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排序方式: 共有574条查询结果,搜索用时 31 毫秒
1.
Karen Beatriz Méndez-Rodríguez Nicté Figueroa-Vega César Arturo Ilizaliturri-Hernandez Mónica Cardona-Alvarado Jaime Antonio Borjas-García Carlos Kornhauser Juan Manuel Malacara Rogelio Flores-Ramírez Francisco Javier Pérez-Vázquez 《Biomedical chromatography : BMC》2020,34(12):e4956
Metabolomics is a potential tool for the discovery of new biomarkers in the early diagnosis of diseases. An ultra-fast gas chromatography system equipped to an electronic nose detector (FGC eNose) was used to identify the metabolomic profile of Volatile Organic Compounds (VOCs) in type 2 diabetes (T2D) urine from Mexican population. A cross-sectional, comparative, and clinical study with translational approach was performed. We recruited twenty T2D patients and twenty-one healthy subjects. Urine samples were taken and analyzed by FGC eNose. Eighty-eight compounds were identified through Kovats's indexes. A natural variation of 30% between the metabolites, expressed by study groups, was observed in Principal Component 1 and 2 with a significant difference (p < 0.001). The model, performed through a Canonical Analysis of Principal coordinated (CAP), allowed a correct classification of 84.6% between healthy and T2D patients, with a 15.4% error. The metabolites 2-propenal, 2-propanol, butane- 2,3-dione and 2-methylpropanal, were increased in patients with T2D, and they were strongly correlated with discrimination between clinically healthy people and T2D patients. This study identified metabolites in urine through FGC eNose that can be used as biomarkers in the identification of T2D patients. However, more studies are needed for its implementation in clinical practice. 相似文献
2.
3.
Arturo Kohatsu-Higa 《Probability Theory and Related Fields》2003,126(3):421-457
In this article, we generalize the lower bound estimates for uniformly elliptic diffusion processes obtained by Kusuoka and
Stroock. We define the concept of uniform elliptic random variable on Wiener space and show that with this definition one
can prove a lower bound estimate of Gaussian type for its density. We apply our results to the case of the stochastic heat
equation under the hypothesis of unifom ellipticity of the diffusion coefficient.
Received: 6 November 2001 / Revised version: 27 February 2003 /
Published online: 12 May 2003
Key words or phrases: Malliavin Calculus – Density estimates – Aronson estimates 相似文献
4.
Aurora Molinari Alfonso Oliva Luc Snchez Arturo San Feliciano 《Journal of heterocyclic chemistry》1997,34(4):1297-1299
1-Phenyl-3,5-dioxopyrazolidine 1 reacts with carbon disufide and alkyl halides in presence of excess of sodium acetate in dimethylformamide to afford the ketene dithioacetals 3a-h . The 13C chemical shift assignments of these compounds were made on the basis of two-dimensional nmr studies performed on the N-methylketene dithioacetal derivative 4. 相似文献
5.
Jesús Castro Paulo Prez Lourido Antonio Sousa‐Pedrares Elena Labisbal Jos Piso Jos Arturo García‐Vzquez 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(5):m319-m322
The crystal structure of the title compound, [CoCl2(C6H12N2S)2], consists of monomer units of a CoII atom coordinated to two 1‐propylimidazolidine‐2‐thione ligands and to two chloride ions. The heterocyclic thione ligand is monodentate and coordinated to the metal through the thione S atom. The environment around the CoII atom is a slightly distorted tetrahedron. The Co—S bond lengths are 2.341 (2) and 2.330 (2) Å, and the Co—Cl bond lengths are 2.234 (2) and 2.238 (2) Å. The most important point of distortion is the S—Co—S bond angle of only 97.83 (8)°. Intramolecular classical hydrogen bonds are found between the chloride ions and the N—H groups. Additionally, intra‐ and intermolecular non‐classical hydrogen bonds are found. 相似文献
6.
