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41.
A one-pot synthesis of 2,3,5-trisubstituted cyclopentadienones has been delineated through ring contraction of suitably functionalized 2H-pyran-2-ones using either cyanoacetamide or methyl cyanoacetate. 相似文献
42.
43.
Pilot calculations have been performed to study the effect of surrounding plasma on several doubly excited states for a few astrophysically important, highly stripped ions of helium isoelectronic sequence Al11+, Si12+, P13+, S14+, and Cl15+. The transitions from 1s2:1Se → 2s2:1Se, 2p2:1De, 2s2p:1Po, 2s3d:1De and 2p3d:1Fo are studied. The effect of the plasma background is taken care of using the Debye screening model which admits of a wide variety of plasma conditions. Transition energies as well as the analytical wave functions of the doubly excited states have been obtained from a study of the pole positions of the collective oscillation modes in the two‐electron charge cloud under a time‐dependent harmonic perturbation. The response properties of the system are analyzed from the linearized version of a suitably constructed variational functional. Most of the calculated data are new. Our results agree well with the relatively few existing experimental and theoretical data for the free ions. The general trend of the results show systematic behavior with respect to increased plasma strength, and the data may be useful from the astrophysical viewpoint. The doubly excited state wave functions have been used to calculate the Coulomb repulsion integrals to check their consistency and may be useful for evaluating other physical properties connected with transitions and also estimating the rate coefficients for dielectronic recombination processes, which play a major role in the diagnostic determination of high‐temperature plasmas. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
44.
L. S. Koroleva A. A. Donina N. V. Tamkovich N. A. Kovalev M. A. Zenkova V. N. Sil’nikov 《Russian Chemical Bulletin》2005,54(11):2682-2691
Tetrapeptides based on amino acids involved in the catalytic site of RNase T1 were synthesized. These peptides interact with
a 96-mer fragment of HIV-1 RNA, which results in phosphodiester bonds splitting. The efficacy of RNA cleavage depends on the
mutual arrangement of oppositely charged amino acids (Glu and Arg or Lys) in a peptide. The introduction of an additional
cationic fragment (based on bis-quaternary salts of 1,4-diazabicyclooctane) into an RNase mimetic leads to a considerable
increase in the efficiency of RNA depolymerization.
For Part 5, see Ref. 1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2596–2604, November, 2005. 相似文献
45.
Aminocyclopentadienyl ruthenium complexes as racemization catalysts for dynamic kinetic resolution of secondary alcohols at ambient temperature 总被引:1,自引:0,他引:1
Choi JH Choi YK Kim YH Park ES Kim EJ Kim MJ Park J 《The Journal of organic chemistry》2004,69(6):1972-1977
Aminocyclopentadienyl ruthenium complexes, which can be used as room-temperature racemization catalysts with lipases in the dynamic kinetic resolution (DKR) of secondary alcohols, were synthesized from cyclopenta-2,4-dienimines, Ru(3)(CO)(12), and CHCl(3): [2,3,4,5-Ph(4)(eta(5)-C(4)CNHR)]Ru(CO)(2)Cl (4: R = i-Pr; 5: R = n-Pr; 6: R = t-Bu), [2,5-Me(2)-3,4-Ph(2)(eta(5)-C(4)CNHR)]Ru(CO)(2)Cl (7: R = i-Pr; 8: R = Ph), and [2,3,4,5-Ph(4)(eta(5)-C(4)CNHAr)]Ru(CO)(2)Cl (9: Ar = p-NO(2)C(6)H(4); 10: Ar = p-ClC(6)H(4); 11: Ar = Ph; 12: Ar = p-OMeC(6)H(4); 13: Ar = p-NMe(2)C(6)H(4)). The tests in the racemization of (S)-4-phenyl-2-butanol showed that 7 is the most active catalyst, although the difference decreased in the DKR. Complex 4 was used in the DKR of various alcohols; at room temperature, not only simple alcohols but also functionalized ones such as allylic alcohols, alkynyl alcohols, diols, hydroxyl esters, and chlorohydrins were successfully transformed to chiral acetates. In mechanistic studies for the catalytic racemization, ruthenium hydride 14 appeared to be a key species. It was the major organometallic species in the racemization of (S)-1-phenylethanol with 4 and potassium tert-butoxide. In a separate experiment, (S)-1-phenylethanol was racemized catalytically by 14 in the presence of acetophenone. 相似文献
46.
