期刊文献+
共找到6,559篇文章
< 1 2 250 >
每页显示 20 50 100
Existence of Monotone Positive Solution for a Fourth-Order Three-Point BVP with Sign-Changing Green’s Function
1
作者 Junrui Yue Yun Zhang Qingyue Bai 《Open Journal of Applied Sciences》 2024年第1期63-69,共7页
This paper is concerned with the following fourth-order three-point boundary value problem , where , we discuss the existence of positive solutions to the above problem by applying to the fixed point theory in cones a... This paper is concerned with the following fourth-order three-point boundary value problem , where , we discuss the existence of positive solutions to the above problem by applying to the fixed point theory in cones and iterative technique. 展开更多
关键词 Fourth-Order Three-Point Boundary Value Problem Sign-Changing Green’s Function Fixed Point Index Iterative Technique Monotone positive solution EXISTENCE
下载PDF
Simulation research on surface growth process of positive and negative frequency detuning chromium atom lithographic gratings
2
作者 尹志珺 唐朝辉 +9 位作者 谭文 肖光旭 姚玉林 薛栋柏 顾振杰 雷李华 顿雄 邓晓 程鑫彬 李同保 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第10期367-376,共10页
Chromium atom photolithography gratings are a promising technology for the development of nanoscale length standard substances due to their high accuracy,uniformity,and consistency.However,the inherent difference betw... Chromium atom photolithography gratings are a promising technology for the development of nanoscale length standard substances due to their high accuracy,uniformity,and consistency.However,the inherent difference between the interaction of positive and negative frequency detuning standing wave field and the atoms can cause a difference in the adjacent peak-to-valley heights of the grating in positive and negative frequency detuning chromium atom lithography,which greatly reduces its accuracy.In this study,we performed a controlled variable growth simulation using the semi-classical theoretical model and Monte Carlo method with trajectory tracking and ballistic deposition methods to investigate the influence of key experimental parameters on the surface growth process of positive and negative frequency detuning atomic lithography gratings.We established a theoretical model based on simulation results and summarized empirical equations to guide the selection of experimental parameters.Our simulations achieved uniform positive and negative frequency detuning atomic lithography gratings with a period of 1/4 of the wavelength corresponding to the atomic transition frequency,and adjacent peak-to-valley heights differing by no more than 2 nm,providing an important theoretical reference for the controllable fabrication of these gratings. 展开更多
关键词 self-traceable grating atom lithography positive and negative frequency detuning surface growth
下载PDF
EXISTENCE OF POSITIVE SOLUTIONS FOR NEUTRAL DIFFERENCE EQUATIONS WITH POSITIVE AND NEGATIVE COEFFICIENTS 被引量:1
3
作者 Luo Zhiguo Shen JianhuaDept. of Math., Hunan Normal Univ., Changsha 410081,China. 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2002年第3期251-257,共7页
In this paper the sufficient conditions for the existence of positive solutions of the neutral difference equations with positive and negative coefficients are established. The results improve some known conclusions i... In this paper the sufficient conditions for the existence of positive solutions of the neutral difference equations with positive and negative coefficients are established. The results improve some known conclusions in the literature. 展开更多
关键词 positive solutions neutral difference equations positive and negative coefficients.
下载PDF
STRUCTURE OF NONNEGATIVE NONTRIVIAL AND POSITIVE SOLUTIONS OF SINGULARLY PERTURBED p-LAPLACE EQUATIONS 被引量:1
4
作者 张正策 李开泰 LINZong-chi 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2004年第8期929-936,共8页
Structure of nonnegative nontrivial and positive solutions was precisely studied for some singularly perturbed p-Laplace equations. By virtue of sub- and supersolution method, it is shown that there are many nonnegati... Structure of nonnegative nontrivial and positive solutions was precisely studied for some singularly perturbed p-Laplace equations. By virtue of sub- and supersolution method, it is shown that there are many nonnegative nontrivial spike-layer solutions and positive intermediate spike-layer solutions. Moreover, the upper and lower bound on the measure of each spike-layer were estimated when the parameter is sufficiently small. 展开更多
关键词 p-Laplace equation nonnegative nontrivial solution positive solution spike-layer solution sub- and supersolution
下载PDF
POSITIVE SOLUTIONS WITH HIGH ENERGY FOR FRACTIONAL SCHRODINGER EQUATIONS
5
作者 郭青 赵雷嘎 《Acta Mathematica Scientia》 SCIE CSCD 2023年第3期1116-1130,共15页
In this paper, we study the Schrodinger equations (-△)^(s)u + V(x)u = a(x)|u|^(p-2)u + b(x)|u|^(q-2)u, x∈R^(N),where 0 < s < 1, 2 < q < p < 2_(s)^(*), 2_(s)^(*) is the fractional Sobolev critical expo... In this paper, we study the Schrodinger equations (-△)^(s)u + V(x)u = a(x)|u|^(p-2)u + b(x)|u|^(q-2)u, x∈R^(N),where 0 < s < 1, 2 < q < p < 2_(s)^(*), 2_(s)^(*) is the fractional Sobolev critical exponent. Under suitable assumptions on V, a and b for which there may be no ground state solution, the existence of positive solutions are obtained via variational methods. 展开更多
