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1.
A stripping voltammetric signal is used as the source of information in the new version of electrochemical analysis, stripping voltammetric titration (SVT). The reaction RSH + AgNO3 = AgSR + HNO3 is used to substantiate the method. A procedure is developed to study the thiol-disulfide equilibrium in the whole blood and its fractions (hemolysate, plasma, and erythrocyte mass). Disulfides are reduced by sodium sulfite before their determination. The accuracy of the results is verified in the analysis of model solutions and using the added-found method. A version of rapid analysis from a single aliquot portion of a test sample is proposed.  相似文献   
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The reactions of the [Mo33-Q)(μ2-Q)3(H2O)3(C2O4)3]2− complex (Q = S or Se) with CuX salts (X = Cl, Br, I, or SCN) in water produce the cuboidal heterometallic clusters [Mo3(CuX)(μ3-Q)4(H2O)3(C2O4)3]2−, which were isolated as the potassium and tetraphenylphosphonium salts. Two new compounds, K2[Mo3(CuI)(μ3-S)4(H2O)3(C2O4)3]·6H2O and (PPh4)2[Mo3(CuBr)(μ3-S)4(H2O)3(C2O4)3]·7H2O, were structurally characterized. All compounds were characterized by elemental analysis and IR spectroscopy. The K2[Mo3(CuI)(μ3-Se)4(H2O)3(C2O4)3] compound was characterized by the 77Se NMR spectrum; the (PPh4)2[Mo3(CuI)(μ3-S)4(H2O)3(C2O4)3], (PPh4)2[Mo3(CuI)(μ3-Se)4(H2O)3(C2O4)3] and K2[Mo3(CuSCN)(μ3-S)4(H2O)3(C2O4)3]·7H2O compounds, by electrospray mass spectra. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1639–1644, September, 2007.  相似文献   
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In this paper, we study numerical methods for an optimal control problem with pointwise state constraints. The traditional approaches often need to deal with the deltasingularity in the dual equation, which causes many difficulties in its theoretical analysis and numerical approximation. In our new approach we reformulate the state-constrained optimal control as a constrained minimization problems only involving the state, whose optimality condition is characterized by a fourth order elliptic variational inequality. Then direct numerical algorithms (nonconforming finite element approximation) are proposed for the inequality, and error estimates of the finite element approximation are derived. Numerical experiments illustrate the effectiveness of the new approach.  相似文献   
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A sandwich-type rhodium polyoxotungstate with unprecedented tetrarhodium-oxo core Na(12)[(Rh(4)(μ(3)-O)(2)(H(2)O)(2))(H(2)W(9)O(33))(2)]·38H(2)O (1) was obtained by hydrothermal reaction of rhodium(II) acetate and sodium tungstate; crystal structure was determined by X-ray diffractometry and was confirmed by (183)W NMR data; 1 is active in electrocatalytic water oxidation.  相似文献   
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A linear copolymer made of two reciprocally attracting N-monomer blocks collapses to a compact phase through a novel transition, whose exponents are determined with extensive Monte Carlo simulations in two and three dimensions. In the former case, an identification with the statistical geometry of suitable percolation paths allows one to predict that the number of contacts between the blocks grows like N9/16. In the compact phase the blocks are mixed and, in two dimensions, also zipped, in such a way to form a spiral, double chain structure.  相似文献   
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We present the first experimental proof for the influence of a nearby nanosized metal object on the angular photon emission by a single molecule. Using a novel angular sensitive detection scheme, we directly quantify the redirection of angular emission for different molecular dipole orientations as an object is scanned laterally over the molecule at different heights. An excellent agreement between experiments and 2D-numerical simulations is found for molecules oriented perpendicular to the sample, whereas, for parallel orientations, the observed behavior contradicts the calculated behavior.  相似文献   
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Inclusion compounds of a macrocyclic cavitand cucurbit[8]uril (CB[8]) with cobalt(III) and nickel(II) complexes of 1,3-diaminopropane (tn) and 1,3-diamino-2-propanol (tmOH) { trans-[Co(tn) 2Cl 2]@CB[8]}Cl.14H 2O ( 1), { trans-[Co(tmOH)(tmO)]@CB[8]}Cl 2.22H 2O ( 2), and { trans-[Ni(tmOH) 2]@CB[8]}Cl 2.22H 2O ( 3) were synthesized and characterized by X-ray single crystal analysis, IR spectroscopy, ESI-MS, and by solid-state stripping voltammetry. The encapsulation of trans-[Co(tn) 2Cl 2] (+) within the cavity of CB[8] stabilizes the complex toward ligand substitution reactions in aqueous solution. The electrochemical study demonstrates that CB[8] prefers the oxidized species in trans-[Co(tn) 2Cl 2] (+)/ trans-[Co(tn) 2Cl 2] (0) and trans-[Co(tmO)(tmOH) 2] (2+)/ trans-[Co(tmO)(tmOH) 2] (+) redox couples, but stabilizes the reduced form trans-[Ni(tmOH) 2] (2+) against the oxidized species. The reversibility of voltammogram shapes evidence that for the inclusion compounds 1- 3 electron transfer reactions proceed within the cavity of the host.  相似文献   
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