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941.
José Glaüco Ribeiro Tostes 《Theoretical chemistry accounts》1981,59(3):229-235
Certain features of the chemist's molecular structure model, viz. size and shape, are retrieved even in the best non-adiabatic variational calculations thus far carried out for ground states of H
2
+
and H2. Those features do not conflict with the full symmetry of exact molecular eigenstates, once they are properly understood as correlation effects. 相似文献
942.
气相色谱质谱联用仪与微机的数据传输和处理 总被引:1,自引:0,他引:1
报道了一种用于气相色谱质谱联用仪和微机之间实现数据传输和处理的方法。方法可更有效地利用质谱仪采集的数据,解决了工作站处理数据的局限性。经数据格式转换,原始数据可以在微机上实现色谱峰再现,从而为色谱条件的优化和定量数据处理创造了条件。 相似文献
943.
用转换器和IBMPC/XT微机与Dionex2020i型离子色谱仪连接组成自动控制与数据处理系统,转换器由8031及8255等芯片组成,其功能是采集数据和转送数据,软件由汇编及C语言编制。这套新系统增加了注入/记录同步,分级梯度淋洗,自动连续进样等功能以及很强的数据处理能力。 相似文献
944.
采用电沉积-热解法在3Cr25Ni7N合金表面制备了Y2O3薄膜,并研究了薄膜处理对合金在1000℃空气中的抗高温氧化性能的影响。氧化动力学曲线、SEM及XRD分析结果表明,Y2O3薄膜处理使合金表面氧化膜以尖晶石结构为主,氧化膜致密,有效地抑制了Cr2O3的挥发反应,且氧化膜与基体的附着性好,因此合金在高温下的抗氧化性能得到提高,这与氧化钇薄膜在较低温度下抗高温氧化性能提高的机制是不同的。在不同温度下,Y2O3薄膜处理均可以有效提高合金的抗高温氧化性能。 相似文献
945.
A new in-loop solid-phase microextraction (in-loop-SPME) technique, based on an aluminum capillary tube coupled to HPLC, is described for on-line isolation, concentration, and analysis of analytes from aqueous samples. L-Dopa and L-dopamine, in aqueous solutions, were selected as model compounds. The main conditions affecting extraction of the analytes from aqueous samples, desorption, injection, and chromatographic separation were investigated. The method is simple and reproducible. Using the proposed method, reliable determination of L-dopa and L-dopamine at parts-per-billion concentrations was achieved. The calibration plots were linear in the range of 2.5–1500 ng mL−1 with correlation coefficients of 0.999 and 0.998 for L-dopa and L-dopamine, respectively. The detection limits were 0.5–1 ng mL−1 with a relative standard deviation less than 4.1%. Concentration factors more than 100-fold were obtained for these compounds. 相似文献
946.
947.
I.K. Battisha 《Journal of Sol-Gel Science and Technology》2004,30(3):163-172
Visible up-conversion emissions at (435, 545, 580, 675 and 690 nm) and (437, 547 575 and 675 nm) have been observed from the sol-gel derived nano-crystalline Ho3+: BaTiO3 powders and thin films respectively, under 808 nm laser diode excitation emissions. Combined with the energy level structure of Ho3+ ions and the kinetics of the visible emissions, the up-conversion mechanism has been analyzed and explained. The blue, green and red emissions of both samples has been attributed to the ground state-directed transition from (5F1), (5S2) and (5F5), which are populated through excited state absorption (ESA) for 808 nm excitation. Nano-structure pure barium titanate and doped with different concentrations of Ho3+ ions in the from of powder and thin film have been prepared by sol-gel technique, using barium acetate (Ba(Ac)2), and titanium butoxide (Ti(C4H9O)4), as precursors. The thin films were prepared by sol-gel spin coating method. The as-grown thin films and powders were found to be amorphous, which crystallized to the tetragonal phase after heating at 750°C in air for 30 minutes. The crystallite sizes of the thin film and powder both doped with 4% Ho3+ ions was found to be equal to 11 and 16 nm, respectvely. 相似文献
948.
K. Dimroth A. Berndt F. Br A. Schweig R. Volland 《Angewandte Chemie (International ed. in English)》1967,6(1):34-40
The distribution of the unpaired electron over the oxygen and the 24 carbon atoms in the free 2,4,6-triphenylphenoxy radical was determined by electron spin resonance spectroscopy and quantum-mechanical approximation methods. The hyperfine splitting was evaluated with the aid of the spectra of triphenylphenoxyls deuterated in some or all of the substituent phenyl groups. The results of the quantum-mechanical approximations were checked by recording the ESR spectra of triphenylphenoxyls labeled with 13C in positions 1,2,3, or 4 of the central ring. The spin density distribution permits a first discussion of the 17O-coupling constants of correspondingly labeled triphenylphenoxyl and other organic free radicals. 相似文献
949.
Publications on the binding characteristics of metals with humic acid (HA) are sparse. Here we investigated the release of nickel from Ni(II)-HA complexes using model solutions of three different [Ni(II)]/[HA] mole ratios at three different pH values; we also compared the results with those of [Ni(II)]/[FA] complexes from previous work in this laboratory. Ligand exchange kinetics using the competing ligand exchange method (CLEM) were studied using two different techniques: graphite furnace atomic absorption spectrometry (GFAAS) with Chelex 100 resin as the competing ligand, and adsorptive cathodic stripping voltammetry (AdCSV) with dimethylglyoxime as the competing ligand to measure the rate of dissociation of Ni(II)-HA complexes. The results of the kinetic studies showed that as the [Ni(II)]/[HA] mole ratio was decreased, the rate of dissociation of Ni(II)-HA complexes decreased, and the proportion of free Ni2+ ions plus very labile nickel complexes decreased while the proportion of the less labile kinetically distinguishable components increased. Generally, the rate of dissociation of Ni(II)-HA complexes was slower than that of Ni(II)-FA complexes. Studies on the validity of the kinetic model showed that the concentrations of chemical species varied in a reasonable way with pH and the [Ni(II)]/[HA] mole ratios, indicating that the kinetically distinguishable components have chemical significance and the kinetic model is valid. 相似文献
950.
采用SCF-X_α-MS方法, 对于C(2×2)S/Fe(001)吸附体系, 选择Fe_5S和Fe_9S两种原子簇模型, 研究了该吸附体系的电子结构、吸附成键特征及其相互作用图象。结果表明, S吸附于Fe(001)单晶表面具有较强的定域性质, S原子与底物Fe原子之间的吸附相互作用主要表现为S(3p)-Fe(4s,3d)之间的轨道相互作用。通过对表面吸附键长的优化, 其结果与X.S.Zhang等的ARPEFS的实验结果一致。 相似文献