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排序方式: 共有202条查询结果,搜索用时 15 毫秒
1.
Ligia E. Zamora G. A. Perez Alcazar J. M. Greneche S. Suriñach 《Hyperfine Interactions》2006,168(1-3):1057-1063
Fe60Mn10Al20Nb10, (Fe60Mn10Al30)95Nb5 and (Fe60Mn10Al30)90Nb10 ball milled powdered alloys were investigated using X-ray diffraction, Mössbauer spectrometry, thermomagnetic (TGM) and magnetization measurements. We studied the influence of Nb content and of different milling times on the structural and magnetic properties. Two main features can be concluded: (1) the FeAlMn induces a BCC phase whatever the Nb content is, and (2) as both increasing Nb content and milling time give rise to an highly disordered state in conjunction with a decrease of the ferromagnetic behavior. 相似文献
2.
Frunza L Kosslick H Pitsch I Frunza S Schönhals A 《The journal of physical chemistry. B》2005,109(18):9154-9159
The rotational molecular dynamics of water confined to nanoporous molecular sieves of a regular hexagonal (SBA-15) and of a foamlike pore structure was studied by dielectric spectroscopy in the frequency range from 10(-2) to 10(9) Hz and in a broad temperature interval. Two relaxation processes were observed: the process at lower frequencies is related to water molecules forming a layer, which is strongly adsorbed at the pore surface, whereas the relaxation process at higher frequencies is assigned to fluctuations of water molecules situated close to the center of the pore. The relaxation times of the low-frequency process for both materials and of the high-frequency process for the SBA-15 material have an unusual saddlelike temperature dependence, reported here for the first time. To describe this temperature dependence, a model developed for water confined to nanoporous glasses by Ryabov et al. [J. Phys. Chem. B 2001, 105, 1845] was applied, which considers two competing effects. The characteristic features of these two competing processes were compared with those reported for other porous systems. 相似文献
3.
Cornelia Uncuta Teodor-Silviu Balaban Mircea D. Gheorghiu Ligia Stănescu Aurica Petride Alexandru T. Balaban 《Tetrahedron letters》1985,26(38):4673-4676
Two Isomeric pyridines were designed and prepared : 2-isopropyl-4,5,6-trimethyl-(3) and 2-isopropyl-3,4,6-trimethyl-pyridine (7); the latter, with a buttressed isopropyl, leads to much lower induced shifts by Eu(dpm)3 and Pr(dpm)3 than the former, owing to the conformation in which the Janus-type iPr group how to the LSR a t-butyl-like face. 相似文献
4.
Felicia Dragan I. Bratu Gh. Borodi Mihaela Toma A. Hernanz S. Simon Gh. Cristea R. Peschar 《Journal of inclusion phenomena and macrocyclic chemistry》2007,59(1-2):125-130
Aqueous-solution complexes of β-cyclodextrin (β-CD) with metoprolol tartrate (MET) have been analysed with 1H NMR and UV–vis spectroscopy. With 1H NMR a [1:1] stoichiometry could be established for the β-CD-MET complex while its stability constant was determined with
UV–vis spectroscopy. Powder diffraction data of a polycrystalline sample of the β-CD-MET complex show that a novel product
has been formed, likely to be a β-CD-MET [1:1] inclusion complex. Also Hyperchem MM+ molecular-dynamics results suggest an
inclusion complex and from 1H NMR data it is inferred that probably the MET is docked in the CD with the formers methoxyethyl-benzene moiety in front.
Mihaela Toma is Socrates/Erasmus student at UNED Madrid 相似文献
5.
Ligia Bicudo de Almeida Marilene De Vuono Camargo Penteado George Britton Peter Uebelhart Murat Acemoglu Conrad Hans Eugster 《Helvetica chimica acta》1988,71(1):31-32
The 5,6:5′,6′-diepoxy-5,6:5′,6;-tetrahydro-β,β-carotene, isolated from tubers of a white-fleshed variety of sweet potato (Ipomoea batatas LAM .) has been assigned the (5R,6S,5′R,6′S)-chirality on the basis of its HPLC, UV/VIS, and CD data. 相似文献
6.
