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1.
A two-dimensional steady-sate analysis of semi-infinite brittlecrack growth at a constant subcritical rate in an unboundedfully-coupled thermoelastic solid under mixed-mode thermomechanicalloading is made. The loading consists of normal and shear tractionsand heat fluxes applied as point sources (line loads in theout-of-plane direction). A related problem is solved exactly in an integral transformspace, and robust asymptotic forms used to reduce the originalproblem to a set of integral equations. The equations are partiallycoupled and exhibit operators of both Cauchy and Abel types,yet can be solved analytically. The temperature change field at a distance from the moving crackedge is then constructed, and its dominant term is found tobe controlled by the imposed heat fluxes. The role of this termis, indeed, enhanced if the heat fluxes serve to render thecrack as a net heat source/sink for the solid, as opposed tobeing a transmitter of heat across its plane. More generally,the influence of the thermoelastic coupling on this field, aswell as other functions, is found to increase with crack speed. 相似文献
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RostislavE. Trifonov AnnaP. Volovodenko SergeiN. Vergizov NabiI. Shirinbekov VladimirA. Gindin AndreiO. Koren VladimirA. Ostrovskii 《Helvetica chimica acta》2005,88(7):1790-1797
The basicity of a series of 3,5‐disubstituted 1,2,4‐oxadiazoles in aqueous H2SO4 was examined by means of UV and 1H‐NMR spectroscopy. The experimental data were analyzed by the modified Yates–McClelland method to yield the following pK values: 3,5‐dimethyl‐1,2,4‐oxadiazole, −1.66±0.06; 3‐methyl‐5‐phenyl‐1,2,4‐oxadiazole, −2.61±0.02; 3‐phenyl‐5‐methyl‐1,2,4‐oxadiazole, −2.95±0.01; 3,5‐diphenyl‐1,2,4‐oxadiazole, −3.55±0.06. A pK value of ca. −3.7 was estimated for the parent unsubstituted 1,2,4‐oxadiazole based on substituents' additivity increments. Possible protonation sites of the compounds were discussed in terms of both experimental data and theoretical calculations (HF/6‐31G**). Generally, protonation is most likely to occur at N(4) of the 1,2,4‐oxadiazole ring. However, concurrent formation of both N(4)‐ and N(2)‐protonated species in comparable amounts is possible in the case of 3‐phenyl‐1,2,4‐oxadiazoles. 相似文献
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V. é. Zakhs I. P. Yakovlev N. A. Smorygo V. A. Gindin B. A. Ivin 《Chemistry of Heterocyclic Compounds》1987,23(3):325-332
1H,13C NMR, IR, and UV spectra have been studied for solutions of a number of potentially tautomeric 2-aryl-1,3-oxazine-4,6-diones and their 5-methyl substituted analogs with variation of substituent at the para position of the benzene ring, as well as compounds with a fixed structure that simulates possible tautomeric forms. The data have been compared with the results of quantum chemical calculations carried out in SSO MO LCAO approximation by the CNO, CNDO/2, and MPNDO/3 methods. In DMSO and THF solution the test compounds exist predominantly as 2-aryl-4-hydroxy-6H-1,3-oxazin-6-ones. The para substituent in the benzene ring does not affect the composition of the tautomer mixture significantly.For Communication 61, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 386–394, March, 1987. 相似文献
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Dreyfuss JM Jacobs C Gindin Y Benson G Staples GO Zaia J 《Analytical and bioanalytical chemistry》2011,399(2):727-735
Hydrophilic interaction chromatography (HILIC) liquid chromatography/mass spectrometry (LC/MS) is appropriate for all native
and reductively aminated glycan classes. HILIC carries the advantage that retention times vary predictably according to oligosaccharide
composition. Chromatographic conditions are compatible with sensitive and reproducible glycomics analysis of large numbers
of samples. The data are extremely useful for quantitative profiling of glycans expressed in biological tissues. With these
analytical developments, the rate-limiting factor for widespread use of HILIC LC/MS in glycomics is the analysis of the data.
