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排序方式: 共有4883条查询结果,搜索用时 328 毫秒
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Fernando Bento Cunha Karina Torres Pomini Ana Maria de Guzzi Plepis Virgínia da Conceio Amaro Martins Eduardo Gomes Machado Renato de Moraes Marcelo de Azevedo e Souza Munhoz Michela Vanessa Ribeiro Machado Marco Antonio Hungaro Duarte Murilo Priori Alcalde Daniela Vieira Buchaim Rogrio Leone Buchaim Victor Augusto Ramos Fernandes Eliana de Souza Bastos Mazuqueli Pereira Andr Antonio Pelegrine Marcelo Rodrigues da Cunha 《Molecules (Basel, Switzerland)》2021,26(6)
Autologous bone grafts, used mainly in extensive bone loss, are considered the gold standard treatment in regenerative medicine, but still have limitations mainly in relation to the amount of bone available, donor area, morbidity and creation of additional surgical area. This fact encourages tissue engineering in relation to the need to develop new biomaterials, from sources other than the individual himself. Therefore, the present study aimed to investigate the effects of an elastin and collagen matrix on the bone repair process in critical size defects in rat calvaria. The animals (Wistar rats, n = 30) were submitted to a surgical procedure to create the bone defect and were divided into three groups: Control Group (CG, n = 10), defects filled with blood clot; E24/37 Group (E24/37, n = 10), defects filled with bovine elastin matrix hydrolyzed for 24 h at 37 °C and C24/25 Group (C24/25, n = 10), defects filled with porcine collagen matrix hydrolyzed for 24 h at 25 °C. Macroscopic and radiographic analyses demonstrated the absence of inflammatory signs and infection. Microtomographical 2D and 3D images showed centripetal bone growth and restricted margins of the bone defect. Histologically, the images confirmed the pattern of bone deposition at the margins of the remaining bone and without complete closure by bone tissue. In the morphometric analysis, the groups E24/37 and C24/25 (13.68 ± 1.44; 53.20 ± 4.47, respectively) showed statistically significant differences in relation to the CG (5.86 ± 2.87). It was concluded that the matrices used as scaffolds are biocompatible and increase the formation of new bone in a critical size defect, with greater formation in the polymer derived from the intestinal serous layer of porcine origin (C24/25). 相似文献
3.
We report on the first observation and studies of a weak delocalizing logarithmic temperature dependence of the conductivity,
which causes the conductivity of the 2D metal to increase as T decreases down to 16 mK. The prefactor of the logarithmic dependence is found to decrease gradually with density, to vanish
at a critical density n
c
, 2∼2×1012 cm−2, and then to have the opposite sign at n>n
c
,2. The second critical density sets the upper limit on the existence region of the 2D metal, whereas the conductivity at the
critical point, G
c
,2∼120e
2/h, sets an upper (low-temperature) limit on its conductivity.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 6, 497–501 (25 September 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
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The effect of hydrophilic ionic liquids (ILs) on the activity of chloroperoxidase (CPO) was checked through kinetic and stereochemical studies. The possibility to employ this enzyme in synthesis has been demonstrated investigating the chemo- and stereoselectivity of oxidation of phenyl methylsulfide in several citrate buffer-IL mixtures. 相似文献
6.
D. De Salvador A. Coati E. Napolitani M. Berti A.V. Drigo M.S. Carroll J.C. Sturm J. Stangl G. Bauer L. Lazzarini 《Applied Physics A: Materials Science & Processing》2002,75(6):667-672
In this work we investigate the diffusion and precipitation of supersaturated substitutional carbon in 200-nm-thick SiGeC
layers buried under a silicon cap layer of 40 nm. The samples were annealed in either inert (N2) or oxidizing (O2) ambient at 850 °C for times ranging from 2 to 10 h. The silicon self-interstitial (I) flux coming from the surface under
oxidation enhances the C diffusion with respect to the N2-annealed samples. In the early stages of the oxidation process, the loss of C from the SiGeC layer by diffusion across the
layer/cap interface dominates. This phenomenon saturates after an initial period (2–4 h), which depends on the C concentration.
This saturation is due to the formation and growth of C-containing precipitates that are promoted by the I injection and act
as a sink for mobile C atoms. The influence of carbon concentration on the competition between precipitation and diffusion
is discussed.
Received: 19 October 2001 / Accepted: 19 December 2001 / Published online: 20 March 2002 / Published online: 20 March 2002 相似文献
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Ornella Azzolina Simona Collina Daniela Rossi Enrica Lanza 《Tetrahedron letters》2004,45(7):1355-1357
The diastereoselective synthesis of naphthyl amino alcohols via nucleophilic addition to racemic 1-dimethylamino-2-methylpentan-3-one was studied. The use of the appropriate experimental conditions allowed the synthesis of both diastereoisomers. The relative configurations were established via NOESY experiments. 相似文献
9.
Hana Macková Daniela Králová Daniel Horák 《Journal of polymer science. Part A, Polymer chemistry》2007,45(24):5884-5898
The aim of this study was to develop novel thermally responsive polymer microspheres with magnetic properties. Dispersion and inverse emulsion copolymerization of N‐isopropylacrylamide (NIPAAm) and N,N′‐methylenebisacrylamide (MBAAm) was investigated in the presence of γ‐Fe2O3 nanoparticles. The resulting microspheres were characterized in terms of morphology, size, polydispersity, iron content, and temperature‐dependent swelling using optical microscopy, transmission electron microscopy, scanning electron microscopy, QELS, and AAS. The effects of several variables, such as the concentration of γ‐Fe2O3, MBAAm crosslinking agent, Span 80 surfactant, 2,2′‐azobis(2‐methyloctanenitrile) (AMON) initiator, and polymerization temperature on the properties of the microspheres were studied. Swelling and thermoresponsive behavior of the microspheres containing γ‐Fe2O3 nanoparticles were also investigated. The microspheres contained about 8 wt % of iron. The presence of magnetic nanoparticles and their concentration changes did not have any significant effect on the temperature sensitivity of the composites. The particles gradually shrink into an increasingly collapsed state when the temperature is raised to 40 °C since the increase in temperature weakens the hydration and PNIPAAm chains gradually become more hydrophobic, which leads to the collapse of the particles. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5884–5898, 2007 相似文献
10.