全文获取类型
收费全文 | 6613篇 |
免费 | 566篇 |
国内免费 | 602篇 |
专业分类
化学 | 592篇 |
晶体学 | 24篇 |
力学 | 353篇 |
综合类 | 151篇 |
数学 | 5968篇 |
物理学 | 693篇 |
出版年
2024年 | 9篇 |
2023年 | 45篇 |
2022年 | 82篇 |
2021年 | 136篇 |
2020年 | 120篇 |
2019年 | 141篇 |
2018年 | 130篇 |
2017年 | 203篇 |
2016年 | 214篇 |
2015年 | 133篇 |
2014年 | 305篇 |
2013年 | 509篇 |
2012年 | 307篇 |
2011年 | 394篇 |
2010年 | 341篇 |
2009年 | 426篇 |
2008年 | 461篇 |
2007年 | 490篇 |
2006年 | 397篇 |
2005年 | 351篇 |
2004年 | 335篇 |
2003年 | 293篇 |
2002年 | 274篇 |
2001年 | 236篇 |
2000年 | 221篇 |
1999年 | 170篇 |
1998年 | 184篇 |
1997年 | 162篇 |
1996年 | 135篇 |
1995年 | 89篇 |
1994年 | 76篇 |
1993年 | 47篇 |
1992年 | 37篇 |
1991年 | 41篇 |
1990年 | 37篇 |
1989年 | 20篇 |
1988年 | 22篇 |
1987年 | 19篇 |
1986年 | 11篇 |
1985年 | 24篇 |
1984年 | 22篇 |
1983年 | 30篇 |
1982年 | 20篇 |
1981年 | 24篇 |
1980年 | 22篇 |
1979年 | 14篇 |
1978年 | 11篇 |
1977年 | 3篇 |
1969年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有7781条查询结果,搜索用时 31 毫秒
991.
In this paper, we introduce and analyze a new singular value decomposition (SVD) called weighted SVD (WSVD) using a new inner product instead of the Euclidean one. We use the WSVD to approximate the singular values and the singular functions of the Fredholm integral operators. In this case, the new inner product arises from the numerical integration used to discretize the operator. Then, the truncated WSVD (TWSVD) is used to regularize the Nyström discretization of the first‐kind Fredholm integral equations. Also, we consider the weighted LSQR (WLSQR) to approximate the solution obtained by the TWSVD method for large problems. Numerical experiments on a few problems are used to illustrate that the TWSVD can perform better than the TSVD. 相似文献
992.
993.
We consider a higher order rational difference equation. Firstly, we skillfully give a sufficient and necessary condition for the existence and uniqueness of the initial value problem. And then we investigate the local stability, asymptotic behavior, periodicity and oscillation of solutions for the difference equation. Finally, we give some numerical simulations to illustrate our results. 相似文献
994.
Vladimir Ivanovich Mironenko Vladimir Vladimirovich Mironenko 《Journal of Applied Analysis & Computation》2016,6(3):876-883
In the paper we are giving the new method for searching periodic solutions of periodic differential systems. For this we construct a differential system with the same Reflecting Function as the Reflecting Function of the given system and with a known periodic solution. Then the initial data of the periodic solutions of this two systems coincide. In such a way the problem of existance periodic solutions goes to the Cauchy problem. 相似文献
995.
In this paper, by using methods from complex analysis and quaternionic analysis, we investigate an initial-boundary value problem for the Maxwell equations and obtain the general solutions and solvable conditions of the problem respectively in different cases. In addition, by using a similar method, we also discuss an initial-boundary value problem for a hyperbolic complex system of first order equations in R3. 相似文献
996.
The paper studies the longtime behavior of the Kirchhoff type equation with a strong dissipation utt−M(‖∇u‖2)Δu−Δut+h(ut)+g(u)=f(x). It proves that the related continuous semigroup S(t) possesses in the phase space with low regularity a global attractor which is connected. And an example is shown. 相似文献
997.
Singular values of a real rectangular tensor 总被引:3,自引:0,他引:3
Real rectangular tensors arise from the strong ellipticity condition problem in solid mechanics and the entanglement problem in quantum physics. In this paper, we systematically study properties of singular values of a real rectangular tensor, and give an algorithm to find the largest singular value of a nonnegative rectangular tensor. Numerical results show that the algorithm is efficient. 相似文献
998.
Stefan Balint 《Journal of Mathematical Analysis and Applications》2010,362(1):231-1649
A boundary value problem in the case of the second order axi-symmetric Young-Laplace differential equation (some of whose solutions describe the static meniscus free surface, i.e. the static liquid bridge free surface between the shaper and the crystal, occurring in single crystal rod growth) is analyzed. The analysis concerns the dependence of the solution of an initial value problem of the equation on a parameter p (the controllable part of the pressure difference Δp across the free surface). Inequalities are established for p which are necessary or sufficient conditions for the existence of a solution which represents a stable and convex free surface of a static meniscus. The analysis is numerically illustrated for the static menisci occurring in the NdYAG laser single crystal rod growth from the melt by edge-defined film-fed growth (E.F.G.) technique. This kind of inequalities can be useful in the experiment planning and technology design. 相似文献
999.
Zuji Guo 《Journal of Mathematical Analysis and Applications》2010,367(1):273-277
In this note existence of infinitely many solutions is proved for an elliptic equation with indefinite concave nonlinearities. 相似文献
1000.
Under barrier strip type arguments we investigate the existence of global solutions to the initial value problem x′=f(t,x,x′), x(0)=A, where the scalar function f(t,x,p) may be singular at x=A. 相似文献