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   673篇
  免费   26篇
  国内免费   10篇
化学   46篇
力学   3篇
综合类   1篇
数学   384篇
物理学   52篇
无线电   223篇
  2024年   1篇
  2023年   17篇
  2022年   20篇
  2021年   15篇
  2020年   24篇
  2019年   17篇
  2018年   16篇
  2017年   13篇
  2016年   14篇
  2015年   20篇
  2014年   26篇
  2013年   55篇
  2012年   27篇
  2011年   37篇
  2010年   41篇
  2009年   48篇
  2008年   47篇
  2007年   35篇
  2006年   40篇
  2005年   28篇
  2004年   26篇
  2003年   23篇
  2002年   15篇
  2001年   16篇
  2000年   11篇
  1999年   10篇
  1998年   5篇
  1997年   10篇
  1996年   8篇
  1995年   12篇
  1994年   5篇
  1993年   6篇
  1992年   1篇
  1991年   3篇
  1990年   3篇
  1989年   1篇
  1988年   1篇
  1986年   2篇
  1985年   3篇
  1984年   4篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
排序方式: 共有709条查询结果,搜索用时 343 毫秒
91.
数字技术的快速发展,以及其在民族声乐教学中的应用,为改变传统民族声乐教学方法,提高教学水平提供了很大的便利。将民族声乐教学与数字教育技术进行结合,能够确保民族声乐教学内容更加丰富、形象更加多样、教学更加具体,进而能够有效提高民族声乐教学的教学质量。  相似文献   
92.
tree是web开发中比较常用的展示控件,用来显示信息的分级视图,具有层次分明,表意清晰的特点。因此许多web插件中都包含tree,例如ExtJS、JQuery UI和easy UI,它们有一个共同的特点就是数据格式都是json,并且由于树分层的特性使得json数据还会嵌套多层。而在关系型数据库中取出的sql结果集却往往不能友好地支持这种分层的json格式。本文根据具有树形结构的数据在数据库中存储的方式以及其与json数据之间的复杂映射关系,提出一种sql结果集到json数据的转换算法。  相似文献   
93.
94.
Diassociative algebras form a category of algebras recently introduced by Loday. A diassociative algebra is a vector space endowed with two associative binary operations satisfying some very natural relations. Any diassociative algebra is an algebra over the diassociative operad, and, among its most notable properties, this operad is the Koszul dual of the dendriform operad. We introduce here, by adopting the point of view and the tools offered by the theory of operads, a generalization on a nonnegative integer parameter γ of diassociative algebras, called γ-pluriassociative algebras, so that 1-pluriassociative algebras are diassociative algebras. Pluriassociative algebras are vector spaces endowed with 2γ associative binary operations satisfying some relations. We provide a complete study of the γ-pluriassociative operads, the underlying operads of the category of γ-pluriassociative algebras. We exhibit a realization of these operads, establish several presentations by generators and relations, compute their Hilbert series, show that they are Koszul, and construct the free objects in the corresponding categories. We also study several notions of units in γ-pluriassociative algebras and propose a general way to construct such algebras. This paper ends with the introduction of an analogous generalization of the triassociative operad of Loday and Ronco.  相似文献   
95.
In positive theories, we have an axiom scheme of comprehension for positive formulas. We study here the “generalized positive” theory GPK+. Natural models of this theory are hyperuniverses. The author has shown in [2] that GPK+ interprets the Kelley Morse class theory. Here we prove that GPK+ + ACWF (ACWF being a form of the axiom of choice allowing to choose elements in well-founded sets) and the Kelley-Morse class theory with the axiom of global choice and the axiom “On is ramifiable” are mutually interpretable. This shows that GPK+ + ACWF is a “strong” theory since “On is ramifiable” implies the existence of a proper class of inaccessible cardinals.  相似文献   
96.
Jitendra Nath Roy 《Optik》2009,120(7):318-324
Interferometric devices for optical processing have been of great interest in recent years. Semiconductor optical amplifier (SOA)-based Mach-Zehnder interferometer (MZI) has already taken a significant role in the field of ultra-fast all-optical signal processing. Optical tree architecture (OTA) provides important contributions in optical interconnecting networks. In this communication, we have tried to exploit the advantages of both OTA and SOA-based MZI switches. We have proposed SOA-MZI-based tree architecture, a new and alternative scheme, for integrated all-optical logic and arithmetic operations. This architecture can enable one to perform all-optical processing of signals, including two input logic operations, half-adder, full-adder, full-subtractor, one-bit data comparator, etc.  相似文献   
97.
基于回归神经网络的雷达辐射源识别算法   总被引:3,自引:2,他引:1  
尹健 《电讯技术》2005,45(4):188-192
本文在研究带偏差单元内部回归神经网络(Internally Recurrent Net,IRN)算法的基础上,分析了雷达特征参数和雷达威胁类型的内在联系;利用统计分析和特征建模的方法获取先验知识、设计分类器并求取模糊隶属函数,结合IRN自学习特性和模糊隶属函数的分类功能识别出目标雷达辐射源可能的威胁类型,给出识别可信度。  相似文献   
98.
Denote by the set of trees of order 2k with perfect matchings. GUO [Guo, Linear Algebra Appl. 368:379–385, 2003.] determined the largest value of Laplacian spectral radii μ(T) of the trees T in and gave the corresponding tree T in whose μ(T) reaches this largest value. In this paper, we determine the second to the sixth largest values of μ(T) of the trees T in and also give the corresponding trees T in whose μ(T) reach these values.  相似文献   
99.
We present intensional dynamic programming (IDP), a generic framework for structured dynamic programming over atomic, propositional and relational representations of states and actions. We first develop set-based dynamic programming and show its equivalence with classical dynamic programming. We then show how to describe state sets intensionally using any form of structured knowledge representation and obtain a generic algorithm that can optimally solve large, even infinite, MDPs without explicit state space enumeration. We derive two new Bellman backup operators and algorithms. In order to support the view of IDP as a Rosetta stone for structured dynamic programming, we review many existing techniques that employ either propositional or relational knowledge representation frameworks.  相似文献   
100.
Knowledge based proximal support vector machines   总被引:1,自引:0,他引:1  
We propose a proximal version of the knowledge based support vector machine formulation, termed as knowledge based proximal support vector machines (KBPSVMs) in the sequel, for binary data classification. The KBPSVM classifier incorporates prior knowledge in the form of multiple polyhedral sets, and determines two parallel planes that are kept as distant from each other as possible. The proposed algorithm is simple and fast as no quadratic programming solver needs to be employed. Effectively, only the solution of a structured system of linear equations is needed.  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