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81.
Amita Agrawal Nidhi Sharma Som K. Mishra Prem D. Sharma 《Transition Metal Chemistry》1992,17(6):547-551
The second order kinetics of uric acid oxidation by hexacyanoferrate(III) in acetate buffers were studied by estimating oxidant
colorimetrically at 420 nm. Two moles of organic acid react with one mole of the oxidant and oxidation products are alloxan
and urea.
TMC 2661 相似文献
82.
The dependence of geomagnetic activity on solar features and interplanetary (IP) parameters is investigated. Sixty-seven intense
(−200 nT ≤ Dst < −100 nT) and seventeen superintense (Dst < −200 nT) geomagnetic storms (GMSs) have been studied from January
1996 to April 2006. The number of intense and superintense GMSs show three distinct peaks during the 11-year period of 23rd
solar cycle. The largest number of high strength GMSs are observed during maximum phase of solar cycle. Halo and partial halo
CMEs are likely to be the major cause for these GMSs of high intensity. No relationship is observed between storm duration
and the number of CMEs involved in its occurrence. The intensity of the GMS is also independent of the number of CMEs causing
the occurrence of storm. These geoeffective CMEs show western and northern bias. Majority of the geoeffective CMEs are associated
with X-ray solar flares (SFs). Solar and IP parameters, e.g., V
CME, V
SW, B, B
z
(GSE and GSM coordinates) and their products, e.g., V
SW · B and V
SW · B
z
are observed and correlated to predict the occurrence of intense GMSs. V
CME does not seem to be the appropriate parameter with the correlation coefficient, r = −0.2 with Dst index, whereas the correlation coefficient, r = −0.57, −0.65, 0.75, −0.68 and 0.77 of the parameters V
SW, B, B
z
, V
SW · B and V
SW · B
z
respectively, with Dst indicating that V
SW · B
z
and B
z
may be treated as the significant contributors in determining the strength of GMSs.
相似文献
83.
Assessing agreement is often of interest in biomedical sciences to evaluate the similarity of measurements produced by different raters or methods on the same subjects. We investigate the agreement structure for a class of frailty models that are commonly used for analyzing correlated survival outcomes. Conditional on the shared frailty, bivariate survival times are assumed to be independent with Weibull baseline hazard distribution. We present the analytic expressions for the concordance correlation coefficient (CCC) for several commonly used frailty distributions. Furthermore, we develop a time-dependent CCC for measuring agreement between survival times among subjects who survive beyond a specified time point. We characterize the temporal pattern in the time-dependent CCC for various frailty distributions. Our results provide a better understanding of the agreement structure implied by different frailty models. 相似文献
84.
Alcohol based sols of cerium chloride (CeCl3·7H2O) and titanium propoxide (Ti(OPr)4) in ethanol mixed in different mole ratios have yielded mixed oxide films on densification at 500 °C. The reversibility of the intercalation/deintercalation reactions has shown electrochemical stability of the films. Addition of TiO2 in an equivalent mole ratio manifests in producing highly transparent films with appreciable ion storage capacity. The electrochemical studies have revealed the significant role of TiO2 in controlling the ion storage capacity of the films, as it tends to induce the disorder. In addition, the films prepared from an aged sol are observed to exhibit a much higher ion storage capacity than the films deposited using the as-prepared sol. The X-ray photoelectron spectroscopic studies have provided information on the variation of Ce4+/Ce3+ ratio as a function of increased TiO2 content in the films. This study has led to a better understanding of the increased ion storage capacity with the increased TiO2 proportion. The transmission electron microscopic study has demonstrated the presence of CeO2 nanograins even in films, which are amorphous to X-rays. Elucidation of the structural, optical and electrochemical features of the films has yielded information on aspects relevant to their usage in transmissive electrochromic devices. The films have been found to exhibit properties that can find application as counter electrode in electrochromic smart windows in which they are able to retain their transparency under charge insertion, high enough for practical uses. Also, the fastest coloration-bleaching kinetics for the primary electrochromic electrode (WO3) working in combination with Ce/Ti (1:1) electrode stimulates the use of latter in electrochromic windows (ECWs). 相似文献
85.
86.
87.
A simple generic one-dimensional continuum model of driven dissipative systems is proposed to explain self-organized bursty heat transport in tokamaks. Extensive numerical simulations of this model reproduce many features of present day tokamaks such as submarginal temperature profiles, intermittent transport events, 1/f scaling of the frequency spectra, propagating fronts, etc. This model utilizes a minimal set of phenomenological parameters, which may be determined from experiments and/or simulations. Analytical and physical understanding of the observed features has also been attempted. 相似文献
88.
The Hartree-Bogoliubov (HB) framework of calculations has been applied for calculating various nuclear structure quantities
for 154–166Dy mass chains. In this framework, the intrinsic quadrupole moments, the low-lying yrast states (E
2+ and E
4+) and occupation numbers for various shell model orbits have been obtained. The calculated results indicate that the observed
onset of deformation in going from 154Dy to 166Dy arises due to enhanced occupation of (h
11/2)π orbit, increased polarization of (d
5/2)π orbit and increase in the occupation of down-slopping ‘k’ components of (i
13/2)υ and (h
9/2)υ orbits.
相似文献
89.
90.
The conformational preferences of thiohydroxamic acids (N-hydroxythioamides) are investigated by the density functional B3LYP/6-311++G(3df,3pd)//B3LYP/6-31G(d) method in this work. Unlike hydroxamic acids, the thione and thiol forms are found to be equally stable in the gas phase, and the reaction pathways for the interconversion between the thione and thiol forms have been deduced to involve rotation about the C[double bond, length as m-dash]N bond of the thiol tautomer in the rate-determining step. The effect of aqueous solvation on the reactions has also been investigated. It is found that inclusion of a few explicit water molecules in an implicit solvent calculation is necessary in order to accurately account for hydrogen bonding effects. Thiohydroxamic acids, like their hydroxamic acid analogues, are found to be N-acids, both in the gas phase and in aqueous solution. 相似文献