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排序方式: 共有1430条查询结果,搜索用时 15 毫秒
1.
Saqib Kamal Arif I. Inamdar Kuan-Ru Chiou Batjargal Sainbileg Muhammad Usman Jenq-Wei Chen Tzuoo-Tsair Luo Michitoshi Hayashi Chen-Hsiung Hung Wen-Feng Liaw Kuang-Lieh Lu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(30):e202103905
The dielectric properties of coordination polymers has been a topic of recent interest, but the role of different functional groups on the dielectric properties of these polymers has not yet been fully addressed. Herein, the effects of electron-donating (R=NH2) and electron-withdrawing (R=NO2) groups on the dielectric behavior of such materials were investigated for two thermally stable and guest-free Zn-based coordination polymers, [Zn(L1)(L2)]n ( 1 ) and [Zn(L1)(L3)]n ( 2 ) [L1=2-(2-pyridyl) benzimidazole (Pbim), L2=5-aminoisophthalate (Aip), and L3=5-nitroisophthalate (Nip)]. The results of dielectric studies of 1 revealed that it possesses a high dielectric constant (κ=65.5 at 1 kHz), while compound 2 displayed an even higher dielectric constant (κ=110.3 at 1 kHz). The electron donating and withdrawing effects of the NH2 and NO2 substituents induce changes in the polarity of the polymers, which is due to the inductive effect from the aryl ring for both NO2 and NH2. Theoretical results from density functional theory (DFT) calculations, which also support the experimental findings, show that both compounds have a distinct electronic behavior with diverse wide bandgaps. The significance of the current work is to provide information about the structure-dielectric property relationships. So, this study promises to pave the way for further research on the effects of different functional groups on coordination polymers on their dielectric properties. 相似文献
2.
3.
K. Yatsu T. Cho H. Higaki M. Ichimura K. Ishii Y. Ishimoto M. K. Islam A. Itakura I. Katanuma J. Kohagura Y. Nakashima T. Saito Y. Takemura Y. Tatematsu M. Yoshida M. Yoshikawa 《Czechoslovak Journal of Physics》2002,52(10):1143-1148
GAMMA 10 experiments have advanced in high density experiments after the last EPS Workshop where we reported high density
plasma production by using an ion cyclotron range of frequency heating at a high harmonic frequency and neutral beam injection
in the central cell. Recently a high density plasma was obtained with much improved reproducibility than before and without
degradation of diamagnetic signal. The high density plasma was attained by adjusting the spacing of the conducting plates
installed in the anchor transition regions. Dependencies of particle confinement time, ion energy confinement time and plasma
confining potential on plasma density were obtained for the first time in the high density region.
Presented at 5th Workshop “Role of Electric Fields in Plasma Confinement and Exhaust”, Montreus, Switzerland, June 23–24,
2002. 相似文献
4.
A new enzyme mediated protocol to access versatile chiral building blocks for the synthesis of epoxyquinone natural products is delineated. Total syntheses of (−)-phyllostine, (+)-epoxydon, (+)-epiepoxydon and (−)-panepophenanthrin have been accomplished to demonstrate the efficacy of this approach. 相似文献
5.
U.S. NaziaA.K.M.A. Islam 《Solid State Communications》2003,125(1):37-40
The Eliashberg spectral density function is constructed for the superconducting compound BaxK1−xBiO3 with x=0.5, 0.6, 0.7. The functions, besides yielding some prominent structures, show widely spreading spectra that inhibit lattice instability by yielding not too large values of λ(<1.32). The resulting spectral functions show similar shape as other results, where available, and also successfully reproduce the observed critical temperature, isotope exponent, gap ratio and several other parameters. 相似文献
6.
Laser gas-assisted material processing finds wide application in industry. The modelling of heating, elastic response of the substrate material, and the wave analysis gives insight into the laser workpiece interaction. In the present study, laser gas-assisted heating of steel is considered. The normal component of the thermal stress is taken as the source of load for the flexural wave generation in the material. The flexural wave generated is simulated and the wave characteristics are analyzed at four locations at the workpiece surface. The numerical scheme employing a control volume approach is introduced when solving the governing equations of flow and heat transfer while finite element and spectran element methods are used when solving the stress and wave equations. It is found that the normal component of the stress is tensile. The dispersion effect of the workpiece material, interference of the reflected beam, and partial overlapping of second mode of the travelling wave enable to identify a unique pattern in the travelling wave in the substrate. 相似文献
7.
Atomistic computer simulation techniques are used to investigate the effects of lithium insertion into YBa2Cu3O7. Attention is focused on various possible lattice sites occupied by the inserted lithium ions and pathways for their migration. The square-planar position in the Cu(2) layer is calculated to be the most energetically favorable. This is supported by the structural modeling of the ordered lithiated phase Li0.33YBa2Cu3O7. The calculated activation energies derived from migration profiles are in accord with experimental values and suggest fairly mobile lithium ions. 相似文献
8.
Pongaglabol [8-hydroxy-5-phenyl-furo[2,3-h]benzo(b)pyran-7-one] was synthesized and tested for antibacterial effects againstShigella dysenteriae, Salmonella typhi, Streptococcus β-haemolyticus andStaphylococcus aureus. The synthesized compounds were characterized using UV, IR and1H NMR spectral data 相似文献
9.
10.
Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 °C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu2−xSe phase was confirmed by XRD pattern and spherical grains of 30 ± 4 - 40 ± 4 nm in size aggregated over about 130 ± 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm2 light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells. 相似文献