全文获取类型
收费全文 | 63050篇 |
免费 | 4323篇 |
国内免费 | 4656篇 |
专业分类
化学 | 21755篇 |
晶体学 | 417篇 |
力学 | 4508篇 |
综合类 | 791篇 |
数学 | 22420篇 |
物理学 | 22138篇 |
出版年
2024年 | 83篇 |
2023年 | 592篇 |
2022年 | 1036篇 |
2021年 | 1283篇 |
2020年 | 1416篇 |
2019年 | 1517篇 |
2018年 | 1381篇 |
2017年 | 1572篇 |
2016年 | 1754篇 |
2015年 | 1306篇 |
2014年 | 2201篇 |
2013年 | 4543篇 |
2012年 | 2417篇 |
2011年 | 2884篇 |
2010年 | 2437篇 |
2009年 | 3646篇 |
2008年 | 3951篇 |
2007年 | 4373篇 |
2006年 | 3699篇 |
2005年 | 3025篇 |
2004年 | 2576篇 |
2003年 | 2807篇 |
2002年 | 3175篇 |
2001年 | 2415篇 |
2000年 | 2296篇 |
1999年 | 1971篇 |
1998年 | 1903篇 |
1997年 | 1205篇 |
1996年 | 1077篇 |
1995年 | 901篇 |
1994年 | 910篇 |
1993年 | 673篇 |
1992年 | 742篇 |
1991年 | 520篇 |
1990年 | 456篇 |
1989年 | 366篇 |
1988年 | 324篇 |
1987年 | 299篇 |
1986年 | 281篇 |
1985年 | 266篇 |
1984年 | 256篇 |
1983年 | 162篇 |
1982年 | 215篇 |
1981年 | 206篇 |
1980年 | 151篇 |
1979年 | 177篇 |
1978年 | 148篇 |
1977年 | 138篇 |
1976年 | 85篇 |
1973年 | 65篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Patrick Dehornoy 《Algebra Universalis》2002,48(2):223-248
We solve the word problem of the identity x(yz) = (xy)(yz) by investigating a certain group describing the geometry of that identity. We also construct a concrete realization of the
one-generated free algebra relative to the above identity.
Received March 23, 2001; accepted in final form July 6, 2002. 相似文献
102.
103.
The pure state space of Quantum Mechanics is investigated as Hermitian Symmetric Kähler manifold. The classical principles of quantum mechanics (Quantum Superposition Principle, Heisenberg Uncertainty Principle, Quantum Probability Principle) and Spectral Theory of observables are discussed in this non-linear geometrical context. 相似文献
104.
A convective flow CO laser composed of polytetrafluoroethylene discharge tubes, nickel–chromium steel components, a cupric heat exchanger and other components is described. Operating in liquid nitrogen condition, output power of 60 W has been obtained from a non-selective cavity. 相似文献
105.
A. Khrennikov 《Annalen der Physik》2003,12(10):575-585
We study the probabilistic consequences of the choice of the basic number field in the quantum formalism. We demonstrate that by choosing a number field for a linear space representation of quantum model it is possible to describe various interference phenomena. We analyse interference of probabilistic alternatives induced by real, complex, hyperbolic (Clifford) and p‐adic representations. 相似文献
106.
平行机半在线排序问题研究(Ⅰ) 总被引:15,自引:1,他引:14
对半在线平行机排序问题的研究进展作了详细综述和进一步探讨。文章给出半在线排序问题的背景、定义、分类和求解。介绍它们定义和在不同机器环境和目标函数下半在线排序问题分类,以及第一类半在线模型的近似算法的设计及其竞争比分析。 相似文献
107.
By using the quasi-Lyapunov function, some sufficient conditions of global exponential stability for impulsive systems are established, which is the basis for the following discussion. Then, by employing Riccati inequality and Hamilton-Jacobi inequality approach, some sufficient conditions of robust exponential stability for uncertain linear/nonlinear impulsive systems are derived, respectively. Finally, some examples are given to illustrate the applications of the theory. 相似文献
108.
A.J.?Lpez-Moreno 《Acta Mathematica Hungarica》2005,106(4):343-354
Summary We obtain preservation inequalities for Lipschitz constants of higher order in simultaneous approximation processes by Bernstein type operators. From such inequalities we derive the preservation of the corresponding Lipschitz spaces. 相似文献
109.
Nobuhiro Honda 《Mathematische Nachrichten》2003,256(1):48-57
In a previous paper of the same title the author gave a generalization of the constrution of Donaldson–Friedman, to prove the existence of twistor spaces of n CP 2 with a special kind of divisors. In the present paper, we consider its equivariant version. When n = 3, this gives another proof of the existence of degenerate double solid with C *–action, and we show that the branch quartic surface is birational to an elliptic ruled surface. In case n ≥ 4, this yields new Moishezon twistor spaces with C *–action, which is shown to be the most degenerate ones among twistor spaces studied by Campana and Kreußler. 相似文献
110.
By further generalizing the skew-symmetric triangular splitting iteration method studied by Krukier, Chikina and Belokon (Applied Numerical Mathematics, 41 (2002), pp. 89–105), in this paper, we present a new iteration scheme, called the modified skew-Hermitian triangular splitting iteration method, for solving the strongly non-Hermitian systems of linear equations with positive definite coefficient matrices. We discuss the convergence property and the optimal parameters of this new method in depth. Moreover, when it is applied to precondition the Krylov subspace methods like GMRES, the preconditioning property of the modified skew-Hermitian triangular splitting iteration is analyzed in detail. Numerical results show that, as both solver and preconditioner, the modified skew-Hermitian triangular splitting iteration method is very effective for solving large sparse positive definite systems of linear equations of strong skew-Hermitian parts. 相似文献