关键词 fractional Schr?dinger equations positive solution concentration compactness principle
下载PDF
Hermite Positive Definite Solution of the Quaternion Matrix Equation Xm + B*XB = C
6
作者 Yiwen Yao Guangmei Liu +1 位作者 Yanting Zhang Jingpin Huang 《Journal of Applied Mathematics and Physics》 2023年第11期3760-3772,共13页
This paper discusses the necessary and sufficient conditions for the existence of Hermite positive definite solutions of the quaternion matrix equation X<sup>m</sup>+ B*XB = C (m > 0) and its iterative ... This paper discusses the necessary and sufficient conditions for the existence of Hermite positive definite solutions of the quaternion matrix equation X<sup>m</sup>+ B*XB = C (m > 0) and its iterative solution method. According to the characteristics of the coefficient matrix, a corresponding algebraic equation system is ingeniously constructed, and by discussing the equation system’s solvability, the matrix equation’s existence interval is obtained. Based on the characteristics of the coefficient matrix, some necessary and sufficient conditions for the existence of Hermitian positive definite solutions of the matrix equation are derived. Then, the upper and lower bounds of the positive actual solutions are estimated by using matrix inequalities. Four iteration formats are constructed according to the given conditions and existence intervals, and their convergence is proven. The selection method for the initial matrix is also provided. Finally, using the complexification operator of quaternion matrices, an equivalent iteration on the complex field is established to solve the equation in the Matlab environment. Two numerical examples are used to test the effectiveness and feasibility of the given method. . 展开更多
关键词 QUATERNION Matrix Equation Hermite positive Definite solution Matrix Inequality ITERATIVE CONVERGENCE
下载PDF
Backward Support Computation Method for Positive and Negative Frequent Itemset Mining
7
作者 Mrinmoy Biswas Akash Indrani Mandal Md. Selim Al Mamun 《Journal of Data Analysis and Information Processing》 2023年第1期37-48,共12页
Association rules mining is a major data mining field that leads to discovery of associations and correlations among items in today’s big data environment. The conventional association rule mining focuses mainly on p... Association rules mining is a major data mining field that leads to discovery of associations and correlations among items in today’s big data environment. The conventional association rule mining focuses mainly on positive itemsets generated from frequently occurring itemsets (PFIS). However, there has been a significant study focused on infrequent itemsets with utilization of negative association rules to mine interesting frequent itemsets (NFIS) from transactions. In this work, we propose an efficient backward calculating negative frequent itemset algorithm namely EBC-NFIS for computing backward supports that can extract both positive and negative frequent itemsets synchronously from dataset. EBC-NFIS algorithm is based on popular e-NFIS algorithm that computes supports of negative itemsets from the supports of positive itemsets. The proposed algorithm makes use of previously computed supports from memory to minimize the computation time. In addition, association rules, i.e. positive and negative association rules (PNARs) are generated from discovered frequent itemsets using EBC-NFIS algorithm. The efficiency of the proposed algorithm is verified by several experiments and comparing results with e-NFIS algorithm. The experimental results confirm that the proposed algorithm successfully discovers NFIS and PNARs and runs significantly faster than conventional e-NFIS algorithm. 展开更多
关键词 Data Mining positive Frequent Itemset negative Frequent Itemset Association Rule Backward Support
下载PDF
Utilizing Instilling Negative Pressure Wound Therapy with Vashe Wound Solution for an Infected Sternal Dehiscence: A Case Report
8
作者 Linnea T. Mauro Courtney M. Janowski +5 位作者 Mariah J. Janowski Adalberto C. Gonzalez Eugene J. Sidoti Luis G. Fernandez Paul J. Kim Marc R. Matthews 《Surgical Science》 2023年第3期231-239,共9页
Utilization of negative pressure wound therapy with instillation (NPWTi) for sternal dehiscence wounds secondary to sternal wound infection after surgery has become an accepted therapy. NPWTi accelerates wound healing... Utilization of negative pressure wound therapy with instillation (NPWTi) for sternal dehiscence wounds secondary to sternal wound infection after surgery has become an accepted therapy. NPWTi accelerates wound healing through macrostrain, microstrain, and cyclic fluid instillation. Wounds benefit from additional superficial infection control with the removal of microorganisms, the release of proinflammatory mediators, stimulation of angiogenesis, as well as mechanical debridement. However, very few cases of utilizing NPWTi in the treatment of sternal wound infections have been reported in the literature. This case study describes the use of NPWTi with hypochlorous acid for the treatment of a sternal wound infection. 展开更多
