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321.
Millet R Träff AM Petrus ML Bäckvall JE 《Journal of the American Chemical Society》2010,132(43):15182-15184
β-Aminoketones obtained from imines in an organocatalytic Mannich reaction were transformed to enantio- and diastereomerically pure 1,3-aminoalcohols with two stereogenic centers via a combined reduction/dynamic kinetic asymmetric transformation. Both syn and anti diastereomers were obtained in high yield, dr, and ee. 相似文献
322.
323.
Levi MD Fisyuk AS Demadrille R Markevich E Gofer Y Aurbach D Pron A 《Chemical communications (Cambridge, England)》2006,(31):3299-3301
Incorporation of electron accepting units (oxadiazole) into the 2,5-thienylene conjugated chain leads to a significant improvement in the n-doping-undoping redox stability of the resulting polymer. 相似文献
324.
Beurroies I Agren P Büchel G Rosenholm JB Amenitsch H Denoyel R Linden M 《The journal of physical chemistry. B》2006,110(33):16254-16260
The formation of mesoscopically ordered silica/surfactant composites under alkaline synthesis conditions has been studied by time-resolved in situ small-angle X-ray diffraction with synchrotron radiation. Alkyltrimethylammoniumbromide surfactants, C(n)()TAB, of different chain lengths (n = 14, 16, and 18) as well as mixtures thereof were used as structure directing agents and the measurements were carried out at two different temperatures. A linear relationship between the mean surfactant chain length and the d spacing of the hexagonal phase was observed, suggesting an ideal mixing of the surfactants in the supramolecular surfactant aggregates. It is shown that the formation of the hexagonal phase is kinetically controlled mainly by the rate of silicate condensation, while the effect of changes in the surfactant chain length on the kinetics is small under the studied conditions. Two concominant, albeit partly interlinked, processes, suggested being intra- and intermicellar condensation, followed by aggregate-aggregate condensation, govern the nucleation and growth of the hexagonal phase. The two-step mechanism is confirmed by a microcalorimetric study where the heat evolved during the hydrolysis-condensation reactions is followed as a function of time. 相似文献
325.
326.
Silvia Villar-Rodil Renaud Denoyel Jean Rouquerol Amelia Martínez-Alonso Juan M. D. Tascn 《Thermochimica Acta》2004,420(1-2):141-144
Carbon molecular sieves (CMSs) for separating gaseous mixtures have been prepared through chemical vapour deposition (CVD) of benzene on activated carbon fibres (ACFs) obtained from Nomex aramid fibres. The effect of the CVD treatment on the porous texture of the ACFs has been followed by immersion calorimetry into liquids of different molecular sizes (dichloromethane, benzene and cyclohexane). Both the kinetics of the immersion process and the equilibrium immersion enthalpies have been studied. Besides, the derived specific surface areas accessible to the different liquids employed have been calculated. The results show that the carbon deposition has taken place mainly at the pore entrances and the CVD treatment has succeeded to introduce selectivity without a significant loss of capacity. 相似文献
327.
A phase-sensitive optical low-coherence reflectometry (OLCR) technique is demonstrated to simultaneously measure the absolute chromatic dispersion values of each guided LP mode of a few-mode fiber. We show that the OLCR technique requires only short samples of fiber (<1 m) and has no need for high-ratio mode converters to reach an accurate wavelength-dependent group delay evolution of every mode. As an example we present for the first time to our knowledge a direct and complete analysis of few-mode fibers with high, low, positive, and negative modal dispersion values, leading to chromatic dispersion parameters in good agreement with theoretical predictions. 相似文献
328.
Canon F Ballivian R Chirot F Antoine R Sarni-Manchado P Lemoine J Dugourd P 《Journal of the American Chemical Society》2011,133(20):7847-7852
We used ion mobility spectrometry to explore conformational adaptability of intrinsically disordered proteins bound to their targets in complex mixtures. We investigated the interactions between a human salivary proline-rich protein IB5 and a model of wine and tea tannin: epigallocatechin gallate (EgCG). Collisional cross sections of naked IB5 and IB5 complexed with N = 1-15 tannins were recorded. The data demonstrate that IB5 undergoes an unfolded to folded structural transition upon binding with EgCG. 相似文献
329.
Dr. Julien Rodriguez Dr. Isabelle Beurroies Dr. Thierry Loiseau Dr. Renaud Denoyel Dr. Philip L. Llewellyn 《Angewandte Chemie (International ed. in English)》2015,54(15):4626-4630
In any process, the heat exchanged is an essential property required in its development. Whilst the work related to structural transitions of some flexible metal–organic frameworks (MOFs) has been quantified and linked with potential applications such as molecular springs or shock absorbers, the heat related to such transitions has never been directly measured. This has now been carried out with MIL‐53(Al) using specifically devised calorimetry experiments. We project the importance of these heats in devices such as molecular springs or dampers. 相似文献
330.