排序方式: 共有86条查询结果,搜索用时 0 毫秒
81.
Motiei L Kaminker R Sassi M van der Boom ME 《Journal of the American Chemical Society》2011,133(36):14264-14266
This study provides insight into the internal structure of surface-confined molecular assemblies. The permeability of the layer-by-layer grown thin films can be controlled systematically by varying their composition and the structure of their molecular components. Moreover, the thickness can be used to control molecule permeation versus electron transfer. 相似文献
82.
Luan L Lippman TM Hicks CW Bert JA Auslaender OM Chu JH Analytis JG Fisher IR Moler KA 《Physical review letters》2011,106(6):067001
We measure the penetration depth λab(T) in Ba(Fe(1-x)Co(x))(2)As(2) using local techniques that do not average over the sample. The superfluid density ρs(T) ≡ 1/λab(T)2 has three main features. First, ρs (T = 0) falls sharply on the underdoped side of the dome. Second, λab(T) is flat at low T at optimal doping, indicating fully gapped superconductivity, but varies more strongly in underdoped and overdoped samples, consistent with either a power law or a small second gap. Third, ρs (T) varies steeply near Tc for optimal and underdoping. These observations are consistent with an interplay between magnetic and superconducting phases. 相似文献
83.
Montag M Efremenko I Cohen R Leitus G Shimon LJ Diskin-Posner Y Ben-David Y Martin JM Milstein D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(27):8183-8194
The crystal structure of the new cationic Rh(I) complex trans-[Rh(CO)(2)(L)(2)]BF(4) (L=alpha(2)-(diisopropylphosphino)isodurene) was found to exhibit a nonlinear OC-Rh-CO fragment and weak intramolecular C-H...Rh interactions. These interactions, which have also been shown to occur in solution, have been examined by density functional theory calculations and found to be inextricably linked to the presence of the distorted OC-Rh-CO fragment. This linkage has also been demonstrated by comparison with a highly similar Rh(I) complex, in which these C-H...Rh interactions are absent. Furthermore, the presence of these weak interactions has been shown to have a significant effect on the reactivity of the metal center. 相似文献
84.
The current research deals with the thermal explosion and ignition of a mixture of carbon and air. The size distribution of the carbon particles is taken to be continuous and is characterized by a probability density function. The chemical reaction term is presented in the Arrhenius form with variable pre-exponential factor. Transforming the new model to a dimensionless form enables us to rewrite the model in a singular perturbed system of ordinary differential equations. This form of the model enables us to apply the method of integral manifold (MIM). As a result of this method we can derive an explicit expression for the thermal explosion limit which depends on the initial probability density function. Comparing our numerical results to the analytical results, we observe that the effect of the thermal radiation is significant, especially at high temperatures, and cannot be ignored in the analysis of the phenomena of the explosion and ignition. 相似文献
85.
This paper compares the performance of various spectral shift estimators for use in spectral elastography, namely, the normalized cross-correlation (NCC), sum squared difference (SSD) and sum absolute difference (SAD). Simulation and experimental results demonstrate that the spectral SSD-based elastographic method exhibits no marked difference in performance compared to the more computationally costly NCC-based approach, which has conventionally been the preferred estimator in spectral elastography. The spectral SAD-based strain estimator, despite being computationally less burdening, failed to exhibit performance comparable to that of the NCC- and SSD-based techniques. Furthermore, though spectral subsample estimation techniques using a cosine-fit interpolation method outperformed that of the parabolic-fit method in terms of both reduced bias errors and standard deviations, the latter was analyzed in this study due to computational simplicity. The role of spectral density was evaluated without and with parabolic-based subsample interpolation. Based on minimizing computational complexity, it is concluded that a (low density) spectral SSD strain estimator coupled with parabolic-based subsample estimation is the preferred choice for spectral elastography. 相似文献
86.
Revital Sasson Dan Vaknin Avihai Bross Efraim Lavie 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(3):753-756
A practical and reliable HPLC method was used for the determination of 2-[4-N-(2-hydroxyethyl)-1-piperazinyl]-N′-ethanesulfonic acid (HEPES) content in the 68Ga-labeled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-Nal3-octreotide (DOTANOC). Linearity of this method
was observed in a concentration range of 0.01–10 mg mL−1 and the quantitative limit (signal to noise = 11) was determined as 10 μg mL−1. The HEPES concentration in the final products of 68Ga-DOTANOC was typically lower than the detection limit. Pure water and HEPES buffer as reaction medium were investigated
using various activities of gallium-68. It was demonstrated that the presence of HEPES buffer consistently furnished very
high radiochemical purity of 68Ga-DOTANOC, which remained stable for several hours post-labeling. Evidence is provided that in addition to its role as a
buffer, HEPES also functions as a radioprotectant agent. 相似文献