排序方式: 共有168条查询结果,搜索用时 15 毫秒
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Timur Saliev Dinara M. Baiskhanova Alma Akhmetova Dinara A. Begimbetova Mars Akishev Gulsim Kulsharova 《Electromagnetic biology and medicine》2019,38(1):21-31
The correlation between shape and concentration of silver nanoparticles (AgNPs), their cytotoxicity and formation of reactive oxygen species (ROS) in the presence of electromagnetic fields (EMFs) has been investigated. In addition, the bio-effects caused by the combination of EMFs and graphene nanoparticles (GrNPs) have been also assessed. The AgNPs of three shapes (triangular, spherical and colloidal) and GrNPs were added in high concentrations to the culture of human fibroblasts and exposed to EMF of three different frequencies: 900, 2400 and 7500 MHz. The results demonstrated the dependence of the EMF-induced cytotoxicity on the shape and concentration of AgNPs. The maximal cell killing effect was observed at 900 MHz frequency for NPs of all shapes and concentrations. The highest temperature elevation was observed for GrNPs solution irradiated by EMF of 900 MHz frequency. The exposure to EMF led to significant increase of ROS formation in triangular and colloidal AgNPs solutions. However, no impact of EMF on ROS production was detected for spherical AgNPs. GrNPs demonstrated ROS-protective activity that was dependent on their concentration. Our findings indicate the feasibility to control cytotoxicity of AgNPs by means of EMFs. The effect EMF on the biological activity of AgNPs and GrNPs is reported here for the first time. 相似文献
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Vladimir D. Savitsky Ludmila G. Bezus'ko Natalia G. Butich Zoya M. Tsymbaliuk Olena V. Savitska Timur V. Bezus'ko 《Aerobiologia》1996,12(3):209-211
This article presents the results of aeropalynological observations in Kiev, carried out with a gravimetric method, during
January–October, 1994. The six most abundant pollen types were: Betulaceae (21%), Chenopodiaceae/Amaranthaceae (10%), Ambrosia
(10%), Artemisia (9%) Pinaceae (8%) and Poaceae (6%). Seasonal fluctuations of the atmospheric presence of tree/shurb and
herb/grass pollen during the period March–September, 1993 and 1994, are also shown. 相似文献
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During the systemic development of Plasmopara helianthi Novot. var. helianthi Novot. the hyphae in the stem advance especially through the intercellular spaces of loose parenchyma forming haustoria in adjacent cells. The hyphae which reach leaf blades through petioles continue their growth along the main veins intercellularly in non-vascular tissues enclosing the vascular bundles. At the same time, the hyphae spread to intercellular spaces of spongy parenchyma where the growth is limited by the veinlets resulting in angular chlorotic lesions. Under humid conditions the sporangiophores arising from the aggregated hyphae in a substomatal cavity emerge through the stomatal pore on the lower side of the leaf and zoosporangia are borne terminally on sporangiophores. Soon after biflagellated zoospores are liberated into distilled water from the zoosporangia, they retract their flagellae and then lyse. 相似文献
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Vladimir A. Sirotkin Timur A. Mukhametzyanov Igor A. Komissarov 《Engineering in Life Science》2009,9(1):82-88
The binding of the competitive inhibitor proflavin by bovine pancreatic α‐chymotrypsin in water‐tetrahydrofuran mixtures was studied in the entire range of thermodynamic water activities at 25°C. The data on the binding of proflavin were compared with the results on the storage stability of α‐chymotrypsin in water‐organic mixtures. An analysis of the concentration dependency of these characteristics demonstrated that, at low water activity values, the interprotein contacts in the enzyme formed during its drying largely govern its functional properties, while at high water activity, they are determined by the interaction of the enzyme with the organic solvent. The interplay of these two factors is responsible for the complex shape observed for the isotherm of binding of proflavin, with a maximum degree of binding being attained at medium water activity values. 相似文献