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   563篇
  免费   131篇
  国内免费   20篇
化学   30篇
力学   15篇
综合类   13篇
数学   483篇
物理学   173篇
  2023年   12篇
  2022年   25篇
  2021年   31篇
  2020年   28篇
  2019年   24篇
  2018年   18篇
  2017年   27篇
  2016年   29篇
  2015年   17篇
  2014年   54篇
  2013年   30篇
  2012年   39篇
  2011年   43篇
  2010年   57篇
  2009年   51篇
  2008年   34篇
  2007年   44篇
  2006年   38篇
  2005年   17篇
  2004年   7篇
  2003年   16篇
  2002年   14篇
  2001年   12篇
  2000年   9篇
  1999年   3篇
  1998年   14篇
  1997年   5篇
  1996年   1篇
  1995年   1篇
  1994年   3篇
  1993年   2篇
  1992年   2篇
  1991年   4篇
  1990年   1篇
  1987年   1篇
  1986年   1篇
排序方式: 共有714条查询结果,搜索用时 31 毫秒
581.
A recent study examines the value of information sharing (VIS) in the presence of information errors. Considering a nearly identical model setting, we present entirely different analytical results. The key reason is that the demand considered here is a noninferable process. Our results show that it will never be optimal for the manufacturer to solely use shared customer demand information. Furthermore, the impact of information errors on the VIS found here also differs from the impact in that recent study.  相似文献   
582.
Detection of Cheaters in Vector Space Secret Sharing Schemes   总被引:23,自引:0,他引:23  
A perfect secret sharing scheme is a method of distributing shares of a secret among a set P of participants in such a way that only qualified subsets of P can reconstruct the secret from their shares and non-qualified subsets have absolutely no information on the value of the secret. In a secret sharing scheme, some participants could lie about the value of their shares in order to obtain some illicit benefit. Therefore, the security against cheating is an important issue in the implementation of secret sharing schemes. Two new secret sharing schemes in which cheaters are detected with high probability are presented in this paper. The first one has information rate equal to 1/2 and can be implemented not only in threshold structures, but in a more general family of access structures. We prove that the information rate of this scheme is almost optimal among all schemes with the same security requirements. The second scheme we propose is a threshold scheme in which cheaters are detected with high probability even if they know the secret. The information rate is in this case 1/3 In both schemes, the probability of cheating successfully is a fixed value that is determined by the size of the secret.  相似文献   
583.
为了研究双联行星齿轮在实际设计参数下,其相对角度偏差对复合行星传动系统动力学特性的影响,采用集中参数法建立了3K-I型行星齿轮动力学模型,模型中将双联行星齿轮的相对角度偏差转化为啮合副齿侧间隙的变化,考虑了双联齿轮角度偏差、轮齿侧隙和时变啮合刚度等非线性因素,采用龙格库塔法求解了系统的时域响应并计算其均载系数。分析了不同工况、偏差下系统的动态特性。结果表明,存在双联行星轮角度偏差时,轻载下更容易发生齿轮的脱齿与冲击,系统的均载系数随着双联行星轮角度偏差差值及系统的负载降低而增大,各组行星轮角度偏差分布越集中,角度偏差对系统均载特性的影响越小;角度偏差分布同号时,对系统中某一对齿轮的承载影响明显;角度偏差分布异号时,对系统均载特性的影响最大。  相似文献   
584.
This paper presents a scheme for faithfully distributing a pure entanglement between two parties over an arbitrary collective-noise channel with linear optics. The transmission is assisted by an additional qubit against collective noise. The receiver can take advantage of the time discrimination and the measurement results of the assistant qubit to reconstruct a pure entanglement with the sender. Although the scheme succeeds probabilistically, the resource used to get a pure entanglement state is finite, and so is easier to establish entanglement in practice than quantum entanglement purification.  相似文献   
585.
For a tolled highway where consecutive segments allow vehicles to enter and exit unrestrictedly, we propose a simple toll pricing method. It is shown that the method is the unique method satisfying the classical axioms of Additivity and Dummy in the cost sharing literature, and the axioms of Toll Upper Bound for Local Traffic and Routing-proofness. We also show that the toll pricing method is the only method satisfying Routing-proofness Axiom and Cost Recovery Axiom. The main axiom in the characterizations is Routing-proofness which says that no vehicle can reduce its toll charges by exiting and re-entering intermediately. In the special case when there is only one unit of traffic (vehicle) for each (feasible) pair of entrance and exit, we show that our toll pricing method is the Shapley value of an associated game to the problem. In the case when there is one unit of traffic entering at each entrance but they all exit at the last exit, our toll pricing method coincides with the well-known airport landing fee solution-the Sequential Equal Contribution rule of Littlechild and Owen (1973).  相似文献   
586.
We consider differential polynomials of Fermat–Waring type, const-ructed using polynomials of Yi’s type for meromorphic functions in a non-Archimedean field. Similarly to the Hayman Conjecture, we prove that the considered differential polynomials assume all values. We established also a uniqueness theorem for these differential polynomials.  相似文献   
587.
We examine a supply chain in which a manufacturer participates in a sealed-bid lowest price procurement auction through a distributor. This form of supply chain is common when a manufacturer is active in an overseas market without establishing a local subsidiary. To gain a strategic advantage in the division of profit, the manufacturer and distributor may intentionally conceal information about the underlying cost distribution of the competition. In this environment of information asymmetry, we determine the equilibrium mark-up, the ex-ante expected mark-up and expected profit of the manufacturer and the equilibrium bid of the distributor. In unilateral communication, we demonstrate the informed agent’s advantage resulting to higher mark-up. Under information sharing, we show that profit is equally shared among the supply chain partners and we explicitly derive the mark-up when the underlying cost distribution is uniform in [0, 1]. The model and findings are illustrated by a numerical example.  相似文献   
588.
589.
590.
Binary linear codes with good parameters have important applications in secret sharing schemes, authentication codes, association schemes, and consumer electronics and communications. In this paper, we construct several classes of binary linear codes from vectorial Boolean functions and determine their parameters, by further studying a generic construction developed by Ding et al. recently. First, by employing perfect nonlinear functions and almost bent functions, we obtain several classes of six-weight linear codes which contain the all-one codeword, and determine their weight distribution. Second, we investigate a subcode of any linear code mentioned above and consider its parameters. When the vectorial Boolean function is a perfect nonlinear function or a Gold function in odd dimension, we can completely determine the weight distribution of this subcode. Besides, our linear codes have larger dimensions than the ones by Ding et al.’s generic construction.  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