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1.
Joji Tanaka Satu Hkkinen Parker T. Boeck Yidan Cong Sbastien Perrier Sergei S. Sheiko Wei You 《Angewandte Chemie (International ed. in English)》2020,59(18):7203-7208
An orthogonal combination of cationic and radical RAFT polymerizations is used to synthesize bottlebrush polymers using two distinct RAFT agents. Selective consumption of the first RAFT agent is used to control the cationic RAFT polymerization of a vinyl ether monomer bearing a secondary dormant RAFT agent, which subsequently allows side‐chain polymers to be grafted from the pendant RAFT agent by a radical‐mediated RAFT polymerization of a different monomer, thus completing the synthesis of bottlebrush polymers. The high efficiency and selectivity of the cationic and radical RAFT polymerizations allow both polymerizations to be conducted in one‐pot tandem without intermediate purification. 相似文献
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Nonlinear Dynamics - The absolute nodal coordinate formulation (ANCF) is a nonlinear finite element approach proposed for the large deformation dynamics analysis of beam- and plate/shell-type... 相似文献
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Mikkola S 《Organic & biomolecular chemistry》2004,2(5):770-776
The hydrolysis of diadenosine 5',5'-triphosphate to AMP and ADP has been studied over a wide pH-range. Under acidic conditions the reaction shows a first-order dependence on the hydronium ion concentration. Below pH 3 the rate-increase begins to level off. From pH 6 to 9 the hydrolysis is slow and pH-independent. Base-catalysed hydrolysis is observed in NaOH-solutions. Under alkaline conditions an intramolecular nucleophilic attack on the phosphate producing 3',5'-cAMP is also observed, but it is slower than the intermolecular reaction. Depurination of the adenosine moieties competes with the hydrolysis both under acidic and alkaline conditions, but the mechanisms are different. The temperature-dependence of the hydrolysis of Ap(3)A and the depurination of adenosine moieties were studied under acidic conditions, and the activation parameters of the reactions were calculated. The results of the work reflect the fact that the negatively charged polyphosphate group is very resistant towards nucleophilic attack. An efficient catalysis is only observed under acidic conditions, where the phosphate group becomes protonated. General acids or bases did not catalyse the hydrolysis. Furthermore, hydroxide ion catalysed cleavage is only observed at high base concentrations and other negatively charged nucleophiles did not attack the phosphate groups of diadenosine polyphosphates. 相似文献
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P. Zaleski K. SzymańskiW. Olszewski M. BiernackaK. Perzyńska D. Satu?aA. Go J. Przewo?nikD.A. Zaj?c M. PylakL. Dobrzyński 《Physica B: Condensed Matter》2011,406(17):3196-3205
The lattice site occupation of 3d-type impurities in Cr3Si doped with Fe, Co and Ni were studied using the Extended X-ray Absorption Fine Structure (EXAFS) technique, X-rays and magnetic susceptibility measurements. The EXAFS measurements were performed particularly carefully on the K-edge of chromium and cobalt. EXAFS data strengthened by simulations of the spectra show unambiguously that the impurities are occupying mostly Cr-sites. The magnetic state of the alloys has been studied theoretically using the Wien2k code. It is observed that if calculations are not carried out on an appropriately fine mesh of points in k-space, one can get the result indicating ferromagnetism although the overall magnetic moment per formula unit is weak. 相似文献
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Noora Virtanen Ville Nevalainen Taru Lehtinen Satu Mikkola 《Journal of Physical Organic Chemistry》2007,20(1):72-82
Transesterification of a phosphodiester bond of RNA models has been studied in various buffer solutions, under neutral and slightly alkaline conditions in H2O and D2O. The results show that imidazole is the only buffer system where a clear buffer catalysis on the cleavage of a phosphodiester bond is observed. The rate enhancement in sulphonic acid buffers is smaller, and a sulphonate base, particularly, is inactive as a catalyst. The rate‐enhancing effect of imidazole is, however, catalytic, and the catalytic inactivity of sulphonate buffers can be attributed to their structure and/or charge. The catalysis by imidazole is a complex system which, in addition to first‐order reactions, involves a process that shows a second‐order dependence in imidazole concentration. The latter reaction becomes significant in acidic imidazole buffers (pH < pKa), as the buffer concentration increases. The kinetic solvent deuterium isotope effect kH/kD, referring to first‐order catalysis by imidazole base, is 2.3 ± 0.3. That referring to second‐order catalysis is most probably much larger, but an accurate value could not be obtained. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Nuclear resonance studies of the two different types impurity doped potassium hexachloro-stannates, the isomorphic system
such as (K–Rb)2SnCl6 and K2(Sn–Re)Cl6 and the nonisomorphic system K2SnCl6:Al3+ in the high temperature cubic phase revealed contrasting features with one the other characterized by static in the former
and dynamic feature in the latter case respectively. The resonance spectra of the nonisomorphic system indicate additionally
a sign of the local structural transition above the conventional structural phase transition temperature. This seems to be
triggered by the ligand-deficient octahedral defects and can be explained in terms of the enhanced activity of the octahedral
defects for the hindered rotation. 相似文献
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Kalska B. Szymański K. Dobrzyński L. SatuŁa D. Wäppling R. Broddefalk A. Nordblad P. 《Hyperfine Interactions》2002,141(1-4):169-173
Properties of amorphous alloy Fe0.66Er0.19B0.15 are reported. A reorientation of the Fe and Er magnetic moments during sample cooling through the compensation point in a
large magnetic field is found by means of monochromatic circularly polarised radiation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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M. J. Mikkola 《International Journal of Non》1989,24(6):499-508
The principle of stationary complementary energy for geometrically non-linear problems of beams and trusses is considered. The functional of complementary energy is formulated in terms of force quantities. The stationary conditions describe the conditions of compatibility of the structure. The applications include the problem of elastica, a truss, and a bending problem by use of beam elements. 相似文献