首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 187 毫秒
1.
§ 1 IntroductionInthispaperwediscusstheglobalclassicalsolutionofamultidimensionalquasistationaryproblem .Theproblemcomesfromthediscussionofagrowthmodelofselfmaintainingprotocell(see [1— 3])inmultidimensionalcase .Theprotocellcanbevisualizedashavingaporousst…  相似文献   

2.
邱瑞峰 《东北数学》2000,16(4):484-490
§ 1.Introduction LetMbeacompact 3 manifold .IfthereisaproperlyembeddedclosedsurfaceSinMwhichseparatesMintotwocompressionbodiesH1andH2 ,thenMcanbewrittenasM =H1∪SH2 .ThisstructureonMiscalledaHeegaardsplittingofMandSisasplittingsurface .H1∪SH2 issaidtobereducible…  相似文献   

3.
§1.IntroductionZ.AradandH.Blauintroducedin[1]theconceptoftablealgebrasandusedthistodiscussthecharacteralgebraandthecentralclassalgebraofafinitegroupinauniformway.ThisideagoesbacktoI.Schur.AlittleextendednotionofC-algebraforeshadowedthedevelopmentofcommuta…  相似文献   

4.
§ 1.Introduction Chainablecontinuahavebeenextensivelystudiedformanyyearsandhavegeneratednewinterestintherecentyearsasthechainablecontinuumwhichistheinverselimitspaceofacontinuousmapfromaclosedintervalintoitselfcanberealizedasaglobalattractorofsomeplan…  相似文献   

5.
李玉华 《东北数学》2000,16(4):411-416
§ 1.IntroductionandMainResults ByameromorphicfunctionwealwaysmeanameromorphicfunctioninthecomplexplaneC .WeassumethatthereaderisfamiliarwithNevanlinnatheorythatcanbefound ,forinstance ,in [1 ] .Wesaythattwomeromorphicfunctionsfand gsharethevaluea∈ Cprovidedth…  相似文献   

6.
1.TheChineseAnnalsofMathematics(CAM)Ser.Bisacomprehensivemathematicaljournalcarryingoriginalpapersonpureandappliedmathematics.Itaimsatpresentingthelatestachievementsinmathematicalresearchesandpromotingdomesticandinternationalacademicexchanges.2.CAMSer.Bis…  相似文献   

7.
高中《代数》上册 (必修 )P1 50第 1 7题 :已知tanα =2 ,求sinα +cosαsinα -cosα的值 .此题虽浅显简单 ,但若能正确使用 ,对同学们培养能力 ,发展智力 ,引起兴趣 ,确能起到一定的作用 .1 一题多解解法 1 tanα =2 sinα =2 55,cosα =55.或 sinα =- 2 55,cosα =- 55.∴ sinα +cosαsinα -cosα=3 .解法 2 ∵tanα =2 sinαcosα=2 ,即sinα =2cosα ,∴ sinα +cosαsinα -cosα=2cosα +cosα2cosα -cosα=3 .解法 3 tanα=2 s…  相似文献   

8.
§ 1.Introduction Intopologicalgraphtheory ,agraphmayhavemultipleadjacentiesandselfloops.Agraphiscalledsimplicialifithasnomultipleadjacenciesandselfloops .Asurfacehereisacompact2 manifoldwithoutboundary .Anembeddingofagraphiscellularifeachcomponentofthesur…  相似文献   

9.
瞿成勤  苏维宜 《东北数学》2000,16(4):451-453
§ 1.Introduction LetRnbendimensionalEuclideanspace,and (f1,… ,fm,Rn)acontractioniteratedfunctionsystem .Itiswellknownthatthereexistsauniquenon emptycompactsetEsuchthatE =∪mi=1 fi(E) .WecallthesetEinvarintsetfor (f1,… ,fm,Rn) . Let (f1,… ,fm,Rn)beacontractioniteratedfunct…  相似文献   

10.
§ 1.Introduction Allgraphsconsideredinthispaperarefinite,undirected ,unloopedandsimplegraphs.WedenotethechromaticpolynomialofagraphGbyP(G ,λ)orP(G) .WesaygraphsGandHtobechromatiallyequivalentifP(G) =P(H) .ThechromaticuniquenessofagraphGisestablishedifitcanbeded…  相似文献   

11.
The sufficient condition for the existence of non-constant periodic solutions of the following planar system with four delays are obtained:  相似文献   

12.
Periodicity in a Nonlinear Predator-prey System with State Dependent Delays   总被引:1,自引:0,他引:1  
With the help of a continuation theorem based on Gaines and Mawhin's coincidence degree, easily verifiable criteria are established for the global existence of positive periodic solutions of the following nonlinear state dependent delays predator-prey system where a_i(t),c_j(t),d_i(t) are continuous positive periodic functions with periodic ω>0, b_1(t),b_2(t) are continuous periodic functions with periodic ωand ∫_0~ωbi(t)dt>0. T_i,σ_j, p_i (i=1,2,…,n, j=1, 2,…,m) are continuous and ω-periodic with respect to their first arguments, respectively, α_i, β_j,γ_i(i=1,2,…,n, j=1,2, …, m) are positive constants.  相似文献   

13.
1.IntroductionNeutraldelayffereatialequationsinpopulationdynamicshavebeenstudiedextensivelyforthep88tfewyears.However,onlyafewpapersll--5]havebeenpublishedontheexistencesofperiodicsolutionsoftheneutraldelaypopulationmodels.In[6,7],Kuangproposedtoinve...  相似文献   

