全文获取类型
收费全文 | 38281篇 |
免费 | 6637篇 |
国内免费 | 2904篇 |
专业分类
化学 | 5690篇 |
晶体学 | 88篇 |
力学 | 3191篇 |
综合类 | 401篇 |
数学 | 19857篇 |
物理学 | 18595篇 |
出版年
2024年 | 99篇 |
2023年 | 456篇 |
2022年 | 663篇 |
2021年 | 946篇 |
2020年 | 1292篇 |
2019年 | 1231篇 |
2018年 | 1134篇 |
2017年 | 1087篇 |
2016年 | 1340篇 |
2015年 | 1157篇 |
2014年 | 1921篇 |
2013年 | 3348篇 |
2012年 | 2029篇 |
2011年 | 2481篇 |
2010年 | 2289篇 |
2009年 | 2414篇 |
2008年 | 2724篇 |
2007年 | 2642篇 |
2006年 | 2337篇 |
2005年 | 2223篇 |
2004年 | 1879篇 |
2003年 | 1743篇 |
2002年 | 1566篇 |
2001年 | 1202篇 |
2000年 | 1202篇 |
1999年 | 1016篇 |
1998年 | 985篇 |
1997年 | 775篇 |
1996年 | 556篇 |
1995年 | 473篇 |
1994年 | 376篇 |
1993年 | 268篇 |
1992年 | 252篇 |
1991年 | 250篇 |
1990年 | 221篇 |
1989年 | 146篇 |
1988年 | 125篇 |
1987年 | 115篇 |
1986年 | 120篇 |
1985年 | 112篇 |
1984年 | 103篇 |
1983年 | 51篇 |
1982年 | 90篇 |
1981年 | 82篇 |
1980年 | 55篇 |
1979年 | 59篇 |
1978年 | 42篇 |
1977年 | 33篇 |
1976年 | 28篇 |
1973年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Xuguang Lu 《Journal of statistical physics》2006,124(2-4):517-547
The paper considers macroscopic behavior of a Fermi–Dirac particle system. We prove the L
1-compactness of velocity averages of weak solutions of the Boltzmann equation for Fermi–Dirac particles in a periodic box with the collision kernel b(cos θ)|ρ−ρ
*|γ, which corresponds to very soft potentials: −5 < γ ≤ −3 with a weak angular cutoff: ∫0
π
b(cos θ)sin 3θ dθ < ∞. Our proof for the averaging compactness is based on the entropy inequality, Hausdorff–Young inequality, the L
∞-bounds of the solutions, and a specific property of the value-range of the exponent γ. Once such an averaging compactness is proven, the proof of the existence of weak solutions will be relatively easy. 相似文献
52.
We present a new approach to study the convergence of Newton's method in Banach spaces, which relax the conditions appearing in the usual studies. The approach is based on the bound required for the second derivative of the operator involved. An application to a nonlinear integral equation is presented. 相似文献
53.
Exact closed-form solutions are exhibited for the Hopf equation for stationary incompressible 3D Navier-Stokes flow, for the cases of homogeneous forced flow (including a solution with depleted nonlinearity) and inhomogeneous flow with arbitrary boundary conditions. This provides an exact method for computing two- and higher-point moments, given the mean flow. 相似文献
54.
The theory of free-carrier absorption (FCA) is developed, in the extreme quantum limit when the carriers are assumed to populate
only the lowest quantized energy level, for quasi-two and one-dimensional semiconducting quantum well structures where the
carriers are scattered by ionized impurities. The radiation field is assumed to be polarized in the plane of the layer in
the quasi-two-dimensional case and along the length of the wire in the quasi-one-dimensional case. Expressions for FCA are
obtained for the cases where the impurities are either in the well (background impurities) or outside the well (remote impurities).
Variation of FCA is numerically studied with photon frequency and well width. 相似文献
55.
相对论性无自旋粒子在Hartmann势场中运动的精确解 总被引:1,自引:1,他引:0
在标量势等于矢量势的条件下,本文获得了具有Hartmann型势的Klein-Gordon方程的精确解.给出了束缚态的精确的能谱方程和归一化的径向波函数,对于散射态,获得了按“k/2π标度”归一化的径向波函数和相移的解析计算公式.讨论了散射振幅的解析性质和波函数、能谱方程以及相移的非相对论近似. 相似文献
56.
We inquire into the time evolution of quantum systems associated with pseudo-or quasi-Hermitian Hamiltonians. We obtain, in
the pseudo-Hermitian case, a generalized Liouville-von Neumann equation for closed systems. We show that quantum systems with
quasi-Hermitian Hamiltonians admit the proper interpretation in terms of open quantum system and derive a generalized Lindblad-Kossakowski
equation. Finally, we extend such formalism to the study of decaying systems.
Partially supported by PRIN “Sintesi”. 相似文献
57.
We present a general scheme for entangling any degree of freedom of two uncorrelated identical particles from independent
sources by a combination of two-particle interferometry and which-way detection. We show that this entanglement generation
procedure works for completely random initial states of the variable to be entangled. We also demonstrate a curious complementarity
exhibited by our scheme and its applications in estimating the generated entanglement as a function of wave packet overlap
at the beamsplitter. 相似文献
58.
We obtain a solution of the DGLAP equation for the gluon at low x first by expanding the gluon in a Taylor series and then using the method of characteristics. We test its validity by comparing
it with that of Glück, Reya and Vogt. The convergence criteria of the approximation used are also discussed. We also calculate
εF
2(x,Q)2/ε In Q
2 using its approximate relations with the gluon distribution at low x. The predictions are then compared with the HERA data. 相似文献
59.
60.