排序方式: 共有174条查询结果,搜索用时 15 毫秒
91.
Abazović ND Comor MI Dramićanin MD Jovanović DJ Ahrenkiel SP Nedeljković JM 《The journal of physical chemistry. B》2006,110(50):25366-25370
Nonaqueous reactions between titanium(IV) chloride and alcohols (benzyl alcohol or n-butanol) were used for the synthesis of anatase TiO2 particles, while rutile TiO2 particles were synthesized in aqueous media by acidic hydrolysis of titanium(IV) chloride. The X-ray diffraction measurements proved the exclusive presence of either the anatase or the rutile phase in prepared samples. The photoluminescence of both kinds of particles (anatase and rutile) with several well-resolved peaks extending in the visible spectral region was observed, and the quantum yield at room temperature was found to be 0.25%. Photon energy up-conversion from colloidal anatase and rutile TiO2 particles was observed at low excitation intensities. The energy of up-converted photoluminescence spans the range of emission of normal photoluminescence. The explanation of photon energy up-conversion involves mid-gap energy levels originating from oxygen vacancies. 相似文献
92.
Janssen LM van der Loo MP Groenenboom GC Wu SM Radenović DC van Roij AJ Garcia IA Parker DH 《The Journal of chemical physics》2007,126(9):094304
Ultraviolet photodissociation of SH (X 2Pi, upsilon"=2-7) and SD (X 2Pi, upsilon"=3-7) has been studied at 288 and 291 nm, using the velocity map imaging technique to probe the angular and speed distributions of the S(1D2) products. Photodissociation cross sections for the A 2Sigma+<--X 2Pi(upsilon") and 2Delta<--X 2Pi(upsilon") transitions have been obtained by ab initio calculations at the CASSCF-MRSDCI/aug-cc-pV5Z level of theory. Both the experimental and theoretical results show that SH/SD photodissociation from X 2Pi (upsilon"相似文献
93.
Zamfir AD Serb A Vukeli Ž Flangea C Schiopu C Fabris D Kalanj-Bognar S Capitan F Sisu E 《Journal of the American Society for Mass Spectrometry》2011,22(12):2145-2159
Gangliosides (GGs), sialic acid-containing glycosphingolipids, are known to be involved in the invasive/metastatic behavior
of brain tumor cells. Development of modern methods for determination of the variations in GG expression and structure during
neoplastic cell transformation is a priority in the field of biomedical analysis. In this context, we report here on the first
optimization and application of chip-based nanoelectrospray (NanoMate robot) mass spectrometry (MS) for the investigation
of gangliosides in a secondary brain tumor. In our work a native GG mixture extracted and purified from brain metastasis of
lung adenocarcinoma was screened by NanoMate robot coupled to a quadrupole time-of-flight MS. A native GG mixture from an
age-matched healthy brain tissue, sampled and analyzed under identical conditions, served as a control. Comparative MS analysis
demonstrated an evident dissimilarity in GG expression in the two tissue types. Brain metastasis is characterized by many
species having a reduced N-acetylneuraminic acid (Neu5Ac) content, however, modified by fucosylation or O-acetylation such as Fuc-GM4, Fuc-GM3, di-O-Ac-GM1, O-Ac-GM3. In contrast, healthy brain tissue is dominated by longer structures exhibiting from mono- to hexasialylated sugar
chains. Also, significant differences in ceramide composition were discovered. By tandem MS using collision-induced dissociation
at low energies, brain metastasis-associated GD3 (d18:1/18:0) species as well as an uncommon Fuc-GM1 (d18:1/18:0) detected
in the normal brain tissue could be structurally characterized. The novel protocol was able to provide a reliable compositional
and structural characterization with high analysis pace and at a sensitivity situated in the fmol range. 相似文献
94.
Silicothermic reduction process in magnesium production 总被引:1,自引:0,他引:1
D. Minić D. Manasijević Jelena Ðokić Dragana Živković Ž. Živković 《Journal of Thermal Analysis and Calorimetry》2008,93(2):411-415
In this paper there are presented the results of the characterization and thermal analysis of the slag from the magnesium
plant ‘Bela Stena’, Serbia.
The results of X-ray fluorescence analysis, scanning electron microscopy (SEM), optical microscopy (LOM) and X-ray diffraction
(XRD) were used for chemical and mineralogical analysis of the solidified slag samples. Differential thermal analysis (DTA),
thermo-gravimetric (TG) analysis and thermal microscopy results were used for determination of characteristic phase transformations.
The solidified slag shows dicalcium silicate based structure. Magnesium is mostly present in the form of the following minerals:
periclase, merwinite and melilite. 相似文献
95.
