全文获取类型
收费全文 | 2296篇 |
免费 | 150篇 |
国内免费 | 210篇 |
专业分类
化学 | 181篇 |
晶体学 | 1篇 |
力学 | 182篇 |
综合类 | 34篇 |
数学 | 2045篇 |
物理学 | 213篇 |
出版年
2023年 | 25篇 |
2022年 | 28篇 |
2021年 | 31篇 |
2020年 | 49篇 |
2019年 | 49篇 |
2018年 | 51篇 |
2017年 | 82篇 |
2016年 | 62篇 |
2015年 | 60篇 |
2014年 | 94篇 |
2013年 | 264篇 |
2012年 | 76篇 |
2011年 | 114篇 |
2010年 | 104篇 |
2009年 | 143篇 |
2008年 | 156篇 |
2007年 | 157篇 |
2006年 | 143篇 |
2005年 | 117篇 |
2004年 | 85篇 |
2003年 | 102篇 |
2002年 | 99篇 |
2001年 | 78篇 |
2000年 | 64篇 |
1999年 | 58篇 |
1998年 | 61篇 |
1997年 | 55篇 |
1996年 | 42篇 |
1995年 | 26篇 |
1994年 | 28篇 |
1993年 | 10篇 |
1992年 | 14篇 |
1991年 | 8篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1980年 | 9篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 2篇 |
排序方式: 共有2656条查询结果,搜索用时 560 毫秒
951.
In this paper, we study the strong law of large numbers and the Shannon–McMillan theorem for nonhomogeneous Markov chains indexed by a Cayley tree. This article generalizes the relative results of level nonhomogeneous Markov chains indexed by a Cayley tree. 相似文献
952.
讨论了-般环境中二重随机游动的强泛函大数定律,给出了当过程几乎处处趋向于正无穷时的泛函大数定律成立的几个充分条件. 相似文献
953.
954.
本文研究了一类隐非齐次马尔可夫模型的强极限定理.利用鞅差序列收敛定理,获得了观测链{Y_n,n≥0}的强大数定律,并给出了观测链的Shannon-McMillan定理. 相似文献
955.
We develop a nonconventional single‐node characteristic collocation method with piecewise‐cubic Hermite polynomials for the numerical simulation to unsteady‐state advection‐diffusion transport partial differential equations. This method greatly reduces the number of unknowns in the conventional collocation method, and generates accurate numerical solutions even if very large time steps are taken. The reduction of number of nodes has great potential for problems defined on high space dimensions, which appears in such problems as quantification of uncertainties in subsurface porous media. The method developed here is easy to formulate. Numerical experiments are presented to show the strong potential of the method. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 27: 786–802, 2011 相似文献
956.
N. Navruz 《Phase Transitions》2013,86(7-8):539-545
A detailed understanding of the transformation toughening process in zirconia-containing ceramics requires the application of the crystallographic theory of martensitic transformation. Therefore, the crystallographic analysis of the tetragonal-to-monoclinic transformation in ceria-zirconia was performed by using both the infinitesimal deformation approach and Wechsler–Lieberman–Read phenomenological crystallographic theory. All crystallographic parameters such as the habit plane orientation, orientation relationship between the parent and product phases, the direction of the total shape deformation, the amount of the lattice invariant strain, etc. were calculated. The results obtained from the infinitesimal deformation approach were in agreement with those calculated from phenomenological crystallographic theory and also with experimental observations. 相似文献
957.
The Fibonacci numbers are the numbers defined by the linear recurrence equation,in which each subsequent number is the sum of the previous two.In this paper,we propose Fibonacci networks using Fibonacci numbers.The analytical expressions involving degree distribution,average path length and mean first passage time are obtained.This kind of networks exhibits the small-world characteristic and follows the exponential distribution.Our proposed models would provide the valuable insights into the deterministically delayed growing networks. 相似文献
958.
959.
《International Journal of Solids and Structures》2014,51(25-26):4406-4413
A coupled Eulerian–Lagrangian (CEL) method can be used to model many types of dynamic events. Projectile penetration through solids is particularly well-suited to a CEL method. In this study the CEL method in the commercially-available code Abaqus was used to model a near rigid projectile perforating finite thickness concrete slabs. A near rigid projectile can be modeled as a Lagrangian material with distinct material interfaces, while the solid target can be modeled as an Eulerian material capable of large deformations. An improved concrete constitutive model is also described that was implemented into Abaqus as a user material model. A simplified stochastic model was also implemented to capture some of the heterogeneous nature of concrete. The CEL simulations are compared to experimental data to demonstrate the utility of this method for this type of perforation event. 相似文献
960.
André Adler 《随机分析与应用》2013,31(2):339-358
Abstract Consider independent and identically distributed random variables {X nk , 1 ≤ k ≤ m, n ≥ 1} from the Pareto distribution. We randomly select a pair of order statistics from each row, X n(i) and X n(j), where 1 ≤ i < j ≤ m. Then we test to see whether or not Strong and Weak Laws of Large Numbers with nonzero limits for weighted sums of the random variables X n(j)/X n(i) exist where we place a prior distribution on the selection of each of these possible pairs of order statistics. 相似文献