全文获取类型
收费全文 | 18401篇 |
免费 | 1680篇 |
国内免费 | 2190篇 |
专业分类
化学 | 7870篇 |
晶体学 | 154篇 |
力学 | 2353篇 |
综合类 | 201篇 |
数学 | 6140篇 |
物理学 | 5553篇 |
出版年
2024年 | 42篇 |
2023年 | 209篇 |
2022年 | 312篇 |
2021年 | 420篇 |
2020年 | 563篇 |
2019年 | 502篇 |
2018年 | 490篇 |
2017年 | 604篇 |
2016年 | 724篇 |
2015年 | 544篇 |
2014年 | 853篇 |
2013年 | 1743篇 |
2012年 | 964篇 |
2011年 | 1181篇 |
2010年 | 958篇 |
2009年 | 1173篇 |
2008年 | 1202篇 |
2007年 | 1256篇 |
2006年 | 1030篇 |
2005年 | 838篇 |
2004年 | 810篇 |
2003年 | 693篇 |
2002年 | 683篇 |
2001年 | 567篇 |
2000年 | 557篇 |
1999年 | 515篇 |
1998年 | 428篇 |
1997年 | 346篇 |
1996年 | 295篇 |
1995年 | 308篇 |
1994年 | 240篇 |
1993年 | 213篇 |
1992年 | 168篇 |
1991年 | 156篇 |
1990年 | 100篇 |
1989年 | 93篇 |
1988年 | 73篇 |
1987年 | 63篇 |
1986年 | 48篇 |
1985年 | 51篇 |
1984年 | 49篇 |
1983年 | 30篇 |
1982年 | 34篇 |
1981年 | 29篇 |
1980年 | 29篇 |
1979年 | 25篇 |
1978年 | 11篇 |
1977年 | 17篇 |
1976年 | 10篇 |
1973年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
A. Budhiraja 《Annales de l'Institut Henri Poincaré (B) Probabilités et Statistiques》2003,39(6):2318-941
In this work we study connections between various asymptotic properties of the nonlinear filter. It is assumed that the signal has a unique invariant probability measure. The key property of interest is expressed in terms of a relationship between the observation σ field and the tail σ field of the signal, in the stationary filtering problem. This property can be viewed as the permissibility of the interchange of the order of the operations of maximum and countable intersection for certain σ-fields. Under suitable conditions, it is shown that the above property is equivalent to various desirable properties of the filter such as
- (a) uniqueness of invariant measure for the signal,
- (b) uniqueness of invariant measure for the pair (signal, filter),
- (c) a finite memory property of the filter,
- (d) a property of finite time dependence between the signal and observation σ fields and
- (e) asymptotic stability of the filter.
102.
103.
本文就欧氏空间和球面中紧致子流形的Yang-Mills场进行了讨论.得到了一类不稳定性结果. 相似文献
104.
We show that the tensor product B-spline basis and the triangular Bernstein basis are in some sense best conditioned among all nonnegative bases for the spaces of tensor product splines and multivariate polynomials, respectively. We also introduce some new condition numbers which are analogs of component-wise condition numbers for linear systems introduced by Skeel. 相似文献
105.
V.B. Nalbandyan 《Journal of Physics and Chemistry of Solids》2004,65(6):1201
The irreproducibility of electrical properties of Na0.88Li0.12NbO3 solid solution on thermal cycling reported by M.A.L. Nobre and S. Lanfredi is explained by gradual decomposition of the supersaturated solid solution below ca. 800 °C. 相似文献
106.
A. Savin 《Journal of Physics and Chemistry of Solids》2004,65(12):2025-2029
The phase transition under pressure in iodine is analyzed using the electron localization function (ELF), explaining that the increase of the c/a ratio under compression is due to the presence of the lone pairs.A probabilistic interpretation is given for ELF. 相似文献
107.
The crystal structure of [N(CH3)4]3[As2Cl9] is determined at 293 K. It crystallizes in trigonal space group P31c: a = 9.2199(8), c = 21.065(3)Å, Z = 2, R1 = 0.0505, wR2 = 0.1283. The crystal is built of the discrete bioctahedral [As2Cl9]3— anions and the deformed tetramethylammonium cations. A structural phase transition in [N(CH3)4]3[As2Cl9] is detected by the DSC and dilatometric techniques at 146/151 K (on cooling/heating). Dielectric relaxation studies in the frequency range 75 kHz — 5 MHz indicate reorientations of the tetramethylammonium cations within the high temperature phase. Optical observations show the existence of the ferroelastic domain structure below 146 K. The possible mechanism of phase transition is discussed on the basis of the presented results. 相似文献
108.
A Stability Estimate for a Solution to a Three-Dimensional Inverse Problem for the Maxwell Equations
We consider the problem of determining dielectric permittivity and conductivity in the Maxwell equations. As additional information we prescribe the traces of the tangential components of the electromagnetic field on the lateral surface of a cylindric domain. We establish a stability estimate for a solution to the inverse problem and a uniqueness theorem. 相似文献
109.
V. V. Struzhanov V. V. Bashurov 《Journal of Applied Mechanics and Technical Physics》2003,44(4):549-556
Some iterative methods for calculating self-balanced stresses under shrinkage of a ball inclusion enclosed in a spherical matrix of a physically nonlinear damageable material. The stability of this system was studied using methods of catastrophe theory. It has been established that the beginning of divergence of the proposed iterative processes coincides with the moment of transition of the system to an unstable position of equilibrium. 相似文献
110.
In this paper, we study the linearization of the Cauchy problem and the mixed problem for the system of Grad--Hermite moments in nonequilibrium thermodynamics in the neighborhood of the equilibrium state. Stability conditions for solutions of the Cauchy problem are proved as a generalization of the classical Hermite--Biller theorem on stable polynomials. For the mixed problem, we prove an analog of the Vishik--Lyusternik theorem on small singular perturbations of general elliptic problems. The last observation allows us to introduce the Shapiro--Lopatinskii condition, which implies the well-posedness of the mixed problem. 相似文献