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121.
CM Thaker S Rayaprol Krushna Mavani DS Rana MS Sahasrabudhe SI Patil DG Kuberkar 《Pramana》2002,58(5-6):1035-1039
The effect of simultaneous substitution of a fluctuating cation and a divalent cation in LaMnO3 perovskite modifies the properties of the material to exhibit large valence colossal magnetoresistance (CMR) effect. A good
example of these properties is (La1−2x
Pr
x
Ca
x
)MnO3 (LPCMO) type CMR material. In this communication it is reported that, with the increase in x (for x=0.1, 0.15, 0.2), the T
c varies between 100 and 120 K with improvisation in metal-insulator transition. Interestingly, resistance increases with x from few hundred ohms to few kilo ohms with corresponding decrease in the unit cell volume. The results of the studies using
X-ray diffraction (XRD), electrical resistivity, magnetoresistance and ac susceptibility measurements on LPCMO samples for
understanding the structural, transport and magnetic properties are discussed in detail. 相似文献
122.
123.
In this paper we investigate the question: When does the direct product of partial orders each satisfying the normalized matching condition also satisfy it? A proof of Harper's result that a sufficient condition for this is that factor partial orders have rank populations that are multiplicatively convex, is presented. A general necessary and sufficient condition is described, and conditions which occur when one factor is a chain are obtained. In particular we show that under these circumstances it is necessary that the product order have multiplicatively convex population rank. 相似文献
124.
A shell-model calculation of the N = 51, 39 ≦ Z ≦ 42 nuclei is presented. The 88Sr nucleus is assumed to be an inert closed core. The extra-core protons are restricted to the (, ) configurations, and the active neutron is allowed to occupy the , , and orbits. The proton-proton effective interaction is directly taken from the previous analysis on the energy levels for N = 50 isotones by Ball et al. The proton-neutron effective interaction is assumed to be of the form of the surface δ-interaction. The energy spectra are calculated from a least-squares fit to the experimental data, varying the T = 0 and T = 1 strengths of the surface δ-interaction. Spectroscopic factors, E2 transition rates and two-body matrix elements are also calculated and compared with the observed values and the previous theoretical results. 相似文献
125.
Incorporation of precursors into aflatoxin-B1 总被引:2,自引:0,他引:2
J A Donkersloot D P Hsieh R I Mateles 《Journal of the American Chemical Society》1968,90(18):5020-5021
126.
R Setiono S-L Pan M-H Hsieh A Azcarraga 《The Journal of the Operational Research Society》2005,56(1):3-14
Data collected from a survey typically consist of attributes that are mostly if not completely binary-valued or binary-encoded. We present a method for handling such data where the underlying data analysis can be cast as a classification problem. We propose a hybrid method that combines neural network and decision tree methods. The network is trained to remove irrelevant data attributes and the decision tree is applied to extract comprehensible classification rules from the trained network. The conditions of the rules are in the form of a conjunction of M-of-N constructs. An M-of-N construct is a rule condition that is satisfied if (at least, exactly, at most) M of the N binary attributes in the construct are present. The effectiveness of the method is illustrated on data collected for a study of global car market segmentation. The results show that besides achieving high predictive accuracy, the method also allows meaningful interpretation of the relationships among the data variables. 相似文献
127.
Rutherford backscattering of 1.75 and 2 MeV 4He+ ions has been utilized to study the high temperature gettering of Fe, Co, Ni, Cu and Au from silicon by ion-damaged surface layers. In a typical experiment a metal film was evaporated onto one side of a silicon wafer (125 microm thick) which had received ion implantation damage (1016/cm2 Si+ ions at 100 keV) on the opposite side; the wafer was then annealed at 900°C, usually for 30 min. The results of such experiments show that the metals studied may be divided into two classes, those which are gettered slowly - Fe, Co, and Au, and those gettered rapidly - Cu and Ni. Fe, Co, and Au were found at levels of 1×1013?1×1014/cm2 in the damaged layer, whereas Cu and Ni appeared at levels of 6×1014 to 5 ×1016cm2. The gettered level of Au, one of the “slow” group, was increased ten-fold by an equal increase in the anneal time to 300 min. The gettered Cu and Au exhibited double peaks in the scattered ion spectra, corresponding to metal concentrated at the most heavily damaged region (end of range for Si implant) and also at the outer surface, with a separation of ~ 1300 Å. A simple model is proposed to explain the slow and fast gettering, based on published interstitial diffusivities and solubilities of the five elements studied.Rutherford scattering has proven to be well suited for the quantitative identification of low levels of impurities on Si surfaces and for impurities gettered at damaged layers close to the surface. 相似文献
128.
M. M. Shemyakin M. N. Kolosov M. G. Karapetyan Hsieh Yü-yüan V. V. Onoprienko 《Russian Chemical Bulletin》1964,13(6):953-962
Summary Intramolecular cyclization reactions were investigated, and the configurations were proved of 2- and 3-substituted 10-oxo-9-hydroxy-9-methyl-1,2,3,4a,9,9a.10-octahydroanthracenes of type (I), which are possible intermediaries for the synthesis of tetracyclines and their analogs.Translated from Izvestiya Akademii Nauk SSSR, Setiya Khimicheskaya, No. 6, pp. 1024–1035, June, 1964 相似文献
129.
Y.Y. Hsieh 《Solid State Communications》1973,12(11):1231-1234
We have studied the zero-temperature local surface modes that occur on a (001) surface of a Heisenberg ferromagnet with singlet-triplet crystal-field level scheme in the random phase approximation of the double-time Green function method. Experimental aspects of the present model are also discussed. 相似文献
130.
The electromigration of copper in lead was measured under isothermal conditions by a steady-state method. 64Cu was introduced into the lead solvent as a radioactive tracer solute. After electromigration, the steady-state, concentration-distance curve was determined by standard sectioning, weighing and counting techniques. Although the experiments extend from 215 to 303°C, the measurements for Z1, the effective charge number for copper in lead, appear to show at low temperature a strong dependence on concentration and are also difficult to reproduce satisfactorily in this temperature range. Accordingly only the results in the range from 240°C and up have been included in calculating the electromigration parameters. These results give Z1 in the range 1.1 ± 0.3 and indicate an electrostatic charge, Zel, of 1,8 ±0.9. 相似文献