关键词 negative Pressure Wound Therapy with Instillation NPWT NPWTi NPWT with Dwell Hypochlorous Acid Vashe Wound solution Sternal Dehiscence
下载PDF
Effects of positive thinking intervention on negative emotions and quality of life in stroke patients:a scoping review
9
作者 Xin Fan Mei Wang Xiang-Shu Cui 《Nursing Communications》 2023年第9期1-6,共6页
Objective:To analyze domestic and international studies on the effects of positive thought intervention therapy on negative emotions and the quality of life of stroke patients to provide a reference for future related... Objective:To analyze domestic and international studies on the effects of positive thought intervention therapy on negative emotions and the quality of life of stroke patients to provide a reference for future related studies.Methods:Using the scoping review method as a guide,computer searches of PubMed,Web of Science,Embase,Cochrane Library,China National Knowledge Infrastructure,Wanfang Database,China Vipers Full Text Database and China Biomedical Literature Database were conducted to collect relevant studies on the application of positive thinking interventions in stroke patients from the establishment to January 2023,and the literature was screened according to the inclusion and exclusion criteria,and the data were extracted and analyzed by two investigators independently.Results:The search yielded 964 publications,and a total of 19 were included.The time of publication,study site,study population,study design,study length,and type of results of the included studies was summarized and analyzed.Conclusions:Positive thinking-based interventions have shown significant changes in negative emotions such as anxiety and depression in stroke patients and can reduce somatic pain,enhance their social integration,and improve their quality of life.However,interventions in the areas of self-compassion,artificial intelligence and the adoption of tailoring need to be further explored. 展开更多
关键词 positive thinking intervention STROKE negative emotions quality of life scoping revie
下载PDF
Semi-analytical solution for mechanical analysis of tunnels crossing strike-slip fault zone considering nonuniform fault displacement and uncertain fault plane position
10
作者 YANG Heng-hong WANG Ming-nian +1 位作者 YU Li ZHANG Xiao 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第6期2116-2136,共21页
The tunnel subjected to strike-slip fault dislocation exhibits severe and catastrophic damage.The existing analysis models frequently assume uniform fault displacement and fixed fault plane position.In contrast,post-e... The tunnel subjected to strike-slip fault dislocation exhibits severe and catastrophic damage.The existing analysis models frequently assume uniform fault displacement and fixed fault plane position.In contrast,post-earthquake observations indicate that the displacement near the fault zone is typically nonuniform,and the fault plane position is uncertain.In this study,we first established a series of improved governing equations to analyze the mechanical response of tunnels under strike-slip fault dislocation.The proposed methodology incorporated key factors such as nonuniform fault displacement and uncertain fault plane position into the governing equations,thereby significantly enhancing the applicability range and accuracy of the model.In contrast to previous analytical models,the maximum computational error has decreased from 57.1%to 1.1%.Subsequently,we conducted a rigorous validation of the proposed methodology by undertaking a comparative analysis with a 3D finite element numerical model,and the results from both approaches exhibited a high degree of qualitative and quantitative agreement with a maximum error of 9.9%.Finally,the proposed methodology was utilized to perform a parametric analysis to explore the effects of various parameters,such as fault displacement,fault zone width,fault zone strength,the ratio of maximum fault displacement of the hanging wall to the footwall,and fault plane position,on the response of tunnels subjected to strike-slip fault dislocation.The findings indicate a progressive increase in the peak internal forces of the tunnel with the rise in fault displacement and fault zone strength.Conversely,an augmentation in fault zone width is found to contribute to a decrease in the peak internal forces.For example,for a fault zone width of 10 m,the peak values of bending moment,shear force,and axial force are approximately 46.9%,102.4%,and 28.7% higher,respectively,compared to those observed for a fault zone width of 50 m.Furthermore,the position of the peak internal forces is influenced by variations in the ratio of maximum fault displacement of the hanging wall to footwall and the fault plane location,while the peak values of shear force and axial force always align with the fault plane.The maximum peak internal forces are observed when the footwall exclusively bears the entirety of the fault displacement,corresponding to a ratio of 0:1.The peak values of bending moment,shear force,and axial force for the ratio of 0:1 amount to approximately 123.8%,148.6%,and 111.1% of those for the ratio of 0.5:0.5,respectively. 展开更多
关键词 strike-slip fault tunnel engineering semi-analytical solution fault zone width nonuniform fault displacement uncertain fault plane position
