全文获取类型
收费全文 | 10403篇 |
免费 | 1285篇 |
国内免费 | 1142篇 |
专业分类
化学 | 2346篇 |
晶体学 | 38篇 |
力学 | 1094篇 |
综合类 | 134篇 |
数学 | 4667篇 |
物理学 | 4551篇 |
出版年
2024年 | 25篇 |
2023年 | 115篇 |
2022年 | 252篇 |
2021年 | 222篇 |
2020年 | 306篇 |
2019年 | 300篇 |
2018年 | 268篇 |
2017年 | 318篇 |
2016年 | 325篇 |
2015年 | 263篇 |
2014年 | 455篇 |
2013年 | 772篇 |
2012年 | 502篇 |
2011年 | 637篇 |
2010年 | 606篇 |
2009年 | 769篇 |
2008年 | 731篇 |
2007年 | 730篇 |
2006年 | 666篇 |
2005年 | 579篇 |
2004年 | 531篇 |
2003年 | 496篇 |
2002年 | 421篇 |
2001年 | 311篇 |
2000年 | 353篇 |
1999年 | 277篇 |
1998年 | 317篇 |
1997年 | 223篇 |
1996年 | 178篇 |
1995年 | 117篇 |
1994年 | 116篇 |
1993年 | 88篇 |
1992年 | 93篇 |
1991年 | 70篇 |
1990年 | 47篇 |
1989年 | 55篇 |
1988年 | 50篇 |
1987年 | 31篇 |
1986年 | 30篇 |
1985年 | 32篇 |
1984年 | 34篇 |
1983年 | 10篇 |
1982年 | 14篇 |
1981年 | 17篇 |
1980年 | 16篇 |
1979年 | 16篇 |
1978年 | 14篇 |
1977年 | 5篇 |
1975年 | 4篇 |
1974年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
介绍未确知数学方法,并用未确知数学方法分析处理物理实验数据,与传统的数据处理方法比较,未确知数学方法不必对数据作任何假设,因此更合理,也更符合实际。 相似文献
42.
The steady-state two-phase flow non-linear equation is considered in the case when one of phases has low effective permeability in some periodic set, while on the complementary set it is high; the second phase has no contrast of permeabilities in different zones. A homogenization procedure gives the homogenized model with macroscopic effective permeability of the second phase depending on the gradient and on the second order derivatives of the macroscopic pressure of the first phase. This effect cannot be obtained by classical (one small parameter) homogenization. To cite this article: G.P. Panasenko, G. Virnovsky, C. R. Mecanique 331 (2003). 相似文献
43.
V. P. Maslov 《Theoretical and Mathematical Physics》2007,150(1):102-122
From the standpoint of thermodynamic averaging of fission microprocesses, we investigate the origin of radioactive release
in an NPP after an accident or after resource depletion. The genesis of the NPP release is interpreted as a new thermodynamic
phenomenon, a zeroth-order phase transition. This problem setting results in a problem in probabilistic number theory. We
prove the corresponding theorem leading to quantization of the Zipf law for the frequency of a zeroth-order phase transition
with different values of the jump of the Gibbs thermodynamic potential. We introduce the notion of hole dimension.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 150, No. 1, pp. 118–142, January, 2007. 相似文献
44.
45.
46.
现场抽样调查中,由于测量误差的存在,使得所测变量实测值的方差增大,通过增加每个体的测量次数可以控制测量误差,但这样每个体调查费用增大。本文对测量信度R,每个体测量次数m与相应所需的样本含量nm、调查费用Tn的关系进行了探讨,并介绍了如何根据R,及每个体测量费用占其总费用构成比C,确定最佳测量次数m值,以达到最佳控制调查费用的目的,这对我们在大型现场调查中进行经济效益分析具有重大的理论指导意义。 相似文献
47.
Shayesteh S. Farjami B. Soltani M. A. Solimany 《International Journal of Infrared and Millimeter Waves》2002,23(12):1691-1697
We present and discuss infrared magnetoplasma reflectivity and surface polariton modes in Ga1–xNxAs. It assumed that the sample is characterized by a magnetoplasma dielectric tensor. Surface polariton dispersion for two component magnetoplasma was calculated from reflectivity spectra data. We detect transverse optic phonon of GaN sublattice in 470 cm-1. The origin of sharp feature in p-polarization reflectivity about 300 cm–1 as well as LO phonon frequency of GaAs sublattice is due to Brewster mode. An interesting feature of surface modes in Voigt geometry is nonreciprocalicity, which means that the frequency changes when the direction of propagation is reversed. Also, the infrared magnetoplasma reflectivity of GaNAs should be providing determination of the electrons and heavy holes effective mass and carrier's concentration. 相似文献
48.
Youssef Saab 《Journal of Heuristics》1997,3(3):207-224
A heuristic optimization methodology, Dynamic Contraction (DC), is introduced as an approach for solving a wide variety of hard combinatorial problems. Contraction is an operation that maps an instance of a problem to a smaller instance of the same problem. DC is an iterative improvement strategy that relies on contraction as a mechanism for escaping local minima. As a byproduct of contraction, efficiency is improved due to a reduction of problem size. Effectiveness of DC is shown through simple applications to two classical combinatorial problems: The graph bisection problem and the traveling salesman problem. 相似文献
49.
Algorithms for systematical search of inverse in arithmetic operations with fuzzy numbers are discussed. The fuzzy number derived is considered either in a discrete representation of its support or described by the parameters of the corresponding membership function formula. Both algorithms are easy to be programmed for desk calculators. 相似文献
50.
V. A. Morozov E. M. Mukhamadiev A. B. Nazimov 《Computational Mathematics and Mathematical Physics》2007,47(12):1885-1892
Regularization of singular systems of linear algebraic equations by shifts is examined. New equivalent conditions for the shift regularizability of such systems are derived. 相似文献