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11.
Highly effective direct synthesis of DMC from CH_3OH and CO_2 using novel Cu-Ni/C bimetallic composite catalysts 总被引:1,自引:0,他引:1
Novel Cu-Ni/C has been prepared and utilized as an efficient catalyst system in direct synthesis of DMC from CH3OH and CO2. 相似文献
12.
Poly(trimethylene terephthalate)(PTT) is an excellent fiber material.Its thermal degradation and isothermal crystalline behaviors were in this study investigated using thermogravimetric analysis(TGA),thermogravimetric analysis-Fourier transform infrared spectroscopy(TGA-FTIR) analysis,differential scanning calorimetry(DSC) and X-ray diffraction(XRD).The thermal degradation mechanism of PTT follows Mclafferty rearrangement principle.The PTTwithintrinsicviscosity(Ⅳ) of 0.74 dL/g has a maximum crystallinity... 相似文献
13.
Zhong Lv Zhang Zhi Jie Sun Fei Xue Xian Jin Luo Nai Yun Xiu Li Teng Zong Gen Peng 《中国化学快报》2009,20(8):921-923
A series of novel benzimidazole derivatives was synthesized and their anti-Coxsackie virus B_3(CVB_3) activity was evaluated in VERO cells.Compounds 9 and 10 exhibited better inhibitory activity than those of ribavirin(RBV) with IC_(50) values of 5.30 and 1.06μg/mL,respectively. 相似文献
14.
Xiao Chi Ma Bao Jing Zhang Sha Deng Shan Shan Huang Ke Xin Liu Jing Ming Jia 《中国化学快报》2009,20(3):317-319
A new ent-labdane diterpenoid lactone with a new natural product was isolated from Andrographis paniculata. Their structures were elucidated on the basis of spectral evidences including 2D NMR. 相似文献
15.
Pradeep R. Varadwaj Arpita Varadwaj Helder M. Marques Koichi Yamashita 《Molecules (Basel, Switzerland)》2022,27(5)
The phosphorus bond in chemical systems, which is an inter- or intramolecular noncovalent interaction, occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a covalently or coordinately bonded phosphorus atom in a molecular entity and a nucleophile in another, or the same, molecular entity. It is the second member of the family of pnictogen bonds, formed by the second member of the pnictogen family of the periodic table. In this overview, we provide the reader with a snapshot of the nature, and possible occurrences, of phosphorus-centered pnictogen bonding in illustrative chemical crystal systems drawn from the ICSD (Inorganic Crystal Structure Database) and CSD (Cambridge Structural Database) databases, some of which date back to the latter part of the last century. The illustrative systems discussed are expected to assist as a guide to researchers in rationalizing phosphorus-centered pnictogen bonding in the rational design of molecular complexes, crystals, and materials and their subsequent characterization. 相似文献
16.
Nanocrystalline indium (nano-In) was prepared with different particle sizes by electrochemical deposition. The temperature
dependence of the local electric field gradient (EFG) of nano-In was investigated in a temperature range of 20–300 K using
the probe 111In for perturbed γγ angular correlation (PAC) experiments. The temperature dependence of the EFG of nano-In can be described
by a (1−BT
3/2) dependence as in bulk-In. It is shown that the low temperature value of the EFG and the proportionality constant B vary
systematically with particle size. 相似文献
17.
An ab initio (RHF) and DFT-B3LYP level spectroscopic studies of BrCCCN and the analysis of atomic polar tensors 总被引:1,自引:0,他引:1
Conventional ab initio (RHF) and DFT-B3LYP level calculations in conjunction with a variety of basis sets have been used to investigate the variations in the bond lengths, dipole moment, rotational constant, quadruple coupling constants, infrared frequencies, IR intensities and rotational invariants of BrCCCN. Satisfactory agreements between the B3LYP and experimental values were found for bond lengths, rotational constant, dipole moment and all other parameters. All the calculated bond lengths are in good agreement with each other for a given method having the average standard deviations varying between ±0.005 Å at the B3LYP level. Harmonic vibrational frequencies obtained from the B3LYP calculations show good agreement with the available experimental data. The global atomic polar tensor charges, used for interpreting the IR intensities, of all the atoms of BrCCCN have been calculated at the RHF and B3LYP levels in conjunction with the 6-311g(d) and 6-311++g(d,p) basis sets. Linear regression analysis between calculated and experimental infrared frequencies as well as between IR intensities in a series of 15 similar type of nitrile compounds have been achieved at the B3LYP/6-311++g(d,p) level and gives linear regression coefficients 0.983 and 0.970 respectively. Finally, a number of linear relations were found between r(CN) bond lengths and GAPT charges, and GAPT charges on CHELPG and MK charges at the nitrogen atom for these molecules and proved to be producing satisfactory results at the B3LYP/6-311++g(d,p) level of calculations. 相似文献
18.
PEG-400 as an efficient reaction medium for the synthesis of 2,4,5-triaryl-1H-imidazoles and 1,2,4,5-tetraaryl-1H-imidazoles 总被引:1,自引:0,他引:1
An efficient protocol for the one-pot multicomponent synthesis of various 2,4,5-triaryl- IH-imidazoles and 1,2,4,5-tetraaryl-1H-imidazoles using PEG-400 as reaction medium is described. This method has the advantages of good yields, less pollution and simple reaction conditions. 相似文献
19.
Varadwaj PR 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,65(3-4):874-881
DFT(B3LYP, B3PW91) calculations in conjunction with three different basis sets have been utilized to investigate the variations in the bond lengths, dipole moment, rotational constants, IR frequencies, IR intensities and rotational invariants of ClCCCN. The nuclear quadrupole constants of chlorine ((35)Cl, (37)Cl) and nitrogen ((14)N) of ClCCCN have been calculated on the experimental r(s) structure as well as on the B3PW91/6-311++g(d,p) optimized geometry and were found to be within the scale length of the experimental uncertainty. The slope and intercept obtained from the regression analysis between the B3LYP/6-311++g(d,p) level calculated and experimental B(o) values of ClCCCN were used to calculate reasonable values of rotational constants of all the rare isotopic species of ClCCCN having standard deviation +/-0.048 MHz. All the spectroscopic parameters obtained from DFT calculations show satisfactory agreement with the available experimental data. 相似文献
20.
A new free recoverable and reusable mono-alkaloid-type ligand has been synthesized by a simple method.With highly polar groups,the ligand can be recycled and reused eight times to prepare ethyl(2R,3S)-2,3-dihydroxy-3-phenylpropionate with high yield and ee via asymmetric dihydroxylation(AD) reaction. 相似文献