Milica Pantelić Dragana Dabić Zagorac Uroš Gašić Sonja Jović Zoran Bešlić Slavica Todić 《Natural product research》2018,32(19):2356-2359
Phenolic profiles of young monovarietal white and red wines from the Central Serbia were investigated. Quantification of phenolics was done using ultra-high-performance liquid chromatography (UHPLC) coupled with a diode array detector and a triple-quadrupole mass spectrometer. Generally, red wines were characterised with higher phenolics content when compared to the white wines. This applies also for the total phenolics content (TPC) and radical scavenging activity (RSA) values. Among all the samples, the red wine from autochthonous Serbian variety ‘Prokupac’ stood out with unique composition, showing the highest TPC, RSA and the highest concentration of the individual phenolics. Finally, based on a specific phenolic pattern, principal component analysis (PCA) indicated clustering of red and white wines, with the ‘Prokupac’ as a prominent outlier. 相似文献
96.
Živković Dragana Živković ž. Šesták J. 《Journal of Thermal Analysis and Calorimetry》1998,52(2):393-401
The results of a comparative thermodynamic study of the Pb-Al binary system: activities, activity coefficients, partial and
integral molar quantities at 1000 K, obtained by experimental Oelsen calorimetry and thermodynamic predicting according to
Chou for systems with miscibility gap are presented in this paper. Also, infinite dilution constants and interaction parameters
at the mentioned temperature were determined by means of the Hajra method.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
97.
Dragana Stevanovi Anka Pejovi Sladjana B. Novakovi Goran A. Bogdanovi Vladimir Divjakovi Rastko D. Vukievi 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(2):m37-m40
Recrystallization of the title compound, [Fe(C5H5)(C14H13N2O3)], from a mixture of n‐hexane and dichloromethane gave the new polymorph, denoted (I), which crystallizes in the same space group (P) as the previously reported structure, denoted (II). The Fe—C distances in (I) range from 2.015 (3) to 2.048 (2) Å and the average value of the C—C bond lengths in the two cyclopentadienyl (Cp) rings is 1.403 (13) Å. As indicated by the smallest C—Cg1—Cg2—C torsion angle of 1.4° (Cg1 and Cg2 are the centroids of the two Cp rings), the orientation of the Cp rings in (I) is more eclipsed than in the case of (II), for which the value was 15.3°. Despite the pronounced conformational similarity between (I) and (II), the formation of self‐complementary N—H...O hydrogen‐bonded dimers represents the only structural motif common to the two polymorphs. In the extended structure, molecules of (I) utilize C—H...O hydrogen bonds and, unlike (II), an extensive set of intermolecular C—H...π interactions. Fingerprint plots based on Hirshfeld surfaces are used to compare the packing of the two polymorphs. 相似文献
98.
Anka Pejović Dragana Stevanović Ivan Damljanović Mirjana Vukićević Sladjana B. Novaković Goran A. Bogdanović Tatjana Mihajilov‐Krstev Niko Radulović Rastko D. Vukićević 《Helvetica chimica acta》2012,95(8):1425-1441
A successful aza‐Michael addition of arylamines to a conjugated enone, acryloylferrocene, has been achieved by ultrasonic irradiation of the mixture of these reactants and the catalyst, i.e., montmorillonite K‐10. This solvent‐free reaction, yielding ferrocene containing Mannich bases, 3‐(arylamino)‐1‐ferrocenylpropan‐1‐ones, considered as valuable precursors in organic synthesis, has been performed by using a simple ultrasonic cleaner. Among 17 synthesized β‐amino ketones, three were new ones, and these were fully characterized by spectroscopic means. X‐Ray crystallographic analysis of three of these crystalline products enabled the insight into the conformational details of these compounds. All compounds were evaluated for their antibacterial activities against six Gram‐positive and five Gram‐negative strains in a microdilution assay. The observed promising antibacterial activity (with a MIC value of 25 μg/ml (ca. 0.07 μmol/ml) as the best result for almost all tested compounds against Micrococcus flavus) seems not only to be compound but also bacterial species‐specific. 相似文献
99.
Guifen Zhuang Dragana S. Cvetković-Ilić Yimin Wei 《Linear and Multilinear Algebra》2013,61(8):903-910
In this article, we investigate additive properties on the Drazin inverse of elements in rings. Under the commutative condition of ab?=?ba, we show that a?+?b is Drazin invertible if and only if 1?+?a D b is Drazin invertible. Not only the explicit representations of the Drazin inverse (a?+?b) D in terms of a, a D , b and b D , but also (1?+?a D b) D is given. Further, the same property is inherited by the generalized Drazin invertibility in a Banach algebra and is extended to bounded linear operators. 相似文献
100.
Dragana Cvetkovic-Ilic Robin Harte 《Proceedings of the American Mathematical Society》2007,135(11):3547-3552
The ``algebraic closure" of a subset of a ring is an algebraic analogue of topological closure.