In order to eliminate this problem, a Java-based open source software tool, Manatee, was developed for targeted analysis of
HILIC LC/MS glycan datasets. This tool uses user-defined lists of compositions that specify the glycan chemical space in a
given biological context. The program accepts high-resolution LC/MS data using the public mzXML format and is capable of processing
a large data file in a few minutes on a standard desktop computer. The program allows mining of HILIC LC/MS data with an output
compatible with multivariate statistical analysis. It is envisaged that the Manatee tool will complement more computationally
intensive LC/MS processing tools based on deconvolution and deisotoping of LC/MS data. The capabilities of the tool were demonstrated
using a set of HILIC LC/MS data on organ-specific heparan sulfates. 相似文献
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A. B. Nikol’skii Yu. S. Varshavsky T. G. Cherkasova I. S. Podkorytov V. A. Gindin 《Russian Chemical Bulletin》2012,61(4):813-820
The complex trans-[RuPy4(CN)2] cleaves chloride bridges in the binuclear rhodium(i) and palladium(ii) complexes [Rh(CO)2Cl]2, [Rh(η4-C8H12)Cl]2, [(η4-C8H12)Rh(μ-Cl)2Rh(CO)2], [Pd(η3-C3H5)Cl]2, and [(η3-C3H5)Pd(μ-Cl)2Rh(CO)2] to form heterometallic triad complexes [(CO)2ClRh(NC)RuPy4(CN)RhCl(CO)2] (1), [(η4-C8H12)ClRh(NC)RuPy4(CN)RhCl-(η4-C8H12)] (2), [(CO)2ClRh(NC)RuPy4(CN)RhCl(η4-C8H12)] (3), [(η3-C3H5)ClPd(NC)-Ru(Py)4(CN)PdCl(η3-C3H5)] (4), and [(CO)2ClRh(NC)Ru(Py)4(CN)PdCl(η3-C3H5)] (5), respectively. In solutions, complex 3 coexists with equilibrium amounts of compounds 1 and 2; complex 5 is in the equilibrium with compounds 4 and 1. In both cases, the ratio of concentrations is close to binomial. Complexes 2 and 5 treated with [Rh(CO)2Cl]2 are converted into 1 with the simultaneous formation of [Rh(η4-C8H12)Cl]2 and [Pd(η3-C3H5)Cl]2, respectively. The δH and δC values for the ligands η4-C8H12, η3-C3H5, and CO are sensitive to the nature of the remote triad unit. The ligand effects are shown to be transmitted along the chain L′-M′-(NC)-Ru-(CN)-M″-L″. 相似文献
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V. A. Vasin P. S. Petrov M. Genaev V. A. Gindin V. V. Razin 《Journal of Structural Chemistry》2010,51(5):949-955
In the 1 H and 13 C NMR spectra of methyl 6,7-endo,sin-dibromo-7-anti-(phenylsulfonyl)bicycle-[3.1.1]heptane-6-exo-carboxylate, H(1) and H(5) protons as well as C(1) and C(5) carbon atoms show their chemical inequivalence determined by
the hindered rotation of sulfonyl and ester groups about simple C-S and C-C bonds due to the existence of donor-acceptor interaction
between the carbonyl C atom and the oxygen atom of the SO2Ph group. This interaction is indicated by the single crystal X-ray diffraction study detecting the shortened intramolecular
contacts (2.49 ? with the sum of the C…O van der Waals radii of 3.00 ?). Other features of the norpinane skeleton conformation
and the spatial orientation of substituents in the single crystal are discussed. By 1 H NMR methods, the parameters of the dependence of molecular conformations on the temperature of DMSO-d
6 solution and the activation free energy △G
c
≠ = 80.1 kJ/mol of conformational transitions are determined. By a quantum chemical DFT calculation of the potential energy
surface it is revealed that the hindered rotation of the ester group makes the main contribution to the barrier of conformational
transitions. 相似文献
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Vadim I. Ponomarenko Dmitrii V. Krupenya Elena V. Grachova Vladimir A. Gindin Stanislav I. Selivanov Igor O. Koshevoy Sergey P. Tunik Prof. Dr. Matti Haukka Jouni Pursiainen Päivi Pirilä 《无机化学与普通化学杂志》2009,635(15):2515-2526
A novel chiral phosphane (S)‐2‐(4‐isopropyl‐2‐oxazoline‐2‐yl)phenyl‐di‐N‐pyrrolylphosphane (S‐PyrPOx) based on asymmetric oxazoline ring has been prepared and characterised. Reaction of this ligand and its phenyl‐substituted analogue (S‐PhPOx) with H4Ru4(CO)12 and H3RhOs3(CO)12 gave substituted derivatives H4Ru4(CO)10(1,1‐PhPOx) ( 2 ), H4Ru4(CO)10(1,1‐PyrPOx) ( 3 ), and H3RhOs3(CO)10(1,1‐PyrPOx) ( 4 ), which were structurally characterised by X‐ray crystallography in solid state and by a variety of multinuclear NMR spectroscopic measurements in solution. In all studied clusters the coordinated ligands form five‐membered chelate rings through phosphorus and nitrogen atoms of oxazoline moiety to afford a novel chiral center associated with the substituted metal atom. The substitution reactions demonstrate extremely high stereoselectivity, which results in formation of only one diastereomer in all three cases to give S,S isomer in 2 and S,R isomer in 3 and 4 . 相似文献
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