全文获取类型
收费全文 | 9924篇 |
免费 | 837篇 |
国内免费 | 598篇 |
专业分类
化学 | 1325篇 |
晶体学 | 145篇 |
力学 | 768篇 |
综合类 | 105篇 |
数学 | 7369篇 |
物理学 | 1647篇 |
出版年
2024年 | 23篇 |
2023年 | 79篇 |
2022年 | 119篇 |
2021年 | 127篇 |
2020年 | 264篇 |
2019年 | 258篇 |
2018年 | 261篇 |
2017年 | 281篇 |
2016年 | 299篇 |
2015年 | 233篇 |
2014年 | 422篇 |
2013年 | 917篇 |
2012年 | 373篇 |
2011年 | 550篇 |
2010年 | 549篇 |
2009年 | 614篇 |
2008年 | 697篇 |
2007年 | 632篇 |
2006年 | 564篇 |
2005年 | 504篇 |
2004年 | 432篇 |
2003年 | 399篇 |
2002年 | 356篇 |
2001年 | 282篇 |
2000年 | 237篇 |
1999年 | 241篇 |
1998年 | 181篇 |
1997年 | 186篇 |
1996年 | 163篇 |
1995年 | 117篇 |
1994年 | 114篇 |
1993年 | 86篇 |
1992年 | 72篇 |
1991年 | 63篇 |
1990年 | 55篇 |
1989年 | 36篇 |
1988年 | 44篇 |
1987年 | 31篇 |
1986年 | 46篇 |
1985年 | 52篇 |
1984年 | 59篇 |
1983年 | 42篇 |
1982年 | 54篇 |
1981年 | 43篇 |
1980年 | 40篇 |
1979年 | 48篇 |
1978年 | 30篇 |
1977年 | 19篇 |
1976年 | 23篇 |
1973年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
61.
本文提出了一类特殊的n人合作对策模型─—弱1—凸对策,研究了弱1—凸对策的解的性质,并证明弱1—凸对策的解满足所有常见的公理化特征. 相似文献
62.
Liquid-liquid phase equilibria of aqueous two-phase systems containing salts and polyethylene glycol 总被引:2,自引:0,他引:2
Liquid-liquid phase equilibria of the ternary systems: (a) polyethylene glycol - ammonium sulfate- water and (b) polyethylene glycol - sodium carbonate -water have been determined experimentally at 15°, 25°, 35° and 45°C and for two different molecular weights of the polymer (Avg. M.W. 1000 and 2000). Details of the glass cell and of the equilibration and analytical procedures used are described. Equilibrium data along with phase diagrams are presented. Finally the effect of temperature and of the molecular weight of the polymer are also discussed. 相似文献
63.
The direct growth of ZnSe–CdSe solid solution onto metallic cathodes by electrodeposition from acidic aqueous sulphate solutions
is described. The plating process is studied by simple voltammetry, while the structure and composition of the electrolytic
deposits are investigated by X-ray diffraction. The experimental d-spacing values of the as-grown mixed lattice are compared to data from reference Zn
x
Cd1-x
Se pellets of standard composition, produced by a sintering method. The findings are supplemented with energy-dispersive X-ray
(EDX) elemental analysis. Thereupon, the variation of the mole fraction x in Zn
x
Cd1-x
Se, and the solid phase constitution of the electrodeposits are determined and correlated to the electrochemical conditions
of growth. The resulting films contain admixtures of CdSe compound and metallic Cd. 相似文献
64.
65.
Jean-Franç ois Coulombel Thierry Goudon 《Transactions of the American Mathematical Society》2007,359(2):637-648
We construct global smooth solutions to the multidimensional isothermal Euler equations with a strong relaxation. When the relaxation time tends to zero, we show that the density converges towards the solution to the heat equation.
66.
B. M. Azizur Rahman A. K. M. Saiful Kabir Muttukrishnan Rajarajan Kenneth T. V. Grattan 《Optical and Quantum Electronics》2005,37(1-3):171-183
Modal solutions of planar photonic crystal waveguides with rectangular air-holes are presented by using a rigorous full-vectorial finite element-based approach. The effective indices, mode field profiles, spot-sizes, power confinements, modal hybridness, beat lengths and group velocity dispersions are shown for the fundamental and higher order modes of the quasi-TE and TM polarizations. 相似文献
67.
三种群食物链交错扩散模型的整体 总被引:1,自引:0,他引:1
本文应用能量估计方法和Gagliardo-Nirenberg型不等式证明了一类强耦合反应扩散系统整体解的存在性和一致有界性,该系统是带自扩散和交错扩散项的三种群Lotka-Volterra食物链模型.通过构造Lyapunov函数给出了该模型正平衡点全局渐近稳定的充分条件. 相似文献
68.
In this paper, we establish the existence of upper and lower solutions for a periodic boundary value problems (PBVP for short) of impulsive differential equations. which guarantees the existence of at least one solution for the problem. As an application, these results are applied to PBVP of ODE and some examples are given to illustrate our results. 相似文献
69.
Daniel Pa?ca 《Journal of Mathematical Analysis and Applications》2007,325(1):90-100
Some existence results are obtained for periodic solutions of nonautonomous second-order differential inclusions systems with p-Laplacian. 相似文献
70.
Differential inequality method, bounding function method and topological degree are applied to obtain the existence criterions of at least one solution for the general fourth-order differential equations under nonlinear boundary conditions, and many existing results are complemented. 相似文献