全文获取类型
收费全文 | 208篇 |
免费 | 6篇 |
国内免费 | 6篇 |
专业分类
化学 | 13篇 |
综合类 | 1篇 |
数学 | 138篇 |
物理学 | 68篇 |
出版年
2023年 | 5篇 |
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 7篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 2篇 |
2013年 | 13篇 |
2012年 | 6篇 |
2011年 | 11篇 |
2010年 | 7篇 |
2009年 | 16篇 |
2008年 | 19篇 |
2007年 | 11篇 |
2006年 | 13篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 8篇 |
2001年 | 16篇 |
2000年 | 14篇 |
1999年 | 8篇 |
1998年 | 8篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有220条查询结果,搜索用时 15 毫秒
211.
For
the mapping
is onto R. It was shown by G. Boole in the 1850's that
We give an n-dimensional analogue of this result. The proof makes use of the Griffiths–Harris residue theorem from algebraic geometry. 相似文献
212.
Francisco Marcellán M. Francisca Pérez-Valero Yamilet Quintana 《Journal of Mathematical Analysis and Applications》2015
The aim of this paper is to present some new results about the asymptotic behavior of the partial derivatives of the kernel polynomials associated with the Gamma distribution. We also show how these results can be used in order to obtain the inner relative asymptotics for certain Laguerre–Sobolev type polynomials. 相似文献
213.
Max Wakefield 《代数通讯》2019,47(7):2654-2666
In this note, we study the logarithmic derivation module of a non-free arrangement. We prove a generalized addition theorem for all arrangements. This addition theorem allows us to find various relationships between non-free arrangements, free arrangements, and restriction counts. For graphic arrangements, we can use these results to find a lower bound for the maximal degree generator in terms of triangles in the associated graph. We also apply these results to the case of hypersolvable arrangements where we define hyperexponents and use them to find a lower bound for their maximal degree generator. 相似文献
214.
M. Reehuis C. Ulrich P. Pattison M. Miyasaka Y. Tokura B. Keimer 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,64(1):27-34
The crystal structure and the magnetic ordering pattern of the electrically insulating perovskite CeVO3 was investigated by high-resolution powder X-ray diffraction and single-crystal neutron diffraction. A structural phase transition
from an orthorhombic to a monoclinic structure (with space groups Pbnm and P21/b, respectively) was observed upon cooling below T
s = 136 K. This transition is associated with a strong distortion of the VO6-octahedra and can be attributed to orbital ordering. A magnetic ordering transition driven by exchange interactions between
vanadium moments is observed at T
N = 124 K, and antiferromagnetic interactions between magnetic moments on vanadium and cerium ions induce a progressive magnetic
polarization of the cerium sublattice at lower temperatures. The full magnetic structure is described by a superposition of
the modes (C
x
, F
y
, −) and (F
x
, C
y
, −). The unit cell volume and the tilt angles of the VO6-octahedra in the CeVO3-crystal structure are anomalous compared to those of other members of the series RVO3 (R = lanthanide atom), and the ordered magnetic moments on both vanadium and cerium sublattices at low temperatures are considerably
smaller than the free-ion values of V3+ and Ce3+. Possible origins of this behavior are discussed. 相似文献
215.
Y. Li T. X. Wang H. Y. Liu X. W. Xu Z. M. Lu Y. X. Li 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,66(3):369-373
Monte Carlo simulation is adopted to study the spin ordering in ferromagnet(FM)/antiferromagnet(AFM) bilayers with a mixed
interface. We introduce the time-dependent autocorrelation function to describe the thermal stability of the spin ordering
for each plane, especially the interface, in FM/AFM bilayers with uncompensated and compensated AFM surfaces. It is found
that the thermal decay of spin ordering depends on the plane, the interface coupling and the interface roughness. For the
uncompensated AFM surfaces, when the interface coupling is small, the thermal decay of spin ordering is faster at the interface
than other planes, while the large interfae coupling makes the spin ordering at the interface become relatively stable. In
the case of compensated AFM surfaces, the spin ordering at the interface is thermally disordered much before that at other
planes, and the thermal decay becomes slow gradually as the interface coupling increases. 相似文献
216.
217.
Enrique Artal Bartolo Shinzo Bannai Taketo Shirane Hiro-o Tokunaga 《Mathematische Nachrichten》2023,296(6):2214-2235
There is a close relationship between the embedded topology of complex plane curves and the (group-theoretic) arithmetic of elliptic curves. In a recent paper, we studied the topology of some arrangements of curves that include a special smooth component, via the torsion properties induced by the divisors in the special curve associated to the remaining components, which is an arithmetic property. When this special curve has maximal flexes, there is a natural isomorphism between its Jacobian variety and the degree zero part of its Picard group. In this paper, we consider curve arrangements that contain a special smooth component with a maximal flex and exploit these properties to obtain Zariski tuples, which show the interplay between topology, geometry, and arithmetic. 相似文献
218.
The higher order degrees are Alexander-type invariants of complements to an affine plane curve. In this paper, we characterize the vanishing of such invariants for a curve C given as a transversal union of plane curves and in terms of the finiteness and the vanishing properties of the invariants of and , and whether or not they are irreducible. As a consequence, we prove that the multivariable Alexander polynomial is a power of , and we characterize when in terms of the defining equations of and . Our results impose obstructions on the class of groups that can be realized as fundamental groups of complements of a transversal union of curves. 相似文献
219.
We compute the rational Betti cohomology groups of the coarse moduli spaces of geometrically marked Del Pezzo surfaces of degree 3 and 4 as representations of the Weyl groups of the corresponding root systems. The proof uses a blend of methods from point counting over finite fields and techniques from arrangement complements. 相似文献
220.
This paper investigates a reconfigurable intelligent surface (RIS)-aided underlay cognitive radio (CR) multiple-input multiple-output (MIMO) wiretap channel where the secondary transmitter (ST) communicates with primary user (PU) and secondary user (SU) in the absence of the eavesdropper’s (Eve’s) channel state information (CSI). To enhance the secrecy performance in CR MIMO wiretap channel, the power of useful signal is minimized at ST, and then the residual power is further utilized to design artificial noise (AN) based on statistical CSI at ST. Specifically, we first optimize the transmit covariance matrix at ST and the diagonal phase-shifting matrix at RIS jointly leveraging large-system approximation results. Then the power allocation for SU is optimized to obtain the minimum transmit power of useful information at ST. Besides, we further design AN with the residual power by aligning it into the null space of the SU channel and thus avert the harmful effects of AN to improve the secure communication quality of SU. Finally, through numerical simulations, we illustrate the effectiveness of the proposed algorithm and validate the existence of a trade-off between the quality-of-service (QoS) at SU and secrecy rate. 相似文献