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排序方式: 共有634条查询结果,搜索用时 15 毫秒
541.
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Monika J. Sienkowska Brad M. Rosen Virgil Percec 《Journal of polymer science. Part A, Polymer chemistry》2009,47(16):4130-4140
The development of Cu(0)/TREN/CuBr2‐catalyzed SET‐LRP of VC initiated with CHBr3 in DMSO at 25 °C is reported. The use of CuBr2 additive allows for the first LRP of low molecular weight VC (target DP = 100), as well as lower Cu powder loading levels, improved Ieff and control in the synthesis of higher molecular VC, targeted degree of polymerization = 350, 700, 1,000, 1,400. 1H NMR and HSQC confirm the bifunctionality of CHBr3 as an initiator and suggest that deleterious side‐reactions such as the formation of allylic chlorides occur primarily at the onset of the reaction. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4130–4140, 2009 相似文献
544.
Susana P. Boeykens Marta E. Daraio Norma Temprano Marta Rosen 《Macromolecular Symposia》2005,227(1):307-310
Scleroglucan aqueous solutions and gels were selected to study the dependence of diffusion behavior of alkali and alkaline-earth metal ions on matrix structural characteristics. Stokes and free diffusion experimental methods for obtaining diffusion coefficients were contrasted. Three different behaviors, corresponding to three well-defined concentration regimes of the polymeric system were found. 相似文献
545.
This paper is concerned with an extended growth curve model with two within-individual design matrices which are hierarchically related. For the model some random-coefficient covariance structures are reduced. LR tests for testing the adequacy of each of these random-coefficient structures and their asymptotic null distributions are derived. 相似文献
546.
Credit risk optimization with Conditional Value-at-Risk criterion 总被引:27,自引:0,他引:27
Fredrik Andersson Helmut Mausser Dan Rosen Stanislav Uryasev 《Mathematical Programming》2001,89(2):273-291
This paper examines a new approach for credit risk optimization. The model is based on the Conditional Value-at-Risk (CVaR)
risk measure, the expected loss exceeding Value-at-Risk. CVaR is also known as Mean Excess, Mean Shortfall, or Tail VaR. This
model can simultaneously adjust all positions in a portfolio of financial instruments in order to minimize CVaR subject to
trading and return constraints. The credit risk distribution is generated by Monte Carlo simulations and the optimization
problem is solved effectively by linear programming. The algorithm is very efficient; it can handle hundreds of instruments
and thousands of scenarios in reasonable computer time. The approach is demonstrated with a portfolio of emerging market bonds.
Received: November 1, 1999 / Accepted: October 1, 2000?Published online December 15, 2000 相似文献
547.
Mathematische Annalen - 相似文献
548.
549.
Tönu Kollo Dietrich von Rosen 《Annals of the Institute of Statistical Mathematics》1995,47(4):767-783
Approximations of density functions are considered in the multivariate case. The results are presented with the help of matrix derivatives, powers of Kronecker products and Taylor expansions of functions with matrix argument. In particular, an approximation by the Wishart distribution is discussed. It is shown that in many situations the distributions should be centred. The results are applied to the approximation of the distribution of the sample covariance matrix and to the distribution of the non-central Wishart distribution. 相似文献
550.