Arturo Arnau Estanislao Silla Iaki Tun 《International journal of quantum chemistry》1993,46(2):231-238
By means of ab initio calculations, the rotational constants and dipole moments of HnC3N (n = 1, 3, 5, 7, and 9) species have been calculated at the HF / 6-31G * level of theory. Selected cases have been also calculated at the MP 2/6-31G * level and the influence of calculation level on rotational constant values is briefly discussed. Some of these species were discovered in the interstellar medium, while others have still not been detected there, although their existence is very probable. The results given here could help in their detection. © 1993 John Wiley & Sons, Inc. 相似文献
7.
Arturo ArduiniElisabetta Brindani Giovanna GiorgiAndrea Pochini Andrea Secchi 《Tetrahedron》2003,59(38):7587-7594
The synthesis of new hosts specifically designed for the recognition of neutral guests bearing donor-acceptor hydrogen bonding groups is described. These hosts are characterized by the presence of two distinct binding region in close proximity: the rigid π-donor cavity and the H-bond donor N-methylene-N′-phenylureido group inserted onto the upper rim of the calix[4]arene skeleton. The binding abilities of these receptors were investigated toward a series of neutral ditopic organic molecules in CDCl3 solution by 1H NMR spectroscopy. The results obtained show that rigidity of the calix[4]arene apolar cavity is the control element in determining efficiency. In fact, compared with the more rigid 2, host 10, where the rigidity of the cone structure is maintained by hydrogen bonding of the OH of the lower rim, a decrease of efficiency of almost one order of magnitude was observed. The cooperative effect of the two binding region of host 2 was verified with different classes of ditopic guests. Good efficiency in the recognition of urea derivatives and dimethylsulfoxide was achieved. 相似文献
8.
New Hg2+ and Cu2+ selective chromo- and fluoroionophore based on a bichromophoric azine 总被引:1,自引:0,他引:1
[graph: see text] A new probe, 1,4-bis(1-pyrenyl)-2,3-diaza-1,3-butadiene, selectively senses Hg2+ and Cu2+ through two different channels: the yellow-deep-pink color change and the enhancement of the fluorescence with the red shift of the excimer emission, which can visually be discernible by a green fluorescence in the presence of Hg2+ and an orange fluorescence in the presence of Cu2+. 相似文献
9.
Arturo Zizumbo Rosa Maria Félix-Navarro Jorge Cervantes-Jáuregui Felípe Avalos-Belmontes 《Silicon Chemistry》2005,2(5-6):265-269
Electrochemical formation of poly(phenylmethylsilane) in a divided cell containing a Teflon® neutral membrane was studied. The electrolysis of dichlorosilanes was carried out in a solution containing tetrahydrofuran + hexamethylphosphoramide as the solvent, tetrabutylammonium perchlorate as the support electrolyte and stainless steel as the cathode, with Pt and graphite as the resistant anodes or stainless steel as the sacrificial anode. Polysilanes with a number-average molecular weight in the range from 2,600 to 130,000 g/mol were obtained, depending on the conditions used. 相似文献
10.
Wege HA Aguilar JA Rodríguez-Valverde MA Toledano M Osorio R Cabrerizo-Vílchez MA 《Journal of colloid and interface science》2003,263(1):162-169
A new methodology capable of providing reliable and reproducible contact angle (theta) data has been employed to study the effect of clinical treatments grinding, acid etching, and deproteinization on medial dentin tissue. It is based on the application of the ADSA-CD algorithm to the determination of low-rate dynamic contact angles, obtained from slowly growing drops, and on contact angle measurement, as well as spreading behavior analysis, during the relaxation of the system (water on treated dentin) after initial drop growth. The theta data obtained were substantially more reproducible than those obtained with classical methods. A net effect of the treatment on theta was found, increasing dentin wettability: theta (polished) >theta (etched) >theta (deproteinized). The spreading rates correlate with the angles and are adequate for the dentin surface characterization. ANOVA and SNK tests show that for advancing contact angles the means corresponding to all treatments are significantly different. In the relaxing phase, mean angle and spreading rates on polished dentin differ significantly from those on etched and deproteinized dentin, but the latter do not differ significantly from each other. 相似文献