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   1070篇
  免费   58篇
  国内免费   106篇
化学   85篇
力学   8篇
综合类   26篇
数学   998篇
物理学   117篇
  2024年   1篇
  2023年   8篇
  2022年   18篇
  2021年   15篇
  2020年   28篇
  2019年   23篇
  2018年   21篇
  2017年   23篇
  2016年   34篇
  2015年   12篇
  2014年   46篇
  2013年   100篇
  2012年   28篇
  2011年   52篇
  2010年   36篇
  2009年   71篇
  2008年   84篇
  2007年   84篇
  2006年   70篇
  2005年   56篇
  2004年   50篇
  2003年   43篇
  2002年   53篇
  2001年   41篇
  2000年   38篇
  1999年   36篇
  1998年   33篇
  1997年   18篇
  1996年   14篇
  1995年   11篇
  1994年   10篇
  1993年   9篇
  1992年   8篇
  1991年   5篇
  1990年   5篇
  1989年   5篇
  1988年   3篇
  1987年   2篇
  1985年   4篇
  1984年   8篇
  1983年   5篇
  1982年   2篇
  1981年   2篇
  1980年   2篇
  1979年   6篇
  1978年   5篇
  1977年   3篇
  1970年   2篇
  1959年   1篇
排序方式: 共有1234条查询结果,搜索用时 31 毫秒
81.
In this note, we study the well-posedness of the problem of constrained minimization of an integral functional and show that global well-posedness is equivalent to pointwise well-posedness almost everywhere. Our result extends an earlier one by Zolezzi.This research was supported by NSF Grant No. DMS 88-02688.  相似文献   
82.
We study two types of dynamical extensions of Lucas sequences and give elliptic solutions for them. The first type concerns a level-dependent (or discrete time-dependent) version involving commuting variables. We show that a nice solution for this system is given by elliptic numbers. The second type involves a non-commutative version of Lucas sequences which defines the non-commutative (or abstract) Fibonacci polynomials introduced by Johann Cigler. If the non-commuting variables are specialized to be elliptic-commuting variables the abstract Fibonacci polynomials become non-commutative elliptic Fibonacci polynomials. Some properties we derive for these include their explicit expansion in terms of normalized monomials and a non-commutative elliptic Euler–Cassini identity.  相似文献   
83.
We investigate the effects of three-site interactions on the pairwise entanglement in a three-qubit Heisenberg XX model. We find the three-site interactions only in favor of the thermal entanglement and benefit the teleportation between the next-to-nearest neighbor qubits. In addition, we also study the stationary entangled state in the model with intrinsic decoherence taken into account. The influence of different types of three-site interactions on the stationary entangled state is then examined.  相似文献   
84.
We present an overview of the properties of the pseudohyperbolic metric in several real dimensions and study uniformly discrete sequences for the real unit ball in R^n.  相似文献   
85.
A Pairwise Comparison Matrix (PCM) has been used to compute for relative priorities of elements and are integral components in widely applied decision making tools: the Analytic Hierarchy Process (AHP) and its generalized form, the Analytic Network Process (ANP). However, PCMs suffer from several issues limiting their applications to large-scale decision problems. These limitations can be attributed to the curse of dimensionality, that is, a large number of pairwise comparisons need to be elicited from a decision maker. This issue results to inconsistent preferences due to the limited cognitive powers of decision makers. To address these limitations, this research proposes a PCM decomposition methodology that reduces the elicited pairwise comparisons. A binary integer program is proposed to intelligently decompose a PCM into several smaller subsets using interdependence scores among elements. Since the subsets are disjoint, the most independent pivot element is identified to connect all subsets to derive the global weights of the elements from the original PCM. As a result, the number of pairwise comparison is reduced and consistency is of the comparisons is improved. The proposed decomposition methodology is applied to both AHP and ANP to demonstrate its advantages.  相似文献   
86.
87.
In this paper, the complicated dynamics is studied near a double homoclinic loops with bellows configuration for general systems. For the non-twisted multiple homoclinics, the existence of periodic orbit with the specified route and the existence of shift-invariant curve sequences defined on the cross sections of multiple homoclinics corresponding to any specified one-side infinite sequences are given. In addition, the existence regions are also located.  相似文献   
88.
In this paper, we address the problem of finding low cost addition–subtraction sequences for situations where a doubling step is significantly cheaper than a non-doubling one. One application of this setting appears in the computation of the final exponentiation step of the reduced Tate pairing defined on ordinary elliptic curves. In particular, we report efficient addition–subtraction sequences for the Kachisa–Schaefer–Scott family of pairing-friendly elliptic curves, whose parameters involve computing the multi-exponentiation of relatively large sequences of exponents with a size of up to 26 bits.  相似文献   
89.
In 2012,Zhi-Wei Sun posed many conjectures about the monotonicity of sequences of form {n√zn},where {zn} is a familiar number-theoretic or combinatorial sequence. We show that if the sequence {zn+1/zn}is increasing(resp.,decreasing),then the sequence {n√zn} is strictly increasing(resp.,decreasing) subject to a certain initial condition. We also give some sufficient conditions when {zn+1/zn} is increasing,which is equivalent to the log-convexity of {zn}. As consequences,a series of conjectures of Zhi-Wei Sun are verified in a unified approach.  相似文献   
90.
In this paper, the authors study the strong law of large numbers for partial sums of pairwise negatively quadrant dependent (NQD) random variables. The results obtained improve the corresponding theorems of Hu et al. (2013), and Qiu and Yang (2006) under some weaker conditions.  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