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131.
Gamma-radiolysis DNA products: synthesis of 6-(alpha-thyminyl)-5,6-dihydro-4-thiothymine derivatives
Ortiz Mayo JU Dupradeau FY Guillaume D Fourrey JL Clivio P 《The Journal of organic chemistry》2004,69(14):4797-4801
Far-UV photolysis of 4-thiothymidylyl(3'-5')thymidine led to the formation of three stable derivatives: one resulting from a combination between a 3'-end methylene radical and a 5'-end C(4) radical [4-(alpha-thyminyl) derivative] and two formed after a combination between a 3'-end methylene radical and a 5'-end C(6) radical [6-(alpha-thyminyl) derivative]. In the latter series, two stereochemical pathways took place during the reaction between the methylene and C(6) radicals. The major pathway occurred when the 5'-base glycosidic bond had an anti conformation leading to an S configuration of the C(6) Tp-end. The minor pathway, which had never been reported before in this series, involved a 5'-base in a syn conformation leading consequently to the R configuration at the C(6) Tp-end. The 5,6-dihydrothymine moiety of these two adducts presented a 5,6-trans diaxial substitution that resulted from the epimerization, at the 5,6-dihydropyrimidine 5-position, of a less stable cis-disubstituted intermediate. 相似文献
132.
Pascale Bergeret 《Mathematical Methods in the Applied Sciences》1997,20(18):1563-1598
We give a complete classification for breakdown in finite time or global existence of continuously differentiable solutions to hyperbolic systems of two first-order partial differential equations posed on a real bounded interval, with boundary damping and initial data of small magnitude. Structural bounds for the derivatives of the initial data which govern the behavior of the solution are brought to light. We isolate two classes of boundary damping: the strong damping forbids the solution to blow up after a time that we exhibit while the weak damping permits a late breakdown. The results are applied to nonlinear elasticity. © 1997 by B. G. Teubner Stuttgart–John Wiley & Sons Ltd. 相似文献
133.
The accuracy, repeatability, and reproducibility characteristics of a liquid chromatographic method for the determination of ochratoxin A (OTA) in white wine, red wine, and beer were established in a collaborative study involving 18 laboratories in 10 countries. Blind duplicates of blank, spiked, and naturally contaminated materials at levels ranging from < or =0.01 to 3.00 ng/mL were analyzed. Wine and beer samples were diluted with a solution containing polyethylene glycol and sodium hydrogen carbonate, and the diluted samples were filtered and cleaned up on an immunoaffinity column. OTA was eluted with methanol and quantified by reversed-phase liquid chromatography with fluorometric detection. Average recoveries from white wine, red wine, and beer ranged from 88.2 to 105.4% (at spiking levels ranging from 0.1 to 2.0 ng/mL), from 84.3 to 93.1% (at spiking levels ranging from 0.2 to 3.0 ng/mL), and from 87.0 to 95.0% (at spiking levels ranging from 0.2 to 1.5 ng/mL), respectively. Relative standard deviations for within-laboratory repeatability (RSDr) ranged from 6.6 to 10.8% for white wine, from 6.5 to 10.8% for red wine, and from 4.7 to 16.5% for beer. Relative standard deviations for between-laboratories reproducibility (RSDR) ranged from 13.1 to 15.9% for white wine, from 11.9 to 13.6% for red wine, and from 15.2 to 26.1% for beer. HORRAT values were < or =0.4 for the 3 matrixes. 相似文献
134.
Pascale Besse Genevive Baziard-Mouysset Kamal Boubekeur Pierre Palvadeau Henri Veschambre Marc Payard Guy Mousset 《Tetrahedron: Asymmetry》1999,10(24):199-4754
From the microbiological reductions of 2-acetyl or 2-benzoylchromen-4-one both enantiomers of the corresponding alcohols were obtained with high enantiomeric excess. The absolute configurations were determined directly by an X-ray structural determination. The results obtained showed that for most of the microorganisms tested, an inversion of the configuration of the alcohol occurred with the change of the substituent (methyl to phenyl group) in position 2, but also with the presence of a bromine atom in position 6 of the aromatic ring, positioned quite far from the prochiral centre. 相似文献
135.
This research deals with RC beams strengthened with FRP. An experimental research is presented which is aimed at evaluating
the capability of an experimental modal analysis to assess the stiffness decrease due to damage, as well as the stiffness
recovery due to strengthening. Ten beams were tested. All of them were subjected to loading cycles with increasing load levels
in order to induce cracking of different severity in them. The beams were then retrofitted by externally bonded FRP sheets.
Three types of composites were used. The number of layers was varied, too. Modal tests were carried out after each loading-unloading
cycle. The modal frequencies and damping ratios were determined for the first four vibration modes. The results obtained indicate
that an experimental modal analysis can give useful information on the severity of damage and the effectiveness of strengthening.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 1, pp. 3–20, January–February, 2006. 相似文献
136.
137.
Marie O Malicki N Pommier C Massiani P Vos A Schoonheydt R Geerlings P Henriques C Thibault-Starzyk F 《Chemical communications (Cambridge, England)》2005,(8):1049-1051
NO2 disproportionation on alkaline zeolites is used to generate nitrosonium (NO+) and nitrate ions on the surface, and the infrared vibrations observed are very sensitive to the cation chemical hardness and to the basicity of zeolitic oxygen atoms. 相似文献
138.
Pascale Vitse 《Journal of Functional Analysis》2005,228(2):245-269
It is well-known that -sectorial operators generally do not admit a bounded H∞ calculus over the right half-plane. In contrast to this, we prove that the H∞ calculus is bounded over any class of functions whose Fourier spectrum is contained in some interval [ε,σ] with 0<ε<σ<∞. The constant bounding this calculus grows as as and this growth is sharp over all Banach space operators of the class under consideration. It follows from these estimates that -sectorial operators admit a bounded calculus over the Besov algebra of the right half-plane. We also discuss the link between -sectorial operators and bounded Tadmor-Ritt operators. 相似文献
139.
Pascale Vitse 《Journal of Functional Analysis》2004,210(1):43-72
For Banach space operators T satisfying the Tadmor-Ritt condition ||(zI−T)−1||?C|z−1|−1, |z|>1, we prove that the best-possible constant CT(n) bounding the polynomial calculus for T, ||p(T)||?CT(n)||p||∞, deg(p)?n, behaves (in the worst case) as as n→∞. This result is based on a new free (Carleson type) interpolation theorem for polynomials of a given degree. 相似文献
140.
The integration-by-parts methods introduced in this paper improveupon the Lp estimates on transport densities given in the recentpaper by L. De Pascale and A. Pratelli (Calc. Var. Partial DifferentialEquations 14 (2002) 249274). 2000 Mathematics SubjectClassification 35Q99, 35B99. 相似文献