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861.
The degree of alkylation of the side chain nitrogen in tryptamines is one important factor that affects psychoactivity. The method of Speeter and Anthony is considered to be one of the most important synthetic preparative methods. The final step in this reaction is based on the reduction of a (substituted) indole-3-yl-glyoxalylamide to the desired tryptamine with metal hydride. Twelve symmetrically and 13 asymmetrically N,N-disubstituted glyoxalylamides and their corresponding tryptamine derivatives have been synthesised and characterised by gas chromatography EI-ion trap mass spectrometry, electrospray-triple quadrupole-tandem mass spectrometry and NMR spectroscopy. Mass spectral and NMR similarities and differences between the investigated compounds are discussed. A solvent dependency is observed that has to be taken into consideration for the unambiguous assignment of (1)H- and (13)C-NMR chemical shifts. The (1)H-NMR study demonstrated that one can evaluate the rotamer populations of the asymmetrical glyoxalylamides. In a forensic or clinical scenario where single or multiple reaction monitoring approaches are contemplated, the appropriate ion transitions of choice may then focus on the two main fragmentations, namely beta-cleavage ([M+H](+)-->CH(2)N(+)R(2)R(3)) and/or alpha-cleavage ([M+H](+)-->[3-vinylindole](+)), respectively. The synthesis, NMR and MS analytical data presented provide the forensic analyst and clinical biochemist with a detailed and self-consistent body of information and mechanisms for the spectral identification of the more likely psychoactive tryptamines that may be met. 相似文献
862.
Reaction of HCl with [RhCl(C2H4)(PR3)]2 affords the dinuclear alkylrhodium(III) complex [RhCl2(C2H5)(PR3)]2, the structure of which has been determined crystallographically. PR3 is the formerly unknown trialkyl phosphine tBu2PCH2CH2C6H3-2,6-Me2, prepared in three steps from tBuPCl2. Treatment of the title compound with CO gives the mononuclear rhodium dicarbonyl cis-[RhCl(CO)2(PR3)], being the first fully characterized complex of this type. 相似文献
863.
Abazov VM Abbott B Abdesselam A Abolins M Abramov V Acharya BS Adams DL Adams M Ahmed SN Alexeev GD Alton A Alves GA Amos N Anderson EW Arnoud Y Avila C Baarmand MM Babintsev VV Babukhadia L Bacon TC Baden A Baldin B Balm PW Banerjee S Barberis E Baringer P Barreto J Bartlett JF Bassler U Bauer D Bean A Beaudette F Begel M Belyaev A Beri SB Bernardi G Bertram I Besson A Beuselinck R Bezzubov VA Bhat PC Bhatnagar V Bhattacharjee M Blazey G Blekman F Blessing S Boehnlein A Bojko NI Borcherding F 《Physical review letters》2002,88(19):191801
We present the results of a search for leptoquark (LQ) pairs in (85.2+/-3.7) pb(-1) of pp* collider data collected by the D0 experiment at the Fermilab Tevatron. We observe no evidence for leptoquark production and set a limit on sigma(pp*-->LQLQ-->nunu+jets) as a function of the mass of the leptoquark (m(LQ)). Assuming the decay LQ-->nuq, we exclude scalar leptoquarks for m(LQ) < 98 GeV/c(2), and vector leptoquarks for m(LQ) < 200 GeV/c(2) and coupling which produces the minimum cross section, at a 95% confidence level. 相似文献
864.
Bröring M Tejero EC Pfister A Brandt CD Pérez Torrente JJ 《Chemical communications (Cambridge, England)》2002,(24):3058-3059
The metalation reactions of the 2,2'-bidipyrrin 4 with different rhodium(I) precursors yield the complexes 5 and 6 and the unusual corrinoid 7, depending only on the type of the ancillary ligand employed. 相似文献
865.
We show that for a thin superconducting strip placed in a transverse dc magnetic field--the typical geometry of experiments with high-T(c) superconductors--the application of a weak ac magnetic field perpendicular to the dc field generates a dc voltage in the strip. This voltage leads to the decay of the critical currents circulating in the strip, and eventually the equilibrium state of the superconductor is established. This relaxation is not due to thermally activated flux creep but to the "walking" motion of vortices in the two-dimensional critical state of the strip with in-plane ac field. Our theory explains the shaking effect that was used for detecting phase transitions of the vortex lattice in superconductors. 相似文献
866.
L.M. Fisher V.S. Stolyarov M.L. Nesterov E.H. Brandt 《Solid State Communications》2006,138(3):157-159
A contact-free method to obtain the current-voltage characteristics (CVC) of hard superconductors by measuring the relaxation of the magnetization in a perpendicular magnetic field is developed. The relaxation curves obtained for melt-textured YBCO samples are well fitted by curves calculated within the electrodynamic model using a power-law CVC. This procedure uses only two fitting parameters, namely, the critical sheet current Jc and the exponent m of the power-law CVC. 相似文献
867.
868.
We examine the correlation function of an impurity spin I in an interacting spinsystem, containingS-spins of different magnetic moment. ThisS-spin-system is simulated by aXY-model. In the case the impurity spin interacts with all spins of theS-system the correlation function has a Gaussian behaviour. This Gaussian behaviour is fitted quite well by the correlation function for the range of theI-S interaction up to threeS-spins. 相似文献
869.
870.
A new computational approach is developed for the analysis of vortex-dominated flow fields around highly swept wings at high angles of attack. In this approach an inviscid Euler technology is coupled with viscous models, similar to inviscid/boundary layer coupling. The viscous nature of the vortex core is represented by an algebraic model derived from the Navier–Stokes equations. The approach also accounts for the effects of the viscous shear layer near a wing surface through a modified surface boundary condition. The inviscid/viscous coupling consistently provides improved predictions of leading edge separation, vortex bursting and secondary vortex formation at relatively low computational cost. Results for several cases are compared with wind tunnel tests and other Euler and Navier-Stokes solutions. 相似文献