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61.
Trigo-Mouriño P Sifuentes R Navarro-Vázquez A Gayathri C Maruenda H Gil RR 《Natural product communications》2012,7(6):735-738
19-OH-(-)-eburnamonine 1 is a new indole alkaloid isolated from Bonafusia macrocalyx. A natural derivative from (-)-eburnamonine for which absolute configuration and conformation has been determined by making use of residual dipolar couplings enhanced NMR, circular dichroism spectra and high-level computations. 相似文献
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Although the use of hydrogen exchange (HX) mass spectrometry (MS) to study proteins and protein conformation is now over 20 years old, the perception lingers that it still has “issues.” Is this method, in fact, still in the quicksand with many remaining obstacles to overcome? We do not think so. This critical insight addresses the “issues” and explores several broad questions including, have the limitations of HX MS been surmounted and has HX MS achieved “indispensable” status in the pantheon of protein structural analysis tools. 相似文献
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Stable isotopes determination in some Romanian wines 总被引:1,自引:0,他引:1
Magdas DA Cuna S Cristea G Ionete RE Costinel D 《Isotopes in environmental and health studies》2012,48(2):345-353
This paper presents a study concerning the isotopic fingerprint ((18)O and (13)C) of some wines prepared from relevant Romanian grape varieties (e.g. Feteasca Alba (FA), Feteasca Regala (FR) and Cabernet Sauvignon (CS)) obtained in different vintage years (2002, 2003, 2004, 2007 and 2008). These wines were obtained from different vineyards having a significant role in the wine market: Cotesti, Tohani, Stefanesti, Aiud, Cotnari, Bucium, Murfatlar, Bujoru, Dragasani and Valea Calugareasca. Several observations related to the dependence of isotope ratios on geographical origin and climatic conditions were drawn. The authentic wines obtained from the FA grape variety from six different vineyards showed δ(18)O values in the range of+3.28 (Cotesti region - 45?°38'N/27?°04'E) to-2.60 ‰ (Aiud region - 46?°19'N/23?°45'E). The δ(13)C values were very similar for all the samples with an average of about-26 ‰. The difference between the δ(18)O values was due to the different climatic zones, which have an influence on the δ(18)O values of wine water. For the wine variety CS obtained from the Dealu Mare-Tohani vineyard, production years 2003 and 2004, a greater difference in the δ(18)O values of wine water ranging from 1.89 (in 2004) to 5.35 ‰ (in 2003) was noted. This difference is explained by the different mean annual temperatures in 2003 and 2004. 相似文献
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Martín A. Iglesias Arteaga Roxana Perez Gil Carlos S. Pérez Martínez Francisco Coll Manchado 《合成通讯》2013,43(1):163-170
The synthesis of the 23-keto analogues of the steroidal sapogenins hecogenin and isochiapagenin is described. 相似文献
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Miuţa R. Filip Aurelia Pop Ioana Perhaiţa Mărioara Moldovan Roxana Truşcă 《Central European Journal of Chemistry》2013,11(5):725-735
Thermal and catalytic degradation of polystyrene waste over two different samples of natural volcanic tuff catalyst comparative with Florisil catalyst has been carried out in order to establish the conversion degree into styrene monomer. The polystyrene waste (PS) was subjected to a thermal degradation process in the range of 380–500°C in presence of studied catalysts in a ratio of 1/10 in mass, catalyst/PS. The catalysts were characterized by N2 adsorption-desorption isotherms (BET), Scanning Electron Microscopy (SEM) and Fourier-transform infrared spectrometry (FTIR). Influences of temperature and type of catalysts on the yields and on the distribution of end-products obtained by thermal and catalytic degradation of polystyrene waste have been studied. The maximum yields of liquid products were obtained at 460°C degradation temperature and were calculated between 83.45% and 90.11%. The liquid products were characterized by gas chromatography mass spectrometry (GC-MS) and FTIR analytical techniques. The GC-MS results showed that the liquid products contained styrene monomer up to 55.62%. The FTIR spectra of liquid products indicated the specific vibration bands of the functional groups of compounds of liquid products. The amounts of styrene monomer obtained were influenced by structural and textural properties of studied catalyst and the contribution on product distribution is discussed. 相似文献
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Mendiondo ME Juáreza BE Zampini C Isla MI Ordoñez R 《Natural product communications》2011,6(7):965-968
Methanolic extracts of Chuquiraga straminea Sandwith, subfamily Barnadesioideae (Asteraceae) showed the presence of quercetin-3-O-glucoside, quercetin-3-O-rutinoside, kaempferol, kaempferol-3-O-glucoside and kaempferol-3-O-rutinoside. Antioxidant and antimicrobial activity was determined. The total extracts showed antioxidant activity by DPPH and ABTS method (SC50 14.5 to 34.9 microg/mL). A significantly positive correlation was observed between the antioxidant activity and the total phenolics (R2 > 0.93). The extracts were active against ten methicillin resistant and sensitive Staphylococcus aureus strains isolated from nosocomial infection (MIC values between 200 to 800 microg/mL). These preliminary studies are highly interesting as they open new ways for further applications in the treatment of infections by methicillin resistant S. aureus. 相似文献
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E. Jane Maxwell Chitra Ratnayake Roxana Jayo Xuefei Zhong David D. Y. Chen 《Electrophoresis》2011,32(16):2161-2166
A method for adapting widely used CE conditions for the separation of fluorescently labeled carbohydrates to permit online ESI‐MS detection is presented. Reverse polarity separations were performed in bare fused‐silica capillaries with an acidic BGE. Under these conditions, negatively charged 8‐aminopyrene 1,3,6‐trisulfonate‐labeled carbohydrates migrate forward against the EOF, which is towards the capillary inlet. Therefore, the CE‐MS interface must simultaneously back‐fill the capillary, in order to maintain the CE circuit, and provide a stable forward flow at the sprayer tip to support the electrospray process. This was achieved using a junction‐at‐the‐tip interface, which provides a flow of solution to the junction formed by the capillary terminus and the inner wall of the emitter needle tip. Because the flow rate required for this arrangement is much less than in conventional sheath flow interfaces, dilution of the analytes is minimized. Optimized separation conditions permit baseline resolution of glucose oligomers containing up to 15 glucose units, while longer oligomers, up to 33 glucose units, were observed as resolved peaks in the negative ion mode mass spectrum. 相似文献
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Zoran Maria A. Savastru Roxana S. Savastru Dan M. Penache Maria-Cristina V. 《Journal of Radioanalytical and Nuclear Chemistry》2019,320(1):55-70
Journal of Radioanalytical and Nuclear Chemistry - The use of carbon monoxide (CO) and radon (222Rn) during 1 year continuous monitoring in Bucharest, Romania in relation with other air... 相似文献
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