下载PDF
Impact of web-based positive psychological intervention on emotions,psychological capital,and quality of life in gastric cancer patients on chemotherapy
11
作者 Yu-Yu Xin Dan Zhao 《World Journal of Clinical Cases》 SCIE 2024年第26期5877-5884,共8页
BACKGROUND Gastric cancer is a malignant digestive tract tumor that originates from the epithelium of the gastric mucosa and occurs in the gastric antrum,particularly in the lower curvature of the stomach.AIM To evalu... BACKGROUND Gastric cancer is a malignant digestive tract tumor that originates from the epithelium of the gastric mucosa and occurs in the gastric antrum,particularly in the lower curvature of the stomach.AIM To evaluate the impact of a positive web-based psychological intervention on emotions,psychological capital,and quality of survival in gastric cancer patients on chemotherapy.METHODS From January 2020 to October 2023,121 cases of gastric cancer patients on chemotherapy admitted to our hospital were collected and divided into a control group(n=60)and an observation group(n=61)according to the admission order.They were given either conventional nursing care alone and conventional nursing care combined with web-based positive psychological interventions,respectively.The two groups were compared in terms of negative emotions,psychological capital,degree of cancer-caused fatigue,and quality of survival.RESULTS After intervention,the number of patients in the observation group who had negative feelings toward chemotherapy treatment was significantly lower than that of the control group(P<0.05);the Positive Psychological Capital Questionnaire score was considerably higher than that of the control group(P<0.05);the degree of cancer-caused fatigue was significantly lower than that of the control group(P<0.05);and the Quality of Life Scale for Cancer Patients(QLQ-30)score was significantly higher than that of the control group(P<0.05).CONCLUSION Implementing a web-based positive psychological intervention for gastric cancer chemotherapy patients can effectively improve negative emotions,enhance psychological capital,and improve the quality of survival. 展开更多
关键词 Internet positive psychology Gastric cancer chemotherapy negative emotions Psychological capital Quality of survival
下载PDF
The Existence of Solutions for Kirchhoff-Type Equations with General Singular Terms
12
作者 WANG Ji-nan SUN Da-wei 《Chinese Quarterly Journal of Mathematics》 2024年第3期315-323,共9页
We study the existence of solutions for Kirchhoff-type equations.Firstly,we use the Sobolev inequality and the weakly lower semi-continuity of the norm to prove that the corresponding function can reach the global min... We study the existence of solutions for Kirchhoff-type equations.Firstly,we use the Sobolev inequality and the weakly lower semi-continuity of the norm to prove that the corresponding function can reach the global minimum.Then,we use the variational method and some analytical techniques to obtain the existence of the positive solution of the equation whenλis small enough. 展开更多
关键词 Kirchhoff-type equation The existence positive solution Variational method
下载PDF
Existence of Positive Solutions of Nonlinear NeutralEquations with Positive and Negative Coefficients
13
作者 关新平 段广仁 +1 位作者 张友安 杨军 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 1998年第2期32-35,共4页
A class of nonlinear neutral equations with positive and negative coefficients is considered. Seveal conditions for existence of eventually positive solutions are obtained,and they extend and improve some of the crite... A class of nonlinear neutral equations with positive and negative coefficients is considered. Seveal conditions for existence of eventually positive solutions are obtained,and they extend and improve some of the criteria existing in literature. Our conditions are necessary and suffcient when all the coeffcients of the equations are constants. 展开更多
关键词 NONLINEAR NEUTRAL EQUATIONS OSCILLATION EXISTENCE positive solutions
下载PDF
SYMMETRIC POSITIVE DEFINITE SOLUTIONS OF MATRIX EQUATIONS (AX,XB)=(C,D) AND AXB=C 被引量:1
14
作者 戴华 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1996年第2期56+52-55,共5页
The symmetric positive definite solutions of matrix equations (AX,XB)=(C,D) and AXB=C are considered in this paper. Necessary and sufficient conditions for the matrix equations to have symmetric positive de... The symmetric positive definite solutions of matrix equations (AX,XB)=(C,D) and AXB=C are considered in this paper. Necessary and sufficient conditions for the matrix equations to have symmetric positive definite solutions are derived using the singular value and the generalized singular value decompositions. The expressions for the general symmetric positive definite solutions are given when certain conditions hold. 展开更多
关键词 numerical algebra MATRIX EQUATION symmetric positive definite solution
下载PDF
On the Problem of All Equal Positive Odd Number Solutions of the Dissemination of the Ends' Guess 被引量:1
15
作者 刘元宗 《Chinese Quarterly Journal of Mathematics》 CSCD 2000年第2期108-109,共2页
The thesis is concerned with the problem of the dissemination of the Ends’ guess and offers the formula of all equal positive odd number solutions.
