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   1328篇
  免费   143篇
  国内免费   48篇
化学   172篇
力学   48篇
综合类   50篇
数学   358篇
物理学   891篇
  2023年   7篇
  2022年   29篇
  2021年   34篇
  2020年   24篇
  2019年   17篇
  2018年   20篇
  2017年   53篇
  2016年   48篇
  2015年   44篇
  2014年   86篇
  2013年   75篇
  2012年   63篇
  2011年   92篇
  2010年   50篇
  2009年   123篇
  2008年   104篇
  2007年   97篇
  2006年   80篇
  2005年   71篇
  2004年   83篇
  2003年   44篇
  2002年   39篇
  2001年   35篇
  2000年   45篇
  1999年   30篇
  1998年   31篇
  1997年   24篇
  1996年   13篇
  1995年   8篇
  1994年   9篇
  1993年   6篇
  1992年   4篇
  1991年   2篇
  1990年   6篇
  1989年   5篇
  1988年   3篇
  1987年   1篇
  1986年   3篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1980年   2篇
  1975年   1篇
  1971年   1篇
  1969年   1篇
排序方式: 共有1519条查询结果,搜索用时 343 毫秒
141.
We give necessary and sufficient conditions on the wavelet coefficients of a function for being a member of some BMOφ (w) space. We achieve this characterization for a wide variety of wavelet systems. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
142.
We investigate the scheme which enables encoding of n qudits whose Hilbert spaces are of different dimensions to one qudit of dimension smaller than that of the Hilbert space of the n qudits and then probabilistically but error-free decoding any subset of k qudits. We also give a formula for calculating the average probability of successful decoding.  相似文献   
143.
本文提出了用棱镜色散产生莫尔等高线条纹假彩色编码的方法.研究了单棱镜和互补双棱镜两种典型系统.给出了实验验证.  相似文献   
144.
In this paper, a method of meshwork multipicture holography is suggested, which uses spatially coded recording plate with one dimension grating meshwork. The method is simple in coding and easy to realize. The reconstructing images obtained are very clear.  相似文献   
145.
This article reports the design and implementation of a graphical display that presents an approximation to vocal tract area in real time for voiced vowel articulation. The acoustic signal is digitally sampled by the system. From these data a set of reflection coefficients is derived using linear predictive coding. A matrix of area coefficients is then determined that approximates the vocal tract area of the user. From this information a graphical display is then generated. The complete cycle of analysis and display is repeated at ≈20 times/s. Synchronised audio and visual sequences can be recorded and used as dynamic targets for articulatory development. Use of the system is illustrated by diagrams of system output for spoken cardinal vowels and for vowels sung in a trained and untrained style  相似文献   
146.
We highlight a correspondence between order-two densities and wavelet-like transforms of certain fractal measures. We use a variant of the ergodic theorem to demonstrate that these densities and transforms are well-behaved for a large class of quasi-self-similar fractals. We show that parallel ideas can be used to study the local behavior of certain fractal functions.  相似文献   
147.
For the Gaussian channel Y(t) = Φ(ξ(s), Y(s); st) + X(t), the mutual information I(ξ, Y) between the message ξ(·) and the output Y(·) is evaluated, where X(·) is a Gaussian noise. Furthermore, the optimal coding under average power constraints is constructed.  相似文献   
148.
Rebbi's multispin coding technique is improved and applied to the kinetic Ising model with size 600*600*600. We give the central part of our computer program (for a CDC Cyber 76), which will be helpful also in a simulation of smaller systems, and describe the other tricks necessary to go to large lattices. The magnetizationM atT=1.4*T c is found to decay asymptotically as exp(-t/2.90) ift is measured in Monte Carlo steps per spin, and M(t = 0) = 1 initially.  相似文献   
149.
This is the first of several papers dealing with the application of statistical thermodynamic methodology to the solution of coding and communication theory problems. Emphasis is placed on the various ensemble techniques of statistical mechanics, the words or samples of a message taking the place of molecules in the prototype physical system. Analogs of temperature, internal energy, pressure, chemical potential, volume, entropy, etc., are developed. The isomorphism with thermodynamics is complete and these quantities transform (for example, by partial differentiation) in exactly the same way as the prototype physical quantities. The methods are nicely applicable to coding cases involving sources with memory, in which case, correlation can be discussed in terms of analog coupling energies between signals or words so that the store of many-body-problem techniques can be used. In addition, the manipulative freedom stemming from the possibility of choosing from a multiplicity of ensembles constrained by intensive parameters proves a distinct advantage. A concrete example dealing with the choice of a compact code for a nonextended source with memory is presented. The compact code is derived, and some discussion is given concerning the breadth of its power spectrum. In a following paper, its autocorrelation function within the framework of pulse code modulation is derived and transformed by Wiener theory so that the power spectrum is directly exhibited (along with the spectra for several other cases).Research supported under AFOSR Grant No. 70-1877. The present work is contribution No. 2643 of the Department of Chemistry, University of California-Los Angeles.  相似文献   
150.
The biochemical machinery of living systems obeys kinetic laws, but is driven by Gibbs function flows. Both the kinetic and thermodynamic aspects of Gibbs gain, transmission, and utilization are considered. An information-theoretic approach is used to find conditions under which the kinetics encodes the associated Gibbs function flow with the lowest possible error.  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