全文获取类型
收费全文 | 15521篇 |
免费 | 1356篇 |
国内免费 | 517篇 |
专业分类
化学 | 5011篇 |
晶体学 | 17篇 |
力学 | 956篇 |
综合类 | 64篇 |
数学 | 6564篇 |
物理学 | 4782篇 |
出版年
2024年 | 26篇 |
2023年 | 177篇 |
2022年 | 284篇 |
2021年 | 373篇 |
2020年 | 424篇 |
2019年 | 423篇 |
2018年 | 283篇 |
2017年 | 342篇 |
2016年 | 581篇 |
2015年 | 474篇 |
2014年 | 725篇 |
2013年 | 1163篇 |
2012年 | 680篇 |
2011年 | 751篇 |
2010年 | 653篇 |
2009年 | 896篇 |
2008年 | 1058篇 |
2007年 | 1052篇 |
2006年 | 858篇 |
2005年 | 638篇 |
2004年 | 536篇 |
2003年 | 580篇 |
2002年 | 575篇 |
2001年 | 441篇 |
2000年 | 464篇 |
1999年 | 389篇 |
1998年 | 371篇 |
1997年 | 257篇 |
1996年 | 214篇 |
1995年 | 180篇 |
1994年 | 181篇 |
1993年 | 157篇 |
1992年 | 146篇 |
1991年 | 94篇 |
1990年 | 87篇 |
1989年 | 91篇 |
1988年 | 107篇 |
1987年 | 71篇 |
1986年 | 67篇 |
1985年 | 104篇 |
1984年 | 80篇 |
1983年 | 25篇 |
1982年 | 50篇 |
1981年 | 48篇 |
1980年 | 48篇 |
1979年 | 38篇 |
1978年 | 33篇 |
1977年 | 34篇 |
1976年 | 30篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Fabio Scardigli 《Foundations of Physics》2007,37(8):1278-1295
The Titius–Bode law for planetary distances is reviewed. A model describing the basic features of this rule in the “quantum-like”
language of a wave equation is proposed. Some considerations about the ’t Hooft idea on the quantum behavior of deterministic
systems with dissipation are discussed. 相似文献
102.
Shaping command input or preshaping is used for reducing system oscillation in motion control. Desired systems inputs are altered so that the system finishes the requested move without residual oscillation. This technique, developed by N.C. Singer and W.P. Seering, is used for example in the aerospace field, in particular in flexible structure control. This paper presents the study of ZV shaper for explicit fractional derivative systems (generalized derivative systems). A robustness study of ZV shaper is then presented and applied to improve second generation CRONE control response time. Results from simulation and from a DC motor bench are also given. 相似文献
103.
104.
Madalina Deaconu Nicolas Fournier Etienne Tanré 《Methodology and Computing in Applied Probability》2003,5(2):131-158
By continuing the probabilistic approach of Deaconu et al. (2001), we derive a stochastic particle approximation for the Smoluchowski coagulation equations. A convergence result for this model is obtained. Under quite stringent hypothesis we obtain a central limit theorem associated with our convergence. In spite of these restrictive technical assumptions, the rate of convergence result is interesting because it is the first obtained in this direction and seems to hold numerically under weaker hypothesis. This result answers a question closely connected to the Open Problem 16 formulated by Aldous (1999). 相似文献
105.
By using microlocal analysis, the propagation of weak singularities in Cauchy problems for quasilinear thermoelastic systems in three space variables are investigated. First, paradifferential operators are employed to decouple the quasilinear thermoelastic systems. Second, by investigating the decoupled hyperbolic-parabolic systems and using the classical bootstrap argument, the property of finite propagation speeds of singularities in Cauchy problems for the quasilinear thermoelastic systems is obtained. Finally, it is shown that the microlocal weak singularities for Cauchy problems of the thermoelastic systems are propagated along the null bicharacteristics of the hyperbolic operators. 相似文献
106.
V. Sree Krishna Chaitanya 《Nonlinear Analysis: Real World Applications》2005,6(5):845-857
In this paper, a structurally unstable man–machine system is considered and a rigorous mathematical analysis is performed to study the influence of time delays in the control force on stability of the equilibrium solution of this system. Results on stability, instability and conditions for the preservation of stability (instability), besides the existence of bifurcation are presented. 相似文献
107.
In this paper, we introduce a phenomenological measure of ordering in statistical systems. Using this characteristic, we construct a formal model of a system evolving according to the law of steepest ascent as the control parameter increases. 相似文献
108.
求解非对称线性方程组的QMRGCGS方法 总被引:2,自引:1,他引:1
1 引言 求解非对称线性方程组Ax=b的双共轭梯度方法(BCG)[3]和它的变形共轭梯度平方方法(CGS)[6]都有典型的不规则收敛行为,后来Freund和Nachtigal提出一种BCG类方法,即拟极小剩余方法(QMR)[7],用来补救BCG方法的收敛性并且产生了光滑的收敛曲线。然而,象BCG方法一样,QMR方法要用到系数矩阵A及其转置A~T与向量的乘积,为了解决这一问题,Freund提出TFQMR方法,此方法具有拟极小剩余性,同时不需用到A~T与向量的乘积。 相似文献
109.
We solve the problem of describing compatible nonlocal Poisson brackets of hydrodynamic type. We prove that for nonsingular pairs of compatible nonlocal Poisson brackets of hydrodynamic type, there exist special local coordinates such that the metrics and the Weingarten operators of both brackets are diagonal. The nonlinear evolution equations describing all nonsingular pairs of compatible nonlocal Poisson brackets of hydrodynamic type are derived in these special coordinates, and the integrability of these equations is proved using the inverse scattering transform. The Lax pairs with a spectral parameter for these equations are found. We construct various classes of integrable reductions of the derived equations. These classes of reductions are of an independent differential-geometric and applied interest. In particular, if one of the compatible Poisson brackets is local, we obtain integrable reductions of the classical Lamé equations describing all orthogonal curvilinear coordinate systems in a flat space; if one of the compatible brackets is generated by a constant-curvature metric, the corresponding equations describe integrable reductions of the equations for orthogonal curvilinear coordinate systems in a space of constant curvature. 相似文献
110.
We propose an integrable deformation of the known model of two interacting tops on the algebra so(p,q). We consider particular cases including the generalized Lagrange and Kovalevskaya tops. We construct the Lax matrices and the corresponding classical R-matrices. 相似文献