排序方式: 共有41条查询结果,搜索用时 15 毫秒
1.
Edwige Croix 《Comptes Rendus Mathematique》2006,343(5):303-306
The author proves that any ideal generated by a finite number of real analytic functions in an intersection of non-quasi-analytic classes is closed for the natural Frechet topology associated to such a space. She also establishes a closedness criterion when the generators are less regular. To cite this article: E. Croix, C. R. Acad. Sci. Paris, Ser. I 343 (2006). 相似文献
2.
Edwige Jeanneau-Nicolle Claude Bosso Martine Benoit-Guyod Grard Leclerc 《Journal of mass spectrometry : JMS》1993,28(1):37-41
The electron impact mass spectra of two series of 5-oxo-tetrahydro-5H-thiazolo [3,2-a]pyrimidine-6-ethylcarboxylates and 7-oxo-tetrahydro-7H-thiazolo [3,2-a]pyrimidine-6-ethylcarboxylates were measured and fragmentation patterns examined. Structures were assigned from analysis of oxo molecular ion fragmentations. Compounds of the 5-oxo series gave an [M – CO2C2H5]+ fragmentation whereas compounds of the 7-oxo series gave three characteristic cleavages. This decomposition was confirmed for one pair of isomers by high-resolution mass spectrometry and unimolecular mass-analysed ion kinetic energy spectrometry. Electron impact mass spectrometry is a convenient method for assigning structures of 5- and 7-oxo regioisomers of tetrahydrothiazolo[3,2-a]pyrimidine-6-carboxylates. 相似文献
3.
Piotr Kujawa Annie Audibert‐Hayet Joseph Selb Franoise Candau 《Journal of Polymer Science.Polymer Physics》2004,42(9):1640-1655
Multisticker associative polyelectrolytes of acrylamide (≈86 mol %) and sodium 2‐acrylamido‐2‐methylpropanesulfonate (≈12 mol %), hydrophobically modified with N,N‐dihexylacrylamide groups (≈2 mol %), were prepared with a micellar radical polymerization technique. This process led to multiblock polymers in which the length of the hydrophobic blocks could be controlled through variations in the surfactant‐to‐hydrophobe molar ratio, that is, the number of hydrophobes per micelle (NH). The rheological behavior of aqueous solutions of polymers with the same molecular weight and the same composition but with two different hydrophobic block lengths (NH = 7 or 3 monomer units per block) was investigated as a function of the polymer concentration with steady‐flow, creep, and oscillatory experiments. The critical concentration at the onset of the viscosity enhancement decreased as the length of the hydrophobic segments in the polymers increased. Also, an increase in the NH value significantly enhanced the thickening ability of the polymers and affected the structure of the transient network. In the semidilute unentangled regime, the behavior of the polymer with long hydrophobic segments (NH = 7) was studied in detail. The results were well explained by the sticky Rouse theory of associative polymer dynamics. Finally, the viscosity decreased with an increase in the temperature, mainly because of a lowering of the sample relaxation time. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1640–1655, 2004 相似文献
4.
Matthias Bhm Edwige Lorthiois Muthuppalaniappan Meyyappan Andrea Vasella 《Helvetica chimica acta》2003,86(11):3787-3817
Racemic and enantiomerically pure manno‐configured isoquinuclidines were synthesized and tested as glycosidase inhibitors. The racemic key isoquinuclidine intermediate was prepared in high yield by a cycloaddition (tandem Michael addition/aldolisation) of the 3‐hydroxy‐1‐tosyl‐pyridone 10 to methyl acrylate, and transformed to the racemic N‐benzyl manno‐isoquinuclidine 2 and the N‐unsubstituted manno‐isoquinuclidine 3 (twelve steps; ca. 11% from 10 ). Catalysis by quinine of the analogous cycloaddition of 10 to (?)‐8‐phenylmenthyl acrylate provided a single diastereoisomer in high yield, which was transformed to the desired enantiomerically pure D ‐manno‐isoquinuclidines (+)‐ 2 and (+)‐ 3 (twelve steps; 23% from 10 ). The enantiomers (?)‐ 2 and (?)‐ 3 were prepared by using a quinidine‐promoted cycloaddition of 10 to the enantiomeric (+)‐8‐phenylmenthyl acrylate. The N‐benzyl D ‐manno‐isoquinuclidine (+)‐ 2 is a selective and slow inhibitor of snail β‐mannosidase. Its inhibition strength and type depends on the pH (at pH 4.5: Ki=1.0 μM , mixed type, α=1.9; at pH 5.5: Ki=0.63 μM , mixed type, α=17). The N‐unsubstituted D ‐manno‐isoquinuclidine (+)‐ 3 is a poor inhibitor. Its inhibition strength and type also depend on the pH (at pH 4.5: Ki=1.2?103 μM , mixed type, α=1.1; at pH 5.5: Ki=0.25?103 μM , mixed type, α=11). The enantiomeric N‐benzyl L ‐manno‐isoquinuclidine (?)‐ 2 is a good inhibitor of snail β‐mannosidase, albeit noncompetitive (at pH 4.5: Ki=69 μM ). The N‐unsubstituted isoquinuclidine (?)‐ 2 is a poor inhibitor (at pH 4.5: IC50=7.3?103 μM ). A comparison of the inhibition by the pure manno‐isoquinuclidines (+)‐ 2 and (+)‐ 3 , (+)‐ 2 /(?)‐ 2 1 : 1, and (+)‐ 3 /(?)‐ 3 1 : 1 with the published data for racemic 2 and 3 led to a rectification of the published data. The inhibition of snail β‐mannosidase by the isoquinuclidines 2 and 3 suggests that the hydrolysis of β‐D ‐mannopyranosides by snail β‐mannosidase proceeds via a distorted conformer, in agreement with the principle of stereoelectronic control. 相似文献
5.
