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561.
Peng‐Fei Gou Wei‐Pu Zhu Ning Xu Zhi‐Quan Shen 《Journal of polymer science. Part A, Polymer chemistry》2010,48(14):2961-2974
Novel amphiphilic A14B7 multimiktoarm star copolymers composed of 14 poly(ε‐caprolactone) (PCL) arms and 7 poly(acrylic acid) (PAA) arms with β‐cyclodextrin (β‐CD) as core moiety were synthesized by the combination of controlled ring‐opening polymerization (CROP) and atom transfer radical polymerization (ATRP). 14‐Arm star PCL homopolymers (CDSi‐SPCL) were first synthesized by the CROP of CL using per‐6‐(tert‐butyldimethylsilyl)‐β‐CD as the multifunctional initiator in the presence of Sn(Oct)2 at 125 °C. Subsequently, the hydroxyl end groups of CDSi‐SPCL were blocked by acetyl chloride. After desilylation of the tert‐butyldimethylsilyl ether groups from the β‐CD core, 7 ATRP initiating sites were introduced by treating with 2‐bromoisobutyryl bromide, which further initiated ATRP of tert‐butyl acrylate (tBA) to prepare well‐defined A14B7 multimiktoarm star copolymers [CDS(PCL‐PtBA)]. Their molecular structures and physical properties were in detail characterized by 1H NMR, SEC‐MALLS, and DSC. The selective hydrolysis of tert‐butyl ester groups of the PtBA block gave the amphiphilic A14B7 multimiktoarm star copolymers [CDS(PCL‐PAA)]. These amphiphilic copolymers could self‐assemble into multimorphological aggregates in aqueous solution, which were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2961–2974, 2010 相似文献
562.
563.
Abstract The ionic overlap-compression model is used to calculate the equations of state, as well as the equilibrium properties, of sodium and potassium hydrides (NaH and KH). The present results agree with the experimental ones well. The NaC1-to-CsC1 phase transition pressures for both crystals are also determined. The agreement of the theoretical pressures (23.0 GPa for NaH and 4.9 GPa for KH) with the experimental measurements (29.3 GPa and 4 GPa) is rather good. The calculation shows that the effect of the zero-point vibration to the equilibrium properties and the transition pressures should not be ignored. 相似文献
564.
Asymmetric Henry reactions of aldehydes with various nitroalkanes catalyzed by copper(II) complexes of novel chiral N‐monoalkyl cyclohexane‐1,2‐diamines
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A number of novel chiral diamines 3 , (1R,2R)‐N‐monoalkylcyclohexane‐1,2‐diamines, were designed and synthesized from trans‐cyclohexane‐1,2‐diamine and applied to the catalytic asymmetric Henry reaction of benzaldehyde and nitromethane to provide β‐nitroalcohol in high yield (up to 99%) and good enantiomeric excess (up to 89%). By using ligand (1R,2R)‐N1‐(4‐methylpentan‐2‐yl)cyclohexane‐1,2‐diamine ( 3g ), the reaction was optimized in terms of the metal ion, temperature, solvent and base. Further experiments indicated that the complex, 3g –Cu(OAc)2, was an efficient catalyst in the asymmetric Henry reaction between different aldehydes and nitromethane, and the desired products have been obtained with high chemical yields (up to 99%) and high enantiomeric excess (up to 93%). The optimized catalyst promoted the diastereoselective Henry reaction of various aldehyde substrates and nitroalkane, which gave the corresponding anti‐selective adduct with up to 99% yield and 83:17 anti/syn selectivity. Upon scaling up to gram quantities, the β‐nitroalcohol was obtained in good yield (96%) with excellent selectivities (93% ee). The chiral induction mechanism was tentatively explained on the basis of a previously proposed transition‐state model. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
565.
Traditional Chinese medicines (TCMs) have been used in China to prevent and cure diseases for centuries. Due to the complexity of TCMs, fast and highly efficient techniques are required to develop their quality control. Near infrared spectroscopy (NIRS) has been widely applied in TCM analysis for both nonpolar and polar components. This review describes an overview of experimental conditions (spectra pretreatments and multivariate techniques) investigated in NIRS for TCM components that are related to individual compounds such as lipids, essential oils, phenolics, alkaloids, saponins and carbohydrates. Their potential in the separation of TCMs using relevant applications with a particular focus on quantitative analysis is also demonstrated. 相似文献
566.
Xiao Chi Ma Zhan Ping Gou Chang Yuan Wang Ji Hong Yao Xiu Lan Xin Yuan Lin Ke Xin Liu 《中国化学快报》2010,21(5):587-589
<正>A new ent-labdane diterpenoid lactone was isolated from Andrographis paniculata.Its structure was identified on the basis of spectral data including 2D NMR. 相似文献
567.
Sphingomonas xenophaga QYY, capable of growing significantly on more than ten kinds of aromatic compounds as sole carbon source, was used to study
characterization of catechol 1,2-dioxygenase (C12O) in cell extracts. Characterization of the crude C12O showed that the maximum
activity was obtained at 40–70°C and pH 7.8–8.8. Metal ions had different influences on the activity of crude C12O. It was
suggested that strain QYY possessed an inducible and ferric-dependent C12O. Kinetic studies showed that the value of V
max and K
m was 0.25 μmol catechol/L/mg protein/min and 52.85 μmol/L, respectively. In addition, the partial purification of C12O was
achieved by a HiTrap Q Sepharose column chromatography.
Supported by the National Natural Science Foundation of China (Grant No. 50608011) and the 39th Postdoctoral Funds of China
(Grant No. 20060390983) 相似文献
568.
Eight platinum(II) compounds with a new chiral ligand, 2-(((1R,2R)-2-aminocyclohexylamino)methyl)phenol (HL), were designed, prepared and spectrally characterized. All compounds showed better aqueous solubility than cisplatin and oxaliplatin. In vitro cytotoxicity of these compounds against human HepG-2, MCF-7, A549 and HCT-116 cell lines was evaluated. Results indicated that all compounds showed cytotoxicity against A549 and HepG-2 cell lines. Particularly, compounds B1 and B8, which have CF?SO?? and (CH?)?COCH?COO(-) as leaving groups, respectively, exhibited better cytotoxicitiy than that of carboplatin in these two cell lines. 相似文献
569.
Nonlinear Dynamics - Micro-vibrations in satellites mainly originate from the control moment gyroscope because of its mass imbalance, which seriously affect the image accuracy of high-resolution... 相似文献
570.
Hong Shen Lin Cheng Huaze Dong Haibin Zhu Shaohua Gou Xuetai Chen 《Solid State Sciences》2010,12(3):367-372
Interactions of dithioether ligands L2, L4 and L5 (L2 = 1,3-bis(4-(3-pyridyl) pyrimidin-2-ylthio) propane; L4 = 1,3-bis[4-(3-pyridyl) pyrimidinyl thiomethyl]benzene; L5 = 1,4-bis[4-(3-pyridyl)pyrimidinylthiomethyl] benzene) with Mn(II) ions and NH4SCN in an analogous way led to the formation of two discrete mononuclear complexes and a one-dimensional chain, respectively, which may be attributed to the different flexibility and positional isomerism of the ligands. 相似文献