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排序方式: 共有443条查询结果,搜索用时 328 毫秒
51.
Jolanta Skalska Piotr Bednarczyk Marta Piwońska Bogusz Kulawiak Grzegorz Wilczynski Krzysztof Do?owy Alexei P. Kudin Wolfram S. Kunz Adam Szewczyk 《International journal of molecular sciences》2009,10(3):1104-1120
The mitochondrial response to changes of cytosolic calcium concentration has a strong impact on neuronal cell metabolism and viability. We observed that Ca2+ additions to isolated rat brain mitochondria induced in potassium ion containing media a mitochondrial membrane potential depolarization and an accompanying increase of mitochondrial respiration. These Ca2+ effects can be blocked by iberiotoxin and charybdotoxin, well known inhibitors of large conductance potassium channel (BKCa channel). Furthermore, NS1619 – a BKCa channel opener – induced potassium ion–specific effects on brain mitochondria similar to those induced by Ca2+. These findings suggest the presence of a calcium-activated, large conductance potassium channel (sensitive to charybdotoxin and NS1619), which was confirmed by reconstitution of the mitochondrial inner membrane into planar lipid bilayers. The conductance of the reconstituted channel was 265 pS under gradient (50/450 mM KCl) conditions. Its reversal potential was equal to 50 mV, which proved that the examined channel was cation-selective. We also observed immunoreactivity of anti-β4 subunit (of the BKCa channel) antibodies with ~26 kDa proteins of rat brain mitochondria. Immunohistochemical analysis confirmed the predominant occurrence of β4 subunit in neuronal mitochondria. We hypothesize that the mitochondrial BKCa channel represents a calcium sensor, which can contribute to neuronal signal transduction and survival. 相似文献
52.
Elena R. Ranyuk Alexei D. Averin Irina P. Beletskaya 《Advanced Synthesis \u0026amp; Catalysis》2010,352(13):2299-2305
Asymmetric amination of 1,5‐dichloroanthraquinone and 1,5‐dichloroanthracene with di‐ and trioxadiamines catalyzed by palladium complexes with various chiral phosphine ligands gave chiral macrocycles with ee values of up to 60%. The dependence of the chemical yields and enantiomeric excess on the nature of the starting compounds and the phosphine ligands employed was demonstrated. An unexpected spontaneous resolution upon crystallization of the macrocycle comprising anthraquinone and dioxadiamine moieties was observed while in the case of the macrocycle with a trioxadiamine linker racemic monocrystals were obtained. Crystallization of the enantiomerically enriched mixtures afforded chiral macrocycles with 88–99% ee. 相似文献
53.
Alexei V. Shevchenko Elena V. Dudnik Alexei K. Ruban Vladimir M. Vereshchaka Viktor P. Red’ko Lidiya M. Lopato 《Powder Metallurgy and Metal Ceramics》2005,44(3-4):105-111
The properties of ZrO2 - 3 mole% Y2O3 nanocrystalline powder prepared by diffusion impregnation are studied. The original nanocrystalline powder of M-ZrO2 is prepared with hydrothermal treatment of aqueous zirconium hydroxychloride solution by different regimes. It is found that after diffusion impregnation for all of the powders with yttrium oxide two solid solutions are formed (F-ZrO2 and M-ZrO2) in mixture. It is established that the morphological features typical for the original powders are retained. The efficiency of diffusion impregnation is determined by the slightly-agglomerated powder with a high degree of crystallinity.__________Translated from Poroshkovaya Metallurgiya, Nos. 3–4(442), pp. 3–11, March–April, 2005. 相似文献
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55.
Comparative Cytotoxicity of Artemisinin and Cisplatin and Their Interactions with Chlorogenic Acids in MCF7 Breast Cancer Cells 下载免费PDF全文
Dr. John O. Suberu Dr. Isolda Romero‐Canelón Dr. Neil Sullivan Prof. Alexei A. Lapkin Dr. Guy C. Barker 《ChemMedChem》2014,9(12):2791-2797
In parts of Africa and Asia, self‐medication with a hot water infusion of Artemisia annua (Artemisia tea) is a common practice for a number of ailments including malaria and cancer. In our earlier work, such an extract showed better potency than artemisinin alone against both chloroquine‐sensitive and ‐resistant parasites. In this study, in vitro tests of the infusion in MCF7 cells showed high IC50 values (>200 μM ). The combination of artemisinin and 3‐caffeoylquinic acid (3CA), two major components in the extract, was strongly antagonistic and gave a near total loss of cytotoxicity for artemisinin. We observed that the interaction of 3CAs with another cytotoxic compound, cisplatin, showed potentiation of activity by 2.5‐fold. The chelation of cellular iron by 3CA is hypothesized as a possible explanation for the loss of artemisinin activity. 相似文献
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Urmila Shirwadkar Jarek GlodoEdgar V. van Loef Rastgo HawramiSharmishtha Mukhopadhyay Alexei ChurilovWilliam M. Higgins Kanai S. Shah 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,652(1):268-270
Investigations of Ce3+-doped Cs2LiLaBr6 (CLLB) crystals show a systematic trend in their scintillation properties with varying Ce concentrations. The concentration studies provide input in the optimization of growth of the CLLB crystals. Scintillation properties viz. radioluminescence, energy resolution, light yield, decay times, and non-proportionality are discussed for samples from 0% to 20% Ce concentration. 相似文献
58.
Sitalo EI Raevski IP Lutokhin AG Blazhevich AV Kubrin SP Raevskaya SI Zakharov YN Malitskaya MA Titov VV Zakharchenko IN 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2011,58(9):1914-1919
Dielectric, X-ray, and piezoelectric studies of highly-resistive Li-doped (1-x)PbFe(1/2)Nb(1/2)O(3)-(x)PbTiO(3) (PFN-xPT) ceramics from the 0 ≤ x ≤ 0.2 range fabricated by solid-state synthesis and usual sintering have been carried out. Distinct anomalies of dielectric and piezoelectric parameters, corresponding to the transition between rhombohedral (monoclinic) and tetragonal ferroelectric phases, have been observed in pure PFN and PFN-xPT compositions with PbTiO(3) content up to 8 mol.%. The x,T-phase diagram of the PFN-xPT solid solution system has been constructed using these data. 相似文献
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60.
Ivan Gratchev Masyhur Irsyam Ikuo Towhata Bakhtiar Muin Hasbullah Nawir 《Soils and Foundations》2011,51(2):333-341
This paper reports and discusses the results of a field survey conducted by a joint scientific group from Japan and Indonesia to assess the geotechnical aspects of the Sumatra earthquake (Mw=7.6) of September 30, 2009. The studied area included the Padang and Pariaman cities, where a number of buildings collapsed as a result of strong shaking, and a mountainous part of the Pariaman district, a place where massive landslides buried several villages, claiming more than 400 human lives. The main objective of the survey was to investigate the causes and mechanisms of catastrophic landslides; however, other geotechnical problems such as lateral spread and liquefaction were also addressed. Field observations indicated that the catastrophic landslides occurred on relatively gentle slopes, then mobilized into debris flows, and traveled several hundred meters from their points of origin. The failure surfaces developed along the boundary of highly weathered pumice tuff with more intact and less weathered bedrock. Data from a portable cone penetration test showed that the sliding material was rather weak, having SPT N-values in the range of 5-10. The results of the field survey suggested that the main cause of slope instability was high pore-water pressures that generated in the soil mass during the earthquake. 相似文献