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61.
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J. Hockemeyer A. Castel P. Rivire J. Satg K. G. Ryder A. Drury A. P. Davey W. J. Blau 《应用有机金属化学》1997,11(6):513-521
The syntheses of several types of polymers containing silicon, germanium and tin in the main chain are described. Optical studies show that they exhibit absorption in the far-ultraviolet region of the spectrum (200–400 nm). Electrical studies show that these polymers behave as insulators. Preliminary studies indicate, that depending on the chemical structure of the backbone, it is possible to dope some of the polymers via partial oxidation in solution. © 1997 John Wiley & Sons, Ltd. 相似文献
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The semileptonic decay width of heavy baryons such as (Λ
b
→ Λcev) has been estimated in the framework of a nonrelativistic field theoretic quark model where four component quark field
operators along with a harmonic oscillator wave function are used to describe translationally invariant hadronic states. The
present estimation does not make an explicit use of heavy quark symmetry and has a reasonable agreement with the experimentally
measured decay width, polarisation ratio and form factors with the harmonic oscillator radii and quark momentum distribution
inside the hadron as free parameters. 相似文献
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S. Sankar MR. Manikandan S.D. Gopal Ram T. Mahalingam G. Ravi 《Journal of Crystal Growth》2010,312(19):2729-2733
The microbial free single crystals of α and γ glycine were grown from gel at room temperature in a new chemical route. These crystals showed a superior quality than the solution grown crystals. The metastable α-form and the stable γ-form of glycine were crystallized in silica gel by solubility reduction method. The form of crystallization is confirmed by single crystal and powder X-ray diffraction analyses. The crystals of α and γ glycine were found to crystallize in monoclinic and hexagonal crystal systems, respectively. For analyzing the functional group and thermal stability of α and γ glycine crystals, spectroscopic and thermal analyses have been carried out. The dielectric studies were performed to find the dielectric constant of the grown crystals and the results are discussed. Second harmonic generation efficiency of the crystal was measured by Kurtz’s powder method using Nd:YAG laser and it was found to be 2.68 times that of potassium dihydrogen phosphate crystals. 相似文献
68.
Aharonian F Akhperjanian AG Bazer-Bachi AR Beilicke M Benbow W Berge D Bernlöhr K Boisson C Bolz O Borrel V Braun I Breitling F Brown AM Bühler R Büsching I Carrigan S Chadwick PM Chounet LM Cornils R Costamante L Degrange B Dickinson HJ Djannati-Ataï A Drury LO Dubus G Egberts K Emmanoulopoulos D Espigat P Feinstein F Ferrero E Fiasson A Fontaine G Funk S Funk S Gallant YA Giebels B Glicenstein JF Goret P Hadjichristidis C Hauser D Hauser M Heinzelmann G Henri G Hermann G Hinton JA Hofmann W 《Physical review letters》2006,97(22):221102
The detection of gamma rays from the source HESS J1745-290 in the Galactic Center (GC) region with the High Energy Spectroscopic System (HESS) array of Cherenkov telescopes in 2004 is presented. After subtraction of the diffuse gamma-ray emission from the GC ridge, the source is compatible with a point source with spatial extent less than 1.2;{'}(stat) (95% C.L.). The measured energy spectrum above 160 GeV is compatible with a power law with photon index of 2.25+/-0.04(stat)+/-0.10(syst) and no significant flux variation is detected. It is finally found that the bulk of the very high energy emission must have non-dark-matter origin. 相似文献
69.
Dancy BC Ming SA Papazyan R Jelinek CA Majumdar A Sun Y Dancy BM Drury WJ Cotter RJ Taverna SD Cole PA 《Journal of the American Chemical Society》2012,134(11):5138-5148
Reversible lysine acetylation and methylation regulate the function of a wide variety of proteins, including histones. Here, we have synthesized azalysine-containing peptides in acetylated and unacetylated forms as chemical probes of the histone deacetylases (HDAC8, Sir2Tm, and SIRT1) and the histone demethylase, LSD1. We have shown that the acetyl-azalysine modification is a fairly efficient substrate for the sirtuins, but a weaker substrate for HDAC8, a classical HDAC. In addition to deacetylation by sirtuins, the acetyl-azalysine analogue generates a novel ADP-ribose adduct that was characterized by mass spectrometry, Western blot analysis, and nuclear magnetic resonance spectroscopy. This peptide-ADP-ribose adduct is proposed to correspond to a derailed reaction intermediate, providing unique evidence for the direct 2'-hydroxyl attack on the O-alkylimidate intermediate that is formed in the course of sirtuin catalyzed deacetylation. An unacetylated azalysine-containing H3 peptide proved to be a potent inhibitor of the LSD1 demethylase, forming an FAD adduct characteristic of previously reported related structures, providing a new chemical probe for mechanistic analysis. 相似文献
70.
The current-time behaviour has been calculated for successive two dimensional nucleation under potentiostatic conditions. Using numerical integration the contributions due to the first 50 layers have been found and the steady state behaviour has been estimated. 相似文献