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91.
In this study, local least squares (LLS) and principal component analysis (PCA) were applied to deal with the disturbances in a data set of chromatographic fingerprints after necessary data transformations. It has been demonstrated that PCA with standard normal variate (SNV) transformation of data led to meaningful classification of 33 different Erigeron breviscapus herbal samples. The result was also corroborated by variance squares discriminant method. The quality of herbal objects was further evaluated, and the causes of this fact have been explained from a chemical point of view. At the same time, it implied an idea for qualitative evaluation of the herbal objects with a common class pattern of chromatographic fingerprints. 相似文献
92.
93.
Ramendra Pratap 《Tetrahedron letters》2007,48(15):2755-2759
A concise synthesis of highly functionalized 5,6-dihydrobenzo[h]quinoline-3-carbonitriles is delineated through base induced ring transformation of 4-sec-amino-2-oxo-5,6-dihydro-2H-benzo[h]chromene-3-carbonitriles with S-methylisothiourea sulfate and 1-carboxamidinepyrazole hydrochloride, separately, in DMF. Under analogous reaction conditions the ring transformation of 4-sec-amino-2-oxo-5,6-dihydro-2H-benzo[h]chromene-3-carbonitriles by formamidine acetate provided 4-sec-amino-benzo[h]quinoline-3-carbonitriles in moderate yields, while with benzamidine hydrochloride, the reaction followed the same mechanism to yield 2-phenyl-4-sec-amino-5,6-dihydrobenzo[h]quinoline-3-carbonitriles. 相似文献
94.
A facile and short synthesis of 2-oxo-4-sec-amino-2,3,5,6-tetrahydrobenzo[f]isoquinoline-1-carbonitriles has been delineated through base catalyzed ring transformation of 5,6-dihydro-2-oxo-4-sec-amino-2H-benzo[h]chromene-3-carbonitrile by cyanoacetamide in excellent yields. 相似文献
95.
M. Nagy 《Colloid and polymer science》1985,263(3):245-265
96.
Asmita Kumari 《Journal of solid state chemistry》2007,180(7):2013-2019
New cubic-AGaSnS4 (A=Na, K, Rb, Cs, Tl) and orthorhombic-NaGaSnS4 compounds were synthesized by solid-state reactions and characterized by X-ray diffraction and diffuse reflectance spectroscopy. Single crystals of orthorhombic-Na1.263Ga1.263Sn0.737S4 were obtained in the crystal growth attempts of sodium compound. All six new compounds have orthorhombic AgGaGeS4 and cubic BaGa2S4 structures, as determined from single crystal X-ray structures of Na1.263Ga1.263Sn0.737S4 and cubic-AGaSnS4 (A=Na, K, Rb). Orthorhombic-NaGaSnS4 and known layered-KGaSnS4 undergo structural transformation to thermodynamically stable cubic form. 相似文献
97.
以纳米锐钛矿型TiO2粉和(O'+β')-Sialon粉为原料制备出了TiO2/(O'+β')-Sialon复相陶瓷,研究了Yb2O3添加剂对材料中锐钛矿型TiO2相变的影响,对其影响机制进行了探讨。采用XRD对材料进行物相组成和晶格参数表征。结果表明,Yb2O3对锐钛矿相变开始温度无明显影响,但对相变有显著的促进作用,随添加量的增加,其作用逐渐减弱。添加的Yb2O3同时以两种形式存在:一部分进入TiO2晶格,一部分堆积在TiO2晶粒表面。Yb^n+进入TiO2晶格置换Ti^4+和Yb^3+与TiO2发生氧化还原反应促进相变,而存在于TiO2表面的Yb^3+与TiO2相互作用形成Ti-O-Yb键而抑制相变。Yb2O3对锐钛矿相变的影响是这两方面机制共同作用的结果。 相似文献
98.
Sala Vila A Castellote-Bargalló AI Rodríguez-Palmero-Seuma M López-Sabater MC 《Journal of chromatography. A》2003,1008(1):73-80
We developed and validated a new high-performance liquid chromatographic method for the separation of phospholipid classes in human milk, infant formulas and phospholipidic sources of long-chain polyunsaturated fatty acids (LC-PUFAs) used in paediatric nutrition. Phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine and sphingomyelin were separated in less than 25 min using an Extrasil silica column (150 x 4.0 mm I.D., 3-microm particle size) by isocratic elution with a mixture of isopropanol-hexane-water. Phospholipids were determined by an evaporative light-scattering detector. Several chromatographic conditions were assayed to optimise the method, whose suitability is shown by the detection limits, linearity ranges and precision rates obtained. The main advantages of the proposed method are its speed and the direct determination of the main phospholipids present in human milk, infant formulas and the phospholipid sources of LC-PUFAs used in paediatric nutrition. 相似文献
99.
100.
Fusarin C (FC) is a mutagenic and carcinogenic mycotoxin which was isolated from Fu-sarium moniliforme culture extracts. The Fusarium moniliforme is one of most prevalent fungi found on corn in Linxian, a high risk area for esophageal cancer. This paper reports, for the first time, the malignant transformation of rat esophageal epithelial cells induced by FC. The transformed cells showed several characteristics of transformation. Colonies were formed after seeding these transformed cells either into selective medium free of epidermal growth factor (EGF) and serum, or on semi-solid agar; there was an increase in chromosome number; the expression of c-myc and v-erb-B oncogenes was enhanced in the cells; and squamous cell carcinomas arose after inoculating the cells into nude mice. The results demonstrated transforming effect of FC on rat esophageal epithelial cells, and indicate that the abnormal expression of some oncogenes could serve as a hew property of transformed cells. 相似文献