检索结果-南通市图书馆

Variational construction of unbounded orbits in Lagrangian systems

在线全文

学校读者我要写书评

暂无评论

Science china mathematics 2010年第3期53卷 617-624页

作者： CHENG Chong-Qing 1, & li xia 2 1 department of mathematics, nanjing university, nanjing 210093, china 2 department of mathematics, Suzhou university of Science and Technology, Suzhou 215001, china department of mathematics Nanjing University Nanjing China department of mathematics Suzhou University of Science and Technology Suzhou China

We show the existence of unbounded orbits in perturbations of generic geodesic flow in T2 by a generic periodic potential. Different from previous work such as in Mather (1997), the initial values of the orbits obtain... 详细信息

关键词： positive definite Lagrangian variational method unbounded orbit

Regular n-simplices in R^n with vertices in Z^(n)

在线全文

学校读者我要写书评

暂无评论

Science china mathematics 2004年第1期47卷 104-113页

作者： xia Jianguo & QIN Hourongdepartment of mathematics, nanjing Normal university, nanjing 210097, china (email: jgxia@***) department of mathematics, nanjing university, nanjing 210093, china Dept. of Math. Nanjing Normal Univ. Nanjing 210097 China Dept. of Math. Nanjing Univ. Nanjing 210093 China

In this paper the Ⅰ and Ⅱ regular n-simplices are introduced. We prove that the sufficient and necessary conditions for existence of an Ⅰ regular n-simplex in Rn are that if n is even then n = 4m(m + 1), and if n is odd then n = 4m + 1 with that n + 1 can be expressed as a sum of two integral squares or n = 4m - 1, and that the sufficient and necessary condition for existence of a Ⅱ regular n-simplex in Rn is n = 2m2 - 1 or n = 4m(m+1)(m 6 N). The connection between regulars-simplex in Rn and combinational design is given.

关键词： regular n-simplex in Rn, quadratic form.

On contactomorphism group of contact structure overtwisted at infinity on R^3

在线全文

学校读者我要写书评

暂无评论

Science china mathematics 2007年第8期50卷 1087-1092页

作者： li YU department of mathematics,nanjing university,nanjing 210093,china department of mathematics Nanjing University Nanjing China

We compute all the homotopy groups of the compactly supported contactomorphism group of a contact structure on R^3 which is overtwisted at infinity.

关键词： contactomorphism overtwisted contact structure

On the 3-rank of tame kernels of certain pure cubic number fields

在线全文

学校读者我要写书评

暂无评论

Science china mathematics 2010年第9期53卷 2381-2394页

作者： li YuanYuan & QIN HouRong department of mathematics,nanjing university,nanjing 210093,china department of mathematics Nanjing University Nanjing China

In this paper,we present some explicit formulas for the 3-rank of the tame kernels of certain pure cubic number fields,and give the density results concerning the 3-rank of the tame *** examples are given in Tables 1 ... 详细信息

关键词： the 3-rank of the tame kernels pure cubic fields density

Global dimension and left derived functors of Hom

在线全文

学校读者我要写书评

暂无评论

Science china mathematics 2007年第6期50卷 887-898页

作者： li-xin MAO & Nan-qing DING Institute of mathematics, nanjing Institute of Technology, nanjing 211167, china department of mathematics, nanjing university, nanjing 210093, china Institute of mathematics Nanjing Institute of Technology Nanjing China department of mathematics Nanjing University Nanjing China

It is well known that the right global dimension of a ring R is usually computed by the right derived functors of Hom and the left projective resolutions of right R-modules. In this paper, for a left coherent and right perfect ring R, we characterize the right global dimension of R, from another point of view, using the left derived functors of Hom and the right projective resolutions of right R-modules. It is shown that rD(R) ? n (n ? 2) if and only if the gl right Proj-dim M R ? n?2 if and only if Ext n?1(N,M) = 0 for all right R-modules N and M if and only if every (n?2)th Projcosyzygy of a right R-module has a projective envelope with the unique mapping property. It is also proved that rD(R) ? n (n ? 1) if and only if every (n?1)th Proj-cosyzygy of a right R-module has an epic projective envelope if and only if every nth Proj-cosyzygy of a right R-module is projective. As corollaries, the right hereditary rings and the rings R with rD(R) ? 2 are characterized.

