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61.
Malinka P. Stoyanova Boris L. Shivachev Rosica P. Nikolova Vladimir Dimitrov 《Tetrahedron: Asymmetry》2013,24(21-22):1426-1434
Methylidene substituted camphor was easily epoxidized to give bridgehead oxirane-substituted camphor in the form of two diastereoisomers, isolated in pure form. These were used in aminolysis reactions with different secondary amines leading to series of chiral aminoalcohols bearing a ketone functionality. The latter could be reduced by using LAH or DIBAL to a series of aminodiols. For the determination of the configuration of the newly formed stereogenic centre, advanced NMR experiments and X-ray crystallography were used. The new aminoalcohols and aminodiols were tested as pre-catalysts for the enantioselective addition of Et2Zn to benzaldehyde showing moderate enantioselectivity. 相似文献
62.
Lagrange T Reed BW Santala MK McKeown JT Kulovits A Wiezorek JM Nikolova L Rosei F Siwick BJ Campbell GH 《Micron (Oxford, England : 1993)》2012,43(11):1108-1120
The growing field of ultrafast materials science, aimed at exploring short-lived transient processes in materials on the microsecond to femtosecond timescales, has spawned the development of time-resolved, in situ techniques in electron microscopy capable of capturing these events. This article gives a brief overview of two principal approaches that have emerged in the past decade: the stroboscopic ultrafast electron microscope and the nanosecond-time-resolved single-shot instrument. The high time resolution is garnered through the use of advanced pulsed laser systems and a pump-probe experimental platforms using laser-driven photoemission processes to generate time-correlated electron probe pulses synchronized with laser-driven events in the specimen. Each technique has its advantages and limitations and thus is complementary in terms of the materials systems and processes that they can investigate. The stroboscopic approach can achieve atomic resolution and sub-picosecond time resolution for capturing transient events, though it is limited to highly repeatable (>10(6) cycles) materials processes, e.g., optically driven electronic phase transitions that must reset to the material's ground state within the repetition rate of the femtosecond laser. The single-shot approach can explore irreversible events in materials, but the spatial resolution is limited by electron source brightness and electron-electron interactions at nanosecond temporal resolutions and higher. The first part of the article will explain basic operating principles of the stroboscopic approach and briefly review recent applications of this technique. As the authors have pursued the development of the single-shot approach, the latter part of the review discusses its instrumentation design in detail and presents examples of materials science studies and the near-term instrumentation developments of this technique. 相似文献
63.
A number of aminobenzophenones have been synthesized by acylation of benzene and its derivatives with different 2‐,3‐,4‐aminobenzoic and 4‐aminophenylacetic acids in polyphosphoric acid via Friedel–Crafts reaction as compounds with expected antitumor activity. 相似文献
64.
I. Kraicheva E. Vodenicharova B. Shivachev R. Nikolova A. Kril M. Topashka-Ancheva 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):1535-1547
Abstract The X-ray crystal structures of the anthracene-derived bis-aminophosphonates 4.4′-bis[N-methyl(diethoxyphosphonyl)-1-(9-anthryl)]diaminodiphenylmethane (1) and 1,3-bis [N-methyl(diethoxyphosphonyl)-1-(9-anthryl)]diaminobenzene (3) are reported. The X-ray analyses demonstrated that both compounds crystallize in a centrosymmetric manner containing a meso-form (1) and a pair of enantiomers (3). The cytotoxic potential, genotoxicity, and antiproliferative activity of bis-aminophosphonates 1 and bis[N-methyl(diethoxyphosphonyl)-1-(9-anthryl)]benzidine (2), as well as their subcellular distribution in a tumor cell culture system, are also discussed. Compounds 1 and 2 showed optimal antiproliferative activity to human tumor cells from colon carcinoma line HT-29. In vitro and in vivo safety testing revealed that the compounds exert lower toxicity to normal cells as compared with well-known anticancer and cytotoxic agents. Supplemental materials are available for this article. Go to the publisher's online edition ofPhosphorus, Sulfur, and Silicon and the Related Elementsto view the free supplemental file. 相似文献
65.
Coefficients of self-diffusion, absolute speeds of movement of ions and the activation energy of electrical conductivity are found from the conductance measurements of aqueous solutions of selenic acid and sodium selenate at different concentrations in a temperature range of 288–318 K. Both the Stokes and effective radii of ions and their hydrate numbers at 298 K are calculated. The obtained results are interpreted in the frames of Samoilov theory on positive and negative hydration of ions. 相似文献
66.
Within a differential-geometrical framework, the notion of a generalized connection form on a principal fibre bundle is applied to a generalized model for the unification of two (or more) gauge interactions. An example with gauge groups SU(2) and U(1) is considered. 相似文献
67.
In this paper, we study how the limited and weakly compact properties of operators are preserved by interpolation of the real method for infinite families of Banach spaces introduced by Carro in Studia Math. 109 (1994). We apply these results to the case of Sparr, Fernández and Cobos–Peetre methods of interpolation for finite families. 相似文献
68.
69.
In this paper we derive some new inequalities involving the Hardy operator, using some estimates of the Jensen functional, continuous form generalization of the Bellman inequality and a Banach space variant of it. Some results are generalized to the case of Banach lattices on . 相似文献
70.
T. I. Milenov P. M. Rafailov M. V. Abrashev R. P. Nikolova R. Titorenkova M. M. Gospodinov 《Crystal Research and Technology》2009,44(11):1192-1196
Large crystals of La0.63Pb0.37Mn O3+δ with small La(Pb)‐ deficiency of about 0.005‐0.01 at.% were grown by high temperature solution growth method. The structure of the grown crystals was determined as rhombohedral with R‐3 space group by single‐crystal X‐ray diffractometry. The surface morphology of the crystals and the exact chemical composition was examined by scanning electron microscopy and energy dispersive X‐ray analysis methods, respectively. The IR‐transmission spectrum reveals the presence of Mn3+O6‐ and Mn4+O6‐ octahedra in the lattice of La0.63Pb0.37Mn O3+δ crystals. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献