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21.
Berry Frank J. Ren Xiaolin Gancedo J. Ramón Marco José F. 《Hyperfine Interactions》2004,156(1-4):335-340
Hyperfine Interactions - Perovskite-related phases of the type LaFe1?x Co x O3 (x=0 and 0.5) have been synthesised by milling techniques. The materials are of smaller particle size and more... 相似文献
22.
G. Ferro-Flores F. De M. Ramírez M.G. Martínez-mendoza C. Arteaga de Murphy M. Pedraza-lópez L. García-salinas 《Journal of Radioanalytical and Nuclear Chemistry》2002,251(1):7-13
Lanreotide peptide was labeled with 153Sm-H1ETA and 188Re-MAG3 in order to evaluate whether or not their conjugation to the peptide produce significant differences of the in vitro lipophilicity with respect to the 188Re-lanreotide prepared by the direct labeling method (highly lipophilic). The differences of lipophilicity between the complexes, were evaluated using a reverse phase HPLC system. The measured lipophilicity of 153Sm-H1ETA-lanreotide, 188Re-MAG3-lanreotide and 188Re-lanreotide was taken to be the capacity factor [k" = (t
R-t
0)/t
0 where t
R is the retention time and t
0 is the dead time] for each of the complexes under identical chromatography conditions. Results showed that the in vitro lipophilicity decreased in the order 188Re-lanreotide (direct labeling), 188Re-MAG3-lanreotide and 153Sm-H1ETA-lanreotide. Since the last one has a capacity factor (k") similar to that of 188Re-MAG3, some renal elimination for 153Sm-H1ETA-lanreotide could be expected, which probably would reduce the unnecessary radiation dose to normal tissues. 相似文献
23.
24.
Thermal behaviour of a polyhedral oligomeric silsesquioxane with epoxy resin cured by diamines 总被引:1,自引:0,他引:1
Ramírez C. Abad M. J. Barral L. Cano J. Díez F. J. López J. Montes R. Polo J. 《Journal of Thermal Analysis and Calorimetry》2003,72(2):421-429
A new material belongs to the family of polyhedral oligomeric silsesquioxanes, the 1-(3-glycidyl) propoxy-3,5,7,9,11,13,15-isobutylpentacyclo-[9.5.1.1(3,9).1(5,15).1(7,13)]octasiloxane
(glycidylisobutyl-POSS) is characterized by differential scanning calorimetry, thermogravimetric analysis and atomic force
microscopy. Epoxy systems based on diglycidyl ether of bisphenol A (DGEBA) cured with the diamines, 4,4'-diamine-diphenylmethane
(DDM) and 1,4-phenylenediamine (pPDA), were kinetically studied by differential scanning calorimetry in isothermal and dynamic
modes. The thermal behaviour of these systems as the glycidylisobutyl-POSS was added, is discussed later.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
25.
Corona-Avendaño S Rojas-Hernández A Romero-Romo MA Pardavé MP Ramírez-Silva MT 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(13-14):3139-3144
Noradrenaline is a catecholamine which has been largely recognised to play a very important role in biological systems. In view of the neurotransmitter's alleged importance, this work aimed at showing the influence of time on its spectral behaviour using different analytical methods and determining its acidity constants through spectrophotometric titration and by the so-called point-by-point analysis, where the samples are freshly prepared for each pH value investigated at the instant required. Because the catecholamines are light-sensitive and likely to react with the oxygen in the surrounding air, both methods used preclude its incidence onto the samples being analysed under the presence of a nitrogen atmosphere maintained over the solutions. The constants obtained through point-by-point analysis were log beta1 = 30.71+/-0.16, log beta2 = 22.00+/-0.15 and log beta3 = 11.69+/-0.16. 相似文献
26.
Anzalone PW Baru AR Danielson EM Hayes PD Nguyen MP Panico AF Smith RC Mohan RS 《The Journal of organic chemistry》2005,70(6):2091-2096
[reaction: see text] Three one-pot methods for the conversion of aldehydes to homoallyl ethers catalyzed by Bi(OTf)(3).xH(2)O (1 < x < 4) have been developed. The one-pot synthesis of homoallyl ethers can be achieved either by in situ generation of the acetal followed by its reaction with allyltrialkylsilane or by a three-component synthesis in which the aldehyde, trimethylorthoformate or an alkoxytrimethylsilane and allyltrimethylsilane are mixed together in the presence of bismuth triflate (0.1-1.0 mol %). In addition, a three-component synthesis of homoallyl acetates, which is achieved by reacting the aldehyde, acetic anhydride, and allyltrimethylsilane in the presence of bismuth triflate (3.0-5.0 mol %), has been developed. The use of a relatively nontoxic, easy to handle, and inexpensive catalyst adds to the versatility of these methods. 相似文献
27.
28.
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
29.
Summary A study of thermal analysis of some lanthanide polyphosphates has been reported. The DTA curves of Ce, Pr and Sm polyphosphates were of similar nature. They exhibited a sharp exothermic peak indicating crystallization temperature (T
c) around 520 °C. However, no peak indicatingT
m
was observed upto 800 °C. TG curves of Ce, La, Pr, Sm, Y polyphosphates indicated weight loss occurring in three stages. The integral procedural decomposition thermal analysis (ipdt) indicated that these materials had refractory nature.With 4 figures and 2 tables 相似文献
30.
Rodríguez AD Ramírez C Rodríguez II Barnes CL 《The Journal of organic chemistry》2000,65(5):1390-1398
Four diterpenes and a nor-diterpenoid, all of which possess unusual carbocyclic skeletons, were isolated from the hexane solubles of the West Indian gorgonian Pseudopterogorgia elisabethae. The structures and relative configurations of novel metabolites elisabethin D (2), elisabethin D acetate (3), 3-epi-elisabanolide (5), elisapterosin A (6), and elisapterosin B (7) were elucidated by interpretation of overall spectral data, which included 2D NMR correlation methods, IR, UV, and accurate mass measurements (HREI-MS and HRFAB-MS), chemical reactions, and X-ray diffraction analyses. The tetracyclic carbon skeleton of the elisapterosins is undescribed and constitutes a new class of C(20) rearranged diterpenes. Elisapterosin B displays strong in vitro anti-tuberculosis activity. 相似文献