tetrahydrobenzo[b]pyran derivatives 1 were utilized for the synthesis of several new pyrano[2,3-d]pyrimidine derivatives 2. compound 2 was obtained in the presence of ac2o/h2so4 (as a catalyst) and was confirmed by spectroscopic data such as ir, 1h nmr and 13c nmr. ab initio calculation was carried out to study geometric optimization, thermodynamic parameters, aromaticity and dynamic process of...

We have evaluated the NMR shielding tensors for A:T,G:C,A:U in Watson-crick, and U-quartet. We have computed NMR shielding tensors at B31YP level by using 6-31G(d) basis set. We have compute anisotropy and asymmetry in A:T,G:C,A:U and U-quartet. The NMR shielding tensors were calculated using the GIAO method. The natural bonding orbital analysis (NBO) were performed. NBO calculation have been ...

we have evaluated the nmr shielding tensors for a:t,g:c,a:u in watson-crick, and u-quartet. we have computed nmr shielding tensors at b31yp level by using 6-31g(d) basis set. we have compute anisotropy and asymmetry in a:t,g:c,a:u and u-quartet. the nmr shielding tensors were calculated using the giao method. the natural bonding orbital analysis (nbo) were performed. nbo calculation have been ...

hydrolysis of ethylene-vinyl acetate copolymer in alkaline conditions using two systems of naoh/methanol and koh/isopropanol has been studied and the formation of ethylene-vinyl alcohol copolymer was systematically examined using nmr spectroscopy and dsc measurements. vinyl acetate weight percentage and the degree of hydrolysis were calculated from nmr spectroscopy and it is shown that hydrolys...

Abstractl Density functional theory (DFT) was used to investigate the effects of intra-moecular interactions and implicit water molecules on the relative stability and the NMR shielding tensors of hallucinogenic harmine in the monomeric and dimeric states. Results represented that the relative stability and the NMR shielding tensors are dependent on the resonance interactions and chemical envir...

permeability is a property of porous medium that quantifies rock capacity to transmit fluids. frequently, core based permeability data are not available either because of the borehole conditions or due to the high cost of coring. for these reasons, over the years attempts have been made to estimate permeability by alternative ways. permeability is an elusive parameter in hydrocarbon reservoirs ...

introduction: the aim of this study was to evaluate the changes in camp and some other cellular ingredients following adenyl cyclase activation in paragigantocellularis (pgi) neurons of morphine dependent and withdrawn rats. material and methods: the 3.5 mm thick brainstem slice prepared from pgi area (-10.04 to -13.24 from bregma) of control and morphine dependent rats (n=5 in each group). wer...

as drug delivery systems nanoparticulan widely investigated because of many advantages such as smaller size,controlled drug release potential targeting ability, enhancement of therapeutic efficacy and reduction oftoxicity. so, carbon nanotubes have recently received considerable attention as alternative drug delivery carrierin this study we investigate interaction of tamoxifen with open-end of ...

the interaction of dppa which is an important component in cellular membrane with molecules of water asmedia, cause some changes in geometry of dppa .in this study we focused our attention on comparing thismolecule with related hydrated complexes employing different basis sets at hartree-fock levels of theory. thetheoretical nmr shielding tensor of some imported atoms were also reported.

the ethyl acetate partition of dried methanolic extract of aerial parts of euphorbia microsciadia (euphorbiaceae) afforded three pentacyclic triterpenes, betulinic acid (1) from lupane type, oleanolic acid (2) from oleane type and ursolic acid (3) from ursane type triterpenes that are reported for the first time in this plant. these three compounds were structurally compared through their mass ...