A coated-wire ion-selective electrode (ISE) based on cyclam (1,4,8,11-tetraazacyclotetradecane) as a neutral carrier in a polyvinyl chloride (PVC) matrix was fabricated for the determination of Ag(I) ions. The coated-wire ISE exhibited a linear Nernstian response over the range 1 x 10(-1) to 1 x 10(-7) M with a slope of 59 +/- 2 mV per decade change and a detection limit of 5 x 10(-8) M. The ISE shows a greater preference for Ag over other cations with good precision. The electrode was selective towards Ag(I) ions in the presence of 13 different metal ions tested. The selectivity coefficients (K(ij)) were determined for Na(I), K(I), Mg(II), Ca(II), Ba(II), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pb(II) and Hg(II). The selectivity coefficients of these cations are in the range of 10(-4) to 10(-2). This ISE was used for the determination of free silver and total silver in electroplating bath solutions, additives and brighteners. 相似文献
47.
Haimanti Chakrabarti Shreekantha Sil Srinanda Kundu 《Journal of solution chemistry》2010,39(9):1278-1290
This work gives estimated values of the velocity correlation coefficients VCCs for ternary electrolyte solutions (the system
may have a tracer ion as one of the components), utilizing available measured transport coefficients. The VCCs originate from
linear response theory and give a deeper insight into the microdynamic structure of complex ionic solutions. By assuming Onsager’s
relation to be valid, ten sets of velocity correlation coefficients were calculated for a ternary system and were used to
calculate the VCCs for 134Cs+ ion (present in trace amount) transport in aqueous solutions of CsCl and KCl at 25 ○C. 相似文献
48.
Matyshak V. A. Il’ichev A. N. Sadykov V. A. Sil’chenkova O. N. Korchak V. N. 《Kinetics and Catalysis》2015,56(2):226-236
Kinetics and Catalysis - The zirconium dioxide surface has a wide variety of adsorption sites differing in their nature. The proportions of these sites can be changed by varying the oxide... 相似文献
49.
A novel synthesis of highly functionalized alkylsulfanylmethyl arenes 8a-m through the ring transformation of 6-aryl-4-methyl/ethylsulfanyl-2H-pyran-2-one-3-carbonitriles 1a-j, by reaction with methyl vinyl ketone 2, is delineated and illustrated. To ascertain the course of reaction, 3-arylsulfanylmethyl-2-methyl-6-methylsulfanyl-4-phenylbenzonitriles 8k-m were also prepared from the reaction of 1 with 4-arylsulfanyl-butan-2-ones 7c,d. 相似文献
50.
Choi YS Kim YK Shim JH Kim EM Kang HS Yoon do Y Muneta Y Myung PK 《Experimental & molecular medicine》2006,38(5):574-582
Xenotransplantation, the transplantation of cells, tissues or organs between individuals of different species, would resolve the current shortage of organs, but rejection remains the major hurdle to successful xenotransplantation. In the present study, we analyzed mixed lymphocyte reactions (MLRs) and used 51Cr release assays in order to identify the proliferation and expansion of mouse CD8+ cytotoxic T lymphocyte cells against PK15, PK15/pIL-18 or PK15/mIL-18 cells. In addition, we identified T cell populations in mouse splenocytes and lymph node cells using two-color flow cytometry. It was found that the CD8+ T cells of xenograft recipients proliferated extensively and that the survival rates of populations of PK15/mIL-18 or PK15/pIL-18 cells were higher than untransfected controls. Moreover, CD3+ T cells were increased in mice injected with PK15 cells or PK15/pIL-18 cells but PK15/pIL-18 cell numbers were lower in lymph nodes than untransfected controls. CD8+ T cells numbers were reduced in the lymph nodes of PK15/pIL-18 injected mice. These results suggest that porcine IL-18 regulates anti-pig cellular rejection in C57BL/6 mice. 相似文献