全文获取类型
收费全文 | 403篇 |
免费 | 21篇 |
国内免费 | 28篇 |
专业分类
化学 | 18篇 |
力学 | 29篇 |
综合类 | 5篇 |
数学 | 359篇 |
物理学 | 41篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 11篇 |
2020年 | 12篇 |
2019年 | 11篇 |
2018年 | 7篇 |
2017年 | 13篇 |
2016年 | 11篇 |
2015年 | 7篇 |
2014年 | 24篇 |
2013年 | 41篇 |
2012年 | 22篇 |
2011年 | 31篇 |
2010年 | 14篇 |
2009年 | 24篇 |
2008年 | 31篇 |
2007年 | 23篇 |
2006年 | 17篇 |
2005年 | 14篇 |
2004年 | 11篇 |
2003年 | 10篇 |
2002年 | 18篇 |
2001年 | 12篇 |
2000年 | 12篇 |
1999年 | 10篇 |
1998年 | 11篇 |
1997年 | 6篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 9篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有452条查询结果,搜索用时 15 毫秒
101.
《Current Applied Physics》2015,15(11):1389-1396
Predominance of nano-scale effects observed in material behavior at small scales requires implementation of new simulation methods which are not merely based on classical continuum mechanic. On the other hand, although the atomistic modeling methods are capable of modeling nano-scale effects, due to the computational cost, they are not suitable for dynamic analysis of nano-structures. In this research, we aim to develop a continuum-based model for nano-beam vibrations which is capable of predicting the results of molecular dynamics (MD) simulations with considerably lower computational effort. In this classical-based modeling, the surface and core regions are taken to have different mechanical properties, where core atoms are assumed to have macroscale properties whereas surface layer is showing a different elastic modulus from the core components. By estimating physical parameters of proposed classical model using molecular dynamics results and the genetic algorithm, calibrated classical Euler–Bernoulli and Timoshenko beam models are developed. The results demonstrates that a Timoshenko beam model incorporating surface effects and having calibrated parameters, is able to provide almost the same results as molecular dynamics method which can be used to predict the vibrational behavior of nano-beams at different scales from nano to macro. 相似文献
102.
Mehmet Cenkci 《Discrete Mathematics》2009,309(6):1498-1510
We define the generalized potential polynomials associated to an independent variable, and prove an explicit formula involving the generalized potential polynomials and the exponential Bell polynomials. We use this formula to describe closed type formulas for the higher order Bernoulli, Eulerian, Euler, Genocchi, Apostol-Bernoulli, Apostol-Euler polynomials and the polynomials involving the Stirling numbers of the second kind. As further applications, we derive several known identities involving the Bernoulli numbers and polynomials and Euler polynomials, and new relations for the higher order tangent numbers, the higher order Bernoulli numbers of the second kind, the numbers , the higher order Bernoulli numbers and polynomials and the higher order Euler polynomials and their coefficients. 相似文献
103.
In this article, waiting time distributions of compound patterns are considered in terms of the generating function of the
numbers of occurrences of the compound patterns. Formulae for the evaluation of the generating functions of waiting time are
given, which are very effective computational tools. We provide several viewpoints on waiting time problems associated with
compound patterns and develop a general workable framework for the study of the corresponding distributions. The general theory
is employed for the investigation of some examples in order to illustrate how the distributions of waiting time can be derived
through our theoretical results.
This research was partially supported by the ISM Cooperative Research Program (2006-ISM·CRP-2007). 相似文献
104.
Victor Kowalenko 《Acta Appl Math》2009,106(3):369-420
Recently, a novel method based on the coding of partitions was used to determine a power series expansion for the reciprocal
of the logarithmic function, viz. z/ln (1+z). Here we explain how this method can be adapted to obtain power series expansions for other intractable functions. First,
the method is adapted to evaluate the Bernoulli numbers and polynomials. As a result, new integral representations and properties
are determined for the former. Then via another adaptation of the method we derive a power series expansion for the function
z
s
/ln
s
(1+z), whose polynomial coefficients A
k
(s) are referred to as the generalized reciprocal logarithm numbers because they reduce to the reciprocal logarithm numbers
when s=1. In addition to presenting a general formula for their evaluation, this paper presents various properties of the generalized
reciprocal logarithm numbers including general formulas for specific values of s, a recursion relation and a finite sum identity. Other representations in terms of special polynomials are also derived for
the A
k
(s), which yield general formulas for the highest order coefficients. The paper concludes by deriving new results involving
infinite series of the A
k
(s) for the Riemann zeta and gamma functions and other mathematical quantities. 相似文献
105.
