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排序方式: 共有221条查询结果,搜索用时 15 毫秒
1.
The reduction of chromate by glutathione, its mono- and diethyl esters,
-cysteine, 2-mercapto-propionic acid and mercapto-succinic acid has been studied. The empirical rate law kobs = ab[Thiol]2/(1 + b[Thiol]) is obeyed by all of these thiols, at neutral pH. No evidence could be obtained for a first-order pathway in glutathione under these conditions. These observations are used to comment on the stability of intermediates potentially important in explaining chromate toxicity. 相似文献
2.
Jahn A Vreeland WN Gaitan M Locascio LE 《Journal of the American Chemical Society》2004,126(9):2674-2675
Traditional liposome preparation methods are based on mixing of bulk phases, leading to inhomogeneous chemical and/or mechanical conditions during formation; hence liposomes are often polydisperse in size and lamellarity. Here we show the formation of liposomes that encapsulate reagents in a continuous two-phase flow microfluidic network with precision control of size from 100 to 300 nm by manipulation of liquid flow rates. We demonstrate that by creating a solvent-aqueous interfacial region in a microfluidic format that is homogeneous and controllable on the length scale of a liposome, we can facilitate the fine control of liposome size and polydispersity. 相似文献
3.
The method of diatomics-in-molecules (DIM) is applied to the FH2 system. With spin—orbit interaction neglected, all elements of the 24 × 24 hamiltonian matrix are tabulated as analytic functions of the six diatomic fragment potential curves. It is found that neglect of off-diagonal 8 × 8 blocks in the DIM hamiltonian matrix leads to an energy expression for the ground 1 2A′ level which is identical to the valence-bond formula used by Blais and Truhlar in dynamical studies of the F + D2 reaction. The 2A″ excited level from DIM theory is identical to the result derived by Blais and Truhlar, without neglect of the 8 × 8 off-diagonal blocks. The DIM and simple valence-bond energies are compared numerically for noncollinear geometries. 相似文献
4.
We present results of exact calculations on a three-level Morse oscillator modeling HF which suggest that multiphoton absorption proceeds by sequential single-level transitions, transitions arising from coupling between non-adjacent states being dynamically negligible. The time-dependent Schrödinger equation is integrated in the Floquet formalism. 相似文献
5.
Philip Jennings Zhong-Tao Jiang Nicholas M. W. Wyatt David Parlevliet Christine Creagh Chun-Yang Yin Hantarto Widjaja Nick Mondinos 《Applied Physics A: Materials Science & Processing》2013,113(3):723-728
Silicon nanowires (SiNWs) have been grown on crystalline silicon (Si), indium tin oxide (ITO) and stainless steel (SS) substrates using a gold catalyst coating with a thickness of 200 nm via pulsed plasma-enhanced chemical vapor deposition (PPECVD). Their morphological, mineralogical and surface characteristics have been investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman analysis. SiNWs growth is accompanied by oxidation, thus yielding partially (SiO x ) and fully oxidized (SiO2) Si sheaths. The mean diameters of these SiNWs range from 140 to 185 nm. Si with (111) and (220) planes exists in SiNWs grown on all three substrates while Si with a (311) plane is detected only for Si and ITO substrates. Computational simulation using density functional theory (DFT) has also been conducted to supplement the experimental Raman analyses for crystalline Si and SiO2. XPS results reveal that ca. 30 % of the SiNWs have been oxidized for all substrates. The results presented in this paper can be used to aid selection of appropriate substrates for SiNW growth, depending on specific applications. 相似文献
6.
Jonathan T. Smith Janice Ward James A. Guthrie Maria B. Sheridan Sheila Boyes Daniel Wilson Judy I. Wyatt Darren Treanor Philip J. Robinson 《Magnetic resonance imaging》2012
Objective
Chemotherapy commonly causes liver injury through sinusoidal obstructive syndrome and steatosis. Chemotherapy-induced liver injury may make it more difficult to detect metastases secondary to reduced contrast between the injured liver and metastases. The aim of this study was to determine the sensitivity of superparamagnetic iron oxide (SPIO) contrast-enhanced imaging in patients who have undergone chemotherapy prior to liver surgery.Methods
Local ethics committee approval was obtained. Thirty-one patients with hepatic metastases completing preoperative chemotherapy were prospectively recruited. Images were reviewed independently by two blinded observers who identified and localized lesions with a four-point confidence scale. The alternative free-response receiver operator characteristic method was used to analyze the results.Results
The sensitivity in detecting colorectal metastases following chemotherapy was 78% and 76%, respectively, for observers 1 and 2 (95% confidence interval: 71%–85% and 68%–82%). The areas under the alternative free-response receiver operator curves were 0.73 and 0.80 for observers 1 and 2, respectively.Conclusion
Compared to previously published work on chemotherapy-naïve patients, it is clear that the sensitivity of SPIO-enhanced magnetic resonance imaging (MRI) in detecting colorectal metastases following chemotherapy is reduced. It is therefore critical that all imaging — pre-, during and postchemotherapy — is reviewed when reporting liver MRI prior to surgery. 相似文献7.
We derive a geometric phase using the quantum kinematic approach within the complex quantum Hamilton-Jacobi formalism. The single valuedness of the wave function implies that the geometric phase along an arbitrary path in the complex plane must be equal to an integer multiple of 2π. The nonzero geometric phase indicates that we travel along the path through the branch cut of the phase function from one Riemann sheet to another. 相似文献
8.
6s–9s electronic Raman scattering in caesium vapour is used to generate tunable 16m radiation. Output energies in excess of 8 J were obtained, with peak powers in the kilowatt range. 相似文献
9.
We consider a collapsing spherically symmetric inhomogeneous dust cloud in higher dimensional space-time. We show that the
central singularity of collapse can be a strong curvature or a weak curvature naked singularity depending on the initial density
distribution. 相似文献
10.
Laxman Singh Ravikant Sharma Narayan Singh Atendra Kumar Dev K Mahato Youngil Lee Mikhael Bechelany KD Mandal 《Progress in Crystal Growth and Characterization of Materials》2021,67(4):100542
This review paper covers the low temperature wet growth of nano-engineered particles of ZnO-based mixed metal oxides, their growth mechanism, and characterization using X-ray diffraction, SEM, TEM and IR, UV–visible, and XPS spectral techniques. Main focus of this article is centered on low temperature semi-wet methods of synthesis that are suitable for large scale production of zinc oxide-based systems mixed with iron oxide, copper oxide, nickel oxide and cobalt oxide. These mixed metal oxides have broad industrial applications as catalyst, semiconductors, adsorbents, superconductors, electro-ceramics, and antifungal agents in addition to extensive applications in medicines. This paper discusses the low-cost and environment friendly synthesis of these mixed metal oxides, measurement of properties and applicability of these materials systems. 相似文献