排序方式: 共有36条查询结果,搜索用时 31 毫秒
11.
Ulf Pindur Martina Rogge Carsten Rehn Werner Massa Beate Peschel 《Journal of heterocyclic chemistry》1994,31(4):981-988
Indolyl enol ethers, generated from the alkoxy(indolyl)carbenium tetrafluoroborates 1 by treatment with sodium hydride, can be trapped with dimethyl acetylenedicarboxylate or N-phenylmaleimide to furnish the selectively functionalized carbazoles 3,4,5,9,10 , and 13. In addition, the biaryl derivatives 6 and 11 are produced by a ring-opening reaction of the primarily formed Diels-Alder adduct. In the case of the biaryl derivative 6 , an X-ray crystal structure analysis yields valuable information on constitutions and configurations in the biaryl series. The phenomenon of atropisomerism is discussed for this compound. 相似文献
12.
DR.G. Domairry A. Mohsenzadeh M. Famouri 《Communications in Nonlinear Science & Numerical Simulation》2009,14(1):85-95
In this paper Jeffery–Hamel flow has been studied and its nonlinear ordinary differential equation has been solved through homotopy analysis method (HAM). The obtained solution in comparison with the numerical ones represents a remarkable accuracy. The results also indicate that HAM can provide us with a convenient way to control and adjust the convergence region. 相似文献
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14.
Dr. Camilla Gustafsson Dr. Hamid Shirani Petter Leira Dr. Dirk R. Rehn Dr. Mathieu Linares Prof. K. Peter R. Nilsson Prof. Patrick Norman Prof. Mikael Lindgren 《Chemphyschem》2021,22(3):323-335
Anionic pentameric thiophene acetates can be used for fluorescence detection and diagnosis of protein amyloid aggregates. Replacing the central thiophene unit by benzothiadiazole (BTD) or quinoxaline (QX) leads to large emission shifts and basic spectral features have been reported [Chem. Eur. J. 2015 , 21, 15133-13137]. Here we present new detailed experimental results of solvent effects, time-resolved fluorescence and examples employing multi-photon microscopy and lifetime imaging. Quantum chemical response calculations elucidate how the introduction of the BTD/QX groups changes the electronic states and emissions. The dramatic red-shift follows an increased conjugation and quinoid character of the π-electrons of the thiophene backbone. An efficient charge transfer in the excited states S1 and S2 compared to the all-thiophene analogue makes these more sensitive to the polarity and quenching by the solvent. Taken together, the results guide in the interpretation of images of stained Alzheimer disease brain sections employing advanced fluorescence microscopy and lifetime imaging, and can aid in optimizing future fluorescent ligand development. 相似文献
15.
Crystal Blake Kimberly M Fabick Kenneth DR Setchell Trent D Lund Edwin D Lephart 《BMC neuroscience》2011,12(1):28
Background
Soy-derived isoflavones potentially protect against obesity and depression. In five different studies we examined the influence of soy-containing diets or equol injections on depression, serotonin levels, body weight gain (BW) and white adipose tissue (WAT) deposition in female Long-Evans rats at various stages of life [rats were intact, ovariectomized or experienced natural ovarian failure (NOF)]. 相似文献16.
G. Thornton R.A. Rosenberg Victor Rehn A.K. Green C.C. Parks 《Solid State Communications》1981,40(2):131-133
The photon stimulated ion desorption yield of H+ ions from a H2O dosed GaAs (110) surface has been measured in the range 18eV ? hυ ? 30eV. There is a direct correspondence between the PSID H+ yield, reflectance, and the secondary electron yield spectrum of GaAs (110). The data provides evidence that the initial stages of PSID involve core level (Ga(3d), O(2s)) → conduction band excitation followed by Auger decay. 相似文献
17.
Within the energy range 17 hv < 35 eV, the ionic species desorbed and their excitation spectra are reported. The only positive ion desorbed is H+. A model for the surface is suggested which explains the absence of OH+ desorption. The desorption mechanisms are discussed in terms of an energy analysis. 相似文献
18.
Johan Malm Bengt Rehn Anna-Britta Hrnfeldt Salo Gronowitz 《Journal of heterocyclic chemistry》1994,31(1):11-15
Through the use of Pd(0)-catalyzed coupling between 2- and 4-formyl-3-thiopheneboronic acid and 4-iodo-3-aminopyridine ( 1 ) and 3-bromo-2-aminopyridine, convenient one-pot procedures for the preparation of thieno[2,3-c]-1,7-naphthyridine ( 2 ), thieno[3,4-c]-1,7-naphthyridine ( 3 ), thieno[2,3-c]-1,8-naphthyridine ( 6 ) and thieno[3,4-c]-1,8-naphthyridine ( 7 ) have been developed. Thieno[3,2-c]-1,7-naphthyridine ( 4 ) and thieno[3,2-c]-1,8-naphthyridine ( 8 ) were obtained through the coupling of 2-tri-n-butylstannyl-3-thiophenaldehyde with 2,2-dimethyl-N-(4-iodo-3-pyridinyl)propanamide and 3-bromo-2-acetamidopyridine ( 1 ). The yield of 8 was further increased when copper(II) oxide was used as the co-reagent. The 13C nmr spectra of the six isomeric thieno[c]-fused 1,7- and 1,6-naphthyridines are discussed. 相似文献
19.
We report a novel transient phase measurement technique that allows for the interferometric evaluation of a cross-section of a temporally varying phase object in video real time. 相似文献
20.
M. Rehn S. Bergkvist A. Rosengren R. Saers M. Zelán E. Lundh A. Kastberg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(2):223-230
A phase transition for bosonic atoms in a two-dimensional anisotropic optical lattice is considered. If the tunnelling rates
in two directions are different, the system can undergo a transition between a two-dimensional superfluid and a one-dimensional
Mott insulating array of strongly coupled tubes. The connection to other lattice models is exploited in order to better understand
the phase transition. Critical properties are obtained using quantum Monte Carlo calculations. These critical properties are
related to correlation properties of the bosons and a criterion for commensurate filling is established. 相似文献