排序方式: 共有30条查询结果,搜索用时 281 毫秒
1.
Vardevanyan PO Antonyan AP Parsadanyan MA Davtyan HG Karapetyan AT 《Experimental & molecular medicine》2003,35(6):527-533
The pH-induced helix-coil transition of DNA and its complexes with EtBr is carried out at acidic pH in a wide interval of change of concentration ratio of EtBr/DNA. The binding isotherms of EtBr on double and single-stranded DNA at pH = 7.0 and pH = 3.0 (t = 25(o)C) are obtained by absorption and fluorimetric methods. Binding constants (K) and number of bases (n), corresponding to one binding site were determined. Non fluorescent "strong" complex with ds-DNA at pH = 7.0 and t = 25(o)C as well as "strong" and "weak" complexes with ss-DNA at pH = 3.0 and t = 25(o)C are revealed. 相似文献
2.
3.
Sergey Antonyan 《Transactions of the American Mathematical Society》2003,355(8):3379-3404
Let be a compact Lie group, a metric -space, and the hyperspace of all nonempty compact subsets of endowed with the Hausdorff metric topology and with the induced action of . We prove that the following three assertions are equivalent: (a) is locally continuum-connected (resp., connected and locally continuum-connected); (b) is a -ANR (resp., a -AR); (c) is an ANR (resp., an AR). This is applied to show that is an ANR (resp., an AR) for each compact (resp., connected) Lie group . If is a finite group, then is a Hilbert cube whenever is a nondegenerate Peano continuum. Let be the hyperspace of all centrally symmetric, compact, convex bodies , , for which the ordinary Euclidean unit ball is the ellipsoid of minimal volume containing , and let be the complement of the unique -fixed point in . We prove that: (1) for each closed subgroup , is a Hilbert cube manifold; (2) for each closed subgroup acting non-transitively on , the -orbit space and the -fixed point set are Hilbert cubes. As an application we establish new topological models for tha Banach-Mazur compacta and prove that and have the same -homotopy type.
4.
5.
We prove that if G is a compact Hausdorff group then every G-ANR has the G-homotopy type of a G-CW complex. This is applied to extend the James–Segal G-homotopy equivalence theorem to the case of arbitrary compact group actions.
The first author was supported in part by grant U42563-F from CONACYT (Mexico). 相似文献
6.
Minasyan SH Tavadyan LA Antonyan AP Davtyan HG Parsadanyan MA Vardevanyan PO 《Bioelectrochemistry (Amsterdam, Netherlands)》2006,68(1):48-55
The interaction of ethidium bromide (EtBr) with calf thymus DNA is investigated electrochemically with the use of differential pulse voltammetry (DPV) at two different ionic strengths of a solution (0.154 M and 0.02 M [Na+], pH 7.0). It is revealed that EtBr binds with DNA in more than one way. The appropriate values of constants (K) and number site sizes (n) of EtBr binding to DNA are determined. The values of binding constants are equal to 1.9 x 10(6) and 5.6 x 10(5) M(-1), and number site sizes to 9 and 3.6 for strong interactions at ionic strengths of solutions 0.02 and 0.154 M Na+ at 28 degrees C, respectively. For a weaker interaction, these parameters are equal to 7 x 10(4) and 8 x 10(4) M(-1) and 1.5 and 1 at the mentioned ionic strengths of solutions, respectively. Thus, EtBr interacts with DNA in more than one way--intercalative and electrostatic at low ionic strength, and semi-intercalative and electrostatic at a higher strength of the solution. These results are in good accordance with the ones obtained by spectroscopic (absorption and fluorimetric) methods. 相似文献
7.
Yuri A. Karpov Natella A. Arakelian V. E. Kvin Vasilisa B. Baranovskaya Tatyana Yu Alekseeva V. P. Obresumov Lyudmila P. Zhitenko 《Accreditation and quality assurance》2001,6(2):66-71
Our experience of executing proficiency testing programs on the analysis of precious metals and precious metal bearing materials
is summarized. Six proficiency testing programs of the ”distributed sample testing” type were carried out using samples essentially
distinct from each other: (I) certified samples of fine gold and fine silver, and (II) recoverable raw (scrap and catalyst
waste) containing precious metals of unknown contents. The test results were assessed using the London Bullion Market Association
(LBMA) rules and by Z-criteria using the ISO/IEC Guide 43 scale. Satisfactory results were presented by all participants for the analysis of certified
samples of fine gold and fine silver. The results of catalyst waste analysis agreed rather well, whereas the scrap analysis
revealed an essential discrepancy in the data for some samples. The reasons for such discrepancies are discussed.
Received: 9 June 2000 Accepted: 21 November 2000 相似文献
8.
K. Yu. Amirbekyan A. P. Antonyan P. O. Vardevanyan Sh. A. Markarian 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(12):2027-2029
Interaction between benzimide (Hoechst 33258, H33258) and calf thymus DNA in aqueous dimethyl sulfoxide is investigated by means of UV-Vis and fluorescence spectroscopy at a constant ratio (r) of the number of H33258 molecules and DNA base pairs. Melting curves of the DNA-H33258 complex are obtained from the temperature dependences of the normalized optical density and fluorescence intensity, and the melting temperatures of the complex are determined. It is shown that adding dimethyl sulfoxide (DMSO) lowers the complex’s melting temperature. It is concluded that a long wavelength shift of the fluorescence spectra occurs when the temperature is raised. 相似文献
9.
10.