Tiberiu-M. Gianga Edwige Audibert Anamaria Trandafir Gabriele Kociok-Khn G. Dan Panto 《Chemical science》2020,11(35):9685
We report herein the first all-donor aromatic [2]catenane formed through dynamic combinatorial chemistry, using single component libraries. The building block is a benzo[1,2-b:4,5-b′]dithiophene derivative, a π-donor molecule, with cysteine appendages that allow for disulfide exchange. The hydrophobic effect plays an essential role in the formation of the all-donor [2]catenane. The design of the building block allows the formation of a quasi-fused pentacyclic core, which enhances the stacking interactions between the cores. The [2]catenane has chiro-optical and fluorescent properties, being also the first known DCC-disulphide-based interlocked molecule to be fluorescent.An all-donor [2]catenane has been synthesised via dynamic combinatorial chemistry. It features stacked benzodithiophenes which are quasi-pentacyclic through hydrogen bonding. 相似文献
6.
Mannini M Tancini E Sorace L Sainctavit P Arrio MA Qian Y Otero E Chiappe D Margheriti L Cezar JC Sessoli R Cornia A 《Inorganic chemistry》2011,50(7):2911-2917
Surface-supported arrays of Fe(4)-type Single-Molecule Magnets retain a memory effect and are of current interest in the frame of molecule-based information storage and spintronics. To reveal the spin structure of [Fe(4)(L)(2)(dpm)(6)] (1) on Au, an isomorphous compound [Fe(3)Cr(L)(2)(dpm)(6)] was synthesized and structurally and magnetically characterized (H(3)L is tripodal ligand 11-(acetylthio)-2,2-bis(hydroxymethyl)undecan-1-ol and Hdpm is dipivaloylmethane). The new complex contains a central Cr(3+) ion and has a S = 6 ground state as opposed to S = 5 in 1. Low-temperature X-ray Magnetic Circular Dichroism studies at Fe- and Cr-L(2,3) edges revealed that the antiparallel alignment between Fe and Cr spins is preserved on surfaces. Moreover, the different Fe-L(2,3) spectral features found in the homo- and heterometallic species disclose the opposing contribution of the central Fe(3+) ion in the former compound, proving that its ferrimagnetic spin structure is retained on surfaces. 相似文献
7.
Marie-Martine Audibert Ramon Vilaseca Jacques Lukasik Jacques Ducuing 《Chemical physics letters》1975,31(2):232-236
The vibrational relaxation of ortho-para-H2 mixtures was studied in the interval 400-50 K. At and above 300 K the ortho and para self-relaxation rates, koo and kpp, are identical within experimental error. In the low temperature range, koo >kpp and koo is found to vary slowly with temperature. 相似文献
8.
9.
Dry and wet cotton linters were compressed under elevated pressure in a home-made Bridgman anvil press designed to reach 2.5 GPa and 180 °C. The structural organisation of cotton was changed under the joint action of temperature and pressure. Cotton having high moisture content shows that only a thin surface layer is partially destructured to a compact mat of nanofibres, while the initial cotton fibres are only deformed inside the sample. For dried cotton, the whole sample undergoes a destructuration into a compact mat of nanometre-sized fibres. The mechanical properties were studied by nano-indentation and dynamic mechanical analysis. Compressed dry cotton has higher modulus (10.3 GPa) than wet cotton (6.8 GPa). We postulate that the transverse elastic modulus of cotton microfibrils is around the value of 10 GPa. This work showed that nano-sized fibrils can also be separated in the solid state without flow, and re-compacted to form a solid object. 相似文献
10.
Dr. Yoann Prado Dr. Marie‐Anne Arrio Dr. Florence Volatron Dr. Edwige Otero Dr. Christophe Cartier dit Moulin Dr. Philippe Sainctavit Dr. Laure Catala Prof. Dr. Talal Mallah 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(21):6685-6694
The local symmetry and local magnetic properties of 6 nm‐sized, bimetallic, cyanide‐bridged CsNiCr(CN)6 coordination nanoparticles 1 and 8 nm‐sized, trimetallic, CsNiCr(CN)6@CsCoCr(CN)6 core–shell nanoparticles 2 were studied by X‐ray absorption spectroscopy (XAS) and X‐ray magnetic circular dichroism (XMCD). The measurements were performed at the NiII, CoII, and CrIII L2,3 edges. This study revealed the presence of distorted NiII sites located on the particle surface of 1 that account for the uniaxial magnetic anisotropy observed by SQUID measurements. For the core–shell particles, a combination of the exchange anisotropy between the core and the shell and the pronounced anisotropy of the CoII ions is the origin of the large increase in coercive field from 120 to 890 Oe on going from 1 to 2 . In addition, XMCD allows the relative orientation of the magnetic moments throughout the core–shell particles to be determined. While for the bimetallic particles of 1 , alignment of the magnetic moments of CrIII ions with those of NiII ions leads to uniform magnetization, in the core–shell particles 2 the magnetic moments of the isotropic CrIII follow those of CoII ions in the shell and those of NiII ions in the core, and this leads to nonuniform magnetization in the whole nanoobject, mainly due to the large difference in local anisotropy between the CoII ions belonging to the surface and the NiII ions in the core. 相似文献