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排序方式: 共有1215条查询结果,搜索用时 187 毫秒
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Andrey Vyacheslavovich Vasilyev Valeriya Sergeevna Kuznetsova Tatyana Borisovna Bukharova Timofei Evgenevich Grigoriev Yuriy Dmitrievich Zagoskin Irina Alekseevna Nedorubova Igor Ivanovich Babichenko Sergey Nicolaevich Chvalun Dmitry Vadimovich Goldstein Anatoliy Alekseevich Kulakov 《Molecules (Basel, Switzerland)》2021,26(2)
Compositions based on chitosan/β-glycerophosphate hydrogels with highly porous polylactide granules can be used to obtain moldable bone graft materials that have osteoinductive and osteoconductive properties. To eliminate the influence of such characteristics as chain length, degree of purification, and molecular weight on a designed material, the one-stock chitosan sample was reacetylated to degrees of deacetylation (DD%) of 19.5, 39, 49, 55, and 56. A study of the chitosan/β-glycerophosphate hydrogel with chitosan of a reduced DD% showed that a low degree of deacetylation increased the MSCs (multipotent stromal cells) viability rate in vitro and reduced the leukocyte infiltration in subcutaneous implantation to Wistar rats in vivo. The addition of 12 wt% polylactide granules resulted in optimal composite mechanical and moldable properties, and increased the modulus of elasticity of the hydrogel-based material by approximately 100 times. Excessive filling of the material with PLA (polylactide) granules (more than 20%) led to material destruction at a ~10% strain. Osteoinductive and osteoconductive properties of the chitosan hydrogel-based material with reacetylated chitosan (39 DD%) and highly porous polylactide granules impregnated with BMP-2 (bone morphogenetic protein-2) have been demonstrated in models of orthotopic and ectopic bone formation. When implanted into a critical-size calvarial defect in rats, the optimal concentration of BMP-2 was 10 μg/mL: bone tissue areas filled the entire material’s thickness. Implantation of the material with 50 μg/mL BMP-2 was accompanied with excessive growth of bone tissue and material displacement beyond the defect. Significant osteoinductive and osteoconductive properties of the material with 10 μg/mL of BMP-2 were also shown in subcutaneous implantation. 相似文献
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Some features of software implementation of the Pulay scaling procedure are considered. The advantages of the single value decomposition method for maintaining well-conditionality of the scale factor determination problem are demonstrated. The necessity of using a rational number of scale factors is shown. The possibility of obtaining transferable scale factors with the Pulay method and thus predict the vibrational spectra of related compounds is emphasized. 相似文献
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Nikolaií N. Nekhoroshev Dmitrií A. Sadovskií Boris I. Zhilinskií 《Annales Henri Poincare》2006,7(6):1099-1211
We introduce fractional monodromy in order to characterize certain non-isolated critical values of the energy–momentum map
of integrable Hamiltonian dynamical systems represented by nonlinear resonant two-dimensional oscillators. We give the formal
mathematical definition of fractional monodromy, which is a generalization of the definition of monodromy used by other authors
before. We prove that the 1:( − 2) resonant oscillator system has monodromy matrix with half-integer coefficients and discuss
manifestations of this monodromy in quantum systems.
Communicated by Eduard Zehnder
Submitted: February 25, 2005; Accepted: November 17, 2005 相似文献
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Nikolai Neumaier 《Communications in Mathematical Physics》2002,230(2):271-288
In this paper we explicitly construct local ν-Euler derivations , where the ξα are local, conformally symplectic vector fields and the are formal series of locally defined differential operators, for Fedosov star products on a symplectic manifold (M,ω) by means of which we are able to compute Deligne's characteristic class of these star products. We show that this class
is given by , where is a formal series of closed two-forms on M the cohomology class of which coincides with the one introduced by Fedosov to classify his star products. Moreover, we consider
star products that have additional algebraic structures and compute the effect of these structures on the corresponding characteristic
classes of these star products. Specifying the constituents of Fedosov's construction we obtain star products with these special
properties. Finally, we investigate equivalence transformations between such special star products and prove existence of
equivalence transformations being compatible with the considered algebraic structures.
Dedicated to the memory of Moshé Flato
Received: 28 June 1999 / Accepted: 11 April 2002?Published online: 11 September 2002 相似文献
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Nikolai Yu. Bakaev 《BIT Numerical Mathematics》1998,38(3):462-485
We consider a Cauchy problem for the sectorial evolution equation with generally variable operator in a Banach space. Variable
stepsize discretizations of this problem by means of a strongly A(φ)-stable Runge-Kutta method are studied. The stability
and error estimates of the discrete solutions are derived for wider families of nonuniform grids than quasiuniform ones (in
particular, if the operator in question is constant or Lipschitz-continuous, for arbitrary grids). 相似文献