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排序方式： 共有1333条查询结果，搜索用时 15 毫秒
21.
《Materials Letters》2005,59(24-25):3069-3072
The nanocrystalline ribbons Fe90.3−xZr7B2.7Cux with low Cu contents can be directly obtained through melt-spinning technique with an appropriate low quenching speed such as 22 m/s. Sizes of bcc-Fe grains precipitated in Fe90.3−xZr7B2.7Cux as-spun ribbons were 17 nm for x = 0.75, 15 nm for x = 1 and 12 nm for x = 1.25. The addition of Cu reduces grain size of bcc-Fe in as-spun nanocrystalline Fe90.3−xZr7B2.7Cux ribbons. Among the investigated samples (0.5 ≤ x ≤ 1.5), the largest magnetoimpedance can be obtained in the nanocrystalline Fe80.3Zr7B2.7Cu1 as-spun ribbon with x = 1. The value of magnetoimpedance (Z(H) − Z(0)) / Z(0) under H = 90 Oe for Fe80.3Zr7B2.7Cu1 as-spun ribbon reaches − 28.2% at a frequency of 1 MHz. 相似文献
22.
《International Journal of Engineering Science》2003,41(3-5):495-506
We introduce some geometrical structures in the phase space of a dynamical system, naturally defined by the system. We study some properties of these structures and discuss their use for the constructing new characteristics of chaotic dynamical behaviour. 相似文献
23.
《Materials Letters》2004,58(12-13):1956-1958
Rod-like single-phase crystals of Y-α-SiAlON were synthesized by combustion of Si, Al, α-Si3N4, SiO2 and Y2O3 powders. SEM observation of crystals, separated by chemical etching (HNO3/HF=2:1) followed by ultrasonic agitation in ethanol showed rod-like crystals, assigned to almost pure and well crystallized α-SiAlON. 相似文献
24.
25.
《Chemometrics and Intelligent Laboratory Systems》1999,45(1-2):347-351
In this paper, genetic algorithm (GA) was used to both sample the conformational spaces and thoroughly search the global conformations of peptides. δ-conotoxin PVIA, a peptide of 29 amino acids, was used to test our procedure. The results indicated that this procedure could not only successfully explore a set of the conformational spaces using a hybrid Monte Carlo simulations/GA minimization but also find the global conformations for most of peptides using pure GA minimization. 相似文献
26.
《Current Opinion in Solid State & Materials Science》1998,3(2):209-215
In the past two years molecular rectification and single electron transistor effects in molecular devices have been demonstrated. Because of the ambiguity of assigning these effects to particular molecules, research has turned to carbon nanotubes which are larger than more classical molecules. For optical applications bright and multicoloured organic light emitting diodes are available. 相似文献
27.
28.
《Optical Materials》2010,32(12):1828-1830
The results of the photoluminescence (PL) investigation of pure and chromium-doped MAlP2O7 (M = Na, K, Cs) compounds are presented. The spectra of the intrinsic luminescence of MAlP2O7 crystals consist of a separated UV band at a peak position near 330 nm and a complex wide band which covers the region of visible light up to 750 nm at excitation by VUV synchrotron radiation. The “red” band in 600–1000 nm diapason appears in the PL spectra of crystals doped with chromium ions. The effect of the temperature on the structure, the peak positions and intensities of the luminescence bands was studied. An assumption about the nature of the intrinsic PL was made. The “red” luminescence was considered as a result of the 4Т2 → 4А2 radiation transitions in the impurity Cr3+ ions located in the intermediate crystal field. 相似文献
29.
《Materials Chemistry and Physics》1986,15(6):559-566
New mixed valence oxides KTi2−xNb5+xO17', chemical twins of the rutile structure have been isolated, with O ⩽ x ⩽ 1.75. The electron transport and magnetic properties have been studied and compared to those of reduced rutile. These physical properties are interpreted in terms of a band model and of the existence of Nb(IV)-Nb(IV) pairs and Ti(III) species. 相似文献
30.