14.
By using the continuation theorem of Mawhin's coincidence degree theory, a sufficient condition is derived for the existence of positive periodic solutions for a distributed delay competition modelwhere ri and r2 are continuous w-periodic functions in R+=[0,∞) with ,ai,ci(i =1,2) are positive continuous w-periodic functions in R+=[0,∞),bi (i = 1,2) is nonnegative continuous w-periodic function in R+=[0,∞), w and T are positive constants. Ki,Lt ∈ C([-T,0], (01 88)) and Ki(s)ds = 1,ds - 1. i = 1,2. Some known results are improved and extended.  相似文献   

15.
Essentially sharp bounds for small prime solutionsp j ,q i of the following two different types of equations are obtained.
  相似文献   

16.
We obtain an estimate of the modulus of a complete multiple rational trigonometric sum: $$\left| {\sum {_{x_{1, \ldots ,} x_r = 1^{\exp \left( {{{2\pi if\left( {x_{1, \ldots ,} x_r } \right)} \mathord{\left/ {\vphantom {{2\pi if\left( {x_{1, \ldots ,} x_r } \right)} q}} \right. \kern-\nulldelimiterspace} q}} \right)} }^q } } \right| \ll q^{{{r - 1} \mathord{\left/ {\vphantom {{r - 1} {n + \varepsilon }}} \right. \kern-\nulldelimiterspace} {n + \varepsilon }}} ,$$ where $$\begin{gathered} f\left( {x_{1, \ldots ,} x_r } \right) = \sum {_{0 \leqslant t_1 , \ldots ,t_r \leqslant n^a t_1 , \ldots ,t_r x_1^{t_1 } \ldots x_r^{t_r } ,} } \hfill \\ a_{0, \ldots ,0} = 0,\left( {a_{0, \ldots ,0,1} , \ldots ,a_{n, \ldots ,n,} q} \right) = 1 \hfill \\ \end{gathered} $$ , and an estimate of the modulus of a multiple trigonometric integral.  相似文献   

17.
We give some “rational analoga” to metric results in the classical theory of the diophantine approximation of zero by linear forms. That is: we study the behaviour of expressions of the form $$\begin{gathered} \lim _{m \to \infty } \frac{1}{{\left| {P_s (m)} \right|}}|\{ (x_1 , \ldots ,x_s ) \in P_s (m): \hfill \\ \parallel a_1 \frac{{x_1 }}{m} + \ldots + a_s \frac{{x_s }}{m}\parallel _m \geqslant \psi (a_1 , \ldots ,a_s ,m) \hfill \\ for all - \frac{m}{2}< a_1 , \ldots ,a_s \leqslant \frac{m}{2}, \hfill \\ with (a_1 , \ldots ,a_s ) \ne (0, \ldots ,0)\} |, \hfill \\ \end{gathered} $$ whereP s (m) is a certain subset of {1, …,m} s , ψ is a certain nonnegative function, and ‖ · ‖ m means the maximum of 1/m and the distance to the nearest integer. Some of the investigations are also motivated by problems in the theory of uniform distribution and of pseudo-random number generation. The results partly depend on the validity of the generalized Riemann hypothesis.  相似文献   

18.
The inverse problem about two-spectra for the equation (1) $$\begin{gathered} b_0 y_0 + a_0 y_1 = \lambda y_0 , \hfill \\ a_{n - 1} y_{n - 1} + b_n y_n + a_n y_{n + 1} = \lambda y_n \left( {n = 1, 2, 3, ...} \right), \hfill \\ \end{gathered} $$ where {yn} 0 is the desired solution, λ is a complex parameter and $$a_n > 0, \operatorname{Im} b_n = 0 \left( {n = 0, 1 ,2, ...} \right)$$ is studied. Necessary and sufficient conditions for the solvability of the inverse problem about two-spectrafor Eq. (1) are established and also the procedure of reconstruction of the equation from its two-spectra is indicated.  相似文献   

19.
§1 IntroductionAnvarovandLarinov[1]introducedthefollowingprey-predatorsystem:x(t)=x(t)[α-γy(t)-γ∫∞0K1(s)y(t-s)ds-∫∞0∫∞0R1(s,θ)y(t-s)y(t-θ)dθds],y(t)=y(t)[-β μx(t) μ∫∞0K2(s)x(t-s)ds ∫∞0∫∞0R2(s,θ)x(t-θ)x(t-s)dθds],(1)whereα,γ,βandμarepositiveconstants,Ki∈C([0,∞),(0,∞))andRi∈C([0,∞)×[0,∞),(0,∞)),i=1,2.Fortheecologicalsenseofsystem(1),wereferto[1,2]andrefer-encescitedtherein.Sincerealisticmodelsrequiretheinclusionoftheeffectofchangingen-vironment,itmot…  相似文献   

20.
LetW be the Wiener process onT=[0, 1]2. Consider the stochastic integral equation $$\begin{gathered} X_\zeta = x_0 + \int_{R_\zeta } {a_1 (\zeta \prime )X(s\prime ,dt\prime )ds\prime + } \int_{R_\zeta } {a_2 (\zeta \prime )X(ds\prime ,t\prime )dt\prime } \hfill \\ + \int_{R_\zeta } {a_3 (X_{\zeta \prime , } \zeta \prime )W(ds\prime ,dt\prime ) + } \int_{R_\zeta } {a_4 (X_{\zeta \prime , } \zeta \prime )ds\prime ,dt\prime ,} \hfill \\ \end{gathered} $$ whereR ζ =(s, t) ∈ T, andx 0 ∈ ?. Under some assumptions on the coefficients ai, the existence and uniqueness of a solution for this stochastic integral equation is already known (see [6]). In this paper we present some sufficient conditions for the law ofX ζ to have a density.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号