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排序方式: 共有239条查询结果,搜索用时 15 毫秒
91.
Mansour Nawasreh 《中国化学快报》2008,19(12):1391-1394
The symmetrical diketone Ⅱ, which can be synthesized in gram scale using a well established method, was used as a starting material to prepare the 11α-methoxy ketomethylene Ⅵ. This is in continuation of our study aiming at the synthesis of multihydroxylated cephalostatin analogues, as for example cephalostatin 1Ⅰ, a potent anti-tumor natural product. Compound Ⅵ underwent chemo- and regioselective hydroboration reaction at only one of △14.15 double bonds furnishing compound Ⅸ as a major product in a fair yield. 相似文献
92.
93.
讨论了在q=2的情形下,Littlewood-Paley gλ^*函数在加权Herz型Hardy空间中的有界性,即当0〈p〈∞,1/2≤α〈1/2+ε时,gλ^*是HK2^α,p(ω1,ω2)到K2^α,p(ω1,ω2)中的有界算子.推广了文献[3]中的结果. 相似文献
94.
朱茂春 《数学年刊A辑(中文版)》2014,35(1):1-20
设 $X_{1},\cdots ,X_{q}\ (q相似文献
95.
This paper reports the synthesis of 4-arm poly(tert-butyl acrylate) stars of different molar masses up to 106 g/mol by the “core-first” method using ATRP. All obtained stars have a monomodal and narrow molar-mass distribution (<1.2).The dilute-solution properties of these star polymers were investigated in good solvents (tetrahydrofuran and acetone). Gel permeation chromatography and dynamic and static light scattering were used to measure the hydrodynamic properties including intrinsic viscosity [η], radius of gyration Rg, hydrodynamic radius Rh, second virial coefficient A2 and diffusion coefficient D0. These data were used to establish relationships between these parameters and the molar mass of 4-arm poly(tert-butyl acrylate) stars. The branching parameters g and g′ and the shape factor ρ were calculated for all obtained star polymers. 相似文献
96.
在本文中,我们研究了满足条件$D^*=D(~)$的*-双单型$A\omega^2$-半群的同构,给出了它们之间的同构定理. 相似文献
97.
《Optimization》2012,61(2):135-158
Parametric and nonparametric sufficient optimality conditions are established for a class of nonsmooth generalized fractional programming problems containing ρ-univex functions. Subsequently, these optimality criteria are utilized as a basis for construction of two parametric and four parameter–free duality models and proving appropriate duality theorems 相似文献
98.
本文研究ρ-混合随机变量序列的加权和.利用文献[10]的矩不等式,在勿需控制混合系数的情况下,得到了完全收敛的充分条件,对“同分布”情形,得到了完全收敛的必要条件,推广了文献[8,10]中的有关结果. 相似文献
99.
The critical point set plays a central role in the theory of Tchebyshev approximation.Generally,in multivariate Tchebyshev approximation,it is not a trivial task to determine whether a set is critical or not.In this paper,we study the characterization of the critical point set of S 0 1(△) in geometry,where is restricted to some special triangulations(bitriangular,single road and star triangulations).Such geometrical characterization is convenient to use in the determination of a critical point set. 相似文献
100.
From Scalar to Vector Optimization 总被引:3,自引:0,他引:3
Initially, second-order necessary optimality conditions and sufficient optimality conditions in terms of Hadamard type derivatives
for the unconstrained scalar optimization problem ϕ(x) → min, x ∈ ℝ
m
, are given. These conditions work with arbitrary functions ϕ: ℝ
m
→ ℝ, but they show inconsistency with the classical derivatives. This is a base to pose the question whether the formulated
optimality conditions remain true when the “inconsistent” Hadamard derivatives are replaced with the “consistent” Dini derivatives.
It is shown that the answer is affirmative if ϕ is of class
(i.e., differentiable with locally Lipschitz derivative).
Further, considering
functions, the discussion is raised to unconstrained vector optimization problems. Using the so called “oriented distance”
from a point to a set, we generalize to an arbitrary ordering cone some second-order necessary conditions and sufficient conditions
given by Liu, Neittaanmaki, Krizek for a polyhedral cone. Furthermore, we show that the conditions obtained are sufficient
not only for efficiency but also for strict efficiency. 相似文献