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971.
ICP-MS法测定茶叶及其多糖提取物中的降血糖相关性元素 总被引:2,自引:1,他引:1
采用微波溶样ICP-MS法测定了江西婺源绿茶茶叶、茶叶温水及热水浸提液和茶多糖中降血糖相关性元素(ERBS)的含量,探讨了ERBS含量与茶叶品质老嫩以及茶多糖中ERBS含量与茶叶中ERBS总量的关系。结果表明,茶叶品质老嫩不同,茶叶以及茶多糖中各ERBS含量存在一定差异,由品质差的茶叶提取得到的茶多糖中的ERBS的量较高。茶叶中结合于多糖中的各ERBS占相应ERBS总量的比例在0.03%~9.57%之间,与元素种类、茶叶品质有关。结合于多糖中的ERBS占茶叶ERBS总量的比例,鄣山特级和五级茶分别为1.11%和2.10%,对孤山老叶茶,为0.85%。测定结果可以作为选择提取茶多糖茶叶原料的依据,也可为研究茶多糖可能的降血糖机理提供可靠的无机元素方面的数据。 相似文献
972.
One new polyoxometalate compound connected via nickel/potassium cations, H8K{[Ni(H2O)5]2(H2Mo1.80W10.20O42)}Cl3·16H2O 1, was prepared and characterized by elemental analysis and IR spectroscopy. Single-crystal X-ray diffraction analysis results reveal that clusters of [Ni(H2O)5]2(H2Mo1.80W10.20O42)}6-in compound 1 are linked by potassium cations to form one- dimiensional chains, based on which a three-dimensional network is further constructed via the hydrogen bonds of O…O and O…Cl. Magnetic measurements show that compound 1 has para- magnetic properties. Crystal data: H62Cl3KMo1.80Ni2O68W10.20, Mr = 3461.33, monoclinic, space group C2/c, a = 18.9291(19), b = 16.6758(17), c = 19.1064(19)(A), β = 106.6880(10)(, V = 5777.1(10) (A)3, Z = 4, Dc = 3.980 g/cm3, F(000) = 6250, μ = 21.574 mm(1, R = 0.0579 and wR = 0.1623 (Ⅰ > 2σ(I)). 相似文献
973.
CUI Zeng-Nan GUO Jian-Hua YANG En-Cui 《结构化学》2007,26(6):717-720
A new one-dimensional coordination polymer, [Pb(phen)(ANS)2]n (ANS = 2-ami- nonaphthalene-1-sulfonate, phen = 1,10-phenanthroline), has been prepared by hydrothermal synthesis and structurally characterized by elemental analysis, IR and single-crystal X-ray diffrac- tion. The results determined by XRD reveal that the complex crystallizes in monoclinic, space group P21/c with a = 16.8374(14), b = 16.9825(14), c = 9.9392 (8) , β = 95.9830(10)o, V = 2826.5(4) 3, Mr = 831.86, Dc = 1.955 g/cm3, μ(MoKα) = 6.173 mm-1, F(000) = 1624, Z = 4, the final R = 0.0272 and wR = 0.0694 for 4305 observed reflections (I > 2σ(I)). In the complex, the adjacent lead(II) ions are bridged through the oxygen atoms of sulfonate groups in a syn-syn conformation, yielding an infinite zigzag chain. And the intermolecular N–H···O hydrogen bonds link the chains into two-dimensional layered networks, which are further assembled into a separate two-layer-film-like packing structure. 相似文献
974.
YING Xiaoa DENG Qina LIAO Shi-Junb HU Xi-Mingb LIU Hai-Yangb② CHANG Chi-Kwongc② a 《结构化学》2007,26(8):955-961
The second-order nonlinear optical (NLO) properties of 5,10,15-triphenylcorrole (TPC), 5,10,15,20-tetraphenylporphyrin (TPP) and L-amino acid bridged bis-corroles 1, 2, 3 and 4 have been calculated by using TDHF/PM3 method based on the RHF/6-31G (TPC and TPP) or semiempirical PM3 (1, 2, 3, 4) optimized geometries. Calculation results showed TPC and TPP have C1 and D2h symmetry, respectively when N-H protons are localized on the nitrogen atoms. TPC is the second-order NLO active chromophore due to the cancellation of centrosymmetrical structure and its first hyperpolarizability β increases to 11.524×10-30 esu. Under electrical dipole approximation, β values of bis-corroles 1, 2, 3 and 4 vary from 9.831×10-30 to 14.221×10-30 esu, and no much improvement in the first hyperpolarizability was observed as compared to TPC monomer. However, β values of bis-corroles 1, 2, 3 and 4 are improved by about 4 times as compared to their bis-porphyrin counterparts. The analysis of β components indicates that β of this kind of bis-corroles is mainly contributed from its radial component βr. With the variation of amino acid side chains, βHRS, β, βxyz, βr and βa of bis-corroles change remarkably. Chiral L-amino acid bridged bis-corroles 2, 3 and 4 have a right-handed helix structure, and their chiral component βxyz matches βxyz ∝ r2ζ/L4 (helix parameters), showing the second-order chiral NLO response of these bis-corroles could be described by one-electron helical model theory. It was found that the radial component βr of chiral helix bis-corroles also matches β r ∝ r2ζ/L4. 相似文献
975.
