全文获取类型
收费全文 | 247649篇 |
免费 | 16631篇 |
国内免费 | 647篇 |
专业分类
化学 | 155154篇 |
晶体学 | 3388篇 |
力学 | 11202篇 |
综合类 | 5篇 |
数学 | 25067篇 |
物理学 | 70111篇 |
出版年
2023年 | 4275篇 |
2022年 | 2517篇 |
2021年 | 4020篇 |
2020年 | 6186篇 |
2019年 | 4176篇 |
2018年 | 4873篇 |
2017年 | 3166篇 |
2016年 | 9060篇 |
2015年 | 7549篇 |
2014年 | 8310篇 |
2013年 | 13994篇 |
2012年 | 10274篇 |
2011年 | 9706篇 |
2010年 | 9315篇 |
2009年 | 9077篇 |
2008年 | 8890篇 |
2007年 | 8783篇 |
2006年 | 7816篇 |
2005年 | 6959篇 |
2004年 | 6471篇 |
2003年 | 5690篇 |
2002年 | 5527篇 |
2001年 | 6465篇 |
2000年 | 4950篇 |
1999年 | 3826篇 |
1998年 | 3060篇 |
1997年 | 3121篇 |
1996年 | 2861篇 |
1995年 | 2743篇 |
1994年 | 2541篇 |
1993年 | 2541篇 |
1992年 | 2779篇 |
1991年 | 2736篇 |
1990年 | 2653篇 |
1989年 | 2472篇 |
1988年 | 2557篇 |
1987年 | 2542篇 |
1985年 | 3056篇 |
1984年 | 3316篇 |
1983年 | 2727篇 |
1982年 | 2925篇 |
1981年 | 2916篇 |
1980年 | 2820篇 |
1979年 | 2897篇 |
1978年 | 2992篇 |
1977年 | 3120篇 |
1976年 | 3223篇 |
1975年 | 3105篇 |
1974年 | 3094篇 |
1973年 | 3050篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
A formulation of an implicit characteristic-flux-averaging method for the unsteady Euler equations with real gas effects is presented. Incorporation of a real gas into a general equation of state is achieved by considering the pressure as a function of density and specific internal energy. The Ricmann solver as well as the flux-split algorithm are modified by introducing the pressure derivatives with respect to density and internal energy. Expressions for calculating the values of the flow variables for a real gas at the cell faces are derived. The Jacobian matrices and the eigenvectors are defined for a general equation of state. The solution of the system of equations is obtained by using a mesh-sequencing method for acceleration of the convergence. Finally, a test case for a simple form of equation of state displays the differences from the corresponding solution for an ideal gas. 相似文献
52.
53.
54.
Sanzhizhapov D. B. Tonevitskii Yu. V. Mognonov D. M. Doroshenko Yu. E. 《Russian Journal of Applied Chemistry》2003,76(4):619-622
New polyimidates were prepared from bisphenols and mono- and dicarboxylic acid imidoyl chlorides. The structures of the polymers were determined, and their physicochemical, chemical, and thermal properties were studied. The possibility of preparing film and compression materials with good mechanical characteristics from these polymers was examined. 相似文献
55.
D. Shakin 《Journal of Mathematical Sciences》2007,142(4):2302-2366
In this paper, we study the numeric characteristics (the Hilbert function and graded Betti numbers) of monomial ideals in
the polynomial ring and in the exterior algebra.
__________
Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 30, Algebra,
2005. 相似文献
56.
57.
58.
An integrated study of diffusion, solubility, and electrical properties of scandium and praseodymium in silicon annealed in
various media and temperature ranges (1100–1280 °C) was performed for the first time. The tracer technique, autoradiography,
measurements of isothermic capacity and current relaxation, conductivity, and the Hall effect were used for the investigations.
The diffusion parameters, solubility, and an acceptor character of scandium and praseodymium impurities in silicon were determined.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 75–77, January, 2007. 相似文献
59.
60.
We present results for the determination of the equilibrium microstate probability distribution of a class of strongly interacting systems obeying stochastic dynamics but without the necessity of detailed balance. The specific case of Ising systems is highlighted, with applications to non-symmetric synaptic neural networks and more general recurrent Boolean networks. 相似文献