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排序方式: 共有1157条查询结果,搜索用时 46 毫秒
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Babushkina Anastasia A. Mikhaylov Vladimir N. Novikov Alexander S. Sorokoumov Viktor N. Gureev Maxim A. Kryukova Mariya A. Shpakov Alexander O. Balova Irina A. 《Chemistry of Heterocyclic Compounds》2022,58(8-9):432-437
Chemistry of Heterocyclic Compounds - The Richter cyclization was used for the synthesis of 6-halo-3-(hydroxymethyl)cinnolin-4(1H)-ones. X-ray analysis revealed that these compounds exist as dimers... 相似文献
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Dmitrii O. Kharchenko Olga M. Shchokotova Vasyl O. Kharchenko Viktor V. Kupriienko S.V. Kokhan Xiaoyong Wu 《辐射效应与固体损伤》2020,175(7-8):602-626
ABSTRACT We study microstructure transformation in Zr–Nb system under neutron irradiation and its mechanical properties change under mechanical loads in a form of shear deformation by using phase field methodology. The developed phase field approach takes into account defects dynamics based on reaction rate theory and elastic contribution to study mechanical properties change. A numerical modeling is provided in three stages: sample preparation, irradiation of the prepared sample and mechanical loading of the irradiated sample. A precipitation of β-Niobium particles of the size of several nanometers is discussed. Results of phase field modeling indicate that β-Niobium particles grow slowly during irradiation due to point defects rearrangement. Statistical analysis of dynamics of radiation-induced microstructure transformations is provided. Simulation results of shear deformation of pre-irradiated and post-irradiated alloys are discussed. Maps of local distribution of strain and stress and strain–stress curves are obtained. Results are verified with experimental data. 相似文献
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K10Ga3Bi6.65 is the first representative in the ternary system A-Ga-Bi (A = alkali metal). It contains [Ga3Bi6]9– anions with planar triangular-coordinated Ga atoms as the main structural feature, accompanied by isolated Bi–Bi dumbbells. Alkali metal cations are counterbalancing the charges and fill the space between the anionic units. According to the Zintl-Klemm concept charge balance is reached if an almost equal ratio of single and double-bonded Bi2 dumbbells are present according to (K+)10[Ga3Bi6]9–([Bi-Bi]4–)1/6([Bi=Bi]2–)1/6. 相似文献
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Daniela Cappello Dr. Ryan R. Maar Prof. Dr. Viktor N. Staroverov Prof. Dr. Joe B. Gilroy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(24):5522-5529
The creation of dimeric boron difluoride complexes of chelating N-donor ligands is a proven strategy for the enhancement of the optoelectronic properties of fluorescent dyes. We report dimers based on the boron difluoride hydrazone (BODIHY) framework, which offer unique and sometimes unexpected substituent-dependent absorption, emission, and electrochemical properties. BODIHY dimers have low-energy absorption bands (λmax=421 to 479 nm, ϵ=17 200 to 39 900 m −1 cm−1) that are red-shifted relative to monomeric analogues. THF solutions of these dimers exhibit aggregation-induced emission upon addition of water, with emission enhancement factors ranging from 5 to 18. Thin films of BODIHY dimers are weakly emissive as a result of the inner-filter effect, attributed to intermolecular π-type interactions. BODIHY dimers are redox-active and display two one-electron oxidation and two one-electron reduction waves that strongly depend on the N-aryl substituents. These properties are rationalized using density-functional theory calculations and X-ray crystallography experiments. 相似文献
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Sergey G. Il’yasov Viktor A. Cherkashin Gennady V. Sakovich Dmitri A. Parkhomenko 《Chemical Papers》2015,69(11):1445-1453
The chemical structures of Miscanthus var. ‘Soranovskii’ lignin fractions released via extraction of lignin from the lignocellulosic feedstock using moderately heated acetone under atmospheric pressure, without acidic and alkaline catalysts, were studied. A blend of Miscanthus stems and leaves was pretreated with water under thermobaric conditions. The acetone organosolv process subsequently afforded a substance related to a lignin-like matter-acetone organosolv Miscanthus lignin (AOML). Non-destructive analytical techniques such as FTIR spectroscopy, gas chromatography-mass spectrometry, size-exclusion chromatography, and 2D NMR were used. The IR and NMR spectroscopies revealed the AOML structure to comprise all the three major types of phenylpropane units: guaiacyl (G), syringyl (S), and p-hydroxyphenyl (H). The resultant acetone-organosolv lignin exhibits good solubility in polar solvents, moderate solubility in aromatic chemicals, and is insoluble in non-polar solvents, exhibiting the physicochemical properties of a thermoplastic polymer with a softening point of 67.0°C (onset 33.0°C, endset 81.5°C). 相似文献
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Dr. Pilar Ventosa‐Andrés Dr. Agustina La‐Venia Dr. Carlos Alfonso Barea Ripoll Dr. Ludmila Hradilová Dr. Viktor Krchňák 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(37):13112-13119
Herein, we describe the synthesis of molecular scaffolds consisting of medium‐sized fused heterocycles using amino acids, which are some of the most useful building blocks used by nature as well as chemists to create structural diversity. The acyclic precursors were assembled by using traditional Merrifield solid‐phase peptide synthesis, and cyclization was carried out through acid‐mediated tandem endocyclic N‐acyliminium ion formation, followed by nucleophilic addition with internal nucleophiles. The synthesis of molecular scaffolds consisting of seven‐, eight‐, and nine‐membered rings proceeded with full stereocontrol of the newly generated stereogenic center in most cases. 相似文献
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Frontispiece: Monitoring and Understanding the Paraelectric–Ferroelectric Phase Transition in the Metal–Organic Framework [NH4][M(HCOO)3] by Solid‐State NMR Spectroscopy 下载免费PDF全文
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