An inverse forced vibration problem, based on the conjugate gradient method (CGM), (or the iterative regularization method), is examined in this study to estimate the unknown spatial and temporal-dependent external forces for the cutting tools by utilizing the simulated beam displacement measurements. The tool is represented by an Euler–Bernoulli beam. The accuracy of the inverse analysis is examined by using the simulated exact and inexact displacement measurements. The numerical experiments are performed to test the validity of the present algorithm by using different types of external forces, sensor arrangements and measurement errors. Results show that excellent estimations on the external forces can be obtained with any arbitrary initial guesses. 相似文献
106.
给出了高阶Bernoulli数的一个递推公式和Nrlund数的一个计算公式,推广了Namias[4],Deeba和Rodriguez[5],Tuenter[6]的结果. 相似文献
107.
Some rigidity results for non-commutative Bernoulli shifts 总被引:3,自引:0,他引:3
We introduce the outer conjugacy invariants , for cocycle actions σ of discrete groups G on type II1 factors N, as the set of real numbers t>0 for which the amplification σt of σ can be perturbed to an action, respectively, to a weakly mixing action. We calculate explicitly and the fundamental group of σ, , in the case G has infinite normal subgroups with the relative property (T) (e.g., when G itself has the property (T) of Kazhdan) and σ is an action of G on the hyperfinite II1 factor by Connes–Størmer Bernoulli shifts of weights {ti}i. Thus, and coincide with the multiplicative subgroup S of generated by the ratios {ti/tj}i,j, while if S={1} (i.e. when all weights are equal), and otherwise. In fact, we calculate all the “1-cohomology picture” of σt,t>0, and classify the actions (σ,G) in terms of their weights {ti}i. In particular, we show that any 1-cocycle for (σ,G) vanishes, modulo scalars, and that two such actions are cocycle conjugate iff they are conjugate. Also, any cocycle action obtained by reducing a Bernoulli action of a group G as above on to the algebra pNp, for p a projection in N, p≠0,1, cannot be perturbed to a genuine action. 相似文献
108.
Michel WEBER 《数学学报(英文版)》2006,22(2):377-382
Let D be an increasing sequence of positive integers, and consider the divisor functions:
d(n, D) =∑d|n,d∈D,d≤√n1, d2(n,D)=∑[d,δ]|n,d,δ∈D,[d,δ]≤√n1,
where [d,δ]=1.c.m.(d,δ). A probabilistic argument is introduced to evaluate the series ∑n=1^∞and(n,D) and ∑n=1^∞and2(n,D). 相似文献
109.
Claus Köstler 《Journal of Functional Analysis》2010,258(4):1073-933
The extended de Finetti theorem characterizes exchangeable infinite sequences of random variables as conditionally i.i.d. and shows that the apparently weaker distributional symmetry of spreadability is equivalent to exchangeability. Our main result is a noncommutative version of this theorem.In contrast to the classical result of Ryll-Nardzewski, exchangeability turns out to be stronger than spreadability for infinite sequences of noncommutative random variables. Out of our investigations emerges noncommutative conditional independence in terms of a von Neumann algebraic structure closely related to Popa's notion of commuting squares and Kümmerer's generalized Bernoulli shifts. Our main result is applicable to classical probability, quantum probability, in particular free probability, braid group representations and Jones subfactors. 相似文献
110.
Ken Kamano 《Journal of Number Theory》2010,130(10):2259-2271
We give a formula for sums of products of hypergeometric Bernoulli numbers. This formula is proved by using special values of multiple analogues of hypergeometric zeta functions. 相似文献