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排序方式: 共有109条查询结果,搜索用时 15 毫秒
1.
E. de A. Gonçalves V. M. de Oliveira A. Rosas P. R.A. Campos 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(1):127-132
Adaptation of populations takes place with the occurrence and subsequent fixation of mutations that confer some selective
advantage
to the individuals which acquire it. For this reason, the study of the process of fixation of advantageous mutations has a
long history
in the population genetics literature. Particularly, the previous investigations aimed to find out the main evolutionary forces
affecting the strength of natural selection in the populations.
In the current work, we investigate the dynamics of fixation of beneficial mutations in a subdivided population. The subpopulations
(demes)
can exchange migrants
among their neighbors, in a migration network which is assumed to have either a random graph or a scale-free topology. We
have observed that the migration rate
drastically affects the dynamics of mutation fixation, despite of the fact that the probability of fixation is invariant on
the
migration rate, accordingly to
Maruyama's conjecture. In addition, we have noticed a topological dependence of the adaptive evolution of the population when
clonal interference
becomes effective. 相似文献
2.
Adrian Hernandez Santiago Salvador Rosas Castilla Albino Morales Rodriguez Elena Aleskerova Anastasia Lantushenko Viktor Kostjukov 《Molecular physics》2013,111(15):1941-1947
An approximately linear correlation has been found between the enthalpy of complexation and the area of overlap of the chromophores using published structural and thermodynamical data on the self- and hetero-association of aromatic molecules measured under similar solution conditions. This finding is consistent with the assumption that short-range van-der-Waals forces dominate over other contributions to the enthalpy of stacking of aromatic molecules. It provides a ‘model-independent’ approach for a priori estimation of the enthalpy of aromatic–aromatic stacking interactions from knowledge of the structural properties or vice versa. 相似文献
3.
4.
Hang Yin Qian Cheng Roselyne Rosas Prof. Stéphane Viel Dr. Valérie Monnier Prof. Laurence Charles Prof. Didier Siri Dr. Didier Gigmes Dr. Olivier Ouari Prof. Ruibing Wang Dr. Anthony Kermagoret Dr. David Bardelang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(54):12552-12559
A viologen derivative carrying a benzimidazole group ( V-P-I 2+; viologen–phenylene–imidazole V-P-I ) can be dimerized in water using cucurbit[8]uril (CB[8]) in the form of a 2:2 complex resulting in a negative shift of the guest pKa, by more than 1 pH unit, contrasting with the positive pKa shift usually observed for CB-based complexes. Whereas 2:2 complex protonation is unclear by NMR, silver cations have been used for probing the accessibility of the imidazole groups of the 2:2 complexes. The protonation capacity of the buried imidazole groups is reduced, suggesting that CB[8] could trigger proton release upon 2:2 complex formation. The addition of CB[8] to a solution containing V-P- I 3+ indeed released protons as monitored by pH-metry and visualized by a coloured indicator. This property was used to induce a host/guest swapping, accompanied by a proton transfer, between V-P-I 3+ ⋅ CB[7] and a CB[8] complex of 1-methyl-4-(4-pyridyl)pyridinium. The origin of this negative pKa shift is proposed to stand in an ideal charge state, and in the position of the two pH-responsive fragments inside the two CB[8] which, alike residues engulfed in proteins, favour the deprotonated form of the guest molecules. Such proton release triggered by a recognition event is reminiscent of several biological processes and may open new avenues toward bioinspired enzyme mimics catalyzing proton transfer or chemical reactions. 相似文献
5.
Carlos Raimundo Andrade Lima Jefferson da Silva Martins Caroline Pinheiro Luis Fernando de Avila Roberto Rosas Pinho Maria Luiza Miranda Rocco Wilson de Souza Melo Fabio Zappa 《Journal of Polymer Science.Polymer Physics》2019,57(15):967-972
Photopolymerization is a phenomenon that is the basis of much of today's microfabrication technology and intense research is conducted to improve its control and the characteristics of end products for a variety of applications. The design of microscopic structures often relies on the accurate knowledge and modeling of photopolymer's behavior upon exposure, i.e. the Dill parameters, for each radiation species of interest and therefore the development of flexible characterization techniques is of great importance. SU‐8 is a popular compound that is representative of a whole class that relies on cationic polymerization, where an acid is obtained via photolysis of an onium salt during exposure. Here we report on the observation of SbF6? via laser desorption mass spectrometry on SU‐8 exposed to UV light at the wavelength of 365 nm and demonstrate that the yield of this counter‐anion as a function of exposure is consistent with the Dill C parameter value available in the literature. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 967–972 相似文献
6.
Rafael O. Ruggiero Vladimir A. Rosas Meneses 《Bulletin of the Brazilian Mathematical Society》2003,34(2):263-274
In this paper, we show that the Pesin set of an expansive
geodesic flow in compact manifold with no conjugate points and
bounded asymptote coincides a.e with an open and dense set of
the unit tangent bundle. We also show that the set of hyperbolic
periodic orbits is dense in the unit tangent bundle. 相似文献
7.
A 1000 consonant–vowel–consonant structure logatoms corpus (CVC-structure), grouped in 10 phonetically equally balanced lists of 100 words each, was developed to satisfy the need of subjective assessment of speech intelligibility in American Spanish speaking environments. This corpus was tested and correlated with the Speech Transmission Index (STI) measurements to compare its articulation intelligibility score with other lists’ scores.Through the development of this work it was determined that in two different acoustically poor rooms that have the same STI (with STI < 0.50), the intelligibility score is lower when the articulation test is performed in a quiet room with high reverberation time than when it is performed in a very noisy room with low reverberation time. The final correlation curve of the American Spanish CVC-structure corpus was around 10% points higher than the CVCEQB curve obtained by Steeneken and Houtgast in 2002. 相似文献
8.
Roselyne Briere Jean-Claude Espie René Ramasseul André Rassat Paul Rey 《Tetrahedron letters》1979,20(11):941-944
β-Ketoaldehyde derivatives of simple piperidine and pyrrolidine nitroxides as spin labelled ligands give paramagnetic three-electron copper complexes. 相似文献
9.
Roberto Gustavo Furlan Wagner Raphael Correr Ana Flavia Costa Russi Mônica Rosas da Costa Iemma Eliane Trovatti Édison Pecoraro 《Journal of Sol-Gel Science and Technology》2018,88(1):181-191
45S5 bioglass has been widely studied in the last few decades because of its bioactivity and promising applications in the biomedical field. Boron, even few studied, represents a potential element to improve the properties of the 45S5 bioglass derivatives. The bioglasses are conventionally prepared by heat treatment of oxides and silicon. Here, the sol?gel method is proposed for the preparation of the boron-based 45S5 bioglass (45S5B) and the classical 45S5 bioglass (45S5), using water-soluble salts as raw materials. The bioglasses were characterized by FTIR, XRD, and SEM, indicating the success of the sol?gel method for preparation of the samples. The bioglasses were also tested in vitro for bioactivity in biological conditions and cytotoxicity against eukaryotic cells. The bioactivity of 45S5B was similar to the bioactivity of 45S5 bioglass, indicated by the deposition of hydroxyapatite crystals at the surface of the pristine bioglasses. The results of cytotoxicity tests revealed that the IC50 of 45S5B (IC50?=?7.56?mg?mL?1) was similar to the IC50 of 45S5 (IC50?=?8.15?mg?mL?1), indicating its safety for application in the biomedical field. 相似文献
10.