全文获取类型
收费全文 | 8388篇 |
免费 | 844篇 |
国内免费 | 1386篇 |
专业分类
化学 | 2885篇 |
晶体学 | 70篇 |
力学 | 530篇 |
综合类 | 190篇 |
数学 | 5326篇 |
物理学 | 1617篇 |
出版年
2024年 | 10篇 |
2023年 | 111篇 |
2022年 | 146篇 |
2021年 | 172篇 |
2020年 | 283篇 |
2019年 | 264篇 |
2018年 | 254篇 |
2017年 | 325篇 |
2016年 | 327篇 |
2015年 | 250篇 |
2014年 | 410篇 |
2013年 | 647篇 |
2012年 | 508篇 |
2011年 | 435篇 |
2010年 | 412篇 |
2009年 | 540篇 |
2008年 | 549篇 |
2007年 | 567篇 |
2006年 | 455篇 |
2005年 | 458篇 |
2004年 | 439篇 |
2003年 | 390篇 |
2002年 | 357篇 |
2001年 | 308篇 |
2000年 | 293篇 |
1999年 | 259篇 |
1998年 | 205篇 |
1997年 | 201篇 |
1996年 | 206篇 |
1995年 | 139篇 |
1994年 | 117篇 |
1993年 | 70篇 |
1992年 | 83篇 |
1991年 | 64篇 |
1990年 | 53篇 |
1989年 | 29篇 |
1988年 | 33篇 |
1987年 | 30篇 |
1986年 | 19篇 |
1985年 | 29篇 |
1984年 | 24篇 |
1983年 | 18篇 |
1982年 | 19篇 |
1981年 | 9篇 |
1980年 | 24篇 |
1979年 | 17篇 |
1978年 | 18篇 |
1977年 | 10篇 |
1976年 | 11篇 |
1974年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
Sh. R. Shakirov 《Theoretical and Mathematical Physics》2007,153(2):1477-1486
We propose a method for constructing systems of polynomial equations that define submanifolds of degenerate binary forms of
an arbitrary degeneracy degree.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 153, No. 2, pp. 147–157, November, 2007. 相似文献
83.
Wei Mingjun Zhu Wanzhen 《Annals of Differential Equations》2007,23(4):511-518
In this paper we consider the system of classical particles coupled with a Klein-Gordon field in two dimensions.We establish a-priori-bounds on the solutions of this system with initial data satisfying a size restriction derived from conservation of energy.This result,together with the smoothing of"velocity averaging",yields the existence of global weak solutions to the corresponding restricted initial value problem.The size restriction is necessary since energy of the system is indefinite.Finally,we show that the weak solutions preserve the total mass. 相似文献
84.
T. Van Cauteren J. Ryckebusch B. Metsch H. -R. Petry 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):613-615
We present some of our results for the electromagnetic properties of excited Σ hyperons, computed within the framework of the Bonn constituent-quark model, which is based on the Bethe-Salpeter approach.
The seven parameters entering the model are fitted against the best-known baryon masses. Accordingly, the results for the
form factors and helicity amplitudes are genuine predictions. We compare with the scarce experimental data available and discuss
the processes in which Σ
*'s may play an important role. 相似文献
85.
蒋忠樟 《数学的实践与认识》2007,37(15):174-179
实对称正定矩阵的复合矩阵正定性的研究已有结论,但对于一般意义下的正定矩阵的复合矩阵是否仍然是正定的研究需要利用一般的正定矩阵的标准形的复合矩阵进行讨论,给出了一般公式及具体算法,为讨论其复合矩阵的正定性提供了基础条件. 相似文献
86.
利用集合在某点的相依切锥、法向锥和可行方向锥等研究向量优化问题的有效点、 弱有效点和真有效点的特征,对局部有效点、局部弱有效点和局部真有效点与集合的各 锥之间的关系作了刻画. 相似文献
87.
有限混合Gamma分布的拓扑稠密性证明 总被引:2,自引:0,他引:2
首先给出了有限混合Erlang分布在正实数轴上所有概率分布中稠密的理论证明,进而给出了混合Gamma分布具有稠密性的结论,说明有限混合Gamma分布具有广泛的适用性,可以用来刻画正实数轴上的任意随机变量. 相似文献
88.
We consider quasi-isometric mappings of domains in multidimensional Euclidean spaces. We establish that a mapping depends continuously in the sense of the topology of Sobolev classes on its metric tensor to within isometry of the space. In the space of metric tensors we take the topology determined by means of almost everywhere convergence. We show that if the metric tensor of a mapping is continuous then the length of the image of a rectifiable curve is determined by the same formula as in the case of mappings with continuous derivatives. (Continuity of the metric tensor of a mapping does not imply continuity of its derivatives.) 相似文献
89.
L. Bartosch P. Kopietz 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(1):29-36
We consider the effect of Coulomb interactions on the average density of states (DOS) of disordered low-dimensional metals
for temperatures T and frequencies ω smaller than the inverse elastic life-time 1/τ. Using the fact that long-range Coulomb interactions in two dimensions (2d) generate ln2-singularities in the DOS ν(ω) but only ln-singularities in the conductivity σ(ω), we can re-sum the most singular contributions
to the average DOS via a simple gauge-transformation. If σ(ω) > 0, then a metallic Coulomb gapν(ω) ∝ |ω|/e
4 appears in the DOS at T = 0 for frequencies below a certain crossover frequency Ω
2 which depends on the value of the DC conductivity σ(0). Here, - e is the charge of the electron. Naively adopting the same procedure to calculate the DOS in quasi 1d metals, we find ν(ω) ∝ (|ω|/Ω
1)1/2exp(- Ω
1/|ω|) at T = 0, where Ω
1 is some interaction-dependent frequency scale. However, we argue that in quasi 1d the above gauge-transformation method is on less firm grounds than in 2d. We also discuss the behavior of the DOS at finite temperatures and give numerical results for the expected tunneling conductance
that can be compared with experiments.
Received 28 August 2001 / Received in final form 28 January 2002 Published online 9 July 2002 相似文献
90.
Andreas Rößler 《BIT Numerical Mathematics》2006,46(1):97-110
A general class of stochastic Runge–Kutta methods for Itô stochastic differential equation systems w.r.t. a one-dimensional Wiener process is introduced. The colored rooted tree analysis is applied to derive conditions for the coefficients of the stochastic Runge–Kutta method assuring convergence in the weak sense with a prescribed order. Some coefficients for new stochastic Runge–Kutta schemes of order two are calculated explicitly and a simulation study reveals their good performance. 相似文献