全文获取类型
收费全文 | 9389篇 |
免费 | 747篇 |
国内免费 | 892篇 |
专业分类
化学 | 789篇 |
晶体学 | 15篇 |
力学 | 1123篇 |
综合类 | 146篇 |
数学 | 7445篇 |
物理学 | 1510篇 |
出版年
2024年 | 19篇 |
2023年 | 102篇 |
2022年 | 175篇 |
2021年 | 169篇 |
2020年 | 278篇 |
2019年 | 251篇 |
2018年 | 246篇 |
2017年 | 275篇 |
2016年 | 268篇 |
2015年 | 166篇 |
2014年 | 338篇 |
2013年 | 718篇 |
2012年 | 376篇 |
2011年 | 481篇 |
2010年 | 421篇 |
2009年 | 651篇 |
2008年 | 640篇 |
2007年 | 610篇 |
2006年 | 566篇 |
2005年 | 514篇 |
2004年 | 403篇 |
2003年 | 399篇 |
2002年 | 395篇 |
2001年 | 316篇 |
2000年 | 302篇 |
1999年 | 302篇 |
1998年 | 287篇 |
1997年 | 240篇 |
1996年 | 181篇 |
1995年 | 107篇 |
1994年 | 111篇 |
1993年 | 65篇 |
1992年 | 83篇 |
1991年 | 84篇 |
1990年 | 54篇 |
1989年 | 39篇 |
1988年 | 43篇 |
1987年 | 46篇 |
1986年 | 35篇 |
1985年 | 40篇 |
1984年 | 38篇 |
1983年 | 20篇 |
1982年 | 24篇 |
1981年 | 26篇 |
1980年 | 24篇 |
1979年 | 23篇 |
1978年 | 23篇 |
1977年 | 14篇 |
1974年 | 9篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Takahisa Yokoyama 《Annals of the Institute of Statistical Mathematics》1995,47(2):309-320
We consider a parallel profile model which is useful in analyzing parallel growth curves of several groups. The likelihood ratio criterion for a hypothesis concerning the adequacy of a random-effects covariance structure is obtained under the parallel profile model. The likelihood ratio criterion for the hypothesis in the general one-way MANOVA model is also obtained. Asymptotic null distributions of the criteria are derived when the sample size is large. We give a numerical example of these asymptotic results. 相似文献
992.
It is shown that, given a lower semicontinuous convex integrandf satisfying a suitable integrability condition, there exists a sequence of Lipschitz simple integrands which Mosco converges tof and such that the sequence of conjugate integrands Mosco converges tof
*. Moreover, this sequence can be chosen so that the sequence of associated integral functionals, respectively defined onL
1(X) andL
(X
*), Mosco converges as well.We wish to thank Professor Erik J. Balder for interesting remarks on the first version of this work. 相似文献
993.
所谓图R_n是指具有如下结构的平面图:R_n=(V,E),其中顶点集合V={u_1,u_2,…,u_n}U{v_1,v_2,…,v_n},边集合E={u_iu_(i+1),v_iv_(i+1),u_iv_i,u_iv_(i+1)|i=1,2,…,n},其中u_(n+1)=u_1,v_(n+1)=v_1.通过研究R_n的邻点可区别关联着色,给出了当n=4,n是3或者5的正整数倍时,R_n的邻点可区别关联色数. 相似文献
994.
本文主要利用解析方法以及二项指数和与Dirichlet特征的性质,研究多项式的特征和与二项三次指数和的混合均值的计算问题,并得到一个较强的渐近公式. 相似文献
995.