关键词 Ends’ guess DISSEMINATION all equal positive odd number solutions
下载PDF
Positive Solutions of a Semilinear Elliptic Equation with Coefficient That Changes Sign
16
作者 马如云 姚庆六 李宝麟 《Chinese Quarterly Journal of Mathematics》 CSCD 2002年第4期10-14,共5页
We prove the existence of a positive solution to the problem-Δu=a(x)f(u), x∈Ω, u(x)=0,x∈Ω,where Ω is a bounded domain in R n with smooth boundary, a(x) is allowed to change sign.
关键词 elliptic equation positive solution Leray-Schauder fixed point theorem
下载PDF
Existence of Multiple Positive Solutions for Higher-Order p-Laplacian Boundary Value Problems
17
作者 贺小明 葛渭高 《Journal of Beijing Institute of Technology》 EI CAS 2002年第2期212-216,共5页
The existence of multiple positive solutions for a class of higher order p Laplacian boundary value problem is studied. By means of the Leggett Williams fixed point theorem in cones, existence criteria which e... The existence of multiple positive solutions for a class of higher order p Laplacian boundary value problem is studied. By means of the Leggett Williams fixed point theorem in cones, existence criteria which ensure the existence of at least three positive solutions of the boundary value problem are established. 展开更多
关键词 positive solutions cone Leggett Williams fixed point theorem p Laplacian boundary value problems
下载PDF
Existence of Positive Solutions for Nonlinear Conjugate Boundary Value Problems
18
作者 菅典兵 董正华 《Chinese Quarterly Journal of Mathematics》 CSCD 2002年第2期87-93,共7页
The present paper is concerned with the existence of positive solutions of the (k,n-k) conjugate boundary value problems(-1) n-k u (h) (t)=λa(t)f(u(t)),t∈(0,1), u (i) (0)=0,0≤i≤k-1, u (j) (0)=0,0... The present paper is concerned with the existence of positive solutions of the (k,n-k) conjugate boundary value problems(-1) n-k u (h) (t)=λa(t)f(u(t)),t∈(0,1), u (i) (0)=0,0≤i≤k-1, u (j) (0)=0,0≤j≤n-k-1,where λ is a positive parmeter. Krasnoselsii’s fixed point theorem is employed to obtain the existence criteria for positive solution. 展开更多
关键词 existence theorem positive solutions conjugate boundary value problem
下载PDF
An Existence Theorem of Positive Solution for Fourth-order Superlinear Semipositone Eigenvalue Problems
19
作者 江秀芬 姚庆六 《Chinese Quarterly Journal of Mathematics》 CSCD 2001年第2期64-68,共5页
In this paper we investigate the existence of positive solution for a class of fourth_order superlinear semipositone eigenvalue problems. This class of problems usually describes the deformation of the elastic beam wh... In this paper we investigate the existence of positive solution for a class of fourth_order superlinear semipositone eigenvalue problems. This class of problems usually describes the deformation of the elastic beam whose both end_points are fixed. 展开更多
关键词 elastic beam equation existence of positive solution SEMIPOSITONE fixed point theorem on cone
下载PDF
“阴/阳”和“positive/negative”之多义现象的认知对比研究
20
作者 刘臻 张珊珊 梅德明 《语言教育》 2014年第4期53-56,60,共5页
多义现象是当今语言学研究的一个重要方面,从认知语言学的视角对多义现象进行对比研究是当今语义研究的一个热点,已取得了不少的研究成果,但是对于"阴/阳"和"positive/negative"这两组具有独特民族特色的字词的语... 多义现象是当今语言学研究的一个重要方面,从认知语言学的视角对多义现象进行对比研究是当今语义研究的一个热点,已取得了不少的研究成果,但是对于"阴/阳"和"positive/negative"这两组具有独特民族特色的字词的语义研究尚鲜有关注。本文从原型范畴和认知隐喻的视角,详细地分析了这两组字词的语义发展特征,发现它们的语义已经形成错综复杂的语义网状结构,既有语义重合之处,也有自己的独特之处,体现了中西文化的独特文化特征和思维特征。 展开更多
关键词 阴/阳 positive/negative 认知 多义现象 语义网络
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部