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91.
Hindered beta-aminoarylphosphines show promise as bidentate ligands for metal centers, but their reported synthesis requires heating at high temperatures for several days. Herein are reported conditions by which the two steps composing this synthesis, Buchwald-Hartwig amination and nucleophilic phosphorylation reactions, may both be completed in less than 3 h using microwave irradiation. The effects of several parameters on the outcome of the amination reaction are discussed, as are some indications of the scope within which each of these microwave protocols is effective. 相似文献
92.
Eucalyptals A-C (1-3) with a new skeleton of 3,5-diformyl-isopentyl phloroglucinol-coupled cadinane were isolated from the fruits of Eucalyptus globulus. Their structures were elucidated by spectroscopic analysis, and that of 1 was confirmed by single-crystal X-ray diffraction. The biosynthetic pathway of 1-3 was also postulated. Compounds 1-3 exhibited selective cytotoxicity against the HL-60 cell line. 相似文献
93.
94.
The first chiral zeolite-like galloborate, K2[Ga(B5O10)].4H2O, has been synthesized by a mild solvothermal method and characterized by Fourier transform IR, energy-dispersive spectroscopy, thermogravimetric/differential thermal analysis, and single-crystal X-ray diffraction. This compound crystallizes in the orthorhombic system with space group C2221. The structure possesses a 3D open framework constructed by B5O10 clusters and GaO4 units and contains large odd 11-ring channels. 相似文献
95.
Hou ZY Liu RS Liu HR Tian ZA Wang X Zhou QY Chen ZH 《The Journal of chemical physics》2007,127(17):174503
To deeply understand the formation mechanism of a critical nucleus during the nucleation process of liquid metal sodium, a system consisting of 10 000 Na atoms has been simulated by using molecular dynamics method. The evolutions of nuclei are traced directly, adopting the cluster-type index method. It is found that the energies of clusters and their geometrical constraints interplay to form the favorable microstructures during the nucleation process. The nucleus can be formed through many different pathways, and the critical size of the nucleus would be different for each pathway. It is also found that the critical nucleus is nonspherical and may include some metastable structures. Furthermore, the size of the cluster and its internal structure both play a crucial role in determining whether it is a critical nucleus, and this is in agreement with the simulations by computing the free energy of the Lennard-Jones system [D. Moroni, P. R. ten Wolde, and P. G. Bolhuis, Phys. Rev. Lett. 94, 235703 (2005)]. 相似文献
96.
Zhu YZ Cao YL Li ZH Ding J Liu JS Chi YB 《Journal of colloid and interface science》2007,306(1):133-136
With the help of self-assembly, thermal sintering, selective etching techniques and sol-gel process, the non-close packed (ncp) face-centered cubic (fcc) photonic crystals of titanium dioxide (TiO2) hollow spheres connected by TiO2 cylindrical tubes have been fabricated using silica template. The photonic bandgap calculations indicate that the ncp structure of TiO2 hollow spheres was easier to open the pseudogaps than close packed system at the lowest energy. 相似文献
97.
添加少量纯Ni粉不仅可以降低Mo的烧结温度,而且也大大地提高烧结密度。例如,添加2%的纯Ni粉可以使Mo在相应烧结温度一半时达到94%的相对密度。烧结Mo坯的工与烧结温度有很强的关系,其烧结过程中的活化能,与Mo的体弥散能相比迅速下降,在相当短的时间内即完成整个烧结过程。 相似文献
98.
99.
Wu SY Wei LH Zhang ZH Wang XF 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,71(5):2023-2025
The spin Hamiltonian parameters g factors g(i) (i=x, y, z) and the hyperfine structure constants A(i) of vitamin B(12r) have been theoretically studied from the perturbation formulas of these parameters for a Co(2+)(3d(7)) ion with low spin (S=1/2) in rhombically distorted octahedra. The related crystal-field parameters are determined from the point-charge-dipole model and the local structure around Co(2+) in vitamin B(12r). The theoretical spin Hamiltonian parameters are in good agreement with the experimental data. 相似文献
100.
Comparison between conventional indirect competitive enzyme-linked immunosorbent assay (icELISA) and simplified icELISA for small molecules 总被引:3,自引:0,他引:3
A simplified indirect competitive enzyme-linked immunosorbent assay (icELISA) for small molecules was established by modifying the procedure of conventional icELISA. The key change was that the analyte, antibody, and enzyme-labeled second antibody in the simplified icELISA were added in one step, whereas in conventional icELISA these reagents were added in two separate steps. Three small chemicals, namely zeatin riboside, glycyrrhetinic acid, and chlorimuron-ethyl, were used to verify the new assay format and compare the results obtained from conventional icELISA and simplified icELISA. The results indicated that, under optimized conditions, the new assay offered several advantages over the conventional icELISA, which are simpler, less time consuming and higher sensitive although it requires more amount of reagents. The assay sensitivity (IC50) was improved for 1.2-1.4-fold. Four licorice roots samples were analyzed by conventional icELISA and simplified icELISA, as well as liquid chromatography (LC). There was no significant difference among the content obtained from the three methods for each sample. The correlation between data obtained from conventional icELISA and simplified icELISA analyses was 0.9888. The results suggest that the simplified icELISA be useful for high throughput screening of small molecules. 相似文献