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1.
为鉴别补骨脂与其混伪品,对两种种子的可溶性蛋白质进行了聚丙烯酞胺凝胶电泳分析.结果表明,补骨脂及其混伪品的电泳图谱存在显著差异,电泳图谱可作为补骨脂及其混伪品的鉴别依据.  相似文献   

2.
结合粒子群最小二乘支持向量机(PSO-LSSVM)与偏最小二乘法(PLS)提出一种基于气相色谱技术的新方法,对芝麻油进行真伪鉴别,并对掺伪品中掺假比例进行定量分析。采用主成分分析法(PCA)对857个样本的脂肪酸色谱数据进行分析,优选主成分作为最小二乘支持向量机(LSSVM)的输入向量。利用粒子群算法(PSO)优化LSSVM,构建芝麻油掺伪鉴别的两级分类模型,同时运用PLS建立掺伪芝麻油中掺伪油脂的定量校正模型,两级分类模型的准确率分别达到了100%和98.7%,定量分析模型的平均预测标准偏差(RMSEP)为3.91%。结果表明,本方法的鉴别准确性和模型泛化能力均优于经典的BP神经网络和支持向量机(SVM),可用于食用油脂加工和流通环节的质量控制,为食用油质量的准确鉴定提供了一条有效途径。  相似文献   

3.
丹参作为较常见中草药,近年来随着其药用价值的增加,使用量也逐步增加,导致目前市售产品中混淆品和伪品量增多,以致影响药效的同时,还带来较多的质量安全隐患。文章从丹参主要性状特点、显微和理化性质入手,对其进行鉴别分析,并结合目前常见的丹参混淆品、伪品,提出相关的鉴别方法。  相似文献   

4.
采用傅里叶变换红外光谱直接测定法测定了延胡索及其伪品齿瓣元胡、东北延胡索、土元胡、新疆延胡索及夏天无的傅里叶变换红外光谱,采用主成分析法比较了正伪品之间的差异程度.结果表明基于傅里叶变换红外光谱的主成分分析在反映同属不同种植物化学组成差异程度上具有应用价值.  相似文献   

5.
HATR-FTIR-排序法识别中药材紫花地丁及其伪品的研究   总被引:4,自引:0,他引:4  
程存归  吴小华  王森清 《分析化学》2004,32(11):1529-1531
采用水平衰减全反射傅里叶变换红外光谱(HATR-FTIR)法测定了紫花地丁及其伪品如白花地丁、犁头草、辽宁堇菜及匍伏堇的根木质部和茎外表皮部的傅里叶变换红外光谱,采用主成分分析法(PCA)比较了正伪品之间的差异程度。结果表明:基于傅里叶变换红外光谱的主成分分析在反映同科同属不同种植物化学组成差异程度上具有应用价值。  相似文献   

6.
中药黄芩及其混伪品的模糊聚类分析   总被引:1,自引:0,他引:1  
采用模糊聚类分析法对黄芩及其混伪品进行了聚类分析,为中药材的质量鉴定提供了新方法。  相似文献   

7.
<正>不久前,由世界中医药学会联合会评选的2014年度"世界中医药十大新闻"在京发布。国际标准化组织发布首批中医药国际标准、中草药鉴定迈入规范化标准化基因鉴定时代等重大新闻入选其中。由中国中医科学院中药研究所所长陈士林为首的科研团队历经近10年研究完成的"中草药DNA条形码生物鉴定体系",完成了8 000余种中草药及其混伪品的DNA条形码研究,创建了中草药DNA条形码生物鉴证体系,为中药材建立了"基因身份证",从基因层面解决了中草药与混伪品的  相似文献   

8.
孙素琴  刘军  周群 《分析化学》2002,30(2):140-143
利用傅里叶变换红外(FT-IR)和近红外傅里叶变换拉曼(NIR FT-aman)光谱法对大黄(西宁大黄)与伪品大黄(华北大黄、山大黄、水根大黄)进行了无损快速的鉴别。结果表明:尽管正品大黄与伪品大黄差别较小,有大部分的化学成分有很大的相同之处,但在红外、拉曼谱图中各自的特征峰较突出,根据谱峰的强度和位置可容易地将它们区别开来。红外和拉曼光谱法相互印证,相互补充,具有快速、准确、操作简单、重复性好、不需对样品进行分离提取,可直接鉴别等特点。  相似文献   

