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161.
The pressure dependence of the electrical resistivity of bulk GeSe2 glass shows a semiconductor-to-metal transition at 7 GPa pressure. The high pressure phase is examined using the x-ray diffractometer
and is found to be crystalline, with a face-centred cubic structure havinga = 4·06 A. The electrical conductivity has also been studied as a function of temperature at various pressures. 相似文献
162.
A relationship between the efficiency of a quartz transducer oscillating in organic liquids as expressed by the conversion of electricla input to the total heating and the ultrasonic absorption coefficients of those liquids has been worked out on the basis of the experimental work carried out earlier in this laboratory. 相似文献
163.
Withanolides, the secondary metabolite from Withania species is used in Ayurvedic medicine and now proved to have potential use in treating cardiovascular, Alzheimer’s disease, etc. Its production in plants varies between genotypes with very low yield. For improved industrial commercialisation, there is a need to increase its production. Endophytic fungi are symbiotically associated with plants and can synthesise the same bioactive compounds and natural products as their host plant. There are no reports available on withanolide-producing (endophytic) fungi. The present study identified an endophytic fungus (Taleromyces pinophilus) from leaves of Withania somnifera which produces withanolides in the medium. The structure of withanolide was confirmed by 1H NMR, LC-MS analyses and quantified by HPLC analysis. The fungus produces high amount of withanolide when compared to leaf and root of W. somnifera. The fungus can be exploited to produce the withanolide to meet its demand. 相似文献
164.
Electrical transport in Bi doped amorphous semiconductors (GeSe3.5)100?xBix (x=0,4,10) is studied in a Bridgman anvil system up to a pressure of 90 kbar and down to 77 K. A pressure induced continuous transition from an amorphous semiconductor to a metal-like solid is observed in GeSe3.5. The addition of Bi disturbs significantly the behaviour of resistivity with pressure. The results are discussed in the light of molecular cluster model for GeySe1?y proposed by Phillips. 相似文献
165.
The crystal and molecular structure of (—)-menthyl-p-bromophenylglyoxylate has been studied by x-ray diffraction techniques using diffractometer data. Crystals of this compound are triclinic:a= 10.152(3),b=19.661(3),c = 9.220(3) Å, α = 92.45(2), β = 102.74(4), γ = 93.11(4) °, andZ = 4. The structure was refined by least squares toR = 0.064. All 88 hydrogen atoms were determined from electron density difference maps. The significant structural features are the following: (i) the four molecules are conformationally different from one another; (ii) the two > C=O groups of the glyoxylate are twisted with respect to each other across the central C-C bond by angles ranging from 92 ° to 111 °; (iii) the phenyl group is coplanar with the proximal > C=O group; and (iv) all four molecules exhibit a conformation in which the axial hydrogens on the cyclohexane rings eclipse the closer keto oxygen. The absolute configuration was determined by the anomalous dispersion method and is (1R, 3R, 4S). 相似文献
166.
Zircons (20–100 mg) are decomposed within 1 h by fusion with potassium hydrogenfluoride followed by fuming with sulphuric acid. With differential-pulse anodic stripping voltammetry, after deposition for 1 min, the limit of detection for lead is 2 ng ml?1 and the limit of quantitation is 6.6 ng ml?1. Results (7–247 mg kg?1 lead) are reported for nine zircons. 相似文献
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