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71.
Sheau‐Long Lee Chung‐Min Yang Kuan‐Jiunn Shieh Xinmiao Liang Hai‐Yan Li 《中国化学会会志》2000,47(6):1247-1249
Better peak shapes and complete separation of amino‐3,5‐dinitro derivatives by (S)‐N‐(2‐naphthyl)alanine derived chiral stationary phase (CSP) is achieved by adding a trace amount of acetic acid in the mobile phase. This method provides an indication of its broad applicability on direct separation of a series of amino‐containing enantiomers on CSP. In addition, the reversed elution order was obtained on its enatiomeric CSP. 相似文献
72.
Ping Chen Dong-Lin Li Jian-Xiong Yi Li Wen Bi-Yu Tang Li-Ming Peng Wen-Jiang Ding 《Solid State Sciences》2009,11(12):2156-2161
The β′ phase precipitate in Mg–Gd alloy system has been investigated by means of first-principles calculation within the generalized gradient approximation. The lattice parameters are determined theoretically by structural optimization of full relaxation, and the Mg7Gd is found to be energetically more stable compared with the Mg15Gd from the calculated formation energy. The nine independent elastic constants are calculated, indicating the proposed Mg15Gd structure in literature is mechanically unstable. Then the polycrystalline bulk modulus B, Young's modulus E, shear modulus G, Poisson ratio ν of Mg7Gd are gained by the Voigt–Reuss–Hill (VRH) approximation. The ductility and plasticity, especially elastic anisotropy are discussed in details. Based on the electronic density of states and charge density distribution, the covalent bonding and metallic bonding are exhibited in Mg7Gd compound. Last, the Debye temperature is also calculated for the investigation in the future. 相似文献
73.
Yeong‐Tarng Shieh Yawo‐Kuo Twu Chean‐Cheng Su Rong‐Hsien Lin Gin‐Lung Liu 《Journal of Polymer Science.Polymer Physics》2010,48(9):983-989
Effects of carbon nanotubes (CNT) on the isothermal crystallization kinetics of poly(L ‐lactic acid) (PLLA) were quantitatively investigated using the Avrami equation and the secondary nucleation theory of Lauritzen and Hoffman. CNT via grafting modification with PLLA could well disperse in the PLLA matrix and give significantly enhanced crystallization rate and crystallinity of PLLA as analyzed by differential scanning calorimetry and polarized optical microscopy. Analysis of isothermal crystallization kinetics using the Avrami equation demonstrated that CNT significantly enhanced the bulk crystallization of PLLA. Analysis of spherulite growth kinetics using the secondary nucleation theory of Lauritzen and Hoffman found that CNT could expand the temperature range of the crystallization regime III of PLLA. Values of the nucleation constant (Kg) in crystallization regimes III and II of PLLA both increased with increasing CNT contents. The Kg III/Kg II ratios were found to be close to the theoretical value 2 but were not clearly found to depend on the CNT contents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 983–989, 2010 相似文献
74.
75.
Ching‐Ming Wu Ping‐Ching Wu Yun‐Han Wang Tsung‐Ju Li Li‐Xing Yang Ya‐Na Wu Hsi‐Yuan Yang Dar‐Bin Shieh 《中国化学会会志》2009,56(4):703-708
Gold nanoparticles have been developed for the photoacoustic imaging, delivery of genes and laser induced photothermal therapy. In this study, we have developed oligonucleotide conjugated gold nanoparticles as the carrier for simultaneous DNA and anti‐cancer nucleoside delivery. The polynucleotidenanoparticle complex presented higher capacity in carrying 5‐FU anti‐cancer compounds than the original gold particles. The hydrodynamic size of the gold nanoparticles increased from 25 to 35 nm with an increase in the negative surface charge from ?9.58 to 21.66 mV after polynucleotide conjugation and drug loading. A positive association between environmental pH and drug release was observed in PBS, which implied their potential use in the controlled localized drug release in the lower GI tract. The MTT assay revealed dose dependent cytotoxicity to colon cancer cell line than free compounds. These results suggest the potential use of this new polynucleotide‐gold nanoparticles complex as the environmental controlled anti‐cancer nanocapsule, especially suitable for per oral colon cancer chemotherapy. 相似文献
76.
