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排序方式: 共有635条查询结果,搜索用时 31 毫秒
61.
Goverdhan Mehta Raja MohanraoSreenivas Katukojvala Yannick LandaisSaikat Sen 《Tetrahedron letters》2011,52(22):2893-2897
A stereocontrolled synthesis of nine-membered aminocarbasugar analogs (amino-cyclononanoses) from a rigid bicyclo[4.3.1]deca-2,4-dien-10-one platform, harboring a latent functionalized cyclononane ring, is described. 相似文献
62.
Water-dispersible sugar-coated iron oxide nanoparticles. An evaluation of their relaxometric and magnetic hyperthermia properties 总被引:1,自引:0,他引:1
Lartigue L Innocenti C Kalaivani T Awwad A Sanchez Duque Mdel M Guari Y Larionova J Guérin C Montero JL Barragan-Montero V Arosio P Lascialfari A Gatteschi D Sangregorio C 《Journal of the American Chemical Society》2011,133(27):10459-10472
Synthesis of functionalized magnetic nanoparticles (NPs) for biomedical applications represents a current challenge. In this paper we present the synthesis and characterization of water-dispersible sugar-coated iron oxide NPs specifically designed as magnetic fluid hyperthermia heat mediators and negative contrast agents for magnetic resonance imaging. In particular, the influence of the inorganic core size was investigated. To this end, iron oxide NPs with average size in the range of 4-35 nm were prepared by thermal decomposition of molecular precursors and then coated with organic ligands bearing a phosphonate group on one side and rhamnose, mannose, or ribose moieties on the other side. In this way a strong anchorage of the organic ligand on the inorganic surface was simply realized by ligand exchange, due to covalent bonding between the Fe(3+) atom and the phosphonate group. These synthesized nanoobjects can be fully dispersed in water forming colloids that are stable over very long periods. Mannose, ribose, and rhamnose were chosen to test the versatility of the method and also because these carbohydrates, in particular rhamnose, which is a substrate of skin lectin, confer targeting properties to the nanosystems. The magnetic, hyperthermal, and relaxometric properties of all the synthesized samples were investigated. Iron oxide NPs of ca. 16-18 nm were found to represent an efficient bifunctional targeting system for theranostic applications, as they have very good transverse relaxivity (three times larger than the best currently available commercial products) and large heat release upon application of radio frequency (RF) electromagnetic radiation with amplitude and frequency close to the human tolerance limit. The results have been rationalized on the basis of the magnetic properties of the investigated samples. 相似文献
63.
Smaoui S Mellouli L Lebrihi A Coppel Y Fguira LF Mathieu F 《Natural product research》2011,25(8):806-814
Thirty litres of fermentation broth was extracted from the newly isolated Streptomyces sp. strain TN17 and various separation and purification steps led to the isolation of three pure bioactive compounds (1-3). Compound 1: cyclo (L-Leu-L-Arg), a diketopiperazine 'DKP' derivative; 2: di-(2-ethylhexyl) phthalate, a phthalate derivative; and 3: cyclo 1-[2-(cyclopentanecarbonyl-3-phenyl-propionyl]-pyrrolidine-2-carboxylic acid (1-carbamoyl-propyl)-amide, a cyclic tetrapeptide derivative. The chemical structure of these three active compounds was established on the basis of spectroscopic studies (MS and NMR) and by comparison with data from the literature. According to our biological studies, the pure compounds (1-3) possess antibacterial and antifungal activities. 相似文献
64.
Daniel Champion David Glickenstein Andrea Young 《Differential Geometry and its Applications》2011,29(1):108-124
The double tetrahedron is the triangulation of the three-sphere gotten by gluing together two congruent tetrahedra along their boundaries. As a piecewise flat manifold, its geometry is determined by its six edge lengths, giving a notion of a metric on the double tetrahedron. We study notions of Einstein metrics, constant scalar curvature metrics, and the Yamabe problem on the double tetrahedron, with some reference to the possibilities on a general piecewise flat manifold. The main tool is analysis of Regge?s Einstein-Hilbert functional, a piecewise flat analogue of the Einstein-Hilbert (or total scalar curvature) functional on Riemannian manifolds. We study the Einstein-Hilbert-Regge functional on the space of metrics and on discrete conformal classes of metrics. 相似文献
65.
D. Champion C. Loupiac D. Russo D. Simatos J. M. Zanotti 《Journal of Thermal Analysis and Calorimetry》2011,104(1):365-374
This work was undertaken to investigate thermal and dynamic transitions observed in the temperature range close to the bulk
ice melting temperature in sucrose solutions. Measurements of thermal (differential calorimetry) and dynamic (neutron scattering)
properties were compared in order to give a physical interpretation of the thermal transitions observed during the thawing
of amorphous sucrose solutions. In fact, the freezing of biological material leads to the distinction between different pools
of water: bulk water which becomes ice after freezing, unfrozen water trapped in the glassy matrix or close to the interface
of solutes can be considered, and finally freezable confined water with a lower melting point than bulk water and with properties
depending on both the ice presence and the microstructure of the material. The transition temperatures such as glass transition
or melting are dependent on the freezing protocol used and examples of annealing effects are presented, in order to underline
the necessity of a good temperature control during freezing for the study of biological material with freezable water. 相似文献
66.
High sensitive matrix-free mass spectrometry analysis of peptides using silicon nanowires-based digital microfluidic device 总被引:1,自引:0,他引:1
Lapierre F Piret G Drobecq H Melnyk O Coffinier Y Thomy V Boukherroub R 《Lab on a chip》2011,11(9):1620-1628
We present for the first time an electrowetting on dielectric (EWOD) microfluidic system coupled to a surface-assisted laser desorption-ionization (SALDI) silicon nanowire-based interface for mass spectrometry (MS) analysis of small biomolecules. Here, the transfer of analytes has been achieved on specific locations on the SALDI interface followed by their subsequent mass spectrometry analysis without the use of an organic matrix. To achieve this purpose, a device comprising a digital microfluidic system and a patterned superhydrophobic/superhydrophilic silicon nanowire interface was developed. The digital microfluidic system serves for the displacement of the droplets containing analytes, via an electrowetting actuation, inside the superhydrophilic patterns. The nanostructured silicon interface acts as an inorganic target for matrix-free laser desorption-ionization mass spectrometry analysis of the dried analytes. The proposed device can be easily used to realize several basic operations of a Lab-on-Chip such as analyte displacement and rinsing prior to MS analysis. We have demonstrated that the analysis of low molecular weight compounds (700 m/z) can be achieved with a very high sensitivity (down to 10 fmol μL(-1)). 相似文献
67.
Shirsho Mukherjee & Yannick Sire 《分析论及其应用》2021,37(4):520-540
We establish Hölder continuity of the horizontal gradient of weak solutions to quasi-linear $p$-Laplacian type non-homogeneous equations in the Heisenberg Group. 相似文献
68.
Within the scope of a general tensorial study of the 1000 and 2000 cm−1 polyads of CHD3, we have revisited the ground state of this molecule. Infrared ground state combination differences (GSCD) were calculated from 1746 transitions assigned in the ν3/ν5/ν6 triad of CHD3. A set of 10 ground state parameters has been fitted to 613 GSCD providing an agreement of 0.00014 cm−1 between observed and calculated transitions. This corresponds to an improvement of about one order of magnitude with respect to the previous study, reflecting the quality of the experimental spectrum as well as a strict selection of the data used to fit the parameters. 相似文献
69.
70.
P. Champion und H. Pellet 《Fresenius' Journal of Analytical Chemistry》1877,16(1):120-121
Ohne Zusammenfassung 相似文献