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排序方式: 共有750条查询结果,搜索用时 15 毫秒
1.
Adamovich MI Aggarwal MM Alexandrov YA Ameeva ZV Andreeva NP Anzon ZV Arora R Badyal SK Bhalla KB Bhasin A Bhatia VS Bubnov VI Burnett TH Cai X Chasnikov IY Chernova LP Chernyavski MM Dressel B Eligbaeva GZ Eremenko LE Friedlander EM Gadzhieva SI Gaitinov AS Ganssauge ER Garpman S Gerassimov SG Gill A Grote JG Gulamov KG Gulyamov UG Gupta VK Hackel S Heckman HH Haung H Judek B Kachroo S Kadyrov FG Kalyachkina GS Kanygina EK Kaul GL Kaur M Kharlamov SP Koss T Kumar V Lal P Larionova VG 《Physical review letters》1990,65(4):412-415
2.
Single-phase and gram-scale routes toward nearly monodisperse Au and other noble metal nanocrystals 总被引:5,自引:0,他引:5
Single-phase approaches are introduced for the synthesis of nearly monodisperse Au and other noble metal nanocrystals. The new approaches possess all the advantages of the popular Brust method. With weak ligands or surfactants for the metal ions, the control of the size and size distribution of the nanocrystals in synthesis in the size range between 1 and 15 nm was achieved via maintaining balanced nucleation and growth by tuning the activities of the metal precursors and reducing reagents. Because only weak ligands are employed in the new synthetic schemes, surface modification and functionalization of the resulting nanocrystals can be readily carried out. 相似文献
3.
Herein we describe a strategy for the preparation of artificial alpha-helices involving replacement of one of the main-chain hydrogen bonds with a covalent linkage. To mimic the C=O...H-N hydrogen bond as closely as possible, we envisioned a covalent bond of the type C=X-Y-N, where X and Y are two carbon atoms connected through an olefin metathesis reaction. Our results demonstrate that the replacement of a hydrogen bond between the i and i + 4 residues at the N-terminus of a short peptide with a carbon-carbon bond results in a highly stable constrained alpha-helix at physiological conditions as indicated by CD and NMR spectroscopies. The advantage of this strategy is that it allows access to short alpha-helices with strict preservation of molecular recognition surfaces required for biomolecular interactions. 相似文献
4.
Nikhil M. Kriplani David P. Nackashi Christian J. Amsinck Neil H. Di Spigna Michael B. Steer Paul D. Franzon Ramon L. Rick Gemma C. Solomon Jeffrey R. Reimers 《Chemical physics》2006
Two efficient, physically based models for the real-time simulation of molecular device characteristics of single molecules are developed. These models assume that through-molecule tunnelling creates a steady-state Lorentzian distribution of excess electron density on the molecule and provides for smooth transitions for the electronic degrees of freedom between the tunnelling, molecular-excitation, and charge-hopping transport regimes. They are implemented in the fREEDA™ transient circuit simulator to allow for the full integration of nanoscopic molecular devices in standard packages that simulate entire devices including CMOS circuitry. Methods are presented to estimate the parameters used in the models via either direct experimental measurement or density-functional calculations. The models require 6–8 orders of magnitude less computer time than do full a priori simulations of the properties of molecular components. Consequently, molecular components can be efficiently implemented in circuit simulators. The molecular-component models are tested by comparison with experimental results reported for 1,4-benzenedithiol. 相似文献
5.
High pressure behavior of alpha-hydroquinone (1,4-dihydroxybenzene) has been studied using Raman spectroscopy up to pressures of 19 GPa. Evolution of Raman spectra suggests two transitions around 3.3 and 12.0 GPa. The first transition appears to be associated with the lowering of crystal symmetry. Above 12.0 GPa, Raman bands in the internal modes region exhibit continuous broadening suggesting that the system is progressively evolving into a disordered state. This disorder is understood as arising due to distortion of the hydrogen-bonded cage across the second transition around 12 GPa. 相似文献
6.
An investigation of the properties of poly(dimethylsiloxane)-bioinspired silica hybrids 总被引:1,自引:0,他引:1
Siddharth V. Patwardhan Vijay P. Taori Nikhil R. Agashe Gregory Beaucage Stephen J. Clarson 《European Polymer Journal》2006,42(1):167-178
Elastomers typically require the incorporation of reinforcing fillers in order to improve their mechanical properties. For commercial silicone systems silica and titania are typically used as fillers. Fumed and precipitated silica are made on an industrial scale for many applications; however, we have shown recently that biological and synthetic macromolecules can generate new silica structures using a bioinspired route. Herein we have incorporated bioinspired silica fillers into poly(dimethylsiloxane) (PDMS) elastomers and investigated their mechanical, morphological and thermal properties as a function of filler loading. The equilibrium stress-strain characteristics of the PDMS-bioinspired silica hybrids were determined as a function of bioinspired filler loading and the Mooney-Rivlin constants (2C1 and 2C2) were calculated. The thermal characteristics, in particular glass transition temperatures (Tg) and melting points (Tm), of the PDMS-bioinspired silica hybrids were characterized using differential scanning calorimetry (DSC). The thermal stability of these hybrid materials were investigated using thermogravimetric analysis (TGA). The morphology of the samples was characterized using scanning electron microscopy (SEM), and the filler dispersion was characterized using ultra small angle X-ray scattering (USAXS) and scanning electron microscopy (SEM). Although spherical silica particles were used here, we have demonstrated elsewhere that this bioinspired synthetic route also enables highly asymmetric silica structures to be prepared such as fibres and sheets. This methodology therefore offers the interesting possibility of preparing new hybrid systems where the properties are highly anisotropic. 相似文献
7.
Reactions of biscyclopentadienyl (and bisindenyl) titanium (IV) dichlorides with sodium salts of various thiocarboxylic acids in tetrahydrofuran medium, yield the complexes of the general formula (D) 2Ti(SCOR) 2 where D is cyclopentadienyl or indenyl group and R? H, CH3, C2H5, C4H5 or p-C4H4CH3 group. The foul smelling complexes are monomeric in nature. The IR spectra, thermal stabilities and Some physical characteristics of these complexes have been studied. 相似文献
8.
9.
We study the effect of hard-core repulsion (known as the bus effect) betweenB particles on the reaction-diffusion systemA+BB in the continuous-time random walk model in one dimension with theA particles stationary. We show rigorously that the survival probability of theA particles is asymptotically bounded asC
1lim
t{[–logS(t)]/t
0.5}C
2, whereC
1 andC
2 are constants. We also do simulations to confirm our results. 相似文献
10.
Adamovich MI Aggarwal MM Alexandrov YA Andreeva NP Anson ZV Arora R Avetyan FA Badyal SK Basova E Bazarov IK Bhalla KB Bhasin A Bhatia VS Bogdanov VG Bubnov VI Burnett TH Cai X Carshiev DA Chasnicov IY Chernova LP Chernyavski MM Eligbaeva GZ Eremenko LE Gaitinov AS Ganssauge ER Garpman S Gerassimov SG Grote JG Gulamov KG Gupta SK Gupta VK Heckman HH Huang H Jacobsson B Judek B Kachroo S Kalyachkina GS Kanygina EK Karabova M Kharlamov SP Kitroo S Koss T Krasnov SA Kumar V Lal P Larionova VG 《Physical review D: Particles and fields》1993,47(9):3726-3732