关于马氏环境中马氏链的几点注记 总被引:21,自引:1,他引:21
讨论了马氏环境中马氏链与马氏双链间的关系,通过两个例子,纠正了有关文献的一些错误结论。 相似文献
976.
977.
基于FastICA和神经网络的红酒主要品质参数红外检测 总被引:1,自引:0,他引:1
为实现红酒中酒精含量、pH值以及残糖量的快速检测,对44个红酒样品的红外光谱数据进行了分析。使用快速独立分量分析(FastICA)算法对光谱数据矩阵进行分解,得到独立成分和相应的混合系数矩阵,再利用误差反向传播算法(back-propagation, BP)构造了三层的神经网络结构,建立了ICA-NNR模型。利用此模型对红酒样品的酒精含量、pH值以及残糖量进行预测,根据预测相关系数(r)和预测标准偏差(RMSEP)来评价预测模型的性能,结果表明该模型对红酒酒精含量、pH值以及残糖量测定的相关系数r分别为0.953,0.983和0.994,RMSEP分别为0.161,0.017,0.181。此外,预测样品集中的22个样品ICA-NNR模型预测值与参考值相比,酒精含量、pH值以及残糖量的最大相对偏差均小于4%。这为进一步开发红酒成分红外在线分析仪奠定了基础。 相似文献
978.
The dietary properties of minikiwi make them, along with other fruits and vegetables, suitable as the basis for many slimming and pro-health diets. Prolonging the availability of minikiwi can be provided by different storage technologies. This experiment focused on evaluating the effect of various O2 and CO2 concentrations, i.e., low-oxygen atmosphere (DCA, 0.4% CO2:0.4% O2; ULO, 1.5% CO2:1.5% O2) or high-CO2 (CA, 5% CO2:1.5% O2) storage, in order to provide the consumer with fruits with comparable high nutritional values. Evaluation gave the basic characteristics of the fruits that characterize their health-promoting properties, i.e., total polyphenols (TPC), phenolic acids and flavonols, antioxidant activity (AA), monosaccharides, and acid content. The atmosphere with a higher CO2 content of 5% (CA) effectively influenced the high value of ascorbic acid even after 12 weeks of storage. DCA technology contributed to a significant inhibition of phenol loss but not as effectively as CA technology. In contrast, glucose and fructose contents were found to be significantly higher after storage in ULO or DCA, while sucrose content was more stable in fruit stored in CA or DCA. CA technology conditions stabilized the citric acid content of minikiwi, while DCA technology was less effective in inhibiting acid loss. The nutritional value of the fruit after storage in CA or DCA was not significantly reduced, which will allow the supply of fresh minikiwi fruit to be extended and provide a valuable component of the human diet. 相似文献
979.
Dr. Susumu Tsuda Yoshitsugu Komai Prof. Dr. Shin-ichi Fujiwara Prof. Dr. Yutaka Nishiyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(6):1966-1969
A [c2]daisy chain rotaxane with two diarylacetylene cores was efficiently synthesized in 53 % yield by capping a C2-symmetric pseudo[2]rotaxane composed of two diarylacetylene-substituted permethylated α-cyclodextrins (PM α-CDs) with aniline stoppers. The maximum absorption wavelength of the [c2]daisy chain rotaxane remained almost unchanged in various solvents, unlike that of the stoppered monomer, indicating that the two independent diarylacetylene cores were insulated from the external environment by the PM α-CDs. Furthermore, the [c2]daisy chain rotaxane exhibited fluorescence emission derived from both diarylacetylene monomers and the excimer, which implies that the [c2]daisy chain structure can undergo contraction and extension. This is the first demonstration of a system in which excimer formation between two π-conjugated molecules within an isolated space can be controlled by the unique motion of a [c2]daisy chain rotaxane. 相似文献
980.
Md Khairul Islam Tomislav Sostaric Lee Yong Lim Katherine Hammer Cornelia Locher 《Molecules (Basel, Switzerland)》2020,25(22)
Honey adulteration, where a range of sugar syrups is used to increase bulk volume, is a common problem that has significant negative impacts on the honey industry, both economically and from a consumer confidence perspective. This paper investigates High-Performance Thin Layer Chromatography (HPTLC) for the authentication and detection of sugar adulterants in honey. The sugar composition of various Australian honeys (Manuka, Jarrah, Marri, Karri, Peppermint and White Gum) was first determined to illustrate the variance depending on the floral origin. Two of the honeys (Manuka and Jarrah) were then artificially adulterated with six different sugar syrups (rice, corn, golden, treacle, glucose and maple syrup). The findings demonstrate that HPTLC sugar profiles, in combination with organic extract profiles, can easily detect the sugar adulterants. As major sugars found in honey, the quantification of fructose and glucose, and their concentration ratio can be used to authenticate the honeys. Quantifications of sucrose and maltose can be used to identify the type of syrup adulterant, in particular when used in combination with HPTLC fingerprinting of the organic honey extracts. 相似文献