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71.
Background
In order to ensure precise chromosome duplication, eukaryotes "license" their replication origins during late mitosis and early G1 by assembling complexes of Mcm2-7 onto them. Mcm2-7 are essential for DNA replication, but are displaced from origins as they initiate, thus ensuring that no origin fires more than once in a single cell cycle. 相似文献72.
We show that the N.N. Bogolubov generating functional method is a very effective tool for studying distribution functions of both equilibrium and non equilibrium states of classical many-particle dynamical systems. In some cases the Bogolubov generating functionals can be represented by means of infinite Ursell-Mayer diagram expansions, whose convergence holds under some additional constraints on statistical system. The classical Bogolubov idea [1] to use the Wigner density operator transformation for studying the non equilibrium distribution functions is developed and new analytic non-stationary solution to the classical N.N. Bogolubov evolution functional equation is constructed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
73.
The study of electrogenerated chemiluminescence (ECL) in aqueous and non-aqueous media with tetraphenylborate anion as a co-reactant is reported. The obtained results indicate that tetraphenylborate acts according to an oxidative reduction scheme and forms a strong reducer after being homogeneously oxidized by a radical cation or dication of luminophore. Spectral measurements prove that light emission originates from the luminophore present in solution and practically no emission occurs when only tetraphenylborate ion is oxidized at the electrode. Since the tetraphenylborate ion is a well known analytical reactant and precipitates a number of metal and organic cations its electrochemiluminescent detection can be used for their assay. It can also be applied as an efficient co-reactant for electrogenerated chemiluminescence excitation both in aqueous and non-aqueous media. 相似文献
74.
An innovative spectroscopic technique based on balancing and cancellation of modulated signals induced by two excitation sources is reported. For its practical implementation, we used quartz-enhanced photoacoustic spectroscopy as an absorption-sensing technique and applied the new approach to measure small temperature differences between two gas samples. The achieved sensitivity was 30 mK in 17 s. A theoretical sensitivity analysis is presented, and the applicability of this method to isotopic measurements is discussed. 相似文献
75.
Galina V. Kiriukhina Olga V. Yakubovich Larisa V. Shvanskaya Ekaterina M. Kochetkova Olga V. Dimitrova Anatoliy S. Volkov Sergey V. Simonov 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(3):302-310
Two novel K/Mn phosphate hydrates, namely, dipotassium trimanganese dipyrophosphate dihydrate, K2Mn3(H2O)2[P2O7]2, (I), and potassium manganese dialuminium triphosphate dihydrate, KMn(H2O)2[Al2(PO4)3], (II), were obtained in the form of single crystals during a single hydrothermal synthesis experiment. Their crystal structures were studied by X‐ray diffraction. Both new compounds are members of the morphotropic series of phosphates with the following formulae: A2M3(H2O)2[P2O7]2, where A = K, NH4, Rb or Na and M = Mn, Fe, Co or Ni, and AM2+(H2O)2[M3+2(PO4)3], where A = Cs, Rb, K, NH4 or (H3O); M2+ = Mn, Fe, Co or Ni; and M3+ = Al, Ga or Fe. A detailed crystal chemical analysis revealed correlations between the unit‐cell parameters of the members of the series, their structural features and the sizes of the cations. It has been shown that a mixed type anionic framework is formed in (II) by aluminophosphate [(AlO2)2(PO4)2]∞ layers, with a cationic topology similar to the Si/Al‐topology of the crystal structures of feldspars. A study of the magnetic susceptibility of (II) demonstrates a paramagnetic behaviour of the compound. 相似文献
76.
Jorge F. J. Coelho Erica Y. Carvalho Dina S. Marques Anatoliy V. Popov Virgil Percec M. H. Gil 《Journal of polymer science. Part A, Polymer chemistry》2008,46(19):6542-6551
The aim of this work is to the study the influence of the isomer structures of butyl acrylate monomer on the single‐electron transfer/degenerative chain transfer mediated living radical polymerization (SET‐DTLRP). The kinetic of isobutyl acrylate is determined for the first time by SET‐DTLRP in water catalyzed by sodium dithionite. The plots of number‐average molecular weight versus conversion and ln([M]0/[M]) versus time are linear, demonstrating a controlled polymerization. The influence of the isomer t‐butyl, i‐butyl, and n‐butyl on the kinetics, properties, and stereochemistry of the reactions was assessed. To the best of our knowledge, there is no previous report dealing with the synthesis of PiBA by any LRP approach in aqueous medium. The results presented in this work suggest that the stability provided by the acrylate side group has an important influence in the polymerization process. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6542–6551, 2008 相似文献
77.
Virgil Percec Anatoliy V. Popov Ernesto Ramirez‐Castillo Jorge F. J. Coelho 《Journal of polymer science. Part A, Polymer chemistry》2005,43(4):773-778
Single electron transfer–degenerative chain transfer mediated living radical polymerization (SET–DTLRP) of vinyl chloride (VC) initiated with methylene iodide (CH2I2) and catalyzed by sodium dithionite (Na2S2O4) in water at 35 °C produces a telechelic poly(vinyl chloride) (LRP–PVC) with two different active chain ends: ICH 2 (CH2CHCl)n‐1CH2 CHClI , and 2.0 functionality. The reactivity and initiator efficiency of CH2I2 in SET–DTLRP of VC was lower than those of iodoform. A possible mechanism for the CH2I2‐initiated SET–DTLRP of VC was suggested. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 773–778, 2005 相似文献
78.
Rodinovskaya LA Shestopalov AM Gromova AV Shestopalov AA 《Journal of combinatorial chemistry》2008,10(2):313-322
Diverse substituted 4-di(tri)fluoromethyl-3-cyanopyridine-2(1H)-thiones were synthesized via the Claisen condensation of alpha-methyl(methylene)ketones with di(tri)fluoroacetate, followed by the immediate Thorpe-Guareschi reaction of the preformed di(tri)fluoromethyl-1,3-diketones with cyanothioacetamide. The procedure allows facile synthesis of the di(tri)flouromethylated pyridine-2(1H)-thiones in 50-95% yields, without the need for isolation and purification of intermediates. Resultant 4-di(tri)fluoromethyl-3-cyanopyridine-2(1 H)-thiones were subsequently utilized in domino reactions to produce first various substituted thieno[2,3-b]pyridines and, then, thienopyridines polyannulated with pyridine, pyrimidine, benzodiazocine, diazepine, and pyran rings. 相似文献
79.
Rajeev Ranjan Anatoliy Senyshyn Hans Boysen Friedrich Frey 《Journal of solid state chemistry》2007,180(3):995-1001
Neutron powder diffraction studies of Na1/2La1/2TiO3 and Na1/2Tb1/2TiO3, and a synchrotron X-ray powder diffraction study of Na1/2Eu1/2TiO3 have been carried out. Rietveld refinement of the structures confirmed that Na1/2Eu1/2TiO3 and Na1/2Tb1/2TiO3 crystallizes in GdFeO3 type of structure (space group Pbnm). The ambiguity in the literature regarding the crystal structure of Na1/2La1/2TiO3 has been resolved and the correct space group is found to be . A detailed list of refined structural parameters of these compounds is presented for the first time. 相似文献
80.