9.
真伪大黄的二维相关红外光谱   总被引:9,自引:0,他引:9  
周群  李静  刘军  黄昊  孙素琴 《分析化学》2003,31(9):1058-1061
采用红外光谱法并结合二维相关光谱(two-dimensional correlation spectroscopy)分析技术,对药用西宁大黄和伪品华北大黄进行了无损快速鉴别研究。西宁大黄和华北大黄在一维谱图上差别不显著,而在二维谱图上显示出较大的差别。在1200-1700cm-1波段范围内,西宁大黄在同步图上有两个较强的自动峰,分别在1460和1560cm^-1附近,而华北大黄只有一个较强的自动峰,在1460cm^-1附近;同样在1030-1170cm-1波段范围内西宁大黄有两个较强的自动峰,分别在1060和1080cm^-1附近,而伪品大黄也只有一个较强的自动峰,在1080cm^-1附近。两个波段的异步谱也显示出较大的差别。结果表明:二维相关谱可以提高谱图的分辨率,增加谱图的识别能力,可用于药材真伪品的鉴别。该法快速、准确,为客观评价中药材的来源提供了一种新的方法。  相似文献   

10.
金鹏程  张霁  沈涛  王元忠 《分析测试学报》2015,34(10):1113-1118
以灵芝及11种伪品为研究材料,比较了样品的紫外光谱差异,结合化学计量学方法对灵芝及其伪品进行鉴别分析。结果显示,薄盖灵芝、广西假芝、黑假芝、昆明灵芝、小孔栗褐灵芝、假芝和多分枝灵芝的紫外光谱在220~255 nm范围与灵芝的差异较大;树舌灵芝、橡胶灵芝、褐孔灵芝和亮盖灵芝的整体化学成分与灵芝有较大差异。相似度分析结果显示,薄盖灵芝、广西假芝、小孔栗褐灵芝、假芝的紫外光谱与传统中药灵芝的相似度最高,Pearson相关系数(rr)分别为0.949,0.961,0.948和0.919;橡胶灵芝、褐孔灵芝与灵芝的紫外光谱相似度最低,相关系数分别为0.657和0.299。对13批样品的紫外光谱进行预处理和主成分分析(PCA),结果显示SG+SNV为最佳光谱预处理方法,经SG+SNV处理后,PCA第一主成分的贡献率为54.24%,第二主成分的贡献率为36.45%,累计贡献率达90.69%,较其它光谱预处理方法有明显提升。依据主成分分析结果将所有样品聚为7类,灵芝与伪品可被明显区分。该研究结果有助于灵芝的真伪鉴别,为灵芝药材的质量评价与用药安全提供了理论依据。  相似文献   

11.
采用共沉淀法制备了不同Pr/Zr比的PrOy-ZrO2固溶体,用激光拉曼光谱(Raman)、X-射线粉末衍射(XRD)、紫外可见吸收光谱(UV-Vis)等技术对固溶体进行了物相结构表征并选择CO氧化作为模型反应考察了固溶体的催化性能。结果表明,随着Pr含量的增加,无定形ZrO2转化为晶相ZrO2的温度提高、热效应下降,而PrOy-ZrO2固溶体的物相结构从单斜相逐步向四方和立方相转变。XRD和Raman光谱得到的物相结构的差别是PrOy-ZrO2固溶体的表层和体相结构不一致造成的,PrOy-ZrO2固溶体表层更易生成低对称性的物相,而且也容易生成非晶相的物相。CO氧化实验表明PrOy-ZrO2固溶体的催化活性与样品的组成有很大关系,其中高温区和低温区分别是PZ-30和PZ-50的CO氧化活性最高。  相似文献   

12.
Chemical and spectral data establish the structure of an oligomeric proanthocyanidine PZ-5 isolated from Ziziphus jujuba.  相似文献   

13.
Three novel inorganic-organic hybrid materials, [Cu(imi)2(H2O)(MoO4)]n 1, [Cuz(imi)3(MoO4)E]n.nH2O 2 and [Cu3(imi)2(OH)2(MoO4)2]n 3 (imi = imidazole), were synthesized and characterized by X-ray single-crystal structure determination. 1 crystallizes in orthorhombic, space group Pca21 with a = 13.382(4), b = 8.527(2), c = 9.622(3)A, V = 1098.0(5) A^3 Z = 4, C6H10CuMoN4O5, Mr = 377.66, Dc = 2.285 g/cm^3, F(000) = 740,μ(MoKa) = 3.095 mm^-1, the final R = 0.0256 and wR = 0.0722 for 1896 observed reflections with I 〉 2σ(I). 2 crystallizes in monoclinic, space group P2t/c with a= 11.170(2), b = 7.8244(15), c = 22.631(4)A, β = 115.790(7)°, V = 1780.9(6)A^3 Z = 4, C9H14Cu2Mo2N6O9, Mr = 669.24, Dc= 2.496 g/cm^3, F(000)=1295,μ(MoKa) = 3.792 mm^-1, the final R = 0.0225 and wR = 0.0615 for 3838 observed reflections with I 〉 2σ(I). 3 crystallizes in monoclinic, space group P21/c with a = 5.5599(19), b = 23.771(8), c = 7.3044(18)A , β = 129.356(16)°, V = 746.5(4)A^3, Z = 2, C6H10Cu3Mo2N4O10, Mr = 680.71, Dc = 3.029 g/cm^3, F(000) = 650,μ(MoKa) = 5.900 mm^-1, the final R = 0.0215 and wR = 0.0524 for 1620 observed reflections with I 〉 2σ(I).  相似文献   

