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排序方式: 共有188条查询结果,搜索用时 62 毫秒
181.
Orth ES Medeiros M Bortolotto T Terenzi H Kirby AJ Nome F 《The Journal of organic chemistry》2011,76(24):10345-10348
We report a detailed kinetic and mechanistic study of the reaction of a widely used therapeutic agent, deferoxamine (DFO), which contains three nucleophilic hydroxamate groups, with the model phosphate diester bis-2,4-dinitrophenylphosphate BDNPP. We clarify the mechanism by detecting important phosphorylated intermediates in the model reaction and show that the mechanism can be extended to the reaction with DNA. The effectiveness of DFO in cleaving DNA was examined over a range of pH in the absence and presence of a biologically available metal (Zn(2+)). The results inform and complement ongoing studies involving DFO, which can act as a powerful nucleophile toward DNA and other targets susceptible to nucleophilic attack. 相似文献
182.
Orth ES Wanderlind EH Medeiros M Oliveira PS Vaz BG Eberlin MN Kirby AJ Nome F 《The Journal of organic chemistry》2011,76(19):8003-8008
The phosphorylation of imidazole by two activated phosphate diesters and a triester gives phosphorylimidazole derivatives that are stable enough in aqueous solution to be observed and identified by ESI-MS/MS and NMR. Half-lives ranging from hours to days (in the case of the monoethyl ester) show that it is possible to design molecules with variable half-lives with potential to be used for biological intervention experiments as possible inhibitors of biosignaling processes or as haptens for the generation of antibodies. 相似文献
183.
We investigate the optical characteristic,transverse magnetic(TM) and transverse electric(TE) band of twodimensional(2 D) square lattice photonic crystal structure,which is composed of cylindrical air regions positioned at the corners of the square shaped dielectric rods.We obtain the wide photonic bandwidths between TM1–TM2 and TM3–TM4 bands.According to the results,we demonstrate the band gaps close to each other in the TM and TE frequencies for proposed structures.The resulting photonic gaps are formed to be about 8% at the higher frequencies of TE modes(TE4–TE5)and TM modes(TM7–TM8 and TM9–TM10).In addition,we examine isotropically generated structures for light guiding properties and observe that the light is directed in a particular route without using any deflection.We also investigate the self-collimation effect with the designed structure.The obtained results reveal the influences of the radius of cylindrical air holes and the angle between these air holes on absolute and partial photonic band gaps.Moreover,we observe the TM and TE band gaps that overlap.It is thought that the obtained band overlap will provide an easy way to produce the photonic crystals in practical applications like photonic insensitive waveguide.It is also believed that these results can provide the photonic crystal structures to work as a beam deflecting and beam router in integrated optical circuit applications. 相似文献
184.
mer Faruk Karar Mustafa Numan Bucak Mihai Cenariu Mustafa Bodu Mehmet Tapnar Filiz Tapnar 《Molecules (Basel, Switzerland)》2022,27(22)
In the presented study, the effects of ROCK inhibitor Y-27632, antifreeze protein III, and boron at two different doses were investigated on the spermatological parameters of Ankara buck semen after freeze–thawing. Ejaculates were collected from bucks using an electroejaculator during the breeding season. The ejaculates that showed appropriate characteristics were pooled and used in the dilution and freezing of semen. The extender groups were formed by adding two different doses of three different additives (ROCK inhibitor Y-27632, 5 and 20 µM; antifreeze protein III, 1 and 4 µg/mL; boron, 0.25 and 1 mM) to the control extender. The semen was diluted with the different extenders at 35–37 °C and loaded into straws. Sperm samples frozen in liquid nitrogen vapors, following equilibration, were stored in liquid nitrogen. It was observed that extender supplementation improved post-thaw motility of Ankara buck semen after freeze–thawing. Differences were significant (p < 0.01) for 5 and 10 µM doses of ROCK inhibitor (71.82% and 74.04 % motility), as well as for 0.25 and 1 mM doses of boron (76.36% and 72.08% motility), compared to the control group (66.15% motility). With respect to the evaluation of acrosomal integrity and mitochondrial activity after freeze–thawing, although supplementation provided protection at all doses, the efficacy was not statistically significant (p > 0.05). It was observed that DNA damage was improved by antifreeze protein III at 1 µg/mL (1.23% ± 0.23%) and by boron at all doses (0.25 mM: 1.83% and 1 mM: 1.18%) compared to the control group (3.37%) (p < 0.01), following the thawing process. In the present study, it was determined that some additives added to the extender provided significant improvements in buck spermatozoa motility and DNA damage after thawing. 相似文献
185.
Arca Anil Omer Faruk Sadak Bartu Karakurt Dr. Yusuf Kocak Dr. Igor Lyubinetsky Prof. Dr. Emrah Ozensoy 《Chemphyschem》2023,24(13):e202200787
Understanding the activation of CO2 on the surface of the heterogeneous catalysts comprised of metal/metal oxide interfaces is of critical importance since it is not only a prerequisite for converting CO2 to value-added chemicals but also often, a rate-limiting step. In this context, our current work focuses on the interaction of CO2 with heterogeneous bi-component model catalysts consisting of small MnOx clusters supported on the Pd(111) single crystal surface. These metal oxide-on-metal ‘reverse’ model catalyst architectures were investigated via temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS) techniques under ultra-high vacuum (UHV) conditions. Enhancement of CO2 activation was observed upon decreasing the size of MnOx nanoclusters by lowering the preparation temperature of the catalyst down to 85 K. Neither pristine Pd(111) single crystal surface nor thick (multilayer) MnOx overlayers on Pd(111) were not capable of activating CO2, while CO2 activation was detected at sub-monolayer (∼0.7 ML) MnOx coverages on Pd(111), in correlation with the interfacial character of the active sites, involving both MnOx and adjacent Pd atoms. 相似文献
186.
Di Summa Marco Faruk Syed Md Omar 《4OR: A Quarterly Journal of Operations Research》2023,21(3):439-455
4OR - We consider the problem of removing a limited subset of nodes and/or edges from a graph in order to minimize the so-called pairwise connectivity of the residual graph, which is defined as the... 相似文献
187.
Shaval Mamedov Vilayet Alekperov Nursel Can Faruk Aras Gunes Yilmaz 《Macromolecular Symposia》2004,212(1):293-298
Degradation under the simultaneous effects of mechanical stress and temperature in polyolefins (PE, PP), composites on their basis (PE+PP fibre, PP+PP fibre, PP+glass fibre) and radiation low-density polyethylene (X-LDPE) used in high-voltage cables obeys the thermofluctuation theory of Zhourkov (in certain σ and τ0 intervals) based on the theory of Arrhenius is presented in the following form: τσ = τ0 exp[(U0 − γσ)/ RT] (1) where τ is durability. τ0 is a constant (10−12-10−13s) equal to period of vibrations of atoms around equilibrium position, U0 is the activation energy of the mechanical destruction process (at σ = 0), γ is a structure-sensitive parameter, T is absolute temperature and R is universal gas constant. Electric degradation under the effects of electric field and temperature in the materials mentioned above obeys the equation: τE = τ0 exp[(W0 − χE)/ RT] (2) Here, τE, W0 and χ are analogous to τσ, U0 and γ, respectively. It is assumed that the following equation is valid under the simultaneous effects of E, σ and T: τσ,E = τ0 exp[(U0 − (γσ + χE))/ RT]. (3) electric degradation 相似文献
188.
Assuming , we show that generalized eventually narrow sequences on a strongly inaccessible cardinal κ are preserved under a one step iteration of the Hechler forcing for adding a dominating κ-real. Moreover, we show that if κ is strongly unfoldable, and λ is a regular cardinal such that , then there is a set generic extension in which . 相似文献