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   7380篇
  免费   942篇
  国内免费   636篇
化学   413篇
晶体学   2篇
力学   749篇
综合类   176篇
数学   5881篇
物理学   1737篇
  2024年   19篇
  2023年   71篇
  2022年   116篇
  2021年   140篇
  2020年   185篇
  2019年   173篇
  2018年   206篇
  2017年   236篇
  2016年   272篇
  2015年   164篇
  2014年   294篇
  2013年   539篇
  2012年   351篇
  2011年   420篇
  2010年   375篇
  2009年   456篇
  2008年   512篇
  2007年   483篇
  2006年   490篇
  2005年   440篇
  2004年   383篇
  2003年   318篇
  2002年   323篇
  2001年   239篇
  2000年   273篇
  1999年   215篇
  1998年   173篇
  1997年   172篇
  1996年   133篇
  1995年   135篇
  1994年   91篇
  1993年   83篇
  1992年   73篇
  1991年   48篇
  1990年   54篇
  1989年   32篇
  1988年   33篇
  1987年   33篇
  1986年   30篇
  1985年   22篇
  1984年   26篇
  1983年   11篇
  1982年   18篇
  1981年   10篇
  1980年   11篇
  1979年   12篇
  1978年   13篇
  1977年   17篇
  1974年   8篇
  1973年   8篇
排序方式: 共有8958条查询结果,搜索用时 15 毫秒
51.
The multiple lump solutions method is employed for the purpose of obtaining multiple soliton solutions for the generalized Bogoyavlensky-Konopelchenko(BK) equation. The solutions obtained contain first-order, second-order, and third-order wave solutions. At the critical point,the second-order derivative and Hessian matrix for only one point is investigated, and the lump solution has one maximum value. He's semi-inverse variational principle(SIVP) is also used for the generalized BK equation. Three major cases are studied, based on two different ansatzes using the SIVP. The physical phenomena of the multiple soliton solutions thus obtained are then analyzed and demonstrated in the figures below, using a selection of suitable parameter values.This method should prove extremely useful for further studies of attractive physical phenomena in the fields of heat transfer, fluid dynamics, etc.  相似文献   
52.
For conformal mixing repellers such as Julia sets and nonlinear one-dimensional Cantor sets, we connect the pressure of a smooth transformation on the repeller with its generalized dimensions, entropies, and Liapunov exponents computed with respect to a set of equilibrium Gibbs measures. This allows us to compute the pressure by means of simple numerical algorithms. Our results are then extended to axiom-A attractors and to a nonhyperbolic invariant set of the line. In this last case, we show that a first-order phase transition appears in the pressure.  相似文献   
53.
In flat spacetime, the fourth space coordinate in special relativity (SR) is equivalent to the coordinate time tE. We will show, however, that this definition of physical time is not unique. Another natural choice of coordinate time, tA, with absolute synchronization is allowed. Spacetime would exhibit dual properties, namely relativistic and absolute. In an arbitrary inertial frame, the relationship of the above two kinds of coordinate time corresponds to a resynchronization, and the Lorentz transformations can be written in an alternative form, which is called the generalized Galilean transformation (GGT). Although the absolute property is still hidden in nearly all types of experiments, the advantages of the above approach are as follows: (1) It will give us a deeper understanding of SR, including the basis of length contraction, time dilation and the interaction between moving objects and the physical vacuum. (2) It will provide a wider research domain than SR; for example, superluminal motion is predicted and has obtained growing experimental support.  相似文献   
54.
A modified Lorentz theory (MLT) based on the generalized Galilean transformation has recently received attention. In the framework of MLT, some explicit formulas dealing with the one-way velocity of light, slow-clock transport and the Doppler effect are derived in this paper. Several typical experiments are analyzed on this basis. The results show that the empirical equivalence between MLT and special relativity is still maintained to second order terms. We confirm recent findings of other works that predict the MLT might be distinguished from special relativity at the third order by Doppler centrifuge experiments capable of a fractional frequency detection threshold of 10–15.  相似文献   
55.
线性与非线性波的Chebyshev广义有限谱模拟   总被引:2,自引:0,他引:2       下载免费PDF全文
詹杰民  林东  李毓湘 《物理学报》2007,56(7):3649-3654
给出求解二维线性与非线性波的Chebyshev广义有限谱模拟方法.结合时间层次的高精度预报-校正方法,模拟了二维线性浅水驻波和波在浅滩的非线性变形.方法能够准确模拟水波的物理特征. 关键词: Chebyshev广义有限谱 线性波 非线性波  相似文献   
56.
57.
In this paper, we prove several existence theorems of random solutions to nonlinear random Volterra integral equations under the weak topology of Banach spaces. Then, as applications, we obtain the existence theorems of weak random solutions to random differential equations. Existence of extremal random solutions and a random comparison theorem for these random equations are also obtained. Our theorems improve and extend the corresponding results in [4,5,10,11,12]. Projects supported by the Science Fund of the Chinese Academy of Sciences.  相似文献   
58.
This paper divides fixed subsets into three kinds, mainly discusses the existence of II-type fixed subset, connects the investigations infixed subsets with the studies in non-linear problems, such as stability, bifurcation, chaos, etc., and proposes a kind of discrete simulation to Liapunov stability and his second method.  相似文献   
59.
Bézier曲线近似合并算法在几何数据压缩方面有着重要的应用.研究了两条相邻Bézier曲线近似合并的问题,用矩阵的形式给出了相邻Bézier曲线可精确合并的条件,并在此基础上通过广义逆矩阵的方法求解合并逼近后的Bézier曲线.同时,对保端点插值条件的近似合并也给出了结果.最后用实例说明了算法的有效性,得到了很好的逼近效果.  相似文献   
60.
The claim of Mohapatra and Maharana thattb(s) is a better scaling variable thant(lns)2 is put to test in the case of Λ-p scattering, after parametrizingb(s) asC 1 +C 2(lns)α. It was observed that in this case the data also prefer anα value which is close to those obtained by Mohapatra and Maharana for other scattering processes.  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