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91.
以2-溴代-3-甲基环己酮和2-溴代-5-甲基环己酮混合物及2-甲基苯硫酚为原料,经耦合、环化及纯化制得1,2,3,4-四氢-2,6-二甲基二苯并噻吩(3);3在三氟乙酸中经锌粉还原合成了1,2,3,4,4a,9b-六氢-2,6-二甲基二苯并噻吩(4).3和4的结构经1H NMR,13C NMR和GC-MS确证. 相似文献
92.
We study the maximum weighted independent-set problem on interval graphs with uncertainty on the vertex weights. We use the absolute robustness criterion and the min–max regret criterion to evaluate solutions. For a discrete scenario set, we find that the problem is NP-hard for each of the robustness criteria; we also provide pseudo-polynomial time algorithms when there is a constant number of scenarios and show that the problem is strongly NP-hard when the set of scenarios is unbounded. When the scenario set is a Cartesian product, we prove that the problem is equivalent to a maximum weighted independent-set problem on the same interval graph but without uncertainty for the first objective function and that the scenario set can be reduced for the second objective function. 相似文献
93.
94.
Jie Jian Dr. Jordi Poater Dr. Roel Hammink Dr. Paul Tinnemans Prof. Dr. Christine J. McKenzie Prof. Dr. F. Matthias Bickelhaupt Prof. Dr. Jasmin Mecinović 《Chemphyschem》2020,21(11):1092-1100
Molecular recognition between polar groups and aromatic molecules is fundamentally important to rational drug design. Although it has been well established that many polar functionalities interact with electron-rich aromatic residues through energetically favorable polar-π interactions, there is a limited understanding of the association between thiols and aromatic systems. Herein we report physical-organic chemistry studies on 2,6-diarylthiophenols that possess the central thiophenol ring and two flanking aromatic rings with tunable electronic properties caused by substituents at distant para position. Hammett analysis revealed that pKa values and proton affinities correlate well with Hammett sigma values of substituents. Additional energy decomposition analysis supported the conclusion that both through-space SH-π interactions and S−-π interactions contribute to intramolecular stabilization of 2,6-diarylthiophenols. 相似文献
95.
Johannes Bongaerts Simon Esser Volker Lorbach Lay Al‐Momani Michael A. Müller Dirk Franke Christoph Grondal Anja Kurutsch Robert Bujnicki Ralf Takors Leon Raeven Marcel Wubbolts Roel Bovenberg Martin Nieger Melanie Schürmann Natalie Trachtmann Stefan Kozak Georg A. Sprenger Michael Müller 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2011,123(34):7927-7932
96.
De Mondt R Van Vaeck L Lenaerts J Geuens I Van Luppen J 《Rapid communications in mass spectrometry : RCM》2006,20(4):641-652
Chemical engineering of high-technology products requires elucidation of intermolecular interactions in complex materials. As part of an extensive study on thermographic systems, static secondary ion mass spectrometry (S-SIMS) was used to probe the physicochemical behaviour of active compounds, such as different tone modifiers and stabilisers, on silver. In particular, the feasibility of detecting adsorption and/or binding of individual additives and mixtures to silver was examined. Substrates prepared by sputter coating silver on silicon wafers were exposed to solutions of the studied compounds in 2-butanone. The signal intensities measured with S-SIMS for the ad-layers showed reproducibility to within 10%. Radical ions containing silver such as [M-H+Ag]+ * were used as evidence for the formation of bonds in the solid. Also the [M-H+2Ag]+ ions could be assigned to chemisorbed species while [M+Ag]+ ions could be formed by adduct ionisation of molecules with co-ejected Ag+ ions. The signal intensities of [M-H+Ag]+ * and [M-H+2Ag]+ ions were used to monitor the adsorption quantitatively as a function of time. 相似文献
97.
We generalize a result of Kostant and Wallach concerning the algebraic integrability of the Gelfand-Zeitlin vector fields
to the full set of strongly regular elements in
\mathfrakg\mathfrakl \mathfrak{g}\mathfrak{l} (n, ℂ). We use decomposition classes to stratify the strongly regular set by subvarieties XD {X_\mathcal{D}} . We construct an étale cover
[^(\mathfrakg)]D {\hat{\mathfrak{g}}}_\mathcal{D} of XD {X_\mathcal{D}} and show that XD {X_\mathcal{D}} and
[^(\mathfrakg)]D {\hat{\mathfrak{g}}}_\mathcal{D} are smooth and irreducible. We then use Poisson geometry to lift the Gelfand-Zeitlin vector fields on XD {X_\mathcal{D}} to Hamiltonian vector fields on
[^(\mathfrakg)]D {\hat{\mathfrak{g}}}_\mathcal{D} and integrate these vector fields to an action of a connected, commutative algebraic group. 相似文献
98.
We show experimentally the existence of defect modes in mutually coupled microring resonator arrays fabricated in silicon-on-insulator technology. The movements of donor-like and acceptor-like modes are demonstrated for various defect lengths, in good agreement with earlier theoretical prediction. 相似文献
99.
A database is presented of measurements of the fundamental frequency, the frequencies of the first three formants, and the duration of the 15 vowels of Standard Dutch as spoken in the Netherlands (Northern Standard Dutch) and in Belgium (Southern Standard Dutch). The speech material consisted of read monosyllabic utterances in a neutral consonantal context (i.e., /sVs/). Recordings were made for 20 female talkers and 20 male talkers, who were stratified for the factors age, gender, and region. Of the 40 talkers, 20 spoke Northern Standard Dutch and 20 spoke Southern Standard Dutch. The results indicated that the nine monophthongal Dutch vowels /a [see symbol in text] epsilon i I [see symbol in text] u y Y/ can be separated fairly well given their steady-state characteristics, while the long mid vowels /e o ?/ and three diphthongal vowels /epsilon I [see symbol in text]u oey/ also require information about their dynamic characteristics. The analysis of the formant values indicated that Northern Standard Dutch and Southern Standard Dutch differ little in the formant frequencies at steady-state for the nine monophthongal vowels. Larger differences between these two language varieties were found for the dynamic specifications of the three long mid vowels, and, to a lesser extent, of the three diphthongal vowels. 相似文献
100.