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111.
Par Bernard Spiess Franoise Arnaud-Neu Marie-Jos Schwing-Weill 《Helvetica chimica acta》1980,63(8):2287-2294
Stability in Methanol and Thermodynamic Transfer Properties of the Cryptates of some Transition Cations and Heavy Metals The nature and stability of the macrocyclic and macrobicyclic complexes of Ag+, Cd2+, and Pb2+ (Mn+) with 21, 22, 211, 221 and 222 in anhydrous methanol 0.05M in Et4N+ClO?4, at 25° (see Scheme) have been determined by potentiometry and spectrophotometry. Binuclear complexes M2L2n+ have been observed in all cases, besides the mononuclear MLn+ complexes. The macrobicyclic 1:1 complexes MLn+ exhibit an important ‘cryptate effect’ with Mn+=Ag+, Pb2+ and Cd2+, but not with Cu2+ and Zn2+; their stability is in all cases maximum with 221. The applicability to our results of the recent extrathermodynamic hypothesis involving MLn+ cryptates is examined. 相似文献
112.
Let A be a uniform algebra on a compact space X, let M be the maximal ideal space of A, and consider an element ? of A. Choose a component W of ??(X). In 1963 Bishop showed that {} can be made into a one-dimensional complex analytic space provided there is a subset G of W having positive area such that for each λ in is finite. We show that the hypothesis of “positive area” may be replaced by “positive exterior capacity” and that no weaker condition will suffice. 相似文献
113.
Bernard S. Kay 《Communications in Mathematical Physics》1978,62(1):55-70
We give mathematically rigorous results on the quantization of the covariant Klein Gordon field with an external stationary scalar interaction in a stationary curved space-time. We show how, following Segal, Weinless etc., the problem reduces to finding a “one particle structure” for the corresponding classical system. Our main result is an existence theorem for such a one-particle structure for a precisely specified class of stationary space-times. Byproducts of our approach are:
- A discussion of when a given “equal-time” surface in a given stationary space-time is Cauchy.
- A modification and extension of the methods of Chernoff [3] for proving the essential self-adjointness of certain partial differential operators.
114.
Optimised silver staining protocols were devised for the detection of membrane proteins in purified form and as a crude mixture. These were adduced in both sodium dodecyl sulphate (SDS) and native polyacrylamide gel electrophoresis and consisted of ethanol-acetic acid-formaldehyde fixation, Coomassie Brilliant Blue prestaining, Rapidfix pretreatment, formaldehyde enhancement and finally ammoniacal silver staining. With these modifications, numerous staining problems of membrane proteins were overcome. These included reduction in background staining, enhanced detection sensitivity in native gels, elimination of negative staining and the avoidance of metallic silver deposition on the gel surface. In overcoming these problems, some factors determining the colour and stainability of membrane proteins in their native state were determined. Both the anionic Coomassie Brilliant Blue dye and SDS detergent improved the sensitivity of silver staining in native gels, and ammoniacal silver was more sensitive than neutral silver, suggesting silver staining to be a charge dependent process. 相似文献
115.
Philippe Milli Bernard Lvy Gaston Berthier 《International journal of quantum chemistry》1972,6(1):155-166
A first order perturbation treatment starting with SCF-MO 'S in canonical or equivalent quasi-localized form is presented for the hyperfine coupling constants of vinyl and methyl radicals. The spin-polarisation contribution to hyperfine splittings is found to be large, negative for the proton of the radical center in both radicals and positive for the β protons of vinyl. 相似文献
116.
Persephone Canonne Raynald Boulanger Bernard Chantegrel 《Journal of heterocyclic chemistry》1989,26(1):113-117
A one-step synthesis of spiro[cycloalkane-1,4′-2H-3′,1-benzoxazin]-2′-ones and spiro[cycloalkane-1,4′-1H-pyrido[2′,3′-d][1,3′]oxazin]-2′-ones, obtained in good yield from the corresponding 1-(o-aminophenyl) and 1-(2′-amino-3′-pyridinyl)cycloalkanols is described using ethyl carbonate in presence of n-butyllithium. 相似文献
117.
Bruno Ameduri Bernard Boutevin Fouad Malek 《Journal of polymer science. Part A, Polymer chemistry》1994,32(16):3161-3169
The synthesis of maleimides that have pyrazolic or bipyrazolic pendant groups is described. Their homopolymerization and their copolymerization with 2-chloroethyl vinyl ether (CEVE) is reported. The homopolymerizations of such maleimides were performed under various conditions and led to low molecular-weight polymers. However, alternating copolymers were obtained from CEVE as comonomers whatever the monomers feed compositions. A similar behavior was also observed for maleimides that do not exhibit any spacer, whereas for bulky vinyl ethers, random copolymers were produced. A comparison of the thermal behavior between these copolymers (glass transition temperatures, Tg, and decomposition temperatures) and other copolymers having different spacers between the nitrogenated cycles and the chain are related. Thus, an important decrease of Tg, was observed when C3H6CO2CH2 groups were used as the spacer instead of methylene groups. Moreover, the thermal weakness of these copolymers may come from the substituents of the vinyl ether and is discussed. © 1994 John Wiley & Sons, Inc. 相似文献
118.
Bruno Jean Georges Bokias Lay-Theng Lee Ilias Iliopoulos Bernard Cabane 《Colloid and polymer science》2002,280(10):908-914
The structures of aqueous copolymer solutions have been examined through small angle neutron scattering. The copolymers contained mostly N-isopropylacrylamide (NIPAM) monomers. Poly (NIPAM) solutions have a lower critical solution temperature (LCST), above which the macromolecules separate from water. A small fraction of ionizable N,N-[(dimethylamino) propyl] methacrylamide (MADAP) monomers was introduced into the macromolecules. This had dramatic consequences on the solution behavior at temperatures above the LCST of PNIPAM, where phase separation would have been expected for the homopolymer. When all MADAP monomers were ionized, it was found that the solutions resisted the phase separation. At short spatial scales, the chains were collapsed but at large scales they formed branched aggregates that did not separate out of water. When only half of the MADAP monomers are ionized, the electrical charges were able to redistribute themselves along the chains. In this case, the rise in temperature caused a microphase separation where the electrical charges were relocated on a fraction of the chains that remained in solution.The other chains (or section of chains) formed large nodules of a polymer rich phase. 相似文献
119.
We report here our findings on a new and highly efficient strategy for the synthesis of β-amino acids involving the addition of bis(O-silyl) ketene acetals on Mannich type iminium electrophiles. 相似文献
120.
P. Netchitailo Bernard Decroix Jean Morel Paul Pastour 《Journal of heterocyclic chemistry》1978,15(2):337-342
We describe the first synthesis of 2-arylbenzo[4,5]thieno-[2,3-b]pyran-4-one and of 2-arylbenzo [4,5] thieno [3,2-b] pyran-4-one, from benzo [4,5] thiophene and we have extended these cyclizations to obtain the heterocyclic analogs of the xanthones. 相似文献