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排序方式: 共有1192条查询结果,搜索用时 15 毫秒
921.
G. Ramesh Kumar S. Gokul Raj K.A. Bogle S.D. Dhole V.N. Bhoraskar R. Mohan 《Applied Surface Science》2008,254(16):5231-5235
l-Threonine single crystals have been irradiated by 6 MeV electrons. Irradiated crystals at various electron fluences were subjected to various techniques such as UV–vis–NIR, atomic force microscopy (AFM) and thermomechanical analyses. Thermal strength of the irradiated crystals has also been studied through differential scanning calorimetry (DSC) measurements. The results have been discussed in detail. 相似文献
922.
We investigate the Bianchi type-V bulk viscous barotropic fluid cosmological model with variable gravitational constant G and the cosmological constant A, assuming the condition on metric A/A=B/B=C/C=m/tn potential aswhere A, B, and C are functions of time t, while m and n are constants. To obtain the deterministic mo del, we also assume the relations P = p - 3η H, p = 7P, η = ηop^s, where p is the isotropic pressure, η the bulk viscosity,0≤r≤1 H the Hubble constant, ηo and s are constants. Various physical aspects of the model are discussed.The case of n = 1 is also discussed to compare the results with the actual universe. 相似文献
923.
Locally rotationally symmetric (L.R.S.) Bianchi type V bulk viscous tilted stiff fluid cosmological model is investigated. To get the deterministic model of the universe, we have also assumed a condition A=Bn between metric potentials A, B where n is the constant. The behaviour of the model in presence and absence of bulk viscosity and singularities in the model are also discussed. In general, the models represent accelerating, shearing, tilted and non-rotating universe. The models have point type singularity in presence and absence of bulk viscosity both. 相似文献
924.
Bianchi type I cosmological models with time-varying cosmological constant Λ and bulk viscous fluid are investigated. Cosmic
matter is chosen to obey a barotropic equation of state. Exact solutions of Einstein’s field equations are obtained assuming
the volume expansion θ proportional to the eigen values of shear tensor σ
ij
. Physical and kinematical properties of the models are discussed considering bulk viscosity to be a power function of matter
density. 相似文献
925.
Raj Bali Mahbub Ali Vimal Chand Jain 《International Journal of Theoretical Physics》2008,47(9):2218-2229
A magnetized stiff fluid cylindrically symmetric universe with two degrees of freedom for perfect fluid distribution, is investigated.
The magnetic field is due to an electric current produced along x-axis. The distribution consists of an electrically neutral perfect fluid with an infinite electrical conductivity. The behaviour
of the model in presence and absence of magnetic field is discussed. The other physical aspects of the model related to the
observations are also discussed. 相似文献
926.
Elucidating the fitness measures optimized during the evolution of complex biological systems is a major challenge in evolutionary theory. We present experimental evidence and an analytical framework demonstrating how biochemical networks exploit optimal control strategies in their evolutionary dynamics. Optimal control theory explains a striking pattern of extremization in the redox potentials of electron transport proteins, assuming only that their fitness measure is a control objective functional with bounded controls. 相似文献
927.
Vishal Sharma Raj Kumar Karan Devgan Pawan Kumar Mishra Adam Ekielski Vijay Kumar 《光谱学快报》2018,51(5):205-215
The multivariate analysis methods have recently gained high popularity within the field of forensic sciences because of their high accuracy and precision. The accurate and unbiased results are the preliminary need for a forensic investigation. The aim of the present work is to examine the marker pen inks which are widely used in various places like documentation in parcels, for photograph attestation, and also as a study material in the classroom. This research is focused on the three important aspects; first is to characterize the marker inks, second, to discriminate permanent marker and whiteboard marker inks using destructive (extracting of ink samples from paper substrate) and nondestructive (without ink extraction) techniques of ultraviolet–visible absorbance combined with peak identification examination as well as chemometric methods, and the third is to build a classification model for permanent and whiteboard marker inks. It is concluded that the chemometric method, that is, principal component analysis provides better discrimination power as compared to visual examination. However, destructive and nondestructive approaches give almost similar discriminating power. The classification model developed using linear discriminant analysis provides 87.5% of correct classification of marker ink samples. The method can further be used to formulate a statistical model for the determination of class/group of the other forensic exhibits. 相似文献
928.
929.
Pema Raj Sijo Joseph Thandapilly Jeffrey Wigle Shelley Zieroth Thomas Netticadan 《Molecules (Basel, Switzerland)》2021,26(21)
Atherosclerosis, myocardial infarction (MI) and heart failure (HF) are the main causes of mortality and morbidity around the globe. New therapies are needed to better manage ischemic heart disease and HF as existing strategies are not curative. Resveratrol is a stilbene polyphenolic compound with favorable biological effects that counter chronic diseases. Current evidence suggests that resveratrol is cardioprotective in animal models of atherosclerosis, ischemic heart disease, and HF. Though clinical studies for resveratrol have been promising, evidence remains inadequate to introduce it to the clinical setting. In this narrative review, we have comprehensively discussed the relevant compelling evidence regarding the efficacy of resveratrol as a new therapeutic agent for the management of atherosclerosis, MI and HF. 相似文献
930.
Calculations have been made for the quadrupole splitting of a spin state of Te125 in an amorphous GexTe1?x system. The results favour the existence of a threefold coordinated black phosphorus structure with an excess of TeTe chains for x-values between o and 0.5; beyond 0.5, threefold coordinated GeTe and an excess of amorphous Ge coexist. 相似文献