全文获取类型
收费全文 | 21254篇 |
免费 | 3469篇 |
国内免费 | 2434篇 |
专业分类
化学 | 14753篇 |
晶体学 | 210篇 |
力学 | 1548篇 |
综合类 | 199篇 |
数学 | 2348篇 |
物理学 | 8099篇 |
出版年
2024年 | 71篇 |
2023年 | 424篇 |
2022年 | 737篇 |
2021年 | 810篇 |
2020年 | 857篇 |
2019年 | 833篇 |
2018年 | 698篇 |
2017年 | 609篇 |
2016年 | 998篇 |
2015年 | 1040篇 |
2014年 | 1182篇 |
2013年 | 1550篇 |
2012年 | 1829篇 |
2011年 | 1991篇 |
2010年 | 1270篇 |
2009年 | 1208篇 |
2008年 | 1235篇 |
2007年 | 1129篇 |
2006年 | 1120篇 |
2005年 | 932篇 |
2004年 | 834篇 |
2003年 | 615篇 |
2002年 | 571篇 |
2001年 | 507篇 |
2000年 | 455篇 |
1999年 | 431篇 |
1998年 | 381篇 |
1997年 | 323篇 |
1996年 | 335篇 |
1995年 | 319篇 |
1994年 | 301篇 |
1993年 | 232篇 |
1992年 | 247篇 |
1991年 | 205篇 |
1990年 | 181篇 |
1989年 | 152篇 |
1988年 | 91篇 |
1987年 | 89篇 |
1986年 | 75篇 |
1985年 | 75篇 |
1984年 | 42篇 |
1983年 | 44篇 |
1982年 | 37篇 |
1981年 | 22篇 |
1980年 | 15篇 |
1979年 | 8篇 |
1977年 | 5篇 |
1975年 | 6篇 |
1969年 | 4篇 |
1957年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
921.
The main aim of this paper is to prove the existence and uniqueness of the solution for neutral stochastic functional differential
equations with infinite delay, which the initial data belong to the phase space ℬ((−∞,0];ℝ
d
). The vital work of this paper is to extend the initial function space of the paper (Wei and Wang, J. Math. Anal. Appl. 331:516–531,
2007) and give some examples to show that the phase space ℬ((−∞,0];ℝ
d
) exists. In addition, this paper builds a Banach space ℳ2((−∞,T],ℝ
d
) with a new norm in order to discuss the existence and uniqueness of the solution for such equations with infinite delay. 相似文献
922.
In this paper, we give a probabilistic interpretation for a coupled system of Hamilton–Jacobi–Bellman equations using the
value function of a stochastic control problem. First we introduce this stochastic control problem. Then we prove that the
value function of this problem is deterministic and satisfies a (strong) dynamic programming principle. And finally, the value
function is shown to be the unique viscosity solution of the coupled system of Hamilton–Jacobi–Bellman equations. 相似文献
923.
In this paper, the dual code of the binary cyclic code of length 2 n-1 with three zeros α, α t 1 and α t 2 is proven to have five nonzero Hamming weights in the case that n 4 is even and t1 = 2 n/2 + 1, t2 = 2 n-1-2 n/2+1 + 1 or 2 n/2 + 3, where α is a primitive element of the finite field F 2 n . The dual code is a divisible code of level n/2+1, and its weight distribution is also completely determined. When n = 4, the dual code satisfies Ward's bound. 相似文献
924.
用金刚石压砧高压X光衍射技术研究了Ⅱ-Ⅵ族化合物CdTe的室温状态方程和室温高压相变。实验的最高压力达39.2 GPa。实验中发现CdTe从(3.3±0.1)GPa开始从闪锌矿结构相相NaCl结构相转变,相变时体积收缩15.8%;从(10.3±0.2)GPa开始从NaCl相向β-Sn结构相转变,相变时无体积突变;在(12.2±0.2)GPa由β-Sn相向正交结构相转变,相变时也无体积突变。CdTe的压缩数据用最小二乘法以Bridgman状态方程和Murnaghan状态方程拟合,得到其零压时合相变压力时各个相的体弹模量及体弹模量的压力微商,并与其它的实验合理论结果进行比较。 相似文献
925.
926.
We consider a model of an Anderson impurity embedded in a d(x(2)-y(2))--wave superconducting state to describe the low-energy excitations of cuprate superconductors doped with a small amount of magnetic impurities. Because of the Dirac-like energy dispersion, a sharp localized resonance above the Fermi energy, showing a marginal Fermi liquid behavior ( omega ln omega as omega-->0), is predicted for the impurity states. The same logarithmic dependence of self-energy and a linear frequency dependence of the relaxation rate are also derived for the conduction electrons, characterizing a new universality class for the strong coupling fixed point. At the resonant energies, the spatial distribution of the electron density of states around the magnetic impurity is also calculated. 相似文献
927.
928.
A weighted estimate with power weights is established for the maximal operator associated with the commutator of the Bochner-Riesz operator. An application of this weighted estimate is also given.
929.
Z.J. Li X.L. Chen H.J. Li Q.Y. Tu Z. Yang Y.P. Xu B.Q. Hu 《Applied Physics A: Materials Science & Processing》2001,72(5):629-632
Low-dimensional GaN materials, including nanorings, nanoribbons and smooth nanowires have been synthesized by reacting gallium
and ammonia using Ag particles as a catalyst on the substrate of MgO single crystals. They were characterized by field emission
scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). EDX, XRD indicated
that the low-dimensional nanomaterials were wurtzite GaN. New features are found in Raman scatterings for these low-dimensional
GaN materials, which are different from the previous observations of GaN materials.
Received: 16 November 2000 / Accepted: 17 November 2000 / Published online: 21 March 2001 相似文献
930.