全文获取类型
收费全文 | 930篇 |
免费 | 23篇 |
国内免费 | 1篇 |
专业分类
化学 | 769篇 |
晶体学 | 1篇 |
力学 | 7篇 |
数学 | 110篇 |
物理学 | 67篇 |
出版年
2024年 | 2篇 |
2023年 | 9篇 |
2022年 | 54篇 |
2021年 | 45篇 |
2020年 | 14篇 |
2019年 | 24篇 |
2018年 | 12篇 |
2017年 | 11篇 |
2016年 | 31篇 |
2015年 | 32篇 |
2014年 | 27篇 |
2013年 | 78篇 |
2012年 | 70篇 |
2011年 | 57篇 |
2010年 | 55篇 |
2009年 | 39篇 |
2008年 | 48篇 |
2007年 | 55篇 |
2006年 | 62篇 |
2005年 | 56篇 |
2004年 | 53篇 |
2003年 | 26篇 |
2002年 | 27篇 |
2001年 | 10篇 |
2000年 | 9篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有954条查询结果,搜索用时 15 毫秒
61.
Izabella Dascalu Cristian Hornoiu Jose Maria Calderon-Moreno Madalin Enache Daniela Culita Simona Somacescu 《Journal of Sol-Gel Science and Technology》2018,86(1):151-161
The aim of this work was an investigation of structural and electrical properties of ZnO/Zn2-xFexTiO4 (x?=?0.7, 1, 1.4) powders. The compounds obtained by sol-gel method are characterized by several techniques: X-ray diffraction (XRD), N2 adsorption–desorption isotherms, scanning and transmission electron microscopy (SEM and TEM), X-ray photoelectron spectroscopy (XPS), electrical and dielectrical measurements. The XRD, SEM and XPS analysis confirmed the formation of ZnFeTiO4 inverse spinel structure. The electrical and dielectrical properties of ZnO/Zn2-xFexTiO4 (x?=?0.7, 1, 1.4) were measured by impedance spectroscopy, revealing a decrease in the electrical conductivity and the dielectric constant with Fe content. 相似文献
62.
63.
Discriminantal arrangement, 3 × 3 minors of Plücker matrix and hypersurfaces in Grassmannian Gr(3,n)
We show that points in specific degree-2 hypersurfaces in the Grassmannian correspond to generic arrangements of n hyperplanes in with associated discriminantal arrangement having intersections of multiplicity three in codimension two. 相似文献
64.
65.
This paper deals with a scalar conservation law in 1-D space
dimension, and in particular, the focus is on the stability analysis
for such an equation. The problem of feedback stabilization under
proportional-integral-derivative (PID for short) boundary control is
addressed. In the proportional-integral (PI for short) controller
case, by spectral analysis, the authors provide a complete
characterization of the set of stabilizing feedback parameters, and
determine the corresponding time delay stability interval. Moreover,
the stability of the equilibrium is discussed by Lyapunov function
techniques, and by this approach the exponential stability when a
damping term is added to the classical PI controller scheme is
proved. Also, based on Pontryagin results on stability for
quasipolynomials, it is shown that the closed-loop system subject to
PID control is always unstable. 相似文献
66.
Simona Rota Nodari 《Annales Henri Poincare》2010,10(7):1377-1393
The aim of this work is to prove by a perturbation method the existence of solutions of the coupled Einstein–Dirac equations
for a static, spherically symmetric system of two fermions in a singlet spinor state. We relate the solutions of our equations
to those of the nonlinear Choquard equation and we show that the nondegenerate solution of Choquard’s equation generates solutions
of the Einstein–Dirac equations. 相似文献
67.
Yves Crama Michel Grabisch Silvano Martello 《4OR: A Quarterly Journal of Operations Research》2016,14(4):333-336
We recall some cases of ethical misconduct that occurred in the recent years, and we report a new trick that was recently attempted to cheat the journal in order to obtain the publication of an article through usurped identity. 相似文献
68.
Alberto Caprara Andrea Lodi Silvano Martello Michele Monaci 《Discrete Optimization》2006,3(4):317-326
We address the problem of packing a given set of rectangles into the minimum size square. We consider three versions of the problem, arising when the rectangles (i) are squares; (ii) have a fixed orientation; (iii) can be rotated by 90. For each case we study lower bounds, and analyze their worst-case performance ratio. In addition, we evaluate through computational experiments their average performance on instances from the literature. 相似文献
69.
70.
We investigate oscillatory properties of half-linear differential equations. The investigated half-linear equation is viewed as a perturbation of another (nonoscillatory) equation of the same form and perturbation is allowed both in the absolute term and in the derivative term. First, the Sturmian type theorem for solutions of the associated Riccati equation is established. In the second part of the paper we prove new half-linear oscillation criteria using the variational technique. 相似文献