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Chinese Annals of Mathematics,Series B 1997年第4期18卷 429-434页

作者： ZHANG XIANG Institute of Mathematics,Nanjing Normal University,Nanjing 210097,China 南京师范大学数学所江苏南京

Two conjectures in the qualitative theory of quadratic differential systems are proved under certain conditions.

关键词： Quadratic system Limit cycle Dulac function

Some new results on planar harmonic mappings

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Science China Mathematics 2010年第3期53卷 597-604页

作者： CHEN HuaiHui Department of Mathematics, Nanjing Normal University, Nanjing 210097, China Department of Mathematics Nanjing Normal University Nanjing China

This survey paper contains some new results on the Landau theorem, Bloch theorem and Schwarz-Pick lemma for planar harmonic mappings.

关键词： harmonic mapping Landau theorem Bloch constant Schwarz-Pick lemma quasi-regularity

EXISTENCE OF LIMIT CYCLES IN A MULTIPLY-CONNECTED REGION

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Chinese Annals of Mathematics,Series B 1999年第2期20卷 169-172页

作者： ZHANG XIANG(Department of Mathematics, Naming Normal University, Naming 210097, China.) Department of Mathematics Nanjing Normal University Nanjing 210097 China

In this paper,a conjecture about the existence of limit cycles in a multiply-connected regionproposed by Ye Yanqian is proved.

关键词： Multiply-connected region Annulus theorem Limit cycle

Normal Functions and α-Normal Functions

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Acta Mathematica Sinica,English Series 2000年第3期16卷 399-404页

作者： Yan Xu Department of Mathematics,Nanjing Normal University,Nanjing 210097 P.R.China Department of Mathematics Nanjing Normal University Nanjing 210097 P. R. China

This paper has studied two open questions about normal functions due to Lappan,and obtained two corresponding results for α-normal functions.

关键词： Spherical derivative Normal function α-Normal function

Characterizations of α-Bloch functions on the unit ball without use of derivative

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Science China Mathematics 2008年第11期51卷 1965-1981页

作者： CHEN HuaiHui School of Mathematics and Computer Science, Nanjing Normal University, Nanjing 210097, China School of Mathematics and Computer Science Nanjing Normal University Nanjing China

In this paper we establish characterizations of α-Bloch functions on the unit ball without use of derivative, which are stronger, more precise and general than those obtained by Nowak and Zhao.

关键词： α-Bloch function unit ball Bergman metric 32A18 32A37

A specific family of cyclotomic polynomials of order three

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Science China Mathematics 2010年第9期53卷 2269-2274页

作者： JI ChunGang School of Mathematical Sciences,Nanjing Normal University,Nanjing 210097,China School of Mathematical Sciences Nanjing Normal University Nanjing China

Let A(n) be the largest absolute value of any coefficient of n-th cyclotomic polynomial Φn(x).We say Φn(x) is flat if A(n) = *** this paper,for odd primes p < q < r and 2r ≡±1(mod pq),we prove that Φpqr(x) is fla... 详细信息

关键词： cyclotomic polynomial flat cyclotomic polynomial ternary cyclotomic polynomial

Landscape structure and land uese on county level in northeastern Yunnan Province of China——a case study of Huize County

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Journal of Environmental Sciences 2000年第3期12卷 355-360页

作者： WANG Jin\|liang, NI Shao\|xiang (College of Geographical Science, Nanjing Normal University, Nanjing 210097, China) 南京师范大学江苏南京 2 1 0 0 97

Taking Huize County as an example, the paper analyzed the landscape structure(landscape element structure, landscape type structure, landscape spatial structure, landscape succession structure) and the relations between landscape structure and land use. It was pointed out that the agriculture should be developed in harmony with the landscape structure in the study area.

关键词： landscape structure land use agriculture Yunnan Province China

On consensus protocols for high-order multiagent systems

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控制理论与应用（英文版） 2010年第4期8卷 406-412页

作者： Jing KUANG,Jiandong ZHU (School of Mathematical Sciences,Nanjing Normal University,Nanjing Jiangsu 210097,China) School of Mathematical Sciences Nanjing Normal University Nanjing Jiangsu China

In this paper,the static consensus problem and the dynamic consensus problem are considered for a class of high-order multiagent *** the proposed consensus protocols,necessary and sufficient conditions for the consensus problems are *** the static consensus protocol,the desired consensus speed can be achieved by adjusting feedback *** show the effectiveness of the proposed consensus protocols.

关键词： Consensus Multiagent systems Graph theory

Luminosity function of optically-selected type II QSOs

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Science China(Physics,Mechanics & Astronomy) 2010年第S1期53卷 191-195页

作者： BIAN WeiHao & ZHANG ShiYan Department of Physics,Nanjing Normal University,Nanjing 210097,China Department of Physics Nanjing Normal University Nanjing China

For a sample of 411 type II QSOs with redshifts less then 0.3,we use the Balmer decrements to do the reddening correction of the [O III] luminosities and then derive the intrinsic [O III] luminosity *** find that the host reddening correction of the [O III] 5007 luminosity for type II QSOs cannot be *** median Balmer decrement of Hα/Hβ=4.0 corresponds to an extinction of 0.94 mag for the [O III] 5007 line,which is consistent with the result derived from the median Hβ/Hγ.Comparing the intrinsic luminosity function of type II QSOs with that of type I QSOs,we find that the upper limit of the type II QSO’s fraction in the total QSOs is 80% for type II QSOs with z < 0.3 and 8.6≤log(L[O III]/L)≤9.4.

关键词： type II QSOs luminosity function emission lines Balmer decrements

THE MULTIPLICITY OF ZERO AND LIMIT CYCLES FOR ABEL EQUATIONS

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Journal of Systems Science & Complexity 2001年第2期14卷 165-173页

作者： ZHANG Xiang (Department of Mathematics, Nanjing Normal University, Nanjing 210097, China) 南京师范大学江苏南京 210097

In this paper we will investigate the multiplicity of zero solution for a class of Abel equation, and obtain better estimation on multiplicity than that given by Alwash and Lloyd for the equation of a certain form, and solve a conjecture posed by Ye Yanqian for the equation of another form. As a by-product, the considered equation may have at least four small amplitude limit cycles. The method of this paper is useful for computing the focal value of a critical point of focus type for polynomial system that can be transformed into Abel equation or Abel form.

关键词： Abel equation multiplicity limit cycle.