排序方式: 共有41条查询结果,搜索用时 31 毫秒
21.
22.
Guoqing Zhang Qingyan Sun Ying Hou Zhanying Hong Jun Zhang Liang Zhao Hai Zhang Yifeng Chai 《Journal of separation science》2009,32(14):2401-2407
The purpose of this paper was to study the enantioseparation mechanism of triadimenol compounds by carboxymethylated (CM)‐β‐CD mediated CE. All the enantiomers were separated under the same experimental conditions to study the chiral recognition mechanism using a 30 mM sodium dihydrogen phosphate buffer at pH 2.2 adjusted by phosphoric acid. The inclusion courses between CM‐β‐CD and enantiomers were investigated by the means of molecular docking technique. It was found that there were at least three points (one hydrophobic bond and two hydrogen bonds) involved in the interaction of each enantiomer with the chiral selectors. A new mathematic model has been built up based on the results of molecular mechanics calculations, which could analyze the relationship between the resolution of enantioseparation and the interaction energy in the docking area. Comparing the results of the separation by CE, the established mathematic model demonstrated good capability to predict chiral separation of triadimenol enantiomers using CM‐β‐CD mediated CE. 相似文献
23.
Zhanying Zhang Ian M. O’Hara William O. S. Doherty 《Cellulose (London, England)》2013,20(6):3179-3190
Pretreatments of sugarcane bagasse by three high boiling-point polyol solutions were compared in acid-catalysed processes. Pretreatments by ethylene glycol (EG) and propylene glycol solutions containing 1.2 % H2SO4 and 10 % water at 130 °C for 30 min removed 89 % lignin from bagasse resulting in a glucan digestibility of 95 % with a cellulase loading of ~20 FPU/g glucan. Pretreatment by glycerol solution under the same conditions removed 57 % lignin with a glucan digestibility of 77 %. Further investigations with EG solutions showed that increases in acid content, pretreatment temperature and time, and decrease in water content improved pretreatment effectiveness. A good linear correlation of glucan digestibility with delignification was observed with R2 = 0.984. Bagasse samples pretreated with EG solutions were characterised by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction, which confirmed that improved glucan enzymatic digestibility is mainly due to delignification and defibrillation of bagasse. Pretreatment by acidified EG solutions likely led to the formation of EG-glycosides. Up to 36 % of the total lignin was recovered from pretreatment hydrolysate, which may improve the pretreatment efficiency of recycled EG solution. 相似文献
24.
Ruihong Yue Decheng Zou Tianyi Yu Peng Li Zhanying Yang 《General Relativity and Gravitation》2011,43(8):2103-2114
In this paper, we study slowly rotating black hole solutions in Lovelock gravity (n = 3). These solutions are obtained in uncharged and charged cases, respectively. Up to the linear order of the rotating parameter
a, the entropy and gyromagnetic ratio of black holes keep invariant after introducing the Gauss-Bonnet and third order Lovelock
interactions. 相似文献
25.
For convolution-type Calderon-Zygmund operators, by the boundedness on Besov spaces and Hardy spaces, applying interpolation theory and duality, it is known that H5rmander condition can ensure the boundedness on Triebel-Lizorkin spaces Fp^0,q (1 〈 p,q 〈 ∞) and on a party of endpoint spaces FO,q (1 ≤ q ≤ 2), hut this idea is invalid for endpoint Triebel-Lizorkin spaces F1^0,q (2 〈 q ≤ ∞). In this article, the authors apply wavelets and interpolation theory to establish the boundedness on F1^0,q (2 〈 q ≤ ∞) under an integrable condition which approaches HSrmander condition infinitely. 相似文献
26.
Zhanying Zhang Wenjun Xiao Guanrong Chen 《Journal of Applied Analysis & Computation》2016,6(4):1105-1113
Many complex networks possess vertex-degree distributions in a power-law form of $ck^{-\gamma}$, where $k$ is the degree variable and $c$ and $\gamma$ are constants. To better understand the mechanism of power-law formation in real-world networks, it is effective to analyze their degree variable sequences. We had shown before that, for a scale-free network of size $N$ ,if its vertex-degree sequence is $k_11$ , then the length $l$ of the vertex-degree sequence is of order $logN$ . In the present paper, we further study complex networks with more general distributions and prove that the same conclusion holds even for non-network type of complex systems. In addition, we support the conclusion by verifying many real-world network and system examples. We finally discuss some potential applications of the new finding in various fields of science, technology and society. 相似文献
27.
28.
A simple, straightforward, and efficient method for the synthesis of polysubstituted 5-aminopyrimidine-2(1H)-thiones from vinyl azides and thiourea was developed. This reaction proceeded under relatively mild conditions and need no additional additives. Additionally, a possible mechanism for the entire sequence is proposed. 相似文献
29.
30.
Dispersive liquid-liquid microextraction (DLLME) coupled with high-performance liquid chromatography (HPLC)-UV detection was applied in rat urine for the extraction and determination of tetrahydropalmatine (THP) and tetrahydroberberine (THB), both active components in Rhizoma corydalis. Various parameters affecting the extraction efficiency, such as the type and volume of extraction and dispersive solvent, pH, etc. were evaluated. Under the optimal conditions (extraction solvent: 37 μL of chloroform, dispersive solvent: 100 μL of methanol, alkaline with 100 μL of 1 mol/L NaOH, and without salt addition), the enrichment factors of THP and THB were more than 30. The extraction recoveries were 69.8-75.8% and 72.7-77.6% for THP and THB in rat urine, respectively. Both THP and THB showed good linearity in the range of 0.025-2.5 μg/mL, and the limit of quantification was 0.025 μg/mL (S/N=10, n=6). The intra-day and inter-day precision of THP and THB were <12.6%. The relative recoveries ranged from 95.5 to 107.4% and 96.8 to 100.9% for THP and THB in rat urine, respectively. The method has been successfully applied to rat urine samples. The results demonstrated that DLLME is a very simple, rapid and efficient method for the extraction and preconcentration of THP and THB from urine samples. 相似文献