Numeric treatment of contact discontinuity with multi-gases 总被引:2,自引:0,他引:2
In this paper we work with a finite-volume-procedure for the computation of the one-dimensional Euler equations for the treatment of multi-gases and the problem of the correct treatment of the discontinuity was more nearly investigated. A suggested equation was embedded in the finite volumes context and implemented in our code accordingly and regarded as validated. 相似文献
77.
Two new C19-diterpenoid alkaloids, circinadines A (1) and B (2), were isolated from the roots of Aconitum hemsleyanium var. circinacum. Their structures were elucidated by chemical evidence and spectral analyses, including ESI-MS, HR-EI-MS, 1D- and 2D-NMR. 相似文献
78.
The novel hydroxo-bridged dimeric lead-chromium carbonyl complex [Et4N]2[{PbCr2(CO)10}2(mu-OH)2] ([Et4N]2[1]) was synthesized from the reaction of PbCl2 and Cr(CO)6 followed by metathesis with [Et4N]Br in a KOH/MeOH solution. The X-ray crystallographic structure shows that dianion 1 consists of two Pb{Cr(CO)5}2 units bridged by two hydroxo fragments in which the Pb atoms are further coordinated with two Cr(CO)5 groups, resulting in a distorted tetrahedral geometry. A CO2 molecule can insert itself into dianion 1 to form two new carbonate complexes, [Et(4)N]2[{PbCr2(CO)10}(CO3)] ([Et4N]2[2]) and [Et4N]2[{PbCr2(CO)10}2(CO3)] ([Et4N]2[3]), depending on the reaction conditions. In addition, complex 2 can be transformed into 3 in CH2Cl2 solution at an elevated temperature. While the carbonate group in dianion 2 is bonded to one Pb atom, which is coordinated with two Cr(CO)5 fragments, the carbonate group in 3 bridges the two Pb centers in a mu-1kappa2OO':2kappa2OO' fashion in which each Pb atom is further bonded to two Cr(CO)5 moieties. Complexes 2 and 3 can be converted back the hydroxo complex 1 under appropriate conditions. All three unprecedented lead-chromium compounds, 1-3, were fully characterized by spectroscopic methods and single-crystal X-ray diffraction analyses. The nature and formation of complexes 1-3 were also examined by molecular orbital calculations using the B3LYP method of the density functional theory. 相似文献
79.
Li WS Kim KS Jiang DL Tanaka H Kawai T Kwon JH Kim D Aida T 《Journal of the American Chemical Society》2006,128(32):10527-10532
Dendritic molecules appended with multiple zinc porphyrin units (DPm, m [number of zinc porphyrin units] = 6, 12, and 24) trap bipyridine compounds carrying multiple fullerene units (Py2Fn, n [number of C60 units] = 1-3), affording coordination complexes DPm superset Py2Fn having a photoactive layer consisting of spatially segregated donor and acceptor arrays on their surface. Complexes DPm superset Py2Fn are stable enough (K [average binding affinity] = 1.1 x 10(6)-4.4 x 10(6) M(-1) in CHCl3 at 25 degrees C) to be isolated by gel permeation chromatography. UHV-STM microscopy enables clear visualization of a petal-like structure of DP12 superset Py2F3. Photoexcitation of the zinc porphyrin units in DPm superset Py2Fn results in a zinc porphyrin-to-fullerene electron transfer to generate a charge separation. The charge-separation rate constant (kCS) in CH2Cl2 at 20 degrees C increases from 0.26 x 10(10) to 2.3 x 10(10) s(-1) upon increment of m and n, whereas the charge-recombination rate constant (kCR) remains almost unchanged at 4.5 x 10(6)-6.7 x 10(6) s(-1). Consequently, DP24 supersetPy2F3 furnishes the largest ratio of kCS/kCR (3400) among the family. 相似文献
80.
Leung MK Chang CC Wu MH Chuang KH Lee JH Shieh SJ Lin SC Chiu CF 《Organic letters》2006,8(12):2623-2626
Dye-doped organic light-emitting diode of ITO/alpha-NPB (70 nm)/Bebq(2)-1 (7 nm)/BCP (5 nm)/Bebq(2) (33 nm)/LiF (1 nm)/Al (150 nm) shows red electroluminescence with the efficiency of 2.9 cd/A at 100 cd/m(2) and maximum brightness of 62000 cd/m(2). The physical organic aspects of the current-induced fluorescent quenching effect are discussed. [structure: see text] 相似文献