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101.
Harrison AM South DR Willett P Artymiuk PJ 《Journal of computer-aided molecular design》2003,17(8):537-549
We describe a graph theoretic method designed to perform efficient searches for substructural patterns in nucleic acid structural coordinate databases using a simplified vectorial representation. Two vectors represent each nucleic acid base and the relative positions of bases with respect to one another are described in terms of distances between the defined start and end points of the vectors on each base. These points comprise the nodes and the distances the edges of a graph, and a pattern search can then be performed using a subgraph isomorphism algorithm. The minimal representation was designed to facilitate searches for complex patterns but was first tested on simple, well-characterised arrangements of bases such as base pairs and GNRA-tetraloop receptor interactions. The method performed very well for these interaction types. A survey of side-by-side base interactions, of which the adenosine platform is the best known example, also locates examples of similar base rearrangements that we consider to be important in structural regulation. A number of examples were found, with GU platforms being particularly prevalent. A GC platform in the RNA of the Thermus thermophilus small ribosomal subunit is in an analogous position to an adenosine platform in other species. An unusual GG platform is also observed close to one of the substrate binding sites in Haloarcula marismortui large ribosomal subunit RNA. 相似文献
102.
Résumé Etant donnée {M
p
}
p0 une suite de réels strictement positifs, on considère la classe de CarlemanC{p!M
p
} (resp. BeurlingB{p!M
p
}) des fonctionsf indéfiniment dérivables sur
n
. SoitE un sous ensemble compact de
n
; on peut associer à la classeC{p!M
p
} (resp.B{p!M
p
}) la classe des jets de Whitney surE,C
E
{p!M
p
}, (resp.B
E
{p!M
p
}) et on a une application de restriction naturelle deC{p!M
p
} dansC
E
{p!M
p
} (resp.B{p!M
p
} dansB
E
{p!M
p
}).Dans ce travail, on donne des conditions sur deux suites {M
p
}
p0 et {M
p
}
p0 pour que l'on ait les inclusions suivantes ou Ceci est, en quelque sorte, une généralisation du problème de prolongement de Whitney.
相似文献
相似文献
103.
Béatrice Serckx-Poncin Anne-Marie Hesbain-Frisque Léon Ghosez 《Tetrahedron letters》1982,23(32):3261-3264
The α,β unsaturated hydrazone reacts regioselectivity with a wide range of dienophiles to give the corresponding [4+2] adducts. Reductive cleavage of the NN bond in the adducts gives tetrahydropyridines. 相似文献
104.
Darcos V Duréault A Taton D Gnanou Y Marchand P Caminade AM Majoral JP Destarac M Leising F 《Chemical communications (Cambridge, England)》2004,(18):2110-2111
A first generation phosphorus-containing dendrimer with twelve terminal benzyl dithiobenzoate functions was designed and subsequently used as a multifunctional agent to derive hybrid star copolymers consisting of a dendritic core surrounded by twelve polystyrene branches by reversible addition-fragmentation chain transfer (RAFT). 相似文献
105.
106.
The title compound, isolated from leaves, is a new alkyl-3-phthalide characterized by an acylated side chain. It has been identified by spectral analysis as [3-(1-β-D-glucosyloxy)-2-hydroxy]benzoyl 3-(3-phthalidyl)-propyl ester. 相似文献
107.
The proton affinities of imidazole, oxazole, and thiazole rings, relevant to the binding of lexitropsins that contain these rings to the minor groove of DNA, are calculated using ab initio (Hartree–Fock) calculations. It is found that the proton affinities decrease in the order imidazole, oxazole, thiazole and that a methyl group substituent increases the proton affinity of imidazole, while a peptidic group decreases it. 相似文献
108.
Kim BS Lebedeva OV Kim DH Caminade AM Majoral JP Knoll W Vinogradova OI 《Langmuir : the ACS journal of surfaces and colloids》2005,21(16):7200-7206
We report the preparation, characterization, and mechanical properties of polyelectrolyte/phosphorus dendrimer multilayer microcapsules. The shells of these microcapsules are composed either by alternating poly(styrenesulfonate) (PSS) and positively charged dendrimer G4(NH+Et2Cl-)96 or by alternating poly(allylamine hydrochloride) (PAH) and negatively charged dendrimer G4(CH-COO-Na+)96. The same multilayers were constructed on planar support to examine their layer-by-layer growth and to measure the multilayer thickness. Surface plasmon resonance spectroscopy (SPR) showed regular linear growth of the assembly upon each bilayer deposited. We probe the mechanical properties of these polyelectrolyte/dendrimer microcapsules by measuring force-deformation curves with the atomic force microscope (AFM). The experiment suggests that they are much softer than PSS/PAH microcapsules studied before. This softening is attributed to an enhanced permeability of the polyelectrolyte/dendrimer multilayer shells as compared with multilayers formed by linear polyelectrolytes. In contrast, Young's modulus of both dendrimer-based multilayers was found to be on the same order as that of PSS/PAH multilayers. 相似文献
109.
Anne-Marie Alquie-Redon Jacky Vigneron Claude Lamy 《Journal of Electroanalytical Chemistry》1978,92(2):163-177
The kinetic behaviour of a two-step sequential reaction including a 2nd order adsorption process is treated theoretically in the case of semiconductor electrodes. It is shown that the electronic structure of the semiconductor can be taken into account in some simplified cases by introducing a formal transfer coefficient comprised between 0 and 1 and potential independent. In both linear potential sweep voltammetry and steady state cyclic voltammetry, the usual characteristic features (EM, M, iM) of the voltammetric curves are calculated as a function of the sweep rate for different values of the transfer coefficient. 相似文献
110.
A method was developed for the determination of Sb in wine by electrothermal atomic absorption spectrometry, based on preconcentration
by hydride generation with collection directly in the graphite furnace. Thiourea was added for prereduction of Sb(V) to Sb(III).
The hydride was directly generated from diluted wine. Palladium was used as modifier in the collection step; the overall efficiency
of the hydride/trapping system was found to be 67%. Sb was determined in several samples of red wine; the concentrations found
were in the range 0.6 to 5.7 μg/L Sb. The detection limit of the method was 39 pg Sb, corresponding to 0.13 μg/L Sb in wine
when 0.3 mL wine was analyzed.
Received: 3 November 1995/Revised: 22 February 1996/Accepted: 24 February 1996 相似文献