全文获取类型
收费全文 | 1907篇 |
免费 | 108篇 |
国内免费 | 109篇 |
专业分类
化学 | 196篇 |
力学 | 215篇 |
综合类 | 11篇 |
数学 | 1220篇 |
物理学 | 482篇 |
出版年
2024年 | 4篇 |
2023年 | 17篇 |
2022年 | 24篇 |
2021年 | 31篇 |
2020年 | 51篇 |
2019年 | 44篇 |
2018年 | 36篇 |
2017年 | 45篇 |
2016年 | 43篇 |
2015年 | 52篇 |
2014年 | 88篇 |
2013年 | 171篇 |
2012年 | 77篇 |
2011年 | 108篇 |
2010年 | 87篇 |
2009年 | 148篇 |
2008年 | 148篇 |
2007年 | 151篇 |
2006年 | 104篇 |
2005年 | 71篇 |
2004年 | 81篇 |
2003年 | 78篇 |
2002年 | 53篇 |
2001年 | 53篇 |
2000年 | 42篇 |
1999年 | 52篇 |
1998年 | 49篇 |
1997年 | 33篇 |
1996年 | 19篇 |
1995年 | 22篇 |
1994年 | 27篇 |
1993年 | 19篇 |
1992年 | 14篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1975年 | 4篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有2124条查询结果,搜索用时 31 毫秒
101.
Frank Morgan Wacharin Wichiramala 《Proceedings of the American Mathematical Society》2002,130(9):2745-2751
We prove that the only equilibrium double bubble in which is stable for fixed areas is the standard double bubble. This uniqueness result also holds for small stable double bubbles in surfaces, where it is new even for perimeter-minimizing double bubbles.
102.
Atsushi Moriwaki 《Compositio Mathematica》2002,132(2):191-228
Let M
g
be the moduli space of smooth curves of genus g 3, and M¯
g
the Deligne-Mumford compactification in terms of stable curves. Let M¯
g
[1] be an open set of M¯
g
consisting of stable curves of genus g with one node at most. In this paper, we determine the necessary and sufficient condition to guarantee that a
-divisor D on M¯
g
is nef over M¯
g
[1], that is, (D · C) 0 for all irreducible curves C on M¯
g
with C M¯
g
[1] . 相似文献
103.
A new class of distributions for the microcanonical ensemble, which are shown to be stable laws, are derived by applying the central limit theorem to the canonical ensemble. This opens up a whole new host of phenomena that can be treated from a unified thermodynamic point of view. Pressure broadening of line shapes is used as an illustration.1. Work supported, in part, by contributions from the Consiglio Nazionale di Ricerche and the Ministero dell'Università e della Ricerca Scientifica e Tecnologica.2. The interaction parameterC is proportional to the mean square dipole moment. As an order of magnitude of the dipole moment, we can take it as the product of the electric charge and a typical atomic radius for a moderately excited state, which is several times the Bohr radius. Multiplication by the fine structure constant converts the Bohr radius into the Compton wavelength, thereby reducing the magnitude of the interaction by 1/137. 相似文献
104.
A. Y. Lee 《Journal of Optimization Theory and Applications》1988,57(3):519-536
Neighboring extremals of dynamic optimization problems with path equality constraints and with an unknown parameter vector
are considered in this paper. With some simplifications, the problem is reduced to solving a linear, time-varying two-point
boundary-value problem with integral path equality constraints. A modified backward sweep method is used to solve this problem.
Two example problems are solved to illustrate the validity and usefulness of the solution technique.
This research was supported in part by the National Aeronautics and Space Administration under NASA Grant No. NCC-2-106.
The author is indebted to Professor A. E. Bryson, Jr., Department of Aeronautics and Astronautics, Stanford University, for
many stimulating discussions. 相似文献
105.
J. D. Gunton 《Journal of statistical physics》1984,34(5-6):1019-1037
A review is given of recent developments involving the dynamics of random interfaces formed in the evolution of metastable and unstable systems. Topics which are discussed include interface growth and nonequilibrium dynamical scaling. The possibility of there being dynamical universality classes in first-order phase transitions is also discussed. There are a large number of systems of experimental interest which include binary alloys, binary fluids, and polymer mixtures. Other systems studied by computer simulation include the kinetic Ising, Potts, andZ
N
models.Work supported by NSF grant No. DMR-8013700. 相似文献
106.
Alfredo De Rossi Gaetano Assanto Stefano Trillo William E. Torruellas 《Optics Communications》1998,150(1-6):390-398
We have identified a family of (2+1)D spatial solitary waves which can stably propagate in bulk media in the presence of coexisting diffraction, self-focusing Kerr and quadratic nonlinearities. In a conspicuous range of excitation conditions close to the stationary solutions, the emerging wavepackets are immune to the detrimental occurrence of filamentation and collapse, typical of pure Kerr media. The presence of a second-order contribution to the cubic nonlinear response is, therefore, able to prevent optical damage in applications relying on self-guidance. We show that the cross-phase modulation plays an important effect on stability. Our estimate shows that the effects of the cubic susceptibility cannot be neglected below a certain beam size in realistic crystals (e.g. KTP or similar). 相似文献
107.
David M. Mason 《Journal of multivariate analysis》1984,14(2):181-200
One and two sample rank statistics are shown in general to be more efficient in the Bahadur sense than their sequential rank statistic analogues as defined by Mason (1981, Ann. Statist.9 424–436) and Lombard (1981, South African Statist. J.15 129–152), even though the two families of statistics (those based on full ranks and those based on sequential ranks) have the same Pitman efficiency against local alternatives. In the process, general results on large deviation probabilities and laws of large numbers for statistics based on sequential ranks are obtained. 相似文献
108.
109.
Clyde D Hardin 《Journal of multivariate analysis》1982,12(3):385-401
The so-called spectral representation theorem for stable processes linearly imbeds each symmetric stable process of index p into Lp (0 < p ≤ 2). We use the theory of Lp isometries for 0 < p < 2 to study the uniqueness of this representation for the non-Gaussian stable processes. We also determine the form of this representation for stationary processes and for substable processes. Complex stable processes are defined, and a complex version of the spectral representation theorem is proved. As a corollary to the complex theory we exhibit an imbedding of complex Lq into real or complex Lp for 0 < p < q ≤ 2. 相似文献
110.
Ramachandramurty Ponnapalli 《Journal of multivariate analysis》1975,5(2):278-281
Optimality of estimators of a vector parameter in terms of the probability of the estimators being contained in suitable region(s) around the parameter point is defined. Conditions under which optimal estimators in the usual senses are also optimal in the above sense are investigated. 相似文献