首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   8篇
  免费   3篇
化学   6篇
数学   5篇
  2017年   2篇
  2016年   4篇
  2015年   1篇
  2014年   1篇
  2011年   1篇
  2010年   1篇
  1975年   1篇
排序方式: 共有11条查询结果,搜索用时 78 毫秒
1.
2.
3.
In this paper the improved photometric or the so called “Shape From Shading” method is presented. In comparison to known and established approaches the efficiency of the detector system was considered and the requirements of the cosine Lambert’s law for the angle distribution of the emitted electrons are suppressed. The method retrieves more accurate data of sub-micrometer substructures like diffractive optical elements (DOE) due to an increased lateral resolution and works more efficiently than widely used comparable techniques.  相似文献   
4.
In this paper, we consider a discrete fractional boundary value problem of the form: where 0 < α,β≤1, 1 < α + β≤2, λ and ρ are constants, γ > 0, , is a continuous function, and Eβx(t) = x(t + β ? 1). The existence and uniqueness of solutions are proved by using Banach's fixed point theorem. An illustrative example is also presented. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
5.
Journal of Sol-Gel Science and Technology - Pure orthorhombic phase of La1?xSmxFeO3 (x?=?0, 0.1, 0.2, and 0.3) nanoparticles can be obtained by sol–gel method after...  相似文献   
6.
The effect of heat treatments on the electrical responses of the electrode and surface layer in a giant-permittivity CuO ceramic is investigated. It is found that the giant low-frequency relative permittivity of the CuO ceramic can be tuned by annealing in Ar and O2—it can be reduced by annealing in Ar, and then it can be enhanced up to the initial value by annealing in O2. The results indicate to the effect of oxygen vacancy concentration on the giant dielectric properties of the CuO ceramic. Interestingly, three sets of dielectric relaxations are observed in the O2–annealed sample, which can be assigned as the effects of outmost surface layer, electrode, and grain boundary. Our results reveal that the giant low-frequency dielectric response in the CuO ceramic is associated with both of the interfacial polarization at the sample–electrode interface resulted from a non-Ohmic electrode contact and the outmost surface layer-inner part interface.  相似文献   
7.
8.
In this paper, we study a new class of three-point boundary value problem of nonlinear Caputo fractional difference equation. Our problem contain an argument with a shift. The existence of at least one positive solution is proved by using the Guo-Krasnoselskii’s fixed point theorem. Some illustrative examples are given.  相似文献   
9.
Ba0.5Sr0.5Ti1?xNixO3 (BSTN) ceramics were prepared from BSTN nanopowders synthesized by a hydrothermal method. The phase and microstructure of samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy. XRD results indicate a cubic structure of the pure BST nanopowders. The cubic structure can be converted to the orthorhombic phase with increasing of Ni content to x = 0.01 and returned to the cubic structure with the presence of Ni(OH)2 impurity phase for x = 0.03 and 0.05. However, the BSTN ceramics sintered at 1,200 °C for 3 h revealed the orthorhombic phase structure with NiO impurity phase for all Ni content. The doping of Ni in Ba0.5Sr0.5TiO3 structure can increase the grain size of samples from 1.47 to 3.26 μm. The dielectric constant, loss tangent (tanδ) and phase transition temperature of BSTN ceramics were reduced with increasing Ni content.  相似文献   
10.
In this paper, we consider a discrete fractional boundary value problem of the form where 0 < α,β≤1, 1 < α + β≤2, 0 < γ≤1, , ρ is a constant, and denote the Caputo fractional differences of order α and β, respectively, is a continuous function, and ?p is the p‐Laplacian operator. The existence of at least one solution is proved by using Banach fixed point theorem and Schaefer's fixed point theorem. Some illustrative examples are also presented. Copyright © 2015 John Wiley & Sons, Ltd.  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