排序方式: 共有22条查询结果,搜索用时 15 毫秒
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Photodynamic degradation of nucleic acids 总被引:1,自引:0,他引:1
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Emery N Hérold C d'Astuto M Garcia V Bellin Ch Marêché JF Lagrange P Loupias G 《Physical review letters》2005,95(8):087003
We have obtained bulk samples of the graphite intercalation compound, CaC6, by a novel method of synthesis from highly oriented pyrolytic graphite. The crystal structure has been completely determined showing that it is the only member of the MC6, metal-graphite compounds that has rhombohedral symmetry. We have clearly shown the occurrence of superconductivity in the bulk sample at 11.5 K, using magnetization measurements. 相似文献
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C A Cuenod M F Bellin J C Bousquet A Duron E Auberton B M Mazoyer D Khayat P Opolon J Grellet 《Magnetic resonance imaging》1991,9(2):235-245
Thirty-nine patients with liver tumors were examined using MRI at 0.5 T before and after intravenous bolus injection of either 0.1 mmol/kg (n = 18) or 0.2 mmol/kg (n = 21) of Gadolinium-Dota, using spin-echo T1-and T2-weighted sequences before injections and spin-echo or gradient-echo sequences after injection. When contrast-to-noise (C/N) data were normalized relative to time, optimal mean C/N was observed after gadolinium injection. However, subjective study and case-by-case C/N measurement showed better contrast for SE 2000/60 and CT with injection in 62% and 42% of cases, respectively. 相似文献
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Rosa AH Goveia D Bellin IC da Silva Lessa S Dias Filho NL de Magalhães Padilha P 《Analytical and bioanalytical chemistry》2006,386(7-8):2153-2160
A new procedure was developed for the in situ characterization of the lability of metal species in aquatic systems by using
a system equipped with a diffusion membrane and cellulose organomodified with p-aminobenzoic acid groups (DM-Cell-PAB). To this end, the DM-Cell-PAB system was prepared by adding cellulose organomodified
with p-aminobenzoic acid groups (Cell-PAB) to pre-purified cellulose bags. After the DM-Cell-PAB system was sealed, it was examined
in the laboratory to evaluate the influence of complexation time, mass of exchanger, pH, metal ions (Cu, Cd, Fe, Mn, and Ni),
and concentration of organic matter on the relative lability of metal species. It was found that the pH and kinetics strongly
influence the process of metal complexation by the DM-Cell-PAB system. At all pH levels, Cd, Mn, and Ni showed lower complexation
with Cell-PAB resin than Cu and Fe metals. Note that relative lability of metals complexed to aquatic humic substances (AHS)
in the presence of Cell-PAB resin showed the following order: Cu≅Fe≫Ni>Mn=Cd. The results presented here also indicate that
increasing the AHS concentration decreases the lability of metal species by shifting the equilibrium to AHS–metal complexes.
Our results indicate that the system under study offers an interesting alternative that can be applied to in situ experiments
for differentiation of labile and inert metal species in aquatic systems. 相似文献
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J S Bellin 《Photochemistry and photobiology》1968,8(5):383-392
Abstract— A discussion is given of the photophysical and photochemical consequences of the binding of dyes and of pigments of biological importance to polymeric substrates. The modification of the photochemical properties induced by dye binding can in large part be ascribed to the known changes in photophysical properties of dyes engendered by such interactions. Principally, these involve enhanced formation of metastable species of dye molecules and decreased opportunity for self-quenching. In photochemical terms, dye binding thus enhances susceptibility to photoreduction, causes an increase in the quantum yield of photoreduction with increasing concentration of bound dye, and induces enhanced ability to act as a sensi-tizer in photoreduction. Paradoxically, dye binding decreases the ability of the bound dye to act as a sensitizer in photoxidation. 相似文献
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We consider a class of graphs embedded in as noncommutative proof-nets with an explicit exchange rule. We give two characterization of such proof-nets, one representing proof-nets as CW-complexes in a two-dimensional disc,
the other extending a characterization by Asperti. As a corollary, we obtain that the test of correctness in the case of planar
graphs is linear in the size of the data. Braided proof-nets are proof-nets for multiplicative linear logic with Mix embedded
in . In order to prove the cut-elimination theorem, we consider proof-nets in as projections of braided proof-nets under regular isotopy.
Received January 15, 1996 相似文献
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Abstract— Phycocyanin can sensitize the photobleaching of azo dyes in a reaction which is analogous to one sensitized by chlorophyll. The quantum yield of the phycocyanin-sensitized photobleaching of congo red is low compared to the analogous reaction as sensitized by chlorophyll in aqueous pyridine. A kinetic mechanism for the former reaction is proposed and it was found that the manner in which phycocyanin sensitizes photoreduction of azo dyes is in several respects similar to that proposed for chlorophyll. 相似文献