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排序方式: 共有541条查询结果,搜索用时 265 毫秒
1.
2.
Seema Prasad 《Molecular Crystals and Liquid Crystals》2018,665(1):52-63
Molecular structure and vibrational spectroscopic studies of higher homologous series nematogenic p-n-alkylbenzoic acids (nBAC) that have 6 (6BAC) and 7 (7BAC) carbon atoms in the alkyl chain have been investigated using the Density Functional Becke3-Lee-Yang-Parr (B3LYP) level with the basis set 6-31++G (d.p) and Hartree Fock (HF) with the same basis set. The observed vibrational spectra has been resolved and assigned in detail for comparision with both the molecules. These results indicate that DFT and HF values are slightly different at both the levels. A comparision of chemical reactivity such as HOMO (EH), LUMO (EL) energies, energy gap (Eg), ionization energy (I), electron affinity (A), electro negativity (χ), chemical hardness (η), electronic chemical potential (μ), electrophilicity index (ω), and softness (S) has been made. It has been observed that the decrement has occurred in the energy band gap value of isolated molecule with increment in alkyl chain length. This provides valuable information regarding enhancing the stability of liquid crystal materials by maintaining the conductivity. 相似文献
3.
Absolute total electron scattering cross sections for carbon dioxide have been measured at low electron energies using a photoelectron
source. The measurements have been carried out at 27 electron energies varying from 0.91–9.14 eV with an accuracy of ±3%.
The cross sections obtained in the present experiment have been compared with other measurements and theoretical computations. 相似文献
4.
Doshi DA Shah PB Singh S Branson ED Malanoski AP Watkins EB Majewski J van Swol F Brinker CJ 《Langmuir : the ACS journal of surfaces and colloids》2005,21(17):7805-7811
Neutron reflectivity (NR) is used to probe the solid, liquid, vapor interface of a porous superhydrophobic (SH) surface submerged in water. A low-temperature, low-pressure technique was used to prepare a rough, highly porous organosilica aerogel-like film. UV/ozone treatments were used to control the surface coverage of hydrophobic organic ligands on the silica framework, allowing the contact angle with water to be continuously varied over the range of 160 degrees (superhydrophobic) to <10 degrees (hydrophilic). NR shows that the superhydrophobic nature of the surface prevents infiltration of water into the porous film. Atomic force microscopy and density functional theory simulations are used in combination to interpret the NR results and help establish the location, width, and nature of the SH film-water interface. 相似文献
5.
6.
A new tetradentate dihydrogen perchlorate macrocyclic ligand (2,4,9,11-tetraphenyl-1,5,8,12-tetraazacyclotetradeca-1,4,8,11-tetraene dihydrogen perchlorate) was prepared and characterised. The macrocycle behaves as a selective chelating ion-exchanger for some metal ions. The polystyrene-based membrane electrode is found to exhibit quite promising selectivity for Cr3+ ions. It can be used to estimate chromium concentrations in the range 3.16x 10(-6)-1.00x10(-1) M with a near-Nernstian slope of 17.5 mV per decade of concentration between pH 3.0 to 6.5. The electrode is found to possess a fast response time of 15 s and was used over a period of three months with good reproducibility (s = +/- 0.3 mV). The selectivity coefficient values for mono-, di- and trivalent cations indicate excellent selectivity for Cr3+ ions over a large number of other cations. Anions such as Cl- and SO4(2-) do not interfere and the electrode also works satisfactorily in a mixed organic-water solution. The sensor has been used as an indicator electrode for the potentiometric titration of Cr3+ with EDTA. The practical utility of the membrane sensor has also been demonstrated in solutions contaminated with detergents (CTAB and SDS). Above all, the membrane sensor has been very successfully used to determine Cr3+ in some foods. 相似文献
7.
Kamlakar Avasthi Diwan S. Rawat Tilak Chandra Ashoke Sharon Prakas R. Maulik 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(6):o311-o313
In 5-benzyl-1,7-dimethyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-d]pyrimidine-4,6-dione, C14H14N4O2, which crystallizes in space group P, weak intermolecular C—H⋯O hydrogen bonds generate dimers. The isomeric compound 1-benzyl-5,7-dimethyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-d]pyrimidine-4,6-dione, C14H14N4O2, crystallizes in space group P21/n, and shows no such dimerization. Instead, it exhibits C—H⋯π interactions with the phenyl ring. In both structures, the molecules are linked by aromatic π–π-stacking interactions. 相似文献
8.
C. D. Kalkar S. V. Doshi Seema Teli 《Journal of Radioanalytical and Nuclear Chemistry》1989,136(4):283-290
The oxidation of iron/II/ ions has been studied by dissolving -irradiated NaCl crystals in aqueous Fricke solution. The yield of iron/III/ ions was determined as a function of the amount of NaCl added, storage time, dose, concentration of iron/II/ ions and pH of the Fricke solution. The energy transfer parameter, , which is the ratio of G/Fe3+/ obtained by the addition of irradiated NaCl to that by direct radiolysis was evaluated. 相似文献
9.
A new chelating resin was synthesised by the modification of styrene-divinylbenzene (2%) copolymer and incorporation of dithiocarbamate groups. The polydithiocarbamate resin was characterised by elemental analysis, thermal studies and IR studies. The analytical characteristics of the sorbent were established and optimum sorption conditions for Cu, Ni, Pb, Fe, As and Mn determined. The total sorption capacity of the resin was 37 mg g−1 for Ni(II), 35 mg g−1 for Cu(II), 29 mg g−1 for Fe(III) and 23 mg g−1 for Pb(II). The optimum pH for the removal of metal ions was 3-5 for Ni(II), 5 for Cu(II), 4 for Fe(III) and 4-5 for Pb(II). High sorption capacity was observed when compared with other conventional chelating polymers. The sorption kinetics was fairly rapid, as apparent from the loading half time t1/2 values, indicating a better accessibility of the chelating sites. 相似文献
10.
Renu Sharma Santosh K. Agarwal Shikha Rawat Meena Nagar 《Transition Metal Chemistry》2006,31(2):201-206
The synthesis and characterization of some transition metal cis-3,7-dimethyl-2,6-octadiensemicarbazone (CDOSC) complexes are reported. The ligand CDOSC yields: [ML2 Cl2] and [ML2 Cl2] Cl type complexes, where M = CrIII, MnII, FeIII, CoII, NiII, CuII, ZnII, CdII and HgII, L = CDOSC. Structures of the complexes were determined using elemental analysis, molar conductivity, magnetic measurements,
i.r. and electronic, as well as n.m.r spectra. CDOSC acts as a bidentate ligand in all the complexes. All the newly synthesized
metal complexes, as well as the ligand, were screened for their antibacterial activity. All the complexes exhibit strong inhibitory
action against Gram (+) bacteria Staphylococcus aureus and Gram (−) bacteria Escherichia coli. The antibacterial activities of the complexes are stronger than those of the ligand CDOSC itself. 相似文献