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901.
A series of novel N-methyl piperidine (Nmp)-based ionic liquids with 1,2-propanediol group are synthesized and used as catalysts for both hetero-Michael addition of α,β-unsaturated amides and Knoevenagel condensation at room temperature in water; and all the examined substrates could be transformed into corresponding products in good to excellent yields. Meanwhile IL-catalyzed hetero-Michael addition of α,β-unsaturated amides in water has not been reported in the previous literatures. Additionally, the catalyst is recyclable for the two reactions. This finding provides a green catalyst for both hetero-Michael addition of α,β-unsaturated amides and Knoevenagel condensation in water. 相似文献
902.
Bai JZ Bian JG Chen GP Chen HF Chen SJ Chen SM Chen Y Chen YQ Chen YB Cheng BS Cui XZ Ding HL Ding WY Du ZZ Fan XL Fang J Gao CS Gao ML Gao SQ Gu JH Gu SD Gu WX Gu YF Guo YN Han SW Han Y He J He M Hu GY Hu T Hu XQ Huang DQ Huang T Huang YZ Jiang CH Jin S Jin Y Kang SH Ke ZJ Lai YF Lan HB Lang PF Li F Li J Li PQ Li Q Li RB Li W Li WD Li WG Li XH Li XN Lin SZ Liu HM Liu J Liu JH Liu Q Liu RG Liu Y Liu ZA Lu JG Luo SQ Luo Y Ma AM 《Physical review letters》1996,76(19):3502-3505
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908.
Pancracio Palting Shan Tao Lai Ying Nan Chiu Jorge Ricardo Letelier 《Journal of mathematical chemistry》1997,21(1):31-49
Succinct expressions for the matrix elements of various vibrational operators have been derived in the basis of the nondegenerate
harmonic oscillator. Among these are the matrix elements of
and
, which are found to be dependent upon two quantities and their derivatives. Furthermore, the derivative property of the commutator
is used to obtain an explicit expression for the derivatives of an operator in terms of its nested commutator with the conjugate
momentum. It may be applied to any of the above cases to obtain the matrix representatives of expressions such as the mixed
products
, for example. In addition, a simple expression for 1/q is given and its derivatives may be evaluated by this commutator technique. Also the matrix elements of a Gaussian-type operator
has been evaluated.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
909.
Recent accurate data on F 2(x,Q) and on F 2 c (x,Q) from HERA at small-x require a more precise treatment of charm production in the global analysis of parton distributions. We improve on existing global QCD analyses by implementing the leptoproduction formalism of Aivazis et al. which represents a natural generalization of the conventional zero mass QCD parton framework to include heavy quark mass effects. We also perform analyses based on the fixed-flavor-number scheme, which is widely used in the literature, and demonstrate their uses and limitations. We discuss the implications of the improved treatment of heavy quark mass effect in practical applications of PQCD and compare our results with recent related works. 相似文献
910.
V. Fanti A. Lai L. Musa A. Nappi M.G. Setzu 《Zeitschrift fur Physik C Particles and Fields》1997,76(4):653-657
The rate of the decay of the neutral K meson into K L 0 → μμγ has been measured with the NA48 detector at the CERN SPS. A total of 59 events has been observed with an estimated background of 14 events. The overall Kaon flux was determined to be 1.2 × 109. This observation corresponds to a branching ratio of (3.4 ± 0.6stat ± 0.4sys × 10-7. Using this branching ratio the parameter αK* describing the relative strength of the two contributing amplitudes to this decay, through intermediate pseudoscalar or vectorlike mesons, was measured to be αK* = -0.04+ -0.21 +0.24 . 相似文献