全文获取类型
收费全文 | 2263篇 |
免费 | 127篇 |
国内免费 | 3篇 |
专业分类
化学 | 1676篇 |
晶体学 | 11篇 |
力学 | 44篇 |
数学 | 180篇 |
物理学 | 482篇 |
出版年
2024年 | 8篇 |
2023年 | 20篇 |
2022年 | 24篇 |
2021年 | 98篇 |
2020年 | 79篇 |
2019年 | 111篇 |
2018年 | 108篇 |
2017年 | 82篇 |
2016年 | 109篇 |
2015年 | 98篇 |
2014年 | 101篇 |
2013年 | 124篇 |
2012年 | 186篇 |
2011年 | 195篇 |
2010年 | 125篇 |
2009年 | 73篇 |
2008年 | 128篇 |
2007年 | 138篇 |
2006年 | 142篇 |
2005年 | 123篇 |
2004年 | 95篇 |
2003年 | 58篇 |
2002年 | 56篇 |
2001年 | 19篇 |
2000年 | 10篇 |
1999年 | 9篇 |
1998年 | 11篇 |
1997年 | 9篇 |
1996年 | 14篇 |
1995年 | 2篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1981年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有2393条查询结果,搜索用时 17 毫秒
951.
952.
Andrey S. Ostrovsky Ernesto Pino Mota Jesús I. Palma Cuatianquiz 《Optics and Lasers in Engineering》2003,40(1-2):43-53
It is shown that the problem of classification of images that have the perfectly random nature may be solved with the help of synthetic discriminant functions being synthesized by least-squares technique to separate linearly the power spectra of the corresponding random image fields. The realization of the proposed method by means of an optical technique is discussed, and its efficiency is illustrated by two examples of real-life texture classification. 相似文献
953.
Recent theoretical and numerical work on high-field magneto-transport in a percolating medium is described and compared to earlier work on weak-field magneto-transport in such systems. While the weak-field behavior is well described by the simple nodes-links picture, which ignores blobs and loops on a scale smaller than the percolation correlation length ξp, the strong-field behavior is extremely sensitive to those features. The critical behavior at strong magnetic fields H near the percolation threshold is governed by competition between the usual H=0 fixed point and a new H=∞ fixed point. Which of those fixed points dominates the behavior is determined by the relative sizes of two characteristic lenghts: the percolation correlation length ξp and a new, magnetic field dependent length ξH. 相似文献
954.
Wilhelm Czapliński Mariusz Filipowicz Elżzbieta Gulá Andrey Kravtsov Alexander Mikhailov Nicolai Popov 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,41(3):165-169
Radiative, Auger and predissociation decay modes of muonic lithium-hydrogen molecule, Liμh, (h = p, d or t is a hydrogen isotope) are considered. Results obtained for the corresponding reaction rates indicate that predissociation is a dominating decay mode for h = p, d while Auger decay dominates for h = t. The calculated conversion coefficient is significantly larger than that for helium muonic molecule and ranges between 37 and 42 (on the basis of one electron) depending on isotope composition of the molecule. Reaction rates for rotational 1 → 0 transitions in Liμh and Heμh due to inner Auger process are also calculated. 相似文献
955.
Yury G. Galyametdinov Galina Ivanova Igor Ovchinnikov Andrey Prosvirin Daniel Guillon Benoî t Heinrich David A. Dunmur Duncan W. Bruce 《Liquid crystals》1996,20(6):831-833
Low angle X-ray scattering studies have been used to identify the mesophase of some calamitic lanthanide mesogens as smectic A, while magnetic birefringence studies have shown a huge magnetic anisotropy for these complexes. 相似文献
956.
Edward Frenkel Victor Kac Andrey Radul Weiqiang Wang 《Communications in Mathematical Physics》1995,170(2):337-357
We study representations of the central extension of the Lie algebra of differential operators on the circle, the algebra. We obtain complete and specialized character formulas for a large class of representations, which we call primitive; these include all quasi-finite irreducible unitary representations. We show that any primitive representation with central chargeN has a canonical structure of an irreducible representation of the with the same central charge and that all irreducible representations of with central chargeN arise in this way. We also establish a duality between integral modules of and finite-dimensional irreducible modules ofgl
N
, and conjecture