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161.
Abstract This study has investigated docking-based 3D quantitative structure–activity relationships (QSARs) for a range of quinoline carboxylic acid derivatives by comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). A docking study has shown that most of the compounds formed H-bonds with Arg136 and Gln47, which have already been shown to be essential for the binding of ligands at the active site of the hydroorotate dehydrogenase adenovirus (hDHODH). Bioactive conformations of all the molecules obtained from the docking study were used for the 3D QSAR study. The best CoMFA and CoMSIA models were obtained for the training set and were found to be statistically significant, with cross-validated coefficients (q2 ) of 0.672 and 0.613, r2 cv of 0.635 and 0.598 and coefficients of determination (r2 ) of 0.963 and 0.896, respectively. Both models were validated by a test set of 15 compounds, giving satisfactory predicted correlation coefficients (r2 pred) of 0.824 and 0.793 for the CoMFA and CoMSIA models, respectively. From the docking-based 3D QSAR study we designed 34 novel quinoline-based compounds and performed structure-based virtual screening. Finally, in silico pharmacokinetics and toxicities were predicted for 24 of the best docked molecules. The study provides valuable information for the understanding of interactions between hDHODH and the novel compounds. 相似文献
162.
Jaan Aarik Aleks Aidla Arvo Kikas Tanel Kmbre Raul Rammula Peeter Ritslaid Teet Uustare Vino Sammelselg 《Applied Surface Science》2004,230(1-4):292-300
Atomic layer deposition of hafnium dioxide (HfO2) on silicon substrates was studied. It was revealed that due to low adsorption probability of HfCl4 on silicon substrates at higher temperatures (450–600 °C) the growth was non-uniform and markedly hindered in the initial stage of the HfCl4–H2O process. In the HfI4–H2O and HfI4–O2 processes, uniform growth with acceptable rate was obtained from the beginning of deposition. As a result, the HfI4–H2O and HfI4–O2 processes allowed deposition of smoother, more homogeneous and denser films than the HfCl4–H2O process did. The crystal structure developed, however, faster at the beginning of the HfCl4–H2O process. 相似文献
163.
164.
U. D. Vyas 《General Relativity and Gravitation》2008,40(11):2461-2465
It is shown by Clarke and Felice (J Phys A Math Gen 15:2415–2417, 1982) that under certain conditions a stationary space-time
will produce a closed timelike curve through each point of the space-time. Here a simpler proof and a different version of
their theorem are provided. 相似文献
165.
Agnieszka Andrykiewicz Luis Patino Jose Raul Naranjo Matthias Witte Marie-Claude Hepp-Reymond Rumyana Kristeva 《BMC neuroscience》2007,8(1):101
Background
Over the last few years much research has been devoted to investigating the synchronization between cortical motor and muscular activity as measured by EEG/MEG-EMG coherence. The main focus so far has been on corticomuscular coherence (CMC) during static force condition, for which coherence in beta-range has been described. In contrast, we showed in a recent study [1] that dynamic force condition is accompanied by gamma-range CMC. The modulation of the CMC by various dynamic force amplitudes, however, remained uninvestigated. The present study addresses this question. We examined eight healthy human subjects. EEG and surface EMG were recorded simultaneously. The visuomotor task consisted in isometric compensation for 3 forces (static, small and large dynamic) generated by a manipulandum. The CMC, the cortical EEG spectral power (SP), the EMG SP and the errors in motor performance (as the difference between target and exerted force) were analyzed. 相似文献166.
Michaeleen R. Munrow Ranga Subramanian Andrea J. Minei Matthew K. MacLeod Raul Crespo Mitsuaki Izuha Yoshio Tatamitani Kenji Yamanou Stewart E. Novick 《Journal of Molecular Spectroscopy》2007,242(2):129-138
The microwave spectra of the gauche conformer of perfluoro-n-butane, n-C4F10, of perfluoro-iso-butane, (CF3)3CF, and of tris(trifluoromethyl)methane, (CF3)3CH, have been observed and assigned. The rotational and centrifugal distortion constants for gauche n-C4F10 are: A = 1058.11750(7) MHz, B = 617.6832(1) MHz, C = 552.18794(1) MHz, ΔJ = 0.0257(5) kHz, δJ = 0.0052(3) kHz. A C-C-C-C dihedral angle, ω, of ∼55° has been determined. These values agree well with those obtained from a coupled cluster (CCSD/cc-PVTZ) calculation. The rotational and centrifugal distortion constants for iso-C4F10 and iso-C4HF9 are: Bo = 816.4519(4) MHz, DJ = 0.023(2) kHz, and Bo = 903.6985(25) MHz, DJ = 0.043(4) kHz, respectively. The dipole moment of iso-C4F10 and iso-C4HF9 have been measured and found to be 0.0338(8) and 1.69(9) D, respectively. 相似文献
167.
Afarinkia K Bahar A Bearpark MJ Garcia-Ramos Y Ruggiero A Neuss J Vyas M 《The Journal of organic chemistry》2005,70(23):9529-9537
[Reaction: see text]. A variety of 5-chloro-2(H)-1,4-oxazin-2-ones bearing a range of substituents at their 3- and 6-positions undergo Diels-Alder cycloaddition as a 2-azadiene component with electron-rich, electron-deficient, and electron-neutral dienophiles. These reactions proceed with moderate regio- and stereoselectivity to afford relatively stable and readily isolable bridged bicyclic lactone cycloadducts. Chemical manipulation of these cycloadducts affords highly substituted and functionally rich piperidines. The regio- and stereochemical preferences of the cycloadditions of 5-chloro-2(H)-1,4-oxazin-2-ones are investigated computationally using density functional theory (B3LYP/6-31G). 相似文献
168.
Echeverría JC Woolfson MS Crowe JA Hayes-Gill BR Croaker GD Vyas H 《Chaos (Woodbury, N.Y.)》2003,13(2):467-475
Detrended fluctuation analysis (DFA), suitable for the analysis of nonstationary time series, has confirmed the existence of persistent long-range correlations in healthy heart rate variability data. In this paper, we present the incorporation of the alphabeta filter to DFA to determine patterns in the power-law behavior that can be found in these correlations. Well-known simulated scenarios and real data involving normal and pathological circumstances were used to evaluate this process. The results presented here suggest the existence of evolving patterns, not always following a uniform power-law behavior, that cannot be described by scaling exponents estimated using a linear procedure over two predefined ranges. Instead, the power law is observed to have a continuous variation with segment length. We also show that the study of these patterns, avoiding initial assumptions about the nature of the data, may confer advantages to DFA by revealing more clearly abnormal physiological conditions detected in congestive heart failure patients related to the existence of dominant characteristic scales. 相似文献
169.
Raul Quiroga-Barranco 《Comptes Rendus Mathematique》2005,341(6):361-364
Let G be a connected noncompact simple Lie group acting isometrically on a connected compact pseudoRiemannian manifold M. Denote with and the dimension of the maximal null subspaces tangent to G and M, respectively. Then we always have . Our main result states that, if , then the G-action is, up to a finite covering, an algebraic action. We use this to obtain a complete characterization of a large family of G-actions, thus providing a partial positive answer to the conjecture proposed in Zimmer's program for pseudoRiemannian manifolds. To cite this article: R. Quiroga-Barranco, C. R. Acad. Sci. Paris, Ser. I 341 (2005). 相似文献
170.