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101.
Rudzevich Y Rudzevich V Moon C Schnell I Fischer K Böhmer V 《Journal of the American Chemical Society》2005,127(41):14168-14169
Selective and independent dimerization of tri- and tetraurea derivatives was used to build up dendritic assemblies which are uniform in size and structure. Dendrimers with the total molecular masses of about 25 000 g/mol were obtained. The existence of uniform assemblies was proved by 1H and 1H DOSY NMR experiments and also by dynamic light scattering. 相似文献
102.
103.
We prove the following theorems:
- 1.
- It is consistent with ZFC that there exists a - set which is not perfectly meager in the transitive sense.
- 2.
- Every set which is perfectly meager in the transitive sense has the property.
- 3.
- The product of two sets perfectly meager in the transitive sense has also that property.
104.
105.
Using the Green function technique we calculate the mean square of the vibrational amplitude of an ion (or equivalently the Debye Waller factor W, or the Mössbauer recoil free fraction ?) in a magnetic Debye crystal near the magnetic phase transition temperature Tc. We find that the magnon-phonon coupling which leads to the phonon spectrum broadening and frequency shift leads to sharp changes in W near Tc. The frequency shift leads to an increase in W, the broadening leads to a decrease in W. These results can explain the anisotropic critical changes in W near Tc observed recently in the magnetostrictive materials RFe2 and RCo2 (R = rare earth). In addition we calculate the expected changes in the second order Doppler shift near Tc. We find that when T approaches Tc from above a positive discontinuity and decrease in absolute value of slope of the thermal shift should occur. 相似文献
106.
I. Nowik 《Hyperfine Interactions》1983,13(1-3):89-118
In the last ten years the Mössbauer technique has made a considerable contribution to the research of the phenomena of mixed valencies, valence instabilities, valence fluctuations and intermediate valencies of transition elements. The sensitivity of the hyperfine interaction parameters and in particular the isomer shift, to the valency of the Mössbauer ion, enabled the research of dynamics of valence fluctuations and the temperature, pressure and composition dependence of the ionic intermediate valence state. Studies of149Sm,152Sm and153Eu in Sm1?xRxS contributed to the understanding of the outstanding insulator-metal phase transition that occurs in these systems. Studies of57Fe and151Eu in mixed valent systems yield the charge fluctuation rates of the “hopping” mechanism, contributing to the conductivity in these systems. Studies of151Eu in EuRh2, EuCu2Si2, EuPd2Si2, EuFe4Al8, and EuPd6B4 as a function of temperature and pressure reveal many aspects of the thermodynamics of intermediate valencies. Studies of systems like Eu1?xLaxRh2, EuA2?xBx, EuA5?xBx reveal strong local environment dependence of the intermediate valency. Mössbauer spectra of169Tm in TmSe,170Yb in YbAl3 and237Np in NpOs2 also display phenomena associated with fluctuating valencies. 相似文献
107.
108.
109.
Sergiy Shklyar Georgiy Shevchenko Yuliya Mishura Vadym Doroshenko Oksana Banna 《Methodology and Computing in Applied Probability》2014,16(3):539-560
We study the problem of optimal approximation of a fractional Brownian motion by martingales. We prove that there exists a unique martingale closest to fractional Brownian motion in a specific sense. It shown that this martingale has a specific form. Numerical results concerning the approximation problem are given. 相似文献
110.
Man‐Rong Li David Walker Maria Retuerto Tapati Sarkar Joke Hadermann Peter W. Stephens Mark Croft Alexander Ignatov Christoph P. Grams Joachim Hemberger Israel Nowik P. Shiv Halasyamani T. Thao Tran Swarnakamal Mukherjee Tanusri Saha Dasgupta Martha Greenblatt 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2013,125(32):8564-8568