtained with both types of compositions are the same as Bi2212 but the Tc values are different. With additional annealing, Tc zero values were raised from 60 to 72 K in Bi2Sr2−xHgxCa1Cu2Oy and 64 to 92 K in Bi2Sr2−xHgxCa2Cu3Oy. Also, an improved grain boundary linkage has been observed by SEM for the 92 K sample. 相似文献
55.
Manglesh Dixit Shovit Bhattacharya Rajneesh Mohan Kiran Singh P. S. R. Krishna Vilas Shelke N. K. Gaur R. K. Singh 《Pramana》2004,63(2):233-237
The HgO-added YBa2Cu3O7−δ (YBCO) superconductor has been studied for its structural and superconducting properties. Polycrystalline YBCO samples were
synthesized through solid-state reaction method by adding HgO in different concentrations without using oxygen annealing.
All the samples showed a sharp superconducting transition temperature around 90 K. The X-ray diffraction patterns of all the
samples revealed monophasic Y-123 nature. The structural studies were carried out by neutron scattering and Rietveld analysis.
The neutron scattering revealed that Hg is not incorporated in the Y-123 system and has shown optimum oxygen concentration.
The significant role played by the HgO is to provide oxygen ambient through its decomposition, thus changing the oxygen balance
in favour of high Cu-valence state. 相似文献
56.
A transition metal-free protocol for the synthesis of biologically active thiazolo[3,2-a]pyrimidine derivatives has been achieved by the cyclocondensation of 3,4-dihydropyrimidin-2(1H)-thiones with alkynyl(aryl)iodonium tosylates. This reaction demonstrates another useful application of alkynyl(aryl)iodonium tosylates as synthon of alkynyl cation. 相似文献
57.
Pawar Umakant D. Pansare Dattatraya N. Shelke Rohini N. Pawar Chandrakant D. Pathan Asif M. Thakre Vijay J. Dobhal Bhagwan S. Pardeshi Rajendra K. 《平面色谱法杂志一现代薄层色谱法》2022,35(4):431-434
JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
58.
2,4,5-Triarylimidazoles could be obtained in excellent yields by the one-pot three-component condensation of benzil/benzoin, aldehydes and ammonium acetate in the presence of catalytic amount of the inexpensive,readily available and non-toxic ceric(Ⅳ) ammonium nitrate(CAN) in aqueous media under ultrasound at room temperature.In this reaction the products were obtained in short reaction time and easy operation under mild conditions. 相似文献
59.
Shirole Gopinath D. Kadnor Vijay A. Tambe Adinath S. Shelke Sharad N. 《Research on Chemical Intermediates》2017,43(2):1089-1098
Research on Chemical Intermediates - We present a facile and environmentally benign protocol for synthesis of variously substituted imidazole derivatives via multicomponent condensation of benzil,... 相似文献
60.
空气中激光烧蚀Cu产生等离子体发射光谱的研究 总被引:3,自引:3,他引:3
利用Q-开关Nd:YAG激光器产生的1.06 μm、10 ns的脉冲激光聚焦在空气中的Cu靶上,观测了激光诱导的Cu等离子体发射光谱.采用不同的激光能量,分析了波长范围为440 nm到540 nm的空间分辨发射光谱.在局部热力学平衡(LTE)条件近似下,根据谱线的相对强度,得到了等离子体电子温度约在104 K以上,给出了靶面附近电子温度的空间演化规律,并探讨了N(Ⅱ)500.52 nm谱线的谱线强度和半高全宽随激光能量的变化规律. 相似文献