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排序方式: 共有474条查询结果,搜索用时 187 毫秒
91.
Gibaek Lee Stefan L. Schweizer Ralf B. Wehrspohn 《Applied Physics A: Materials Science & Processing》2014,117(3):973-979
The lithiation and delithiation process of silicon nanowire arrays (SiNWs) on silicon substrates has been studied with high-resolution electron microscopy. The composition of lithiated SiNWs was revealed, consisting of the unreacted crystalline silicon core and the reacted amorphous Li–Si shell. In particular, the Li–Si shell was comprised of a mixture of amorphous silicon oxide and crystalline silicon, leading to hindrance during Li–Si alloying/dealloying upon cycling. 相似文献
92.
P Rivera-Fuentes Mv Rekowski WB Schweizer JP Gisselbrecht C Boudon F Diederich 《Organic letters》2012,14(16):4066-4069
A carbopalladation cascade reaction of easily accessible gem-dibromoolefins and alkynes furnishes monobenzo- and mononaphthopentalenes. The new chromophores accessed by this short route exhibit small HOMO-LUMO gaps and redox amphoteric behavior with tunable redox potentials. 相似文献
93.
Chiu M Jaun B Beels MT Biaggio I Gisselbrecht JP Boudon C Schweizer WB Kivala M Diederich F 《Organic letters》2012,14(1):54-57
A formal [2 + 2] cycloaddition-cycloreversion (CA-CR) between N,N'-dicyanoquinone diimides (DCNQIs) and electron-rich alkynes was explored, providing a new class of π-conjugated donor-acceptor chromophores. These DCNQI adducts exist in the solid state as single diastereoisomers, but as two interconverting diastereoisomers in solution. Solid- and solution-state evidence for intramolecular charge transfer (CT) was obtained; additionally, the DCNQI adducts exhibit positive solvatochromism and significant solution-state third-order polarizabilities. 相似文献
94.
95.
TADDOL (=α,α,α′,α′‐Tetraaryl‐1,3‐dioxolane‐4,5‐dimethanol) and the corresponding dichloride are converted to TADDAMINs (=(4S,5S)‐2,2,N,N′‐tetramethyl‐α,α,α′,α′‐tetraphenyl‐1,3‐dioxolan‐4,5‐dimethanamines) (Scheme 2) and ureas, 12 – 15 , and to TADDOP derivatives with seven‐membered O? P? O ester rings (Schemes 3 and 4). Cl/P‐Replacement via the Michaelis? Arbuzov reaction (Scheme 7) on mono‐ and dichlorides, derived from TADDOL, are described. It was not possible to obtain phosphines with the P‐atom attached to the benzhydrylic C‐atom of the TADDOL skeleton (Schemes 6 and 7). The X‐ray crystal structures (Figs. 1 and 2) of ten of the more than 30 new TADDOL derivatives are discussed. Full experimental details are presented. 相似文献
96.
We have characterized the structural behaviour of ethanethiol self-assembled monolayers (SAMs) on Au(1 0 0) in 0.1 M H2SO4 as a function of electrode potential, using in-situ scanning tunneling microscopy (STM). After modification of the Au(1 0 0) electrode in an ethanolic solution of ethanethiol, STM images in air reveal a disordered thiol adlayer and a surface that is covered by 25% of monoatomic high gold islands, which originate from lifting of the (hex) reconstruction during thiol adsorption. In contrast to alkanethiol SAMs on Au(1 1 1), no vacancy islands are seen on the Au(1 0 0) surface. After contact of the SAM-covered Au(1 0 0) electrode with 0.1 M H2SO4 under potential control, two different structures are observed, depending on the potential range positive or negative of +0.3 V vs. SCE. In both cases the emerging ordered structures are quadratic, their unit cells being rotated by 45° with respect to the main crystallographic axes of the substrate. However, the ordered structure at negative potentials is more densely packed than the one at positive potentials, and in addition the surface reveals an almost 50% coverage of monoatomic high gold islands. The structure of the SAM changes reversibly with the electrode potential, the long range order gradually decreasing with each transition. Concomittant with this structure transition monoatomic deep holes are created when the potential is stepped from the cathodic to the anodic region. The experimental observations are rationalized by a high mobility of the gold thiolate moiety, causing the surface density of the SAM-covered gold to change drastically with potential. 相似文献
97.
Noriyasu Hada Tokio Morita Takashi Ueda Kazuki Masuda Hiromi Nakane Mami Ogane Kimiaki Yamano Frank Schweizer Fumiyuki Kiuchi 《Molecules (Basel, Switzerland)》2021,26(18)
Stereocontrolled syntheses of biotin-labeled oligosaccharide portions containing the carbohydrate moiety of glycoprotein from Echinococcus granulosus have been accomplished. Trisaccharide Galβ1-3Galβ1-3GalNAcα1-R (A), tetrasaccharide Galα1-4Galβ1-3Galβ1-3GalNAcα1-R (B), and pentasaccharide Galα1-4Galβ1-3Galβ1-3Galβ1-3GalNAcα1-R (C), (R = biotinylated probe) were synthesized by stepwise condensation and/or block synthesis by the use of 5-(methoxycarbonyl)pentyl 2-azido-4,6-O-benzylidene-2-deoxy-α-d-galactopyranoside as a common glycosyl acceptor. The synthesis of the tetrasaccharide and the pentasaccharide was improved from the viewpoint of reducing the number of synthetic steps and increasing the total yield by changing from stepwise condensation to block synthesis. Moreover, hexasaccharide E, which contains the oligosaccharide sequence which occurs in E. granulosus, was synthesized from trisaccharide D. We examined the antigenicity of these five oligosaccharides by an enzyme-linked immunosorbent assay (ELISA). Although compounds of C–E did not exhibit antigenicity against cystic echinococcosis (CE) patient sera, compounds B, D, and E showed good serodiagnostic potential for alveolar echinococcosis (AE). 相似文献
98.
Ben Schweizer 《Continuum Mechanics and Thermodynamics》2009,20(8):459-477
We propose a new method for the homogenization of hysteresis models of plasticity. For the one-dimensional wave equation with
an elasto-plastic stress-strain relation we derive averaged equations and perform the homogenization limit for stochastic
material parameters. This generalizes results of the seminal paper by Franců and Krejčí. Our approach rests on energy methods
for partial differential equations and provides short proofs without recurrence to hysteresis operator theory.
相似文献
99.
Andreas Schweizer 《Mathematische Zeitschrift》2003,244(3):601-614
In analogy with the famous theorems of Mazur and Merel on the torsion subgroups of elliptic curves, one can formulate similar
conjectures for the torsion points of Drinfeld modules. We prove some partial results for rank 2 Drinfeld 𝔽
q
[T]-modules, for example the uniform boundedness of the 𝔭-primary torsion.
Received: 22 May 2001; in final form 4 September 2002 /
Published online: 1 April 2003 相似文献
100.