Dirichlet空间上的超循环复合算子

设Bn是复平面C中的单位圆盘(n=1)或复空间Cn中的单位球.众所周知,在Hardy空间上存在丰富的符号在Aut(Bn)中的超循环复合算子.然而,在复平面中单位圆盘上的Dirichlet空间中, 任何复合算子都不能是超循环的.本文则证明,当n>1时,Bn上的Dirichlet空间中确有超循环复合算子.     

The Non-Singularity and Regularity of GP-Vˊ-Rings

In this paper,we introduce a non-trivial generalization of ZI-rings-quasi ZI-rings.A ring R is called a quasi ZI-ring,if for any non-zero elements a,b ∈ R,ab = 0 implies that there exists a positive integer n such that an = 0 and anRbn = 0.The non-singularity and regularity of quasi ZI,GP-Vˊ-rings are studied.Some new characterizations of strong regular rings are obtained.These effectively extend some known results.     

Intermolecular cyclocondensation reaction of 3,4-dihydropyrimidine-2-thione under the Mitsunobu reaction conditions

A self-intermolecular cyclocondensation reaction of 3,4-dihydropyrimidine-2-thione(DHPM) to give a novel tricyclic structure containing DHPM core in the presence of diethyl azodicarboxylate(DEAD) and triphenylphosphine(TPP) at room temperature is reported.     

Expression and Characterization of the Intracellular Part of Receptor Protein Tyrosine Phosphatase PTPRU

PTPRU is an MAM domain-containing receptor-like protein tyrosine phosphatase. Previous studies have demonstrated an important role of the enzyme in the maintenance of epithelial integrity and in the regulation of the Wnt/β-catenin signaling pathway. To better understand the function of PTPRU, we cloned and expressed the intracellular portion of PTPRU as a GST fusion protein in E. coli cells. We purified the protein to homogeneity and used it to immunize mice for antibody production. The resultant antibody s...     

Structure of MgSO_4 in Concentrated Aqueous Solutions by X-Ray Diffraction

Detailed time-and-space-averaged structure of MgSO4 in the concentrated aqueous solutions was investigated via X-ray diffraction with an X’pert Pro θ-θ diffractometer at 298 K, yielding structural function and radial distribution function(RDF). The developed KURVLR program was employed for the theoretical investigation in consideration of the ionic hydration and ion association. Multi-peaks Gaussian fitting method was applied to deconvolving the overlapping bands of Differential radial distribution function...     

Synthesis of cyclicβ-silylenones via oxidative rearrangement of tertiaryα-hydroxy allylsilanes with PCC

An oxidative rearrangement of cyclic tertiary a-hydroxy allylsilanes has been carried out in refluxing ClCH₂CH₂Cl with pyridinium chlorochromate（PCC）.The reaction provides a convenient method to synthesize cyclicβ-silylenones in modest to excellent yields.     

Design and Synthesis of Chiral Molecular Tweezers Based on Deoxycholic Acid

Molecular tweezers is a novel type of artificial receptors, which not only offer the advantage of efficient construction but also their surfaces can be tailored for specific applications. The clefts of molecular tweezers are particularly effective in regard to complementarity with substrates since functional groups attached to the interior of the cleft converge on substrates held inside1. So, in recent years, the molecular tweezers receptors have attracted more and more attention in molecular …     

IMMOBILIZED CIBACRON BLUE F3G-A ON CROSSLINKED POLY(VINYL ALCOHOL) FOR AFFINITY CHROMATOGRAPHY

1. INTRODUCTION Biospecific affinity chromatography is a powerful technique for purification of proteins [1]. The biological affinity ligands in common use include enzyme substrates, inhibitors, cofactors, receptors, antibodies, etc. The advantage of these biological ligands is their very high recognition specialty for particular proteins. As a result, proteins can be purified in fewer steps, often to homogeneity, in a laboratory scale. However, scale-up of the analytical and laboratory p…     

First Total Synthesis of 5_α-Hydroxy-isopterocarpolone

Sesquiterpenic compounds of the Eudesmane family have attracted considerable attention due to their intriguing biological properties1,2, particularly significant antifeedant activity, cell growth inhibitory and plant growth regulating activities.In 1996, J. Hu and co-workers3 had isolated eudesmane sesquiterpene 5?-hydroxy-isopterocarpolone 1 from the aerial parts of chinese folk medicine Artemisia eriopoda and elucidated its structure by spectropic methods. Herein, we reported the first tota…     

On surfaces immersed in Euclidean space R~4 Dedicated to Professor Yang Lo on the Occasion of his 70th Birthday

Let M be a closed oriented surface immersed in R4 . Associated it one has the generalized Gauss map from M into the Grassmann manifold G 4,2 . This note will be concerned with the geometry of the generalized Gauss map by using the moving frame theory and the quaternion interpretation of Plcker coordinates. As one of consequences,we get the celebrated theorem of Chern and Spanier,Hoffman and Osserman,who proved it by quite different methods. At last,we give an explicit construction of a series of immersions of S2 in R4 with any given normal Euler number.