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排序方式: 共有754条查询结果,搜索用时 15 毫秒
91.
Valentina Matveeva Alexey Bykov Valentin Doluda Mikhail Sulman Narendra Kumar Stanislaw Dzwigaj Eric Marceau Leonid Kustov Olga Tkachenko Esther Sulman 《Topics in Catalysis》2009,52(4):387-393
In the present work, nanocatalysts prepared on inorganic supports (zeolites) were investigated in d-glucose oxidation and compared to systems supported on polymer (hypercrosslinked polystyrene (HPS)) previously described.
Catalytic activities and selectivities were measured under various reaction conditions. The selectivity of d-glucose oxidation and activity of both Pd-containing zeolites and HPS-Ru were similar (99.7% and TOF 0.013–0.014 mol/(mol Me s)).
Physicochemical analysis X-ray photoelectron spectroscopy, liquid nitrogen physisorption, diffuse reflectance infrared Fourier
transform spectroscopy of adsorbed CO for metal sites evaluation, CD3CN for acid sites evaluation showed that Pd species were in oxidic form, while Ru species were in oxidic and reduced form.
The catalytic activity decreased when acidic sites were present in Pd-containing zeolites. 相似文献
92.
Sergey Y. Nechaev Alexei V. Lutay Valentin V. Vlassov Marina A. Zenkova 《International journal of molecular sciences》2009,10(4):1788-1807
RNA non-enzymatic recombination reactions are of great interest within the hypothesis of the “RNA world”, which argues that at some stage of prebiotic life development proteins were not yet engaged in biochemical reactions and RNA carried out both the information storage task and the full range of catalytic roles necessary in primitive self-replicating systems. Here we report on the study of recombination reaction occuring between two 96 nucleotides (nts) fragments of RNAs under physiological conditions and governed by a short oligodeoxyribonucleotide template, partially complementary to sequences within each of the RNAs. Analysis of recombination products shows that ligation is predominantly template-directed, and occurs within the complementary complex with the template in “butt-to-butt” manner, in 1- or 3- nts bulges or in 2–3 nts internal loops. Minor recombination products formed in the template-independent manner are detected as well. 相似文献
93.
Lázaro Valentin Zuquette Janaina Barrios Palma Osni José Pejon 《Bulletin of Engineering Geology and the Environment》2009,68(1):117-136
The goal of the study was to establish a methodology for territorial zoning based on predicted groundwater pollution. The
31 attributes identified were divided into six different environmental components associated with the transport of contaminants
to the geological medium. Two indices were obtained: the pre-disposition index (PI), and the potential pollution intensity
index (PPII). The paper reports an assessment of the potential pollution of the groundwater in the sandstones of the Botucatu
and Pirambóia Formations, Sao Paulo, Brazil. The region was divided into 447 units according to the type of land use, size
of watershed and degree of lithological homogeneity. The units were assessed for potential pollution in the pre-disposition
condition (based on geological/geotechnical data) and the complete condition (geological/geotechnical and situation specific
data) using the analytical hierarchical process method. A high degree of pollution potential was established for 35 of the
units in the complete condition and 157 units in the pre-disposition condition. The study has highlighted areas where attention
to pollution control should be focused.
相似文献
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96.
Valentin J 《Annals of the ICRP》1999,29(1-2):71-79
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Florina D. Cojocaru Vera Balan Constantin-Edi Tanase Ionel Marcel Popa Maria Butnaru Ovidiu Bredetean Mihai Mares Valentin Nastasa Sorin Pasca Liliana Verestiuc 《Ceramics International》2021,47(8):11209-11219
Fine-tuning of the scaffolds structural features for bone tissue engineering can be an efficient approach to regulate the specific response of the osteoblasts. Here, we loaded magnetic nanoparticles aka superparamagnetic iron oxide nanoparticles (SPIONs) into 3D composite scaffolds based on biological macromolecules (chitosan, collagen, hyaluronic acid) and calcium phosphates for potential applications in bone regeneration, using a biomimetic approach. We assessed the effects of organic (chitosan/collagen/hyaluronic acid) and inorganic (calcium phosphates, SPIONs) phase over the final features of the magnetic scaffolds (MS). Mechanical properties, magnetic susceptibility and biological fluids retention are strongly dependent on the final composition of MS and within the recommended range for application in bone regeneration. The MS architecture/pore size can be made bespoken through changes of the final organic/inorganic ratio. The scaffolds undertake mild degradation as the presence of inorganic components hinders the enzyme catalytic activity. In vitro studies indicated that osteoblasts (SaOS-2) on MS9 had similar cell behaviour activity in comparison with the TCP control. In vivo data showed an evident development of integration and resorption of the MS composites with low inflammation activity. Current findings suggest that the combination of SPIONs into 3D composite scaffolds can be a promising toolkit for bone regeneration. 相似文献
100.
Journal of Logic, Language and Information - We consider systems of rational agents who act and interact in pursuit of their individual and collective objectives. We study and formalise the... 相似文献