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91.
Synthesis of fluoromethylated materials via Michael addition reaction catalyzed by l-proline in an ionic liquid, is described. Further, the synthesis and synthetic application of zinc reagents generated in an ionic liquid, giving trifluoromethylated materials, are described.  相似文献   
92.
A general model for predicting the total residual stresses generated during filling and cooling stages of injection-molded parts has been developed. The model takes into account the phenomena associated with non-isothermal stress relaxation. The main hypothesis in our approach is to use the kinematics of a generalized Newtonian fluid at the end of the filling stage as the initial state for the calculation of residual flow stresses. These stresses are calculated using a single integral rheological model (Wagner model). The calculation of stresses developed during the cooling stage is based on a thermoviscoelastic model with structural relaxation. Illustrative results emphasizing the effect of both the melt temperature and the flow rate during the filling stage are presented.  相似文献   
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The aim of the present study was to assess the short-term effects of Thymoquinone (TQ) on oxidative stress, glycaemic control, and renal functions in diabetic rats. DM was induced in groups II and III with a single dose of streptozotocin (STZ), while group I received no medication (control). The rats in groups I and II were then given distilled water, while the rats in group III were given TQ at a dose of 50 mg/kg body weight/day for 4 weeks. Lipid peroxidase, nitric oxide (NO), total antioxidant capacity (TAC), glycated haemoglobin (HbA1c), lipid profiles, and renal function were assessed. Moreover, the renal tissues were used for histopathological examination. STZ increased the levels of HbA1c, lipid peroxidase, NO, and creatinine in STZ-induced diabetic rats in comparison to control rats. TAC was lower in STZ-induced diabetic rats than in the control group. Furthermore, rats treated with TQ exhibited significantly lower levels of HbA1c, lipid peroxidase, and NO than did untreated diabetic rats. TAC was higher in diabetic rats treated with TQ than in untreated diabetic rats. The histopathological results showed that treatment with TQ greatly attenuated the effect of STZ-induced diabetic nephropathy. TQ effectively adjusts glycaemic control and reduces oxidative stress in STZ-induced diabetic rats without significant damaging effects on the renal function.  相似文献   
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Summary : Temperature-sensitive hydrogels undergo a volume phase transition (VPT) when heated above a critical temperature Tc. For the poly(N-isopropyl acrylamide) (PNIPA)-water system, Tc. = 34 °C. Below Tc the gels are transparent and highly swollen. On warming above Tc they promptly turn white and start to deswell. The rate of deswelling, however, can be orders of magnitude slower than that of swelling below Tc. The unstable intermediate structure above Tc, can retain the solvent and conserve the sample volume for may days, even with millimetre-sized samples. Light scattering observations of the internal structure of these gels above Tc are precluded by their strong turbidity. Small angle X-ray scattering measurements (SAXS), on the other hand, are less subject to multiple scattering as X-rays penetrate more easily into the bulk material. Conventional (incoherent) SAXS observations reveal intense scattering from smooth internal water-polymer interfaces with an estimated surface area of about 7 m2/g in the swollen gel. The dynamics in the off-equilibrium high temperature state, investigated by X-ray photon correlation spectroscopy (XPCS), displays a relaxation rate that is linearly proportional to the wavevector q, rather than to q2 as in diffusion processes. The physical origin of this relaxation is consistent with jamming, a phenomenon that is common in other disordered systems.  相似文献   
96.
A unified treatment of one-electron two-center integrals over noninteger n Slater-type orbitals is described. Using an appropriate prolate spheroidal coordinate system with the two atomic centers as foci, all the molecular integrals are expressed by a single analytical formula which can be readily and compactly programmed. The analysis of the numerical performance of the computational algorithm is also presented. Received: 1 April 1999 / Accepted: 2 July 1999 / Published online: 2 November 1999  相似文献   
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Periodica Mathematica Hungarica - We characterize p-rational real quadratic fields in terms of generalized Fibonacci numbers. We then use this characterization to give numerical evidence to a...  相似文献   
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