关键词： global dimension projective resolution envelope 16E10 16E30 16E05

A regularization algorithm of dynamic light scattering for estimating the particle size distribution of dual-substance mixture in water

在线全文

学校读者我要写书评

暂无评论

Particuology 2024年第6期89卷 246-257页

作者： Yanghong Wang Ziqiang Meng Zipei Zhang Min xia li xia Wei li School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074China

Dynamic light scattering(DLS)is a nondestructive,well-established technique for the size characterization of proteins,nanoparticles,polymers,and colloidal ***,current DLS techniques are only applied to particle groups of single composition due to the limitation of their inversion *** this study,we propose a particle size distribution inversion algorithm based on the Tikhnonov regularization method that can be applied to the dual-substance particle *** algorithm retrieves the particle size distributions of two substances,respectively,by taking advantage of their refractive index *** simulation results reveal that the algorithm has excellent accuracy and stability when the scattering angle is 30°.Instead of the original identity matrix,the first-order difference matrix and second-order difference matrix are used as the regular matrix when utilizing the Tikhnonov algorithm,which obviously improves the anti-interference,accuracy,and stability of the ***,the inversion of particle size distribution is carried out at a 0.01%–1%noise level,which shows that the algorithm has an available antinoise ***,experimental particle size measurements for a mixture of polystyrene beads and toner particles demonstrate that the proposed algorithm is superior to the traditional Tikhnonov algorithm in applicability and accuracy.

关键词： Dynamic light scattering Dual-substance mixture Particle sized istribution Tikhnonov regularization

Formation and evolution of X-ray binaries

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 9-13页

作者： li xiangDong department of Astronomy,nanjing university,nanjing 210093,china department of Astronomy Nanjing University Nanjing China

We review recent progress in theoretical understanding of X-ray binaries,which has largely been driven by new *** select several topics including formation of compact low-mass X-ray binaries,the evolutionary connection between low-mass X-ray binaries and binary and millisecond radio pulsars,and ultraluminous X-ray sources,to illustrate the interplay between theories and observations.

关键词： X-ray binaries pulsars mass transfer stellar evolution

Nonlinear ergodic theorem for semitopological semigroups of non-lipschitzian mappings in Banach spaces

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1997年第1期42卷 8-11页

作者： li Gang and MA Jipu1. department of mathematics, Yangzhou Normal College, Yangzhou 225002, china 2. department of mathematics, nanjing university, nanjing 210093, china department of mathematics Yangzhou Normal College Yangzhou China department of mathematics Nanjing University Nanjing China

LET G be a semitopological semigroup, i. e. G is a semigroup with a Hausdorff topology such that for each s∈G the mapping s|→s·t and s|→t·s from G to G are continuous. G is called right reversible if any two closed left ideals of G have non-void intersection. In this case, (G,≤) is a directed system when the binary relation '≤' on G is defined by a≤b if and only if Let E be the uniformly convex Banach space

关键词： nonlinear semigroup ergodic theorem non-lipschitzian mapping.

Seedless Synthesis of Gold Nanorods with 5–10 nm in Diameters:a Comprehensive Study

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2024年第2期40卷 311-319页

作者： li Yalan xia Yunsheng Anhui Province Key Laboratory of Biomedical Materials and Chemical Measurement Key Laboratory of Functional Molecular SolidsMinistry of EducationCollege of Chemistry and Materials ScienceAnhui Normal UniversityWuhu241000P.R.China

Small gold nanorods(AuNRs),namely AuNRs with less than 10 nm in diameter,possess a high absorption-to-scattering ratio,a large surface area-to-volume ratio,as well as high cellular uptake *** this study,we systematically investigate seedless synthesis of AuNRs with diameters ranging from 5 nm to 10 *** has been found that several experimental conditions,including the chain length of the used cationic surfactants,and the concentrations of ascorbic acid,NaBH4,and AgNO_(3)can profoundly affect the obtained *** optimal conditions,the production yields of the obtained several AuNRs with different diameters can exceed 90%and even reach almost 100%.The conversion of gold precursors to AuNRs was estimated to be 70%–77%as measured by absorption spectroscopy and inductively coupled plasma mass spectrometry.

关键词： Small gold nanorod Diameter Production yield Conversion rate