全文获取类型
收费全文 | 8974篇 |
免费 | 571篇 |
国内免费 | 845篇 |
专业分类
化学 | 703篇 |
晶体学 | 2篇 |
力学 | 403篇 |
综合类 | 113篇 |
数学 | 7744篇 |
物理学 | 1425篇 |
出版年
2024年 | 17篇 |
2023年 | 128篇 |
2022年 | 119篇 |
2021年 | 119篇 |
2020年 | 191篇 |
2019年 | 215篇 |
2018年 | 188篇 |
2017年 | 241篇 |
2016年 | 218篇 |
2015年 | 211篇 |
2014年 | 401篇 |
2013年 | 693篇 |
2012年 | 352篇 |
2011年 | 480篇 |
2010年 | 435篇 |
2009年 | 547篇 |
2008年 | 629篇 |
2007年 | 663篇 |
2006年 | 570篇 |
2005年 | 543篇 |
2004年 | 432篇 |
2003年 | 420篇 |
2002年 | 323篇 |
2001年 | 293篇 |
2000年 | 259篇 |
1999年 | 258篇 |
1998年 | 237篇 |
1997年 | 222篇 |
1996年 | 157篇 |
1995年 | 102篇 |
1994年 | 84篇 |
1993年 | 71篇 |
1992年 | 62篇 |
1991年 | 64篇 |
1990年 | 36篇 |
1989年 | 35篇 |
1988年 | 39篇 |
1987年 | 23篇 |
1986年 | 34篇 |
1985年 | 44篇 |
1984年 | 32篇 |
1983年 | 20篇 |
1982年 | 25篇 |
1981年 | 35篇 |
1980年 | 19篇 |
1979年 | 26篇 |
1978年 | 25篇 |
1977年 | 17篇 |
1976年 | 16篇 |
1973年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
《Mathematische Nachrichten》2017,290(11-12):1905-1917
In this paper, by the method of J. F. Li and X. J. Xu (Differential Harnack inequalities on Riemannian manifolds I: Linear heat equation, Adv. in Math., 226 (2011), 4456–4491 ), we shall consider the nonlinear parabolic equation on Riemannian manifolds with , . First of all, we shall derive the corresponding Li–Xu type gradient estimates of the positive solutions for . As applications, we deduce Liouville type theorem and Harnack inequality for some special cases. Besides, when , our results are different from Li and Yau's results. We also extend the results of J. F. Li and X. J. Xu, and the results of Y. Yang. 相似文献
962.
《Mathematische Nachrichten》2017,290(17-18):2759-2774
Here we give a new approach to the Paley–Wiener theorem in a Mellin analysis setting which avoids the use of the Riemann surface of the logarithm and analytical branches and is based on new concepts of polar‐analytic function in the Mellin setting and Mellin–Bernstein spaces. A notion of Hardy spaces in the Mellin setting is also given along with applications to exponential sampling formulas of optical physics. 相似文献
963.
Ali Akbar Yazdan Pour 《代数通讯》2017,45(4):1483-1492
Let I be a monomial ideal in the polynomial ring S generated by elements of degree at most d. In this paper, it is shown that, if the i-th syzygy of I has no elements of degrees j,…,j+(d?1) (where j≥i+d), then (i+1)-th syzygy of I does not have any element of degree j+d. Then we give several applications of this result, including an alternative proof for Green–Lazarsfeld index of the edge ideals of graphs as well as an alternative proof for Fröberg’s theorem on classification of square-free monomial ideals generated in degree 2 with linear resolution. Among all, we deduce a partial result on subadditivity of the syzygies for monomial ideals. 相似文献
964.
Fernando Szechtman 《代数通讯》2017,45(3):943-953
Clifford theory of possibly infinite dimensional modules is studied. 相似文献
965.
The purpose of this paper is to investigate the eight-dimensional non-associative unital division algebras {0}≠A over finite fields, admitting elementary abelian 2-group of automorphisms E≤Aut(A), of order 8, using tools from algebraic geometry. 相似文献
966.
This paper is concerned with a generalized Arzela–Ascoli's lemma, which has been extensively applied in almost periodic problems by the continuation theorem of degree theory. We give a counter example to show that this lemma is incorrect, and there is a gap in the proof of some existing literature, where the addressed generalized Arzela–Ascoli's lemma was used. Moreover, we make some final comments and introduce an open problem. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
967.
Peijun Li Gaofeng Zheng Weiying Zheng 《Mathematical Methods in the Applied Sciences》2017,40(3):573-588
This paper is concerned with the mathematical analysis of the electromagnetic wave scattering by an unbounded dielectric medium, which is mounted on a perfectly conducting infinite plane. By introducing a transparent boundary condition on a plane surface confining the medium, the scattering problem is modeled as a boundary value problem of Maxwell's equations. Based on a variational formulation, the problem is shown to have a unique weak solution for a wide class of dielectric permittivity and magnetic permeability by using the generalized Lax–Milgram theorem. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
968.
Two homoclinic solutions for a nonperiodic fourth‐order differential equation without coercive condition 下载免费PDF全文
In this paper, we investigate the existence of homoclinic solutions for a class of fourth‐order nonautonomous differential equations where w is a constant, and . By using variational methods and the mountain pass theorem, some new results on the existence of homoclinic solutions are obtained under some suitable assumptions. The interesting is that a(x) and f(x,u) are nonperiodic in x,a does not fulfil the coercive condition, and f does not satisfy the well‐known (AR)‐condition. Furthermore, the main result partly answers the open problem proposed by Zhang and Yuan in the paper titled with Homoclinic solutions for a nonperiodic fourth‐order differential equations without coercive conditions (see Appl. Math. Comput. 2015; 250:280–286). Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
969.
The existence of a positive solution for nonlinear fractional differential equations with integral boundary value conditions 下载免费PDF全文
Alberto Cabada Sladjana Dimitrijevic Tatjana Tomovic Suzana Aleksic 《Mathematical Methods in the Applied Sciences》2017,40(6):1880-1891
In this paper, first, we consider the existence of a positive solution for the nonlinear fractional differential equation boundary value problem where 0≤λ < 1,CDα is the Caputo's differential operator of order α, and f:[0,1] × [0,∞)→[0,∞) is a continuous function. Using some cone theoretic techniques, we deduce a general existence theorem for this problem. Then, we consider two following more general problems for arbitrary α, 1≤n < α≤n + 1: Problem 1: where , 0≤λ < k + 1; Problem 2: where 0≤λ≤α and Dα is the Riemann–Liouville fractional derivative of order α. For these problems, we give existence results, which improve recent results in the literature. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
970.
Stability,periodicity, and symmetries of certain second‐order fractional difference equation with quadratic terms via KAM theory 下载免费PDF全文
Mirela Garić‐Demirović M. Nurkanović Z. Nurkanović 《Mathematical Methods in the Applied Sciences》2017,40(1):306-318
By using the Kolmogorov–Arnold–Moser theory, we investigate the stability of the equilibrium solution of the difference equation where A ,B ,D > 0,u ?1,u 0>0. We also use the symmetries to find effectively the periodic solutions with feasible periods. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献