Gubanova G. N. Timpu D. Cristea M. Kononova S. V. Korytkova E. N. Sapegin D. A. Saprykina N. N. Volkov A. Ya. Klechkovskaya V. V. 《Crystallography Reports》2021,66(7):1185-1199
Crystallography Reports - A new polymer-inorganic nanocomposite composed of fibrous Na–Mg triple chain hydrosilicate with a poly(amide-imide) matrix was developed. Its structure, morphology,... 相似文献
7.
Mihai Cristea 《复变函数与椭圆型方程》2015,60(4):437-469
We study the geometric properties of the mappings for which generalized inverse modular inequalities hold. We generalize in this way known theorems from the theory of analytic mappings and the theory of quasiregular mappings, like the theorems of Fatou, M. and F. Riesz, Beurling and Lindelöf and their extensions given for quasiregular mappings by Martio, Rickman and Vuorinen. 相似文献
8.
Walter Vastarella Livia Della Seta Amedeo Masci Jan Maly Manuela De Leo Ligia Maria Moretto 《International journal of environmental analytical chemistry》2013,93(10-11):701-714
Gold nanowires were synthesized within polycarbonate membranes according to an electroless deposition method, obtaining nanoelectrode ensembles (NEEs) with special electrochemical features. NEEs were coupled with home-produced carbon graphite screen printed electrodes and the electrochemical properties of the original nanoelectrode ensemble on screen printed substrate (NEE/SPS) assembly has been tested for sensors application. Glucose oxidase has been used as model enzyme in order to verify the feasibility of disposable gold NEE/SPS biosensors. Finally, different immobilisation and electrochemical deposition techniques based on either self assembled monolayers of cysteamine (CYS) or amino-propyl-triethoxysilane (APTES) and conductive polyaniline (PANI) molecular wires were used. Spatial patterning of the enzyme on the polycarbonate surface and of PANI wires on gold nanoelectrodes was obtained. Possible direct electron transfer between the enzyme and the PANI modified gold nanoelectrodes has been evaluated. 相似文献
9.
Mihaela Tertis Oana Hosu Bogdan Feier Andreea Cernat Anca Florea Cecilia Cristea 《Molecules (Basel, Switzerland)》2021,26(11)
Food safety and quality control pose serious issues to food industry and public health domains, in general, with direct effects on consumers. Any physical, chemical, or biological unexpected or unidentified food constituent may exhibit harmful effects on people and animals from mild to severe reactions. According to the World Health Organization (WHO), unsafe foodstuffs are especially dangerous for infants, young children, elderly, and chronic patients. It is imperative to continuously develop new technologies to detect foodborne pathogens and contaminants in order to aid the strengthening of healthcare and economic systems. In recent years, peptide-based sensors gained much attention in the field of food research as an alternative to immuno-, apta-, or DNA-based sensors. This review presents an overview of the electrochemical biosensors using peptides as molecular bio-recognition elements published mainly in the last decade, highlighting their possible application for rapid, non-destructive, and in situ analysis of food samples. Comparison with peptide-based optical and piezoelectrical sensors in terms of analytical performance is presented. Methods of foodstuffs pretreatment are also discussed. 相似文献
10.
Soares CR Camargo IM Morganti L Gimbo E Ezequiel de Oliveira J Legoux R Ferrara P Bartolini P 《Journal of chromatography. A》2002,955(2):229-236
Reversed-phase high-performance liquid chromatography methodology for the determination of human prolactin (hPRL) in bacterial periplasmic space or in purified preparations has been developed. The technique, based on the high hydrophobicity of the hPRL molecule, allows its separation from the bulk of bacterial proteins. The precision for periplasmic shock fluid analysis was characterized by relative standard variations of 3-7% for intra-day and of 3-25% for inter-day determinations. Accuracy, evaluated by recovery tests, was of the order of 90%, a calibration curve being constructed with the use of a lyophilized osmotic shock fluid extract, which provided a stable, readily prepared internal reference. Sensitivity was of the order of 0.5 microg of hPRL. The methodology developed also provided a tool for comparing the hydrophobicity of glycosylated and non-glycosylated prolactin molecules obtained from several different species and of different preparations of native or biosynthetic human prolactin. 相似文献