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81.
A one-pot synthesis of 6-mercaptopurines from 4,5-diamino-6-chloro-pyrimidine, an aldehyde and elemental sulfur is presented. The key advantage of this procedure is that it utilizes the in situ generated H2S to convert the chloro to a mercapto group. 相似文献
82.
Dhavale DD Markad SD Karanjule NS PrakashaReddy J 《The Journal of organic chemistry》2004,69(14):4760-4766
The asymmetric dihydroxylation of a d-glucose derived alpha,beta-unsaturated ester 3 afforded syn vicinal diols in good to high diastereoselectivity. The conversion of these vicinal diols to the corresponding cyclic sulfate, regio-, stereoselective nucleophilic ring opening by sodium azide, and LAH reduction afforded amino heptitols 7a,b that were converted to azepane 1c,d and nojirimycin analogues 2c,d. 相似文献
83.
Precise conductance measurements of solutions of lithium chloride, lithium bromide, lithium iodide, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, tetrabutylammonium bromide, and tetrabutylammonium tetraphenylborate in N,N-dimethylacetamide are reported at 25°C in the concentration range 0.005–0.015 mol-dm–3. The conductance data have been analyzed by the 1978 Fuoss conductance equation in terms of the limiting molar conductance (0), the association constant (K
a), and the association diameter (R). The limiting ionic conductances have been estimated from an appropriate division of the limiting molar conductivity of the reference electrolyte Bu4NBPh4. Slight ionic association was found for all these salts in this solvent medium. The results further indicate significant solvation of Li+ion, while the other ions are found to be unsolvated in N,N-dimethylacetamide. 相似文献
84.
Precise conductance measurements have been performed for lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, sodium perchlorate, and sodium tetraphenylborate in 2-methoxyethanol–water mixtures at four different mole fractions, i.e., 0.056, 0.136, 0.262, and 0.486 of 2-methoxyethanol (69.73 D 26.55) at 25°C in the concentration range 0.0004–0.0642 mol-dm–3. The limiting molar conductivity °, the association constant K
A, and the association distance R for the solvent mixtures have been evaluated from the conductance concentration data using the 1978 Fuoss conductance equation. The single-ion conductances have been estimated using the reference electrolyte tetrabutylam-monium tetraphynylborate(Bu4NBPh4). The analysis of the data indicates that for most salts ion association is appreciable in the solvent mixtures with a mole fraction of the cosolvent of 0.262 or higher. The results have been interpreted in terms of ion-solvent interactions and structural changes in the mixed solvent media. 相似文献
85.
M.M. Kanitkar V.N. Shukla P.L. Kanitkar Dilip S. Joag 《Solid State Communications》1984,50(9):817-819
Metallic glass Fe40Ni40B20 is imaged at liquid hydrogen temperature in field ion microscope. Pair and angular distributions are obtained from the analysis of a large number of micrographs. The pair distribution is found to exhibit features typical of metallic glasses. The angular distribution agrees well with the theoretical distribution for Lennard-Jones glass obtained by Jacobaeus et al. The closer agreement achieved has been attributed to the better experimental conditions and the improved resolution of field ion microscope. 相似文献
86.
Wonsook Ha Robert S. Mansell Dilip Shinde Nam-Ho Kim Husein A. Ajwa Craig D. Stanley 《Transport in Porous Media》2009,78(1):77-99
Pre-plant application of toxic fumigants to soil beds covered by plastic film is commonly used in agriculture to control soil-borne
pathogens. Plastic mulch covers tend to physically suppress the emissive loss of gaseous fumigant to the atmosphere. When
liquid fumigant metham sodium (MS) is applied in irrigation water to field soil, it is rapidly transformed to the gaseous
methyl isothiocyanate (MITC). The gaseous MITC is a potential atmospheric contaminant, and any untransformed MS is a potential
contaminant of underlying groundwater due to the high water solubility of MS. A finite element numerical model was developed
to investigate two-dimensional MITC fate/transport under non-isothermal soil conditions. Directional solar heating on soil
beds, coupled heat and water flow in the soil, and non-isothermal chemical transport were included in the model. Field soil
data for MITC distribution, soil water content, meteorological data, and laboratory data were used to verify the model for
soil beds covered with plastic mulch. Four possible scenarios were considered: low and high drip-irrigation rates and low
and high water contents. The movement of the center of MITC mass in the soil profile was effectively simulated. The lower
drip-irrigation rate of MS yielded more extensive coverage of MITC in the plastic-covered soil bed. The lower soil air contents
due to higher soil water contents for the higher irrigation rate resulted in high concentrations of soil MITC. NRMSE (normalized
root mean square error) calculations further verified that the model predicted fumigant fate/transport well under these non-isothermal
field conditions. 相似文献
87.
Ashok B. Bhise Niranjan S. Ramgir Imtiaz S. Mulla Dilip S. Joag 《Applied Surface Science》2007,253(23):9159-9163
Field emission studies of a bunch and a single isolated RuO2:SnO2 wire have been performed. A current density of 5.73 × 104 A/cm2 is drawn from the single wire emitter at an applied field of 8.46 × 104 V/μm. Nonlinearity in the Fowler-Nordheim (F-N) plot has been observed and explained on the basis of electron emission from both the conduction and the valence bands of the semiconductor. The current stability recorded at the preset value of 1.5 μA is observed to be good. Overall the high emission current density, good stability and mechanically robust nature of the RuO2:SnO2 wires offer advantages as field emitters for many potential applications. 相似文献
88.
Dilip K. Sinha 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1965,16(3):411-418
Zusammenfassung Die Gleichungen für die quasi-eindimensionale Strömung einer idealen, reibungslosen, kompressiblen und elektrisch vollkommen leitenden Flüssigkeit unter Wärmezufuhr und unter dem Einfluss eines willkürlichen Magnetfeldes werden in charakteristischer Form dargestellt.Wird die Untersuchung beschränkt auf kleine Störungen in einer ursprünglich parallelen, isentropen Strömung konstanten Querschnittes, so können die Grundgleichungen linearisiert werden. Hierzu wurden allgemeine Lösungen entwickelt.Die Lösungen für die entsprechenden Probleme aus der konventionellen Gasdynamik und für die Strömung unter dem Einfluss eines quergerichteten Magnetfeldes sind als Spezialfälle mitenthalten. 相似文献
89.
Dilip K. Sinha 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1969,20(4):553-556
Summary In the present note, the equations of electricity and the equations of motion have been used to investigate the disturbances in a piezoelectric slab excited by a step electric field. The application of the Laplace transform facilitates the solution of the problem. 相似文献
90.
Two possible methods to determine the spatial average temporal average intensity I(sata) and ultrasonic power W in composite ltrasonic transducers for medical application are described. Results showed that integrals using one method will yield accurate results but a vast amount of computational effort is required. On the other hand, using an alternative method these integrals may readily be solved at the expense of the accuracy of the results deduced. 相似文献