全文获取类型
收费全文 | 27544篇 |
免费 | 1120篇 |
国内免费 | 1696篇 |
专业分类
化学 | 8582篇 |
晶体学 | 971篇 |
力学 | 647篇 |
综合类 | 220篇 |
数学 | 15409篇 |
物理学 | 4531篇 |
出版年
2023年 | 112篇 |
2022年 | 175篇 |
2021年 | 292篇 |
2020年 | 380篇 |
2019年 | 611篇 |
2018年 | 610篇 |
2017年 | 534篇 |
2016年 | 637篇 |
2015年 | 532篇 |
2014年 | 941篇 |
2013年 | 1984篇 |
2012年 | 894篇 |
2011年 | 2022篇 |
2010年 | 1760篇 |
2009年 | 1762篇 |
2008年 | 1874篇 |
2007年 | 1868篇 |
2006年 | 1527篇 |
2005年 | 1308篇 |
2004年 | 1189篇 |
2003年 | 1015篇 |
2002年 | 980篇 |
2001年 | 676篇 |
2000年 | 649篇 |
1999年 | 568篇 |
1998年 | 556篇 |
1997年 | 489篇 |
1996年 | 499篇 |
1995年 | 479篇 |
1994年 | 437篇 |
1993年 | 345篇 |
1992年 | 327篇 |
1991年 | 249篇 |
1990年 | 235篇 |
1989年 | 211篇 |
1988年 | 152篇 |
1987年 | 138篇 |
1986年 | 101篇 |
1985年 | 166篇 |
1984年 | 134篇 |
1983年 | 78篇 |
1982年 | 103篇 |
1981年 | 139篇 |
1980年 | 120篇 |
1979年 | 64篇 |
1978年 | 115篇 |
1977年 | 94篇 |
1976年 | 93篇 |
1975年 | 39篇 |
1974年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
Explicit and partly sharp estimates are given of integrals over the square of Bessel functions with an integrable weight which can be singular at the origin. They are uniform with respect to the order of the Bessel functions and provide explicit bounds for some smoothing estimates as well as for the L2 restrictions of Fourier transforms onto spheres in which are independent of the radius of the sphere. For more special weights these restrictions are shown to be Hölder continuous with a Hölder constant having this independence as well. To illustrate the use of these results a uniform resolvent estimate of the free Dirac operator with mass in dimensions is derived. 相似文献
62.
We study the well‐posedness of the fractional differential equations with infinite delay on Lebesgue–Bochner spaces and Besov spaces , where A and B are closed linear operators on a Banach space X satisfying , and . Under suitable assumptions on the kernels a and b, we completely characterize the well‐posedness of in the above vector‐valued function spaces on by using known operator‐valued Fourier multiplier theorems. We also give concrete examples where our abstract results may be applied. 相似文献
63.
64.
zcan Bekta 《Mathematical Methods in the Applied Sciences》2019,42(16):5215-5232
The split and hyperbolic (countercomplex) octonions are eight‐dimensional nonassociative algebras over the real numbers, which are in the form , where em's have different properties for them. The main purpose of this paper is to define the split‐type octonion and its matrix whose inputs are split‐type octonions and give some properties for them by using the real quaternions, split, and hyperbolic (countercomplex) octonions. On the other hand, to make some definitions, we present some operations on the split‐type octonions. Also, we show that every split‐type octonions can be represented by 2 × 2 real quaternion matrix and 4 × 4 complex number matrix. The information about the determinants of these matrix representations is also given. Besides, the main features of split‐type octonion matrix concept are given by using properties of real quaternion matrices. Then, 8n × 8nreal matrix representations of split‐type octonion matrices are shown, and some algebraic structures are examined. Additionally, we introduce real quaternion adjoint matrices of split‐type octonion matrices. Moreover, necessary and sufficient conditions and definitions are given for split‐type octonion matrices to be special split‐type octonion matrices. We describe some special split‐type octonion matrices. Finally, oct‐determinant of split‐type octonion matrices is defined. Definitive and understandable examples of all definitions, theorems, and conclusions were given for a better understanding of all these concepts. 相似文献
65.
Deguang Zhong Yu Zhou Wenjun Yuan 《Mathematical Methods in the Applied Sciences》2019,42(10):3779-3786
Let be the class of all sense‐preserving homeomorphic self‐mappings of . The aim of this paper is twofold. First, we obtain Heinz‐type inequality for (K,K′)‐quasiconformal mappings satisfying inhomogeneous biharmonic equation Δ(Δω) = g in unit disk with associated boundary value conditions and . Second, we establish biLipschitz continuity for (K,K′)‐quasiconformal mappings satisfying aforementioned inhomogeneous biharmonic equation when and are small enough. 相似文献
66.
George Victor McIlvaine 《Expositiones Mathematicae》2019,37(3):333-346
This paper reports on findings relating to catenaries since the publication in Expositiones Mathematicae of Denzler and Hinz’s pioneering 1999 paper, Catenaria Vera – the True Catenary. New governing differential equations and explicit solutions are derived for the catenary in positive and negative radial potentials with physical constants incorporated in the derivations. In keeping with precedent by Denzler and Hinz, a measure of historical perspective is offered as homage to Gottfried Wilhelm Leibniz, Christiaan Huygens and Johann Bernoulli, the original first-solvers of the catenary. 相似文献
67.
68.
69.
For a general dyadic grid, we give a Calderón–Zygmund type decomposition, which is the principle fact about the multilinear maximal function on the upper half‐spaces. Using the decomposition, we study the boundedness of . We obtain a natural extension to the multilinear setting of Muckenhoupt's weak‐type characterization. We also partially obtain characterizations of Muckenhoupt's strong‐type inequalities with one weight. Assuming the reverse Hölder's condition, we get a multilinear analogue of Sawyer's two weight theorem. Moreover, we also get Hytönen–Pérez type weighted estimates. 相似文献
70.