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排序方式: 共有142条查询结果,搜索用时 31 毫秒
71.
72.
Nikla Baricordi Simonetta Benetti Valerio Bertolasi Carmela De Risi Gian P. Pollini Francesco Zamberlan Vinicio Zanirato 《Tetrahedron》2012,68(1):208-213
‘One-pot’ tandem reactions of commercially available 1,4-dithiane-2,5-diol (the dimer of mercaptoacetaldehyde) with electrophilic alkenes resulted in the facile formation of substituted tetrahydrothiophene derivatives. Thus, sulfa-Michael/Henry and sulfa-Michael/aldol sequences provided polysubstituted tetrahydrothiophenes using in situ generated nitroalkenes and α,β-unsaturated carbonyl compounds as the electrophilic partners of mercaptoacetaldehyde dimer, respectively. 相似文献
73.
Bettini R. Bertolini G. Frigo E. Rossi A. Casini I. Pasquali I. Giordano F. 《Journal of Thermal Analysis and Calorimetry》2004,77(2):625-638
The aim of this work was to study the solubility in supercritical CO2 of the hydrated phase of three model drugs, namely theophylline, carbamazepine, and diclofenac sodium, in comparison with
the respective anhydrous form. Possible solid-state modifications, stemming from the interaction with supercritical CO2, were investigated by differential scanning calorimetry, thermogravimetric analysis, hot stage microscopy, Fourier Transform
infrared spectroscopy and Karl-Fischer titrimetry. It was found that all three pharmaceutical hydrates exhibited higher solubility
in supercritical CO2 than the relevant anhydrous phases. In the case of theophylline monohydrate, the instability of the crystal phase at the
experimental temperature adopted has been evidenced. Diclofenac sodium tetrahydrate represents a peculiar case of chemical
interaction with the acid supercritical fluid, mediated by crystal water.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
74.
75.
Gian Piero Pollini Nikla Baricordi Carmela De Risi Vinicio Zanirato 《Tetrahedron letters》2005,46(21):3699-3701
A simple synthetic approach to chiral, non-racemic, 2-piperazinones has been developed using natural amino acids methyl esters and nitroethylene as starting materials. 相似文献
76.
Axial rotational diffusion of rodlike polymers is important in processes such as microtubule filament sliding and flagella beating. By imaging the motion of small kinks along the backbone of chains of DNA-linked colloids, we produce a direct and systematic measurement of axial rotational diffusivity of rods both in bulk solution and near a wall. The measured diffusivities decrease linearly with the chain length, irrespective of the distance from a wall, in agreement with slender-body hydrodynamics theory. Moreover, the presence of small kinks does not affect the chain's axial diffusivity. Our system and measurements provide insights into fundamental axial diffusion processes of slender objects, which encompass a wide range of entities including biological filaments and linear polymer chains. 相似文献
77.
Matysiak S Montesi A Pasquali M Kolomeisky AB Clementi C 《Physical review letters》2006,96(11):118103
The dynamics of translocation of polymer molecules through nanopores is investigated via molecular dynamics. We find that an off-lattice minimalist model of the system is sufficient to reproduce quantitatively all the experimentally observed trends and scaling behavior. Specifically, simulations show (i) two translocation regimes depending on the ratio of pore and polymer length, (ii) two different regimes for the probability of translocation depending on applied voltage, (iii) an exponential dependence of translocation velocity upon applied voltage, and (iv) an exponential decrease of the translocation time with temperature. We also propose a simple theoretical explanation of each of the observed trends within a free energy landscape framework. 相似文献
78.
Improving the detection of proteins after transfer to polyvinylidene difluoride membranes. 总被引:2,自引:0,他引:2
J C Sanchez F Ravier C Pasquali S Frutiger N Paquet B Bjellqvist D F Hochstrasser G J Hughes 《Electrophoresis》1992,13(9-10):715-717
N-Terminal sequence analysis of proteins separated by two-dimensional polyacrylamide gel electrophoresis and transferred onto polyvinylidene difluoride (PVDF) membranes has become the method for molecular characterization of proteins contained in biological samples. However, the proteins of lower abundance cannot be sequenced directly, without improving the technique. We have studied a drying method on several PVDF membranes including Trans-Blott, Immobilon P and Problott. Using Amido Black, Coomassie Brilliant Blue R-250 and Ponceau S, we have obtained, in comparison with the non-dried membranes, an enormous increase in the number of detectable proteins. 相似文献
79.
80.
Mangiarotti A Maurenzig PR Olmi A Piantelli S Bardelli L Bartoli A Bini M Casini G Coppi C Gobbi A Pasquali G Poggi G Stefanini AA Taccetti N Vanzi E 《Physical review letters》2004,93(23):232701
Peripheral and semiperipheral collisions have been studied in the system 93Nb+93Nb at 38A MeV. The evaporative and midvelocity components of the light charged particle and intermediate mass fragment emissions have been carefully disentangled. In this way it was possible to obtain the average amount not only of charge and mass, but also of energy, pertaining to the midvelocity emission, as a function of an impact parameter estimator. This emission has a very important role in the overall balance of the reaction, as it accounts for a large fraction of the emitted mass and for more than half of the dissipated energy. As such, it may give precious clues on the microscopic mechanism of energy transport from the interaction zone toward the target and projectile remnants. 相似文献