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991.
Grassi G Scala A Piperno A Iannazzo D Lanza M Milone C Pistone A Galvagno S 《Chemical communications (Cambridge, England)》2012,48(54):6836-6838
This work reports for the first time a straightforward solvent-free chemical procedure to gain access to Δ-1-pyrroline grafted onto multiwalled carbon nanotubes by the 1,3-dipolar cycloaddition of the mesoionic 4-methyl-2-phenyloxazol-5(4H)-one. 相似文献
992.
Parkkila S Vullo D Maresca A Carta F Scozzafava A Supuran CT 《Chemical communications (Cambridge, England)》2012,48(29):3551-3553
Acetoacetic acid and R-3-hydroxy-butyric acid (BHB) are "ketone bodies", metabolites produced during the ketogenic diet. We discovered that they inhibit in the submicromolar-micromolar range several carbonic anhydrase (CA, EC 4.2.1.1) isoforms involved in relevant physiologic processes such as lipogenesis and tumorigenesis. The BHB fragment is also present in the molecules of most statins, widely used drugs for inhibiting cholesterol biosynthesis through the 3-hydroxy-3-methyl-glutaryl-CoA reductase pathway. Three such statins, atorvastatin, fluvastatin and rosuvastatin, showed submicromolar-low nanomolar inhibition of the fifteen human isoforms hCA I-XIV. Our data point out that in addition to their cholesterol lowering properties, these drugs may exert a therapeutic effect by inhibiting lipogenesis through mitochondrial CA inhibition. The statins are also low nanomolar inhibitors of the tumor-associated isoforms CA IX and XII. Based on the BHB/statin scaffolds, antiepileptic, antiobesity and antitumor compounds with higher affinity for the various CA isoforms involved in epileptogenesis (CA VA, VB, VII), lipogenesis (CA III, CA VA, CA VB) and tumorigenesis (CA IX and CA XII) may be designed. 相似文献
993.
994.
We report a significant increase of about 50% of the photoinduced birefringence in nanocomposite films of azopolymers doped with ZnO nanoparticles compared with samples made from nondoped azopolymers. This increase is most pronounced at small concentrations of the nanoparticles of 0.5% and for the amorphous polymers used in our study. We observe also an improvement of the response time of more than 25% in some of the polymers, which allows for faster and more effective polarization optical recording. 相似文献
995.
Gouvêa DP Bareño VD Bosenbecker J Drawanz BB Neuenfeldt PD Siqueira GM Cunico W 《Ultrasonics sonochemistry》2012,19(6):1127-1131
The efficient multicomponent synthesis of thiazolidinones from the reaction of arenealdehydes, mercaptoacetic acid and 2-picolilamine or 2-aminopyridine under ultrasound irradiation are reported. The reaction with 2-aminopyridine needs a Lewis acid catalysis to afford the corresponding 2-aryl-3-(pyridin-2-yl)-1,3-thiazolidin-4-ones. All novel compounds were identified and characterized by (1)H and (13)C NMR spectra. Applying the sonochemical methodology, two series of heterocyclic thiazolidinones were synthesized in good yields after short reaction times. 相似文献
996.
The Bernstein operators of second kind were introduced by Paolo Soardi in 1990, in terms of a random walk on a certain hypergroup. They have the same relation with Chebyshev polynomials of second kind as the classical Bernstein operators have with Chebyshev polynomials of first kind. In this paper we describe a de Casteljau type algorithm for these operators. 相似文献
997.
Kean Ming Tan Daniela M. Witten 《Journal of computational and graphical statistics》2013,22(4):985-1008
We consider the task of simultaneously clustering the rows and columns of a large transposable data matrix. We assume that the matrix elements are normally distributed with a bicluster-specific mean term and a common variance, and perform biclustering by maximizing the corresponding log-likelihood. We apply an ?1 penalty to the means of the biclusters to obtain sparse and interpretable biclusters. Our proposal amounts to a sparse, symmetrized version of k-means clustering. We show that k-means clustering of the rows and of the columns of a data matrix can be seen as special cases of our proposal, and that a relaxation of our proposal yields the singular value decomposition. In addition, we propose a framework for biclustering based on the matrix-variate normal distribution. The performances of our proposals are demonstrated in a simulation study and on a gene expression dataset. This article has supplementary material online. 相似文献
998.
Gaggeri R Rossi D Christodoulou MS Passarella D Leoni F Azzolina O Collina S 《Molecules (Basel, Switzerland)》2012,17(2):1665-1674
Phytochemical investigation on the Amygdalus lycioides Spach branchelets resulted in the isolation of four chiral flavanones: (2R,3R)-Taxifolin, (2R,3R)-aromadendrin, (S)-5,7,3',5'-tetrahydroxyflavanone and (S)-naringenin. The flavanones were isolated by semi-preparative HPLC, their structures elucidated based on spectroscopic data and their absolute configuration assigned. As a part of our ethnobotanical-directed search for novel TNFα inhibitors, the bioassay-guided fractionation of the n-hexane-acetone (n-Hex-Ac, 1:1 v/v) Amygdalus lycioides Spach branchelets extract was performed. In this way, (S)-naringenin was identified as the constituent responsible for the TNFα blocking effect, being effective in vitro and in vivo after oral administration. This is the first investigation on bioactive secondary metabolites of Amygdalus lycioides Spach branchelets. 相似文献
999.
1000.