14.
Under hydrothermal (solvothermal) reaction conditions chiral compounds 1, 2, and 3 and one acentric compound 4 were obtained by the reaction of Zn(2+) or Cd(2+) with racemic 3-(3-pyridyl)-3-aminopropionic acid (rac-HPAPA). Compounds 1 and 2 crystallized in chiral space group P2(1)2(1)2(1). At 105 degrees C, racemic 3-pyridyl-3-aminopropionic acid (rac-HPAPA) reacted with Zn(ClO4)(2).6 H2O and dehydrogenated in situ to form the first chiral coordination polymer [Zn[(E)-3-C(5)H4N-C(NH2)=CH-COO]]ClO4 (1) with a beta-dehydroamino acid. Beyond 120 degrees C, the reaction of rac-HPAPA with Zn(ClO4)(2).6 H2O deaminates in situ to form chiral coordination polymer [Zn[(E)-3-C5H4N-CH=CH-COO](OH)] (2). At relatively low temperatures (70 degrees C), the solvothermal reaction of Zn(NO3)(2).6 H2O with rac-HPAPA in methanol does not lead to any change in the ligand and results in the formation of a chiral (P2(1)2(1)2(1)) coordination polymer [Zn(papa)(NO3)] (3). The same reaction of Cd(ClO4)(2).6 H2O with HPAPA also does not lead to any change in ligand and results in the formation of noncentric (Cc) coordination polymer [Cd(papa)(Hpapa)]ClO4.H2O (4). The network topology of both 1 and 3 is 10,3a, while 2 has a diamondoid-like (KDP-like, KDP=potassium dideuterophosphate) network. Particularly interesting from a topological perspective is that 4 has an unprecedented three-dimensional network. Compounds 1, 2, 3, and 4 are all second harmonic generation (SHG) active with 1 exhibiting the strongest response, while only 4 also displays good ferroelectric properties.  相似文献   

15.
Electrical conductivity and oxygen permeation rates in Co-doped Sr(3)Ti(2)O(7-δ) with Ruddesden-Popper type structures were investigated. The effects of metal dopants (M) in the Ti site of Sr(3)Ti(2)(M)O(7-δ) on the mixed conductivity were also studied. Doping of Sr(3)Ti(2)O(7-δ) with Co was found to be effective for improving the electrical conductivity as well as the oxygen permeation rate, which could be assigned to the increased oxygen vacancy concentration by doping Co(3+) into Ti(4+) sites. The nonstoichiometric oxygen of these oxides was measured by using a thermal gravimetric method. The creation of oxygen vacancies, which is compensated with Co(3+) doping, leads to higher oxide ion conductivity. The oxygen permeation rate monotonously increased with increasing amounts of Co in the Ti site. Sr(3)Ti(0.8)Co(1.2)O(7-δ) exhibited high oxide ion conductivity and a large oxygen permeation rate. The highest oxygen permeation rate achieved a value of 2.02 cc min(-1) cm(-2) at 1273 K for Sr(3)Ti(0.8)Co(1.2)O(7-δ). Neutron diffraction analysis and redox titration suggests that the oxygen diffusion occurs through oxygen vacancies in the perovskite block, but not through excess oxygen in the rock salt block.  相似文献   

16.
Bio‐derived polysaccharide aerogels are of interest for a broad range of applications. To date, these aerogels have been obtained through the time‐ and solvent‐intensive procedure of hydrogel fomation, solvent exchange, and scCO2 drying, which offers little control over meso/macropore distribution. A simpler and more versatile route is developed, using freeze drying to produce highly mesoporous polysaccharide aerogels with various degrees of macroporosity. The hierarchical pore distribution is controlled by addition of different quantities of t‐butanol (TBA) to hydrogels before drying. Through a systematic study an interesting relationship between the mesoporosity and t‐butanol/water phase diagram is found, linking mesoporosity maxima with eutectic points for all polysaccharides studied (pectin, starch, and alginic acid). Moreover, direct gelation of polysaccharides in aqueous TBA offers additional time savings and the potential for solvent reuse. This finding is a doorway to more accessible polysaccharide aerogels for research and industrial scale production, due to the widespread accessibility of the freeze drying technology and the simplicity of the method.

