全文获取类型
收费全文 | 10345篇 |
免费 | 725篇 |
国内免费 | 739篇 |
专业分类
化学 | 728篇 |
晶体学 | 2篇 |
力学 | 1722篇 |
综合类 | 77篇 |
数学 | 3653篇 |
物理学 | 1274篇 |
综合类 | 4353篇 |
出版年
2024年 | 26篇 |
2023年 | 87篇 |
2022年 | 120篇 |
2021年 | 156篇 |
2020年 | 206篇 |
2019年 | 228篇 |
2018年 | 210篇 |
2017年 | 242篇 |
2016年 | 309篇 |
2015年 | 335篇 |
2014年 | 416篇 |
2013年 | 555篇 |
2012年 | 514篇 |
2011年 | 540篇 |
2010年 | 429篇 |
2009年 | 612篇 |
2008年 | 567篇 |
2007年 | 660篇 |
2006年 | 611篇 |
2005年 | 567篇 |
2004年 | 549篇 |
2003年 | 482篇 |
2002年 | 398篇 |
2001年 | 336篇 |
2000年 | 300篇 |
1999年 | 299篇 |
1998年 | 239篇 |
1997年 | 255篇 |
1996年 | 190篇 |
1995年 | 175篇 |
1994年 | 179篇 |
1993年 | 163篇 |
1992年 | 120篇 |
1991年 | 132篇 |
1990年 | 101篇 |
1989年 | 102篇 |
1988年 | 69篇 |
1987年 | 53篇 |
1986年 | 39篇 |
1985年 | 34篇 |
1984年 | 31篇 |
1983年 | 21篇 |
1982年 | 29篇 |
1981年 | 17篇 |
1980年 | 13篇 |
1979年 | 29篇 |
1978年 | 12篇 |
1977年 | 15篇 |
1976年 | 14篇 |
1973年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 33 毫秒
31.
We show that the LF-algebra considered by Akkar and Nacir in [1] is topologically simple. 相似文献
32.
赵长占 《内蒙古师范大学学报(自然科学版)》1992,(4):58-62
给出了极限的几个定理及其推论,可以解决或简化某类极限问题。推论2修正了数学通报11(1963)《关于极限的一个定理》。 相似文献
33.
Clelia Marchionna Stefano Panizzi 《Mathematical Methods in the Applied Sciences》2007,30(11):1295-1309
We introduce a set of conserved quantities of energy‐type for a strictly hyperbolic system of two coupled wave equations in one space dimension. The system is subject to mechanical boundary conditions. Some of these invariants are asymmetric in the sense that their defining quadratic form contains second order derivatives in only one of the unknowns. We study their independence with respect to the usual energies and characterize their sign. In many cases, our results provide sharp well‐posedness and stability results. Finally, we apply some of our conservation laws to the study of a singular perturbation problem previously considered by J. Lagnese and J. L. Lions. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
34.
35.
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
36.
Héctor J. Sussmann 《Set-Valued Analysis》2002,10(2-3):233-285
It is shown that the construction of needle variations can be carried out for almost lower semicontinuous differential inclusions rather than for the case of ordinary single-valued continuously differentiable vector fields usually considered in the literature. The construction leads to needle variations whose flows are in general set-valued but still have good differentiability properties. The variations are constructed by using single-valued selections that are not necessarily continuous with respect to the state variable, but have instead a much weaker 'integral continuity' property, somewhat more general that the 'directional continuity' considered in previous work by A. Cambini and S. Querci, A. Pucci, and A. Bressan. The existence of many such selections is proved by slightly adapting an argument due to Bressan, extending it from the lower semicontinuous to the almost lower semicontinuous case, and strengthening it to yield not only directional continuity at all points but also full continuity at a specified point. 相似文献
37.
Anatoliy Malyarenko 《Journal of Theoretical Probability》2006,19(2):263-288
We prove a general functional limit theorem for multiparameter fractional Brownian motion. The functional law of the iterated
logarithm, functional Lévy’s modulus of continuity and many other results are its particular cases. Applications to approximation
theory are discussed.
相似文献
38.
一类平面七次多项式系统赤道环的稳定性与极限环分支 总被引:2,自引:0,他引:2
本文研究一类平面七次多项式系统赤道环的稳定性和极限环分支,给出了系统的前12个奇点量公式,可积性条件及在赤道附近存在3个极限环的条件,较为精细地指出了极限环的存在位置。 相似文献
39.
Youssef Randjiou 《Journal of Theoretical Probability》2006,19(3):701-720
Let μ+(t) and μ−(t) be the locations of the maximum and minimum, respectively, of a standard Brownian motion in the interval [0,t]. We establish a joint integral test for the lower functions of μ+(t) and μ−(t), in the sense of Paul Lévy. In particular, it yields the law of the iterated logarithm for max(μ+(t),μ−(t)) as a straightforward consequence. Our result is in agreement with well-known theorems of Chung and Erdős [(1952) Trans. Amer. Math. Soc. 72, 179–186.], and Csáki, F?ldes and Révész [(1987) Prob. Theory Relat. Fields
76, 477–497].
相似文献
40.
对Hajek-Renyi不等式进行了推广,利用推广的不等式给出了随机变量序列绝对平均意义下的强大数定律的一个条件. 相似文献