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81.
Quenching of the eutectoidal composition of the shape memory alloys (SMA’s) allowed us to display the gradual transition of
the martensitic structure as a function of the composition. Indeed, we have verified that for low Al and Ni percentages, the
martensite structure obtained is β′, while, for high Al and Ni (Al<13.3 mass%) contents, the martensite structure is essentially
of β1′ type. Elsewhere, we have observed that a nickel addition (<4.3 mass%) operates simultaneously on the composition of the
eutectoidal pointand the domain of the different martensitic structures types. During reheating of the quenched structure,
the transformation sequences of the martensite to the parent phase (β1), then the decomposition of the later phase into the
equilibrium phases, and finally, the redissolution of all phases to form the β phase at high temperature, are rather similar.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
82.
83.
The dielectric responses (i.e. the refractive indices and the second order nonlinear susceptibilities) of all orthorhombic rare earth molybdates have been studied on the basis of the relationship between dielectric responses and the average atomic number of constituent atoms of crystals. Both the linear and second order nonlinear optical responses at 1.064 μm decrease with increasing atomic number from La to Lu. 相似文献
84.
Bond covalency and valence of elements in HgBa2Can−1CunO2n+2+δ (n=1, 2, 3, 4) were calculated and their relationship with Tc was discussed. For both oxygen and argon annealed samples, the results indicated that with the increase of n, the trend of bond covalency of Hg-O and Cu-O was the same or opposite compared with that of superconducting temperature. This may suggest that the magnitudes of Cu-O and Hg-O bond covalency are important in governing the superconducting temperature. For the highest Tc sample, Hg had the lowest valence, implying that lower valence of Hg was preferred in order to produce higher Tc. For fixed n, the valence of Cu in oxygen annealed samples was larger than that in argon annealed samples, indicating that oxygen annealed samples produced more carriers than argon annealed samples. 相似文献
85.
The high-temperature cubic phase of non-stoichiometric strontium ferrite SrFeOx (2.5≤x≤3.0) has been studied by in situ neutron powder diffraction in air over the temperature range 300-1273 K. The composition of SrFeOx changes within the range 2.56≤x≤2.81 from 1273 to 673 K, respectively.Rietveld refinements of the diffraction patterns show that the high-temperature cubic phase of SrFeOx is consistent with a face-centred Fm3c structure. This structure leads to agreement with previous density measurements. This cell allows the high-temperature structure of SrFeOx to be described in terms of a solid solution of the composition end members. Cubic SrFeOx at high temperature is found to closely obey Vegard's law. The density of cubic SrFeOx is also found to exhibit a linear relationship with composition. 相似文献
86.
王佐芳 《山东理工大学学报:自然科学版》2005,19(4):107-110
最佳资金结构的确定,关系到股份制企业资金成本的高低和财务风险的大小.如何通过筹资发挥财务杠杆的作用,确定最佳资金结构是股份制企业筹资决策的关键.针对这一问题,比较详细地介绍了每股利润分析法、比较资金成本法在确定最佳资金结构中的运用. 相似文献
87.
曾六川 《数学年刊A辑(中文版)》2002,(6)
设X是p一致凸Banach空间,具有弱一致正规结构与非严格的Opial性质.又设C是X的非空凸弱紧子集.在适当的条件下,证明了C上每个渐近正则半群T={T(t):t∈S}都有不动点进一步,在类似的条件下,也讨论了一致凸Banach空间中渐近正则半群的不动点的存在性. 相似文献
88.
陈孝胜 《重庆三峡学院学报》2002,18(2):85-88
投资主体结构调整是投资结构调整的重点,也是我国全面实施经济结构调整中的重要组成部分,更是西部大开发的关键。西部地区要改变以前不合理的投资主体结构,需要从转变投资观念,改善投资环境,投资主体以政府投资为主转向多元化投资,投资客体从硬件力向软件等方面来调整投资结构。 相似文献
89.
The rotational spectra of the deuterium cyanide isotopic species DCN, D13CN, DC15N, and D13C15N were recorded in the vibrational ground and first excited bending state (v2=1) up to 2 THz. The R-branch transitions from J=3←2 to J=13←12 were measured with sub-Doppler resolution. These very high resolution (∼70 kHz) and precise (±3-10 kHz) saturation dip measurements allowed for resolving the underlying hyperfine structure due to the 14N nucleus in DCN and D13CN for transitions as high as J=10←9. Additional high JR-branch (J=25←24 to J=28←27) transitions around 2 THz and direct l-type (ΔJ=0, J=19 to J=25) transitions from 66 to 118 GHz were recorded in Doppler-limited resolution. For the ground state of D13C15N, the J=1←0 transition was measured for the first time. The transition frequency accuracies for the other deuterated species were significantly improved. These new experimental data, together with the available infrared rovibrational data and previously measured direct l-type transitions, were subjected to a global least squares analysis for each isotopomer. This yielded precise sets of molecular constants for the ground and first excited vibrational states, including the nuclear quadrupole and magnetic spin-rotation coupling constants of the 14N nucleus for DCN and D13CN. The hyperfine structure due to the D, 13C, and 15N nuclei have not been resolved, but led to a broadening of the observed saturation dips. 相似文献
90.
A convective flow CO laser composed of polytetrafluoroethylene discharge tubes, nickel–chromium steel components, a cupric heat exchanger and other components is described. Operating in liquid nitrogen condition, output power of 60 W has been obtained from a non-selective cavity. 相似文献