  相似文献   


17.
The development of solvent-free low-dimensional polymer electrolytes intended for use in solvent-free lithium batteries operating at ambient or sub-ambient temperatures is described. The synthetic routes to the amphiphilic polymers I having 5-alkoxy-3,4-phenylene units connected with oligoethoxy segments via polyester-ether or pure polyether links (abbrev. CmOn, m = 12, 16, 18, n = 1-5) and to the copolymers CmO1-CmOn are described. The structures, thermal properties and SAXS long spacings of their complexes with lithium salts (type A) and with long chain n-alkane or alkyl side chain intercalation (type B) are discussed. However, high ambient conductivities (10(-4)-10(-3) S cm(-1)) are observed in type C systems when a second copolymer based on polytetramethylene oxide segments (II) is incorporated as a microphase between the lamellae of I and serving as an ion bridge or "glue". DC polarization between Li electrodes also gives ambient conductivities >/=ca.10(-3) S cm(-1). In type D systems the I/II interface is stabilized by including a copolymer III, promoting high reproducibility in performance. Copolymers I of CmO1-CmO5 having CmO1 in excess give optimum conductivities with low temperature-dependence. This, together with molecular modeling, suggests uncoupled ion mobilities by hopping between small aggregates in the interlamellar spaces.  相似文献   

18.
By using a Gemini surfactant, [C14H25N+(CH3)2-(CH2)2-N+(CH3)2C14H25]2 Br-(C(14-2-14)), with a short spacer group (s = 2) as structure-directing agent and sodium silicate as precursor, high-quality, ordered cubic mesoporous silica with space group Pm3n was prepared by the S+I-route (S = surfactants, I = precursor). The samples were characterized by small-angle X-ray diffraction, transmission electron microscopy, and N2 adsorption-desorption. The results showed that the pore structure of the resulting mesoporous silica belonged to the cubic system (space group Pm3n). The unit-cell parameter of the cubic system was in the range of 8.81-9.14 nm. The high-quality cubic mesoporous structure was formed at molar ratios of C(14-2-14) to sodium silicate of 0.33:1 to 0.16:1 and a molar ratio of ethyl acetate to sodium silicate of 2:1. N2 adsorption-desorption curves revealed type IV isotherms and H1 hysteresis loops. The primary pore volume, and the most probable pore size according to the Barrett-Joyner-Halenda (BJH) model, increased with increasing molar ratio of C(14-2-14) to sodium silicate.  相似文献   

19.
通过Yamamoto偶联反应,合成了主链含有1,2-取代方酸和1,3-取代方酸结构单元的新型共轭聚合物光伏材料PTST.其结构经过红外光谱和核磁共振表征得以确证.热分析、紫外-可见吸收光谱和电化学性质研究表明,所得新型共轭聚合物PTST具有良好的热稳定性;在270~700 nm光谱范围内有宽而强的吸收,基本覆盖了整个可见光区域;取代方酸结构单元的引入可使聚合物的最低未占有轨道(LUMO)和能隙(Eg)降低.当PTST仅为60%掺混时,即可使聚(3-己基噻吩)的荧光完全淬灭,说明P3HT与PTST之间存在明显的光电子转移.  相似文献   

20.
采用高能球磨法通过不同球磨时间合成 xLiF-(Ni1/6Co1/6Mn4/6)3O4新型正极材料,并对材料进行石墨烯复合改性,提高其性能。结合X-射线衍射(XRD)、扫描电镜(SEM)、电化学性能测试和X-射线电子能谱(XPS)对xLiF-(Ni1/6Co1/6Mn4/6)3O4正极材料性能进行表征。研究表明,球磨24小时产物的放电容量最高,为157.3 mAh g-1。并且LiF与(Ni1/6Co1/6Mn4/6)3O4比例为1.5:1(x=1.5)时放电容量最高。此外正极材料添加石墨烯能改善材料的电化学性能,石墨烯复合量为20%,在室温、0.05 C(1C=250 mAh g-1)、1.5 -4.8 V下,材料首圈的放电比容量为235 mA hg -1,相较于无石墨烯的材料,在1 C和5 C倍率下,放电比容量分别为151和114 mAh g-1。同时分析了正极材料放电容量随截止电压的变化,确定了复合正极材料在高电压下有获得更高放电容量的潜力。  相似文献   

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