全文获取类型
收费全文 | 4603篇 |
免费 | 444篇 |
国内免费 | 488篇 |
专业分类
化学 | 172篇 |
晶体学 | 1篇 |
力学 | 305篇 |
综合类 | 138篇 |
数学 | 4364篇 |
物理学 | 555篇 |
出版年
2024年 | 2篇 |
2023年 | 70篇 |
2022年 | 70篇 |
2021年 | 92篇 |
2020年 | 134篇 |
2019年 | 125篇 |
2018年 | 134篇 |
2017年 | 138篇 |
2016年 | 149篇 |
2015年 | 90篇 |
2014年 | 183篇 |
2013年 | 373篇 |
2012年 | 179篇 |
2011年 | 234篇 |
2010年 | 217篇 |
2009年 | 274篇 |
2008年 | 288篇 |
2007年 | 306篇 |
2006年 | 317篇 |
2005年 | 261篇 |
2004年 | 211篇 |
2003年 | 201篇 |
2002年 | 228篇 |
2001年 | 177篇 |
2000年 | 161篇 |
1999年 | 166篇 |
1998年 | 139篇 |
1997年 | 99篇 |
1996年 | 103篇 |
1995年 | 75篇 |
1994年 | 57篇 |
1993年 | 32篇 |
1992年 | 34篇 |
1991年 | 29篇 |
1990年 | 22篇 |
1989年 | 15篇 |
1988年 | 12篇 |
1987年 | 10篇 |
1986年 | 22篇 |
1985年 | 27篇 |
1984年 | 12篇 |
1983年 | 14篇 |
1982年 | 14篇 |
1981年 | 9篇 |
1980年 | 5篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1957年 | 3篇 |
1936年 | 1篇 |
排序方式: 共有5535条查询结果,搜索用时 46 毫秒
91.
92.
Ramsés Djidjou-Demasse Gbenga J. Abiodun Abiodun M. Adeola Joel O. Botai 《Studies in Applied Mathematics》2020,144(4):389-411
In this paper, we develop and analyze a malaria model with seasonality of mosquito life-history traits: periodic-mosquitoes per capita birth rate, -mosquitoes death rate, -probability of mosquito to human disease transmission, -probability of human to mosquito disease transmission, and -mosquitoes biting rate. All these parameters are assumed to be time dependent leading to a nonautonomous differential equation system. We provide a global analysis of the model depending on two threshold parameters and (with ). When , then the disease-free stationary state is locally asymptotically stable. In the presence of the human disease-induced mortality, the global stability of the disease-free stationary state is guarantied when . On the contrary, if , the disease persists in the host population in the long term and the model admits at least one positive periodic solution. Moreover, by a numerical simulation, we show that a sub-critical (backward) bifurcation is possible at . Finally, the simulation results are in accordance with the seasonal variation of the reported cases of a malaria-epidemic region in Mpumalanga province in South Africa. 相似文献
93.
AbstractIt is well known that when a ring R satisfies ACC on right annihilators of elements, then the right singular ideal of R is nil, in this case, we say R is right nil-singular. Many classes of rings whose singular ideals are nil, but do not satisfy the ACC on right annihilators, are presented and the behavior of them is investigated with respect to various constructions, in particular skew polynomial rings and triangular matrix rings. The class of right nil-singular rings contains π-regular rings and is closed under direct sums. Examples are provided to explain and delimit our results. 相似文献
94.
This paper is concerned with a one-dimensional nonisentropic compressible planar magnetohydrodynamic flow with general initial data, whose behaviors at far fields x→±∞ are different. The low Mach limit for the system is rigorously justified. The limit relies on the uniform estimates including weighted time derivatives and an extended convergence lemma. 相似文献
95.
Elhadi Ait Dads Safoua Khelifi Mohsen Miraoui 《Mathematical Methods in the Applied Sciences》2020,43(17):10262-10275
In this paper, by developing important properties on the composition of functions with reflection, using some exponential dichotomy properties and an application of the fixed-point theorem, several new sufficient conditions for the existence and the uniqueness of an pseudo almost automorphic solutions with measure for some general-type reflection integro-differential equations. We suppose that the nonlinear part is measure pseudo almost automorphic and in which we distinguish the two constant and variable cases for the Lipschitz coefficients of the functions associated with this part. It is assumed that the linear part of the equation considered admits an exponential dichotomy. Finally, an application is given on the very interesting model of Markus and Yamabe. 相似文献
96.
While much attention has been directed to the maximum modulus and maximum real part of chromatic roots of graphs of order (ie, with vertices), relatively little is known about the maximum imaginary part of such graphs. We prove that the maximum imaginary part can grow linearly in the order of the graph. We also show that for any fixed , almost every random graph in the Erdös-Rényi model has a nonreal root. 相似文献
97.
The identification of multiple interacting inclusions with uniform internal stresses in an infinite elastic matrix subjected to a uniform remote loading is of fundamental importance in the mechanics and design of particulate composite materials. In anti-plane shear and plane deformations, certain sufficient conditions have been established in the literature which guarantee uniform internal stresses inside multiple interacting inclusions displaying various symmetries when the matrix is subjected to specific uniform remote loading. Correspondingly, sufficient conditions which allow for the design of multiple interacting inclusions independent of any specific form of (uniform) remote loading have also been established. In this paper, we demonstrate rigorously that, in all cases, these sufficient conditions are also necessary conditions and indeed allow for the identification of all possible collections of such inclusions. 相似文献
98.
The paper is devoted to local and global solvability in locally uniform spaces and to the existence of a global attractor for a parabolic problem containing fractional power of the minus Laplace operator. Several useful technical tools and estimates are also collected in this paper. 相似文献
99.
对二元函数连续性判定条件给出了详细分析,强调有关问题的关键点,纠正了常见的模糊认识,得到一系列连续性充分条件及其推广形式. 相似文献
100.