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排序方式: 共有131条查询结果,搜索用时 171 毫秒
1.
Joaquim Branco Catarina de Jesus Dias Antnio Pereira Gonalves Teresa Almeida Gasche Antnio Pires de Matos 《Thermochimica Acta》2004,420(1-2):169-173
In our laboratories we have been studying the synthesis and reactivity of binary actinide and lanthanide intermetallic compounds. In this work, the air-oxidation of ThCu2 and AnNi2 (An = Th, U) was followed by thermogravimetry (TG) and the products were characterized by X-ray powder diffraction (XRD). The heterobimetallic oxides obtained are described by the formulas 2MO·ThO2 (M = Cu, Ni) and 2NiO·UO3. The thermogravimetric analysis under hydrogen of these heterobimetallic oxides show one mass loss for 2MO·ThO2 and two mass losses for 2NiO·UO3 over a wide range of temperature (293–1273 K). The characterization by XRD shows that the reduction products are 2M·ThO2 (M = Cu, Ni) and 2Ni·UO2, with all the actinides in the 4+ oxidation state. The actinide heterobimetallic oxides were described as copper or nickel supported catalysts. 相似文献
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Branco LC Serbanovic A da Ponte MN Afonso CA 《Chemical communications (Cambridge, England)》2005,(1):107-109
The combination of ionic liquids (ILs) as solvents in the asymmetric Sharpless dihydroxylation (AD) with the use of scCO(2) in the separation process allows a very simple, efficient, clean and robust system for the reuse of the AD catalytic system, which also does not need the use of organic solvents either for the reaction or for the separation of products and allows the isolation of the diol, in high yield and enantiomeric excess and basically without contamination with osmium. 相似文献
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Mário L.A.A. Vasconcellos Mauro L. Mellão Uendel G. Barreiros Marcelo C. Branco Maria T.P.Gambardella Oduvaldo F. Ramos 《合成通讯》2013,43(21):4077-4085
New alcohols 3d, 3e and 3f were efficiently prepared in enantiopure form (2 steps, 50–58%), from available 1-(R)-(+)-camphor 1. The absolute configurations were assigned by NMR and relative X-ray crystallographic analysis. 相似文献
6.
André Luís Branco de Barros Saulo Fernandes de Andrade José Dias de Souza Filho Valbert Nascimento Cardoso Ricardo José Alves 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(1):605-609
Glycodendrimers are neoglycoconjugates that can be considered as bioisosters of glycoproteins, since they can mimic the multivalent interactions of lectin-carbohydrate. The ability of glycodendrimers to present multivalent interactions with lectins as compared to a monovalent ligand is referred to as “cluster effect”. It is expected that, because of the cluster effect, glycodendrimers would result in a better association with lectins than mono-carbohydrate anchored systems. Radioisotopes are useful to evaluate biodistribution of molecules. This study is important to obtain information about molecule–receptor interactions. Indeed, such study can provide an exquisite tool to evaluate the affinity of certain molecules to specific areas in the body, leading to the development of new radiopharmaceuticals and/or drug delivery systems. Herein, we describe a d-galactose coated low molecular weight PAMAM G0 dendrimer that was successfully radiolabeled with technetium-99m. Biodistribution studies and scintigraphic images were performed in healthy mice. It was observed high liver uptake which was significantly reduced in blocking studies, indicating hepatic specificity. Therefore, low molecular weight glycodendrimer can be considered as useful platform for selective targeting of drugs to the liver and to assess hepatic function. 相似文献
7.
Michaela Kohlov Susana Rocha Clia Gomes Amorim Alberto de Nova Araújo Alice Santos‐Silva Petr Solich Maria Conceio Branco da Silva Montenegro 《Macromolecular bioscience》2020,20(7)
The reduction of free radicals by bioactive membranes used for hemodialysis treatment is an important topic due to the constant rise of oxidative stress‐associated cardiovascular mortality by hemodialysis patients. Therefore, it is urgent to find an effective solution that helps to solve this problem. Polysulfone membranes enriched with α‐lipoic acid, α‐tocopherol, and with both components are fabricated by spin coating. The antioxidant properties of these membranes are evaluated in vitro by determining the lipid‐peroxidation level and the total antioxidant status of the blood plasma. The biocompatibility is assessed by quantifying the protein adsorption, platelet adhesion, complement activation, and hemolytic effect. All types of membranes show in vitro antioxidant activity and a trend to reduce oxidative stress in vivo; the best results show membranes prepared with a combination of both compounds and prove to be nonhemolytic and hemocompatible. Moreover, the membrane specific separation ability for the main waste products is not affected by antioxidants incorporation. 相似文献
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M P Chiarelli H P Wu A M Antunes P S Branco 《Rapid communications in mass spectrometry : RCM》1999,13(20):2004-2010
The product ions of the BH(2)(+) ions formed by the glycosidic cleavage of N-(deoxyguanosin-O(6)-yl)-2-methylaniline, 4-(deoxyguanosin-8-yl)-2-methylaniline, and N-(deoxyguanosin-1-yl)-2-methylaniline have been studied using matrix-assisted laser desorption/ionization (MALDI) and post-source decay (PSD) to identify fragment ions and pathways that may be used to differentiate their structures. All three isomers may be distinguished based on their PSD product ion spectra using only femtomole quantities of sample. N-(Deoxyguanosin-O(6)-yl)-2-methylaniline produces product ions at m/z 107 and 134 that are diagnostic for 2-methylaniline attachment to the O(6) position of guanine. The BH(2)(+) ion from 4-(deoxyguanosin-8-yl)-2-methylaniline yields a product ion formed by the consecutive losses of 17 and 42 u neutral fragments that may be regarded as specific for guanine-arylamine adducts that possess two primary amine groups. The BH(2)(+) ion from 4-(deoxyguanosin-8-yl)-2-methylaniline yields no product ions that correlate with specificity for guanine N1 substitution. However, the product ion abundance ratio of the protonated arylamine to that of the ammonia loss ion may be used to differentiate an adduct formed by N1 substitution from other arylamine adducts of guanine studied thus far. 相似文献
10.
Clusters of galaxies are excellent probes of cosmic structure and evolution. X-ray studies of clusters provide some of their
key parameters, viz., temperature of the hot intra-cluster gas, its metallicity, X-ray luminosity and surface brightness giving
mass distribution and mass-flow rate in the case of cooling flows. X-ray measurements for a large sample of clusters have
lead to estimates of the total gravitating mass in them, which can be compared to the virial masses derived from dynamical
considerations and gravitational lensing in some of them. X-ray derived total masses are consistent with masses obtained from
the other methods after the effects due to the presence of cooling flows are taken into account in the analyses. Estimated
virial masses, lack of evolution in X-ray properties, and detection of several very hot clusters at high redshifts indicate
a Universe with a low value (≤ 0.3) for the Ω parameter. 相似文献