全文获取类型
收费全文 | 3174篇 |
免费 | 401篇 |
国内免费 | 283篇 |
专业分类
化学 | 253篇 |
晶体学 | 7篇 |
力学 | 442篇 |
综合类 | 60篇 |
数学 | 2027篇 |
物理学 | 1069篇 |
出版年
2024年 | 4篇 |
2023年 | 39篇 |
2022年 | 46篇 |
2021年 | 62篇 |
2020年 | 71篇 |
2019年 | 86篇 |
2018年 | 83篇 |
2017年 | 88篇 |
2016年 | 114篇 |
2015年 | 99篇 |
2014年 | 209篇 |
2013年 | 278篇 |
2012年 | 154篇 |
2011年 | 215篇 |
2010年 | 172篇 |
2009年 | 215篇 |
2008年 | 218篇 |
2007年 | 211篇 |
2006年 | 189篇 |
2005年 | 176篇 |
2004年 | 150篇 |
2003年 | 128篇 |
2002年 | 130篇 |
2001年 | 104篇 |
2000年 | 76篇 |
1999年 | 94篇 |
1998年 | 78篇 |
1997年 | 54篇 |
1996年 | 60篇 |
1995年 | 42篇 |
1994年 | 18篇 |
1993年 | 28篇 |
1992年 | 27篇 |
1991年 | 23篇 |
1990年 | 14篇 |
1989年 | 12篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 13篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有3858条查询结果,搜索用时 203 毫秒
21.
22.
两类图的(d,1)-全标号 总被引:1,自引:0,他引:1
主要讨论了W_n与C_m的笛卡尔积和均衡完全r-部图K_r(n)的(d,1)-全标号,并得出了(d,1)-全数λ_d~T(W_n□C_m)和λ_d~T(K_(r(n)))的确切值. 相似文献
23.
准确预测风电场风速是解决风能对电力系统所造成的安全、稳定运行和电能质量等问题的有效途径之一.风速的难以预测是由于它的高度随机和非线性.基于一种非参数的非线性自回归随机模型来预测风速,模型的自回归系数随模型依赖变量的变化而变化,因而它有灵活的非线性结构.数值实验和比较结果表明了这种函数系数自回归模型在风电场风速预测中的有效性. 相似文献
24.
给出了Toader型平均T[A(a,b),G(a,b)]关于调和平均H(a,b)与算术平均A(a,b)组合的精确界.作为应用,发现了几个关于第二类完全椭圆积分的精确不等式. 相似文献
25.
利用NA随机变量的矩不等式和截尾方法,研究了NA随机变量阵列的完全矩收敛性,给出了证明NA随机变量阵列完全矩收敛性的一些充分条件.所得结果推广了已有文献关于NA随机变量的相应结果. 相似文献
26.
The resilient dissipative dynamic output feedback control problem for a class of uncertain Markov jump Lur’e systems with piecewise homogeneous transition probabilities and time-varying delays in the discrete-time domain are examined in this study. The designed controller can tolerate additive uncertainties in the controller gain matrix, which result from controller implementations. The time-varying delays are also supposed to be mode-dependent with lower and upper bounds known a priori. By constructing a Lyapunov–Krasovskii functional candidate, the sufficient conditions regarding the existence of desired resilient dissipative controllers are obtained in terms of linear matrix inequalities, thereby ensuring that the resulting closed-loop system is stochastically stable and strictly dissipative. Two numerical examples were established to illustrate the effectiveness of the proposed theoretical results. 相似文献
27.
《Mathematische Nachrichten》2017,290(14-15):2198-2206
The aim of this work is to present results of existence of solutions for a class of superlinear asymmetric elliptic systems with resonance in the first eigenvalue. The asymmetry that we consider has linear behavior on and superlinear on . To obtain these results we apply topological degree theory. 相似文献
28.
Sina Hedayat 《代数通讯》2017,45(4):1711-1718
A proper ideal of a commutative ring is called pseudo-irreducible if it cannot be written as a product of two comaximal proper ideals. In this paper, we give a necessary and su?cient condition for every proper ideal of a commutative ring to be a product of pairwise comaximal pseudo-irreducible ideals. Examples of such rings include Laskerian rings, or more generally J-Noetherian rings and ZD-rings. We study when certain classes of rings satisfy this condition. 相似文献
29.
Ruchi Ruchi Nurhayat Ispir P. N. Agrawal 《Mathematical Methods in the Applied Sciences》2017,40(16):5687-5706
Ren and Zeng (2013) introduced a new kind of q‐Bernstein–Schurer operators and studied some approximation properties. Acu et al. (2016) defined the Durrmeyer modification of these operators and studied the rate of convergence and statistical approximation. The purpose of this paper is to introduce a Kantorovich modification of these operators by using q‐Riemann integral and investigate the rate of convergence by means of the Lipschitz class and the Peetre's K‐functional. Next, we introduce the bivariate case of q‐Bernstein–Schurer–Kantorovich operators and study the degree of approximation with the aid of the partial modulus continuity, Lipschitz space, and the Peetre's K‐functional. Finally, we define the generalized Boolean sum operators of the q‐Bernstein–Schurer–Kantorovich type and investigate the approximation of the Bögel continuous and Bögel differentiable functions by using the mixed modulus of smoothness. Furthermore, we illustrate the convergence of the operators considered in the paper for the univariate case and the associated generalized Boolean sum operators to certain functions by means of graphics using Maple algorithms. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
30.
Monotonicity,uniqueness, and stability of traveling waves in a nonlocal reaction‐diffusion system with delay 下载免费PDF全文
Hai‐Qin Zhao 《Mathematical Methods in the Applied Sciences》2017,40(18):6702-6714
The purpose of this paper is to study the traveling wave solutions of a nonlocal reaction‐diffusion system with delay arising from the spread of an epidemic by oral‐faecal transmission. Under monostable and quasimonotone it is well known that the system has a minimal wave speed c* of traveling wave fronts. In this paper, we first prove the monotonicity and uniqueness of traveling waves with speed c ?c ?. Then we show that the traveling wave fronts with speed c >c ? are exponentially asymptotically stable. 相似文献