M. Subhas AbelP.G. Siddheshwar N. Mahesha 《Applied mathematics and computation》2011,217(12):5895-5909
A study of the hydromagnetic flow due to a stretching sheet and heat transfer in an incompressible micropolar liquid is made. Temperature-dependent thermal conductivity and a non-uniform heat source/sink render the problem analytically intractable and hence a numerical study is made using the shooting method based on Runge-Kutta and Newton-Raphson methods. The two problems of horizontal and vertical stretching are considered to implement the numerical method. The former problem involves one-way coupling between linear momentum and heat transport equations and the latter involves two-way coupling. Further, both the problems involve two-way coupling between the non-linear equations of conservation of linear and angular momentums. A similarity transformation arrived at for the problem using the Lie group method facilitates the reduction of coupled, non-linear partial differential equations into coupled, non-linear ordinary differential equations. The algorithm for solving the resulting coupled, two-point, non-linear boundary value problem is presented in great detail in the paper. Extensive computation on velocity and temperature profiles is presented for a wide range of values of the parameters, for prescribed surface temperature (PST) and prescribed heat flux (PHF) boundary conditions. 相似文献
996.
M.T. Manzari O. Hassan K. Morgan N.P. Weatherill 《Finite Elements in Analysis and Design》1998,30(4):353
An edge-based finite element method is presented for the simulation of compressible turbulent flows on unstructured tetrahedral grids. A two equation k–ω turbulence model is employed and the standard Galerkin approach is used for spatial discretisation. Stabilisation of the resulting procedure is achieved by the addition of an appropriate diffusion. An explicit multistage time-stepping scheme is used to advance the solution in time to steady state. The performance of the algorithm is demonstrated for the simulation of a high Reynolds number transonic separated flow over a wing. 相似文献
997.
Yuxi Wang Weiduo Zhu Ke Lin Lanfeng Yuan Xiaoguo Zhou Shilin Liu 《Journal of Raman spectroscopy : JRS》2016,47(10):1231-1238
The micro‐structure of hydration shell of solute in water is significant for understanding the properties of aqueous solutions. However the spectra of hydration shell are difficult to be obtained. Herein, a novel Raman ratio spectra, which is obtained through dividing the Raman spectra of aqueous solutions from the spectrum of water, was applied to deduce the spectra of hydration shell of organic (acetone‐D6) and inorganic compounds (NaNO3, NaSCN, NaClO4, Na2SO4, NaCl) in water. Those spectra of the hydration shell were employed to study the micro‐structures of the first hydration shells of anions, the number of water molecules in the first hydration shell of free anions and acetone‐D6, and the aggregation behavior of ions in the concentrated aqueous NaNO3. The number of water molecules in the hydration shell was supported by our molecular dynamic simulations. The Raman ratio spectra can be widely employed to obtain the spectra of the first hydration shell, and it is helpful to understand the micro‐structure of aqueous solutions. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
998.
A class of nonlinear coupled system for El Nino-Southern Oscillation(ENSO) model is considered.Using the asymptotic theory and method of variational iteration,the asymptotic expansion of the solution for ENSO models is obtained. 相似文献
999.
Teresa Regińska 《BIT Numerical Mathematics》2004,44(1):119-133
The paper concerns conditioning aspects of finite-dimensional problems arising when the Tikhonov regularization is applied
to discrete ill-posed problems. A relation between the regularization parameter and the sensitivity of the regularized solution
is investigated. The main conclusion is that the condition number can be decreased only to the square root of that for the
nonregularized problem. The convergence of solutions of regularized discrete problems to the exact generalized solution is
analyzed just in the case when the regularization corresponds to the minimal condition number. The convergence theorem is
proved under the assumption of the suitable relation between the discretization level and the data error. As an example the
method of truncated singular value decomposition with regularization is considered.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
1000.
Asymptotic stability and blowup of solutions for a class of viscoelastic inverse problem with boundary feedback
下载免费PDF全文
![点击此处可从《Mathematical Methods in the Applied Sciences》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mohammad Shahrouzi 《Mathematical Methods in the Applied Sciences》2016,39(9):2368-2379
In this paper, we consider a nonlinear viscoelastic inverse problem with memory in the boundary. Under some suitable conditions on the coefficients, relaxation function, and initial data, we proved stability of solutions when the integral overdetermination tends to zero as time goes to infinity. Furthermore, we show that there are solutions under some conditions on initial data that blow up in finite time. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献