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排序方式: 共有613条查询结果,搜索用时 15 毫秒
71.
Designing Excited States: Theory‐Guided Access to Efficient Photosensitizers for Photodynamic Action
72.
Yusuf Mülazim Memet Vezir Kahraman Nilhan Kayaman Apohan 《Journal of Sol-Gel Science and Technology》2011,59(3):613-620
10B containing organic–inorganic hybrid coating material based on a UV-curable formulation was prepared via anhydrous sol–gel
technique. UV curable coatings were applied on Plexiglas (PMMA) substrates. The molecular structure of the coating material
was analyzed by ATR-FTIR spectroscopy technique. The characterization of the UV-curable coating was evaluated by various techniques
such as gel content, abrasion resistance, chemical resistance, pencil hardness, pendulum hardness, MEK rubbing test, contact
angle, cross-cut test, gloss, transmittance test, neutron absorption, Limiting Oxygen Index and stress–strain tests. Hybrid
coatings showed a significant enhancement in radiation shielding properties. The thermal behavior of coatings was also evaluated.
It is observed that the thermal stability of coatings mainly depends on their boron and silicate contents. Results of all
analysis conducted on hybrid films, and coatings were discussed. 相似文献
73.
Can OD Ismail IB Oztürk Y Oztürk N Potoğlu-Erkara I Sagratini G Ricciutelli M Vittori S Maggi F 《Natural product research》2011,25(15):1469-1472
This study was designed to investigate possible antidepressant-like effects of the extract prepared from the flowers of Hypericum montbretti Spach. (Guttiferae, Clusiaceae). Phytochemical constituents of the methanolic extract were analysed by HPLC method. The main flavonoid component was detected as rutin, and another highly concentrated phenolic compound was quercitrin. Antidepressant activity of the extract was examined by tail suspension and modified forced swimming tests, whereas the motor coordination of the animals was tested by the Rota-Rod apparatus. Reboxetine at a dose of 20 mg?kg?1 was used as a reference drug. Dose-dependent antidepressant activity was observed in both tests following the administration of extract at 100 and 250 mg?kg?1 doses. To the best of our knowledge, this is the first study reporting the antidepressant activity of H. montbretti extract. Additionally, the results of this work support previous papers reporting the antidepressant activity of rutin. 相似文献
74.
A new N-TEMPO-3,5-di-tert-butylsalicylaldimine radical (1) has been synthesized and characterized by single crystal X-ray diffraction, elemental analysis, IR, UV–vis, and EPR spectroscopy and temperature dependent magnetic susceptibility. X-ray diffraction revealed that H-atoms of γ-CH in TEMPO and CH3 in salicylaldimine moieties, are located in close contact with the neighboring N–O radical group in crystal 1. The temperature dependence of the magnetic susceptibility (χm) of 1 has been fitted by the Curie–Weiss law with θ = −0.3 K within 10–300 K, suggesting the presence of a weak intermolecular antiferromagnetic interaction between radical centers at T < 10 K. It has been demonstrated that radical 1 possesses crystal structure involving co-existence of antiferromagnetic and ferromagnetic interactions through C–H?O–N contacts of γ-CH and tBu groups hydrogen atoms, in which the former path dominates over the latter. 相似文献
75.
Shale-Gas Permeability and Diffusivity Inferred by Improved Formulation of Relevant Retention and Transport Mechanisms 总被引:5,自引:0,他引:5
A theoretically improved model incorporating the relevant mechanisms of gas retention and transport in gas-bearing shale formations
is presented for determination of intrinsic gas permeability and diffusivity. This is accomplished by considering the various
flow regimes according to a unified Hagen–Poiseuille-type equation, fully compressible treatment of gas and shale properties,
and numerical solution of the non-linear pressure equation. The present model can accommodate a wide range of fundamental
flow mechanisms, such as continuum, slip, transition, and free molecular flow, depending on the prevailing flow conditions
characterized by the Knudsen number. The model indicates that rigorous determination of shale-gas permeability and diffusivity
requires the characterization of various important parameters included in the present phenomenological modeling approach,
many of which are not considered in previous studies. It is demonstrated that the improved model matches a set of experimental
data better than a previous attempt. It is concluded that the improved model provides a more accurate means of analysis and
interpretation of the pressure-pulse decay tests than the previous models which inherently consider a Darcian flow and neglect
the variation of parameters with pressure. 相似文献
76.
Yusuf Uar Nuri M. Yamurlu hsan elikkaya 《Numerical Methods for Partial Differential Equations》2019,35(2):478-492
The aim of this study is to obtain numerical behavior of a one‐dimensional modified Burgers' equation using cubic B‐spline collocation finite element method after splitting the equation with Strang splitting technique. Moreover, the Ext4 and Ext6 methods based on Strang splitting and derived from extrapolation have also been applied to the equation. To observe how good and effective this technique is, we have used the well‐known the error norms L2 and L∞ in the literature and compared them with previous studies. In addition, the von Neumann (Fourier series) method has been applied after the nonlinear term has been linearized to investigate the stability of the method. 相似文献
77.
The differential cross sections for coherent scattering of 59.5 keV γ-rays by Mo and Sn were measured using a high-purity germanium detector. The results were compared with predictions of form factor theories and S-matrix calculations. 相似文献
78.
79.
Baris Kiskan Güniz Demiray Yusuf Yagci 《Journal of polymer science. Part A, Polymer chemistry》2008,46(11):3512-3518
Novel side‐chain benzoxazine functional polyvinylchloride (PVC‐Benzoxazine) was synthesized by using “Click Chemistry” strategy. First, approximately 10% of chloro groups of PVC were converted to azido groups by using NaN3 in N,N‐dimethylformamide. Propargyl benzoxazine was prepared independently by a ring closure reaction between p‐propargyloxy aniline, paraformaldehyde, and phenol. Finally, azidofunctionalized PVC was coupled to propargyl benzoxazine with high efficiency by click chemistry. The spectral and thermal analysis confirmed the presence of benzoxazine functionality in the resulting polymer. It is shown that PVC containing benzoxazine undergoes thermally activated curing in the absence of any catalyst forming PVC thermoset with high thermal stability. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3512–3518, 2008 相似文献
80.
Seda Yurteri Ioan Cianga A. Levent Demirel Yusuf Yagci 《Journal of polymer science. Part A, Polymer chemistry》2005,43(4):879-896
1,4‐Dibromo‐2‐(bromomethyl)benzene and 1,3‐dibromo‐5‐(bromomethyl)benzene were used as initiators in the atom transfer radical polymerization of styrene in conjunction with CuBr/2,2′‐bipyridine as a catalyst. The resulting polystyrene (PSt)‐based macromonomers, possessing at one end a 2,5‐dibromophenylene or 3,5‐dibromophenylene moiety, were used in combination with 2,5‐dihexylbenzene‐1,4‐diboronic acid for Suzuki coupling in the presence of Pd(PPh3)4 as a catalyst or with the system NiCl2/2,2′‐bipyridine/triphenylphosphine/Zn for Yamamoto polymerization. Polyphenylenes (PPs) with PSt chains as substitution groups were obtained. The same macromonomers were used in Yamamoto copolycondensation reactions, in combination with a poly(ε‐caprolactone) (PCL) macromonomer, and this resulted in PPs with PSt/PCL side chains. The obtained PPs had good solubility properties in common organic solvents at room temperature similar to those of the starting macromonomers. The new polymers were characterized with 1H (13C) NMR, IR, and gel permeation chromatography. The optical properties of the polymers were monitored with UV and fluorescence spectroscopy. The thermal behaviors of the macromonomers and final PPs were investigated with differential scanning calorimetry and compared. The morphology of PPs containing PSt and PCL blocks was characterized with atomic force microscopy, and a microphase‐separated layered morphology was observed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 879–896, 2005 相似文献