检索结果-南通市图书馆

A note on certain square functions on product spaces

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2006年第1期49卷 98-108页

作者： WANG Meng, CHEN Jiecheng2 & fan Dashan department of Mathematics, Zhejiang university (at Yuquan campus), hangzhou 310027, china department of Mathematics, Zhejiang university (at Xixi campus), hangzhou 310028, china department of Mathematics, university of Wisconsin-Milwaukee, Milwaukee, WI53201, USA department of Mathematics Zhejiang University [at Yuquan campus] Hangzhou 310027 China department of Mathematics Zhejiang University [at Xixi campus] Hangzhou 310028 China department of Mathematics University of Wisconsin-Milwaukee Milwaukee WI53201 USA

We study certain square functions on product spaces Rn × Rm, whose integral kernels are obtained from kernels which are homogeneous in each factor Rn and Rm and locally in L(log+ L) away from Rn × {0} and {0} × Rm by means of polynomial distortions in the radial variable. As a model case, we obtain that the Marcinkiewicz integral operator is bounded on Lp(Rn × Rm)(P > 1) for Ω∈ e Llog+ L(Sn-1 × Sm-1) satisfying the cancellation condition.

关键词： square function, Marcinkiewicz integral, product space.

Holocene sea level changes and coastline snitts in Zhejiang Province, china

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 1989年第1期8卷 101-111页

作者： Feng Huaizhen and Wang Zongtao department of geography, hangzhou university, hangzhou, china

In the present paper, the Holocene sea level changes and coastline shifts in Zhejiang, china are discussed, based on the ancient coastline evidence related with sea level changes and 21 14C dat-ings of shell, peat or mud and wood samples along the Zhejiang coast. The development of Zhejiang coastline during the Holocene period can be divided into four stages. A lot of data of historical period and modern times have shown that tracing coastline shifts back to its source, we have to consider tremendous effects of man's activities besides natural factors, such as elevation and subsidence of the earth crust, sea level changes, supply of sediment, and littoral hydrodynamics.

关键词： Holocene sea level changes and coastline snitts in Zhejiang Province china

Organic reactions in chiral micelles *** structural effects on the asymmetric oxidation of prochiral sulfides in chiral micelles

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 1990年第1期8卷 89-96页

作者： ZHANG,Yong-Min FU,Chun-Ling fan,Wei-Qiang department of Chemistry,hangzhou university,hangzhou 310028 department of Chemistry Hangzhou University Hangzhou 310028

A variety of phenyl alkyl sulfides were oxidized enantioselectively with NaIO_4 in chiral micellar systems formed from eight chiral surfactants,to give optical active *** enantiomer excesses ranged from 1.6 to 15.0%.To understand the mechanistic detail of this asymmetric oxi- dation in chiral micelle,the effects of structure both in substrates and surfactants on the optical yield of the oxidation were studied and ***,increasing the alkyl chain length both in sur- factants and in substrates enhances the optical yield,also the surfactant with hydroxy group at its appropriate position gives better enantioselectivity,suggesting the enzymic characteristics of the chiral micelle.

关键词： Organic reactions in chiral micelles 7.The structural effects on the asymmetric oxidation of prochiral sulfides in chiral micelles

A Novel Photoproduct of 2-Methoxycytosine in Phosphate Solution Under Far UV Irradiation

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1999年第8期10卷 623-624页

作者： Feng LIN Jin Long WU Xiao Wei fan (department of Chemistry, Zhejiang university. hangzhou 310028) Zhejiang Univ Dept Chem Hangzhou 310028 Peoples R China

Under the irradiation of medium pressure mercury lamp (MPML) the photolysis of 2-methoxycytosine (MAP) in phosphate solution leads to the production of a novel compound C5H8N3O5P. The composition and structure of the ... 详细信息

关键词： UV photolysis 2-methoxycytosine phosphate

A NOVEL DEPROTECTION OF ACETALS AND KETALS USING SODIUM HYDROGEN SELENIDES

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1995年第11期6卷 955-958页

作者： Ping LU Wei Qiang fan Xun Jun ZHOU (department of Chemistry,hangzhou university, 310028.) hangzhou Univ Dept Chem Hangzhou 310028 Peoples R China

The 1,3-dioxolanes, 1,3-dioxanes and open chain acetals or ketals are easily cleavaged by using sodium hydrogen selenide under basic conditions in high yields.

关键词：

Littlewood-Paley operators with variable kernels

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2006年第5期49卷 639-650页

作者： CHEN Jiecheng, DING Yong & fan Dashan department of Mathematics, Zhejiang university (Xixi Campus), hangzhou 310028, china School of Mathematical Sciences, Beijing Normal university, Beijing 100875, china department of Mathematics, university of Wisconsin-Milwaukee, Milwaukee WI 53201, USA department of Mathematics, Central china Normal university, Wuhan 430074, china department of Mathematics Zhejiang University [Xixi Campus] Hangzhou 310028 China School of Mathematical Sciences Beijing Normal University Beijing 100875 China department of Mathematics University of Wisconsin-Milwaukee Milwaukee WI 53201 USA department of Mathematics Central China Normal University Wuhan 430074 China

In this paper we study a certain directional Hilbert transform and the boundedness on some mixed norm spaces. As one of applications, we prove the Lp-boundedness of the Littlewood-Paley operators with variable kernels... 详细信息

关键词： directional Hilbert transform, Sobolev spaces, Littlewood-Paley operator,variable kernel.

STEREOCHEMICAL CONTROL IN PROPYLENE POLYMERIZATION CATALYZED BY UNBRIDGED METALLOCENE CATALYSTS

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2001年第4期19卷 407-413页

作者： Yin-bang Zhu Zhi-qiang fan Tariq Yasin Lin-xian Feng department of Polymer Science and Engineering Zhejiang university hangzhou 310027, china Zhejiang Univ Dept Polymer Sci & Engn Hangzhou 310027 Peoples R China

Two unbridged metallocene catalysts, bis(2,4,7-trimethylindenyl)zirconium dichloride (met-I) and bis(2,4,6-trimethylindenyl)zirconium dichloride (met-II), which are different in the position of substituents on the six-membered ring of the indenyl ligands were synthesized. The effect of substituents in the two metallocenes on the propylene polymerization was studied in the presence of methylaluminoxane (MAO) and triisobutylaluminium (TIBA). From the analysis of microstructure determined by C-13-NMR, it was demonstrated that the polymers produced by met-II have higher [mmmm] isotactic sequences than that of met-I. Using a mechanism based on model statistical analysis, it was found that chain-end model was dominant for met-I. However, met-II obeys the concurrent two-sites model during polymerization, which can be attributed to the existence of 'racemic-like' conformer in its system.

关键词： unbridged metallocene propylene polymerization elastomeric polypropylene stereochemical mechanism

Complete Universal Scaling in First-Order Phase Transitions

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2024年第10期41卷 8-13页

作者： fan Zhong School of Physics and State Key Laboratory of Optoelectronic Materials and Technologies Sun Yat-sen UniversityGuangzhou 510275China

Phase transitions and critical phenomena are among the most intriguing phenomena in nature and *** are classified into first-order phase transitions(FOPTs)and continuous *** the latter shows marvelous phenomena of scaling and universality,whether the former behaves similarly is a long-standing controversial *** we definitely demonstrate complete universal scaling in field driven FOPTs for Langevin equations in both zero and two spatial dimensions by rescaling all parameters and subtracting nonuniversal contributions with singular dimensions from an effective temperature and a special field according to an effective *** offers a perspective different from the usual nucleation and growth but conforming to continuous phase transitions to study FOPTs.

关键词： theory. transitions scaling

Semi-analytical Solutions for Wellbores with Graded Skin Zones in Poroelastic Media

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2024年第3期37卷 385-395页

作者： Zhiqiang fan Zhihe Jin School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an710072China department of Mechanical Engineering University of MaineOronoME04469USA

In analyzing the complex interaction between the wellbore and the reservoir formation,the hydromechanical properties of the region proximal to the wellbore,referred to as the“wellbore skin zone”,play a pivotal role in determining flow dynamics and the resulting formation *** models of the wellbore skin zone generally assume a constant permeability throughout,resulting in a sharp permeability discontinuity at the skin-reservoir *** paper introduces a model for a wellbore with a continuously graded skin zone of finite thickness within a poroelastic *** solutions are derived using the Laplace transform method,addressing both positive and negative skin *** results are presented to illustrate the effects of graded permeability/skin zone thickness on pore pressures and stresses around a *** results highlight a distinct divergence in stress and pore pressure fields when comparing wellbores with negative skin zones to those with positive skin zones or no skin at all.

关键词： Poroelastic Graded permeability Analytical solution Wellbore Skin zone