全文获取类型
收费全文 | 17404篇 |
免费 | 1981篇 |
国内免费 | 2016篇 |
专业分类
化学 | 6025篇 |
晶体学 | 119篇 |
力学 | 2688篇 |
综合类 | 300篇 |
数学 | 9113篇 |
物理学 | 3156篇 |
出版年
2024年 | 57篇 |
2023年 | 216篇 |
2022年 | 395篇 |
2021年 | 444篇 |
2020年 | 578篇 |
2019年 | 546篇 |
2018年 | 550篇 |
2017年 | 635篇 |
2016年 | 736篇 |
2015年 | 534篇 |
2014年 | 828篇 |
2013年 | 1535篇 |
2012年 | 927篇 |
2011年 | 979篇 |
2010年 | 822篇 |
2009年 | 1053篇 |
2008年 | 1111篇 |
2007年 | 1151篇 |
2006年 | 965篇 |
2005年 | 848篇 |
2004年 | 790篇 |
2003年 | 709篇 |
2002年 | 681篇 |
2001年 | 553篇 |
2000年 | 534篇 |
1999年 | 523篇 |
1998年 | 422篇 |
1997年 | 349篇 |
1996年 | 304篇 |
1995年 | 269篇 |
1994年 | 237篇 |
1993年 | 187篇 |
1992年 | 143篇 |
1991年 | 138篇 |
1990年 | 98篇 |
1989年 | 81篇 |
1988年 | 61篇 |
1987年 | 58篇 |
1986年 | 47篇 |
1985年 | 52篇 |
1984年 | 54篇 |
1983年 | 27篇 |
1982年 | 39篇 |
1981年 | 28篇 |
1980年 | 28篇 |
1979年 | 24篇 |
1978年 | 15篇 |
1977年 | 18篇 |
1976年 | 8篇 |
1957年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
一类拟线性大系统的稳定性 总被引:1,自引:0,他引:1
彭晓林 《新疆大学学报(理工版)》1991,8(1):41-45
本文应用大系统的分解方法和一个推广的不等式,研究了一类拟线性大系统的稳定性问题,所得结果简洁、易于验证,且推导过程不复杂,最后给出了应用实例。 相似文献
122.
For linear statistical ill-posed problems in Hilbert spaces we introduce an adaptive procedure to recover the unknown solution from indirect discrete and noisy data. This procedure is shown to be order optimal for a large class of problems. Smoothness of the solution is measured in terms of general source conditions. The concept of operator monotone functions turns out to be an important tool for the analysis.
123.
Wengu Chen Yixin Lai 《分析论及其应用》2006,22(2):195-200
Let μ be a Borel measure on Rd which may be non doubling. The only condition that μ must satisfy is μ(Q) ≤ col(Q)n for any cube Q () Rd with sides parallel to the coordinate axes and for some fixed n with 0 < n ≤ d. The purpose of this paper is to obtain a boundedness property of fractional integrals in Hardy spaces H1 (μ). 相似文献
124.
This paper considers the general synchronization dynamics of coupled Van der Pol–Duffing oscillators. The linear and nonlinear stability analysis on the synchronization process is derived through the Whittaker method and the Floquet theory in addition to the multiple time scales method. A stability map displaying different dynamical states of the system is performed. Numerical simulation is carried out to support and to complement the accuracy of the analytical treatment. 相似文献
125.
De Ming ZHU Ying SUN 《数学学报(英文版)》2007,23(8):1495-1504
In this paper, we study the dynamical behavior for a 4-dimensional reversible system near its heteroclinic loop connecting a saddle-focus and a saddle. The existence of infinitely many reversible 1-homoclinic orbits to the saddle and 2-homoclinic orbits to the saddle-focus is shown. And it is also proved that, corresponding to each 1-homoclinic (resp. 2-homoclinic) orbit F, there is a spiral segment such that the associated orbits starting from the segment are all reversible 1-periodic (resp. 2-periodic) and accumulate onto F. Moreover, each 2-homoclinic orbit may be also accumulated by a sequence of reversible 4-homoclinic orbits. 相似文献
126.
In this paper we formulate a theorem on the persistence of elliptic lower-dimensional invariant tori for nearly integrable analytic Hamiltonian systems under the first Melnikov condition and Rüssmann’s non-degeneracy condition, and give the measure estimates of parameters for the non-resonance conditions under Rüssmann’s non-degeneracy condition, which is essential for the proof of our result. 相似文献
127.
Koen Thas 《Journal of Algebraic Combinatorics》2006,24(1):5-22
In this paper, we classify the finite generalized quadrangles of order (s,t), s,t > 1, which have a line L of elation points, with the additional property that there is a line M not meeting L for which {L, M} is regular. This is a first fundamental step towards the classification of those generalized quadrangles having a line of
elation points.
Mathematics Subject Classification (2000): 51E12, 51E20, 20B25, 20E42 相似文献
128.
The thermal stability and measurement temperature dependence of Schottky contact characteristics on n-GaN using a W2B5/Ti/Au metallization scheme was studied using current-voltage (I-V), scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) measurements. The elemental profile obtained from samples annealed at 350 °C showed some titanium diffusion into the gold layer but little other difference from the as-deposited wafer. Annealing at 700 °C produced significant diffusion of titanium. The Schottky barrier height increased with anneal temperature up to 200 °C, reaching a maximum value of 0.65 eV, but decreased at higher annealing temperatures. The reverse breakdown voltage from diodes fabricated using the W2B5-based contacts showed a similar dependence. The reverse current magnitude was larger than predicted by thermionic emission alone. The barrier height showed only minor changes with measurement temperature up to 150 °C. 相似文献
129.
In this article a stability result for the Falk model system is proven. The Falk model system describes the martensitic phase transitions in shape memory alloys. In our setting, the steady state is a nonlocal elliptic problem. We show the dynamical stability for the linearized stable critical point of the corresponding functional. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
130.
O. A. Veliev 《Mathematical Notes》2007,81(3-4):440-448
We obtain asymptotic formulas for non-self-adjoint operators generated by the Sturm-Liouville system and quasiperiodic boundary conditions. Using these asymptotic formulas, we obtain conditions on the potential for which the system of root vectors of the operator under consideration forms a Riesz basis. 相似文献