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排序方式: 共有190条查询结果,搜索用时 31 毫秒
11.
Francescone David Akula Sujeet Altunkaynak Baris Nath Pran 《Journal of High Energy Physics》2015,2015(1):1-48
Journal of High Energy Physics - We consider the AdS 2 /CFT 1 holographic correspondence near the horizon of rotating five-dimensional black holes preserving four supersymmetries in $$... 相似文献
12.
Experimental results on the extrapolated ultimate enhancement factors of o-, m-, and p-xylene protons at 1.53 mT are obtained for MC800 asphalt solutions. The ultimate enhancement factors are found such as ?26.9, ?25.7, and ?11.7 for o-, m-, and p-xylene, respectively. These results show that the solvent proton Overhauser effect cannot reach the extrapolated enhancement of ?330 in the extreme narrowing case because of occurrence of small scalar interactions in addition to the dipole–dipole interactions between solvent protons and asphalt electrons. The ortho, meta, and para positions of the –CH3 group change the nature of the interactions. The nuclear magnetic resonance (NMR) signal enhancements exhibit a sensitive behavior depending on the chemical environment differing from isomer to isomer. The solvation or association of asphalt in xylene isomers at room temperature is revealed. Quantum chemical calculations for the xylene isomers with the electronic and optical properties; absorption wavelengths, excitation energy, atomic charges, dipole moment and frontier molecular orbital energies, molecular electrostatic potential; are carried out using the density functional theory (DFT) method (B3LYP) with the 6-311G(d,p) basis set by the standard Gaussian 09 software package program. The relative importance of scalar and translational dipolar interaction parameters determined in dynamic nuclear polarization experiments is explained by the electronic structure of HOMO–LUMO of the xylene isomers. 相似文献
13.
Karadeniz-Bilgili MY Semelka RC Hyslop WB Pamuklar E Rivero H Firat Z Woosley JT 《Magnetic resonance imaging》2005,23(3):515-517
We report the MRI findings of primary small-cell carcinoma of the kidney (PSCCK) in a 59-year-old female. This tumor appeared as a 16-cm mass that arose from the right kidney. This lesion had diminished signal on T1-weighted images and heterogeneous mixed signal on T2-weighted images. The tumor primarily involved the renal medulla with persistent thin renal cortex. Despite the tumors' large size, no substantial central necrosis was present. The predominant medullary location and the lack of central necrosis in this large tumor were features unusual for renal cell carcinoma and should raise the suspicion of another malignancy, the differential diagnosis of which should contain extrapulmonary small-cell carcinoma of the kidney. 相似文献
14.
Firat AK Karakaş HM Yakinci C Altinok T Alkan A Biçak U 《Magnetic resonance imaging》2004,22(9):1329-1332
Acute disseminated encephalomyelitis (ADEM) is an immune-mediated demyelinating disorder usually encountered in children or adolescents and characterized by multifocal neurological deficits of rapid onset. Typical target areas of demyelination include the corona radiata, centrum semiovale, periventricular white matter, cerebellar peduncles and brainstem. Involvement of deep gray matter nuclei is also frequent. We report a 6-year-old boy with ADEM who had only brainstem involvement. Serial magnetic resonance images representing the stage of disease and response to steroid treatment are presented. 相似文献
15.
Cagatay Altinkok Baris Kiskan Yusuf Yagci 《Journal of polymer science. Part A, Polymer chemistry》2011,49(11):2445-2450
The preparation of soluble and processable polybenzoxazine precursors capable of forming high performance networks is an important field of research with a broad spectrum of application. This study demonstrates an approach that utilizes aromatic sulfonediamine, bisphenol‐A, and formaldehyde in Mannich‐type polycondesation to prepare polybenzoxazine precursor. The structure of the oligomeric precursor (Mn = 2600) was confirmed by FTIR and 1H NMR spectral analysis. The precursor contained both sulfone and benzoxazine ring structures in the backbone. It was shown that small amount of ring‐opened phenolic groups were also present. Thermally activated self‐curing behavior of precursor in the absence of catalyst was studied by differential scanning calorimetry. Thermal properties of the cured polymers were also investigated by thermo gravimetric analysis. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
16.
Isil Aydin Firat Aydin Abdurrahman Saydut E. Gulhan Bakirdere Candan Hamamci 《Microchemical Journal》2010,96(2):247-251
Composition of phosphate rocks mostly depend on their type and origin. Sedimentary rocks contain high concentration of heavy metals. Phosphate rocks are mainly used for the manufacturing of phosphate fertilizers. The contents of heavy metals Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn, as well as rare earth elements Ce, La, and Th were determined in sedimentary phosphate rock used for production of fertilizer in Turkey. The Kasrik-Semikan, Mazidag (Mardin, SE Anatolia, Turkey) high-grade phosphate rock used in this study is situated near the border with Syria and was deposited during the Turonian and Senonian (Cretaceous) ages. Total phosphorus (P) concentration in the rock is 18.5% on the average. Microwave acid digestion (MW-AD) followed by ?nductively Coupled Plasma-Optical Emission Spectrophotometry (ICP-OES) was carried out for the determination of all the elements of interest in phosphate rock. The results revealed that hazardous metal content of the phosphate rock was lower in Mazidag phosphate than that in samples imported from other countries and were within the safety limits. 相似文献
17.
Graphene is described at low energy by a massless Dirac equation whose eigenstates have definite chirality. We show that the tendency of Coulomb interactions in lightly doped graphene to favor states with larger net chirality leads to suppressed spin and charge susceptibilities. Our conclusions are based on an evaluation of graphene's exchange and random-phase-approximation correlation energies. The suppression is a consequence of the quasiparticle chirality switch which enhances quasiparticle velocities near the Dirac point. 相似文献
18.
In this study, it was aimed to investigate the chemical composition and antioxidant activities of two Euphorbia species. The major component of the fatty acid compositions obtained from the petroleum ether extracts was identified as palmitic acid for Euphorbia gaillardotii and Euphorbia macroclada. The main constituents of the essential oils were identified as arachidic acid for E. gaillardotii and tetratetracontane for E. macroclada. Among the 27 studied compounds, hesperidin, rutin, hyperoside and quinic, malic, gallic and tannic acids were found to be the most abundant compounds in the two Euphorbia species. The methanol extracts of E. gaillardotii and E. macroclada showed strong antioxidant activity in all tested methods. Particularly, IC50 values of E. macroclada methanol extract that was the richest in terms of total phenolic-flavonoid contents were found to be lower than α-tocopherol and butylated hydroxytoluene in β-carotene bleaching, 2,2-diphenyl-1-picrylhydrazyl free and ABTS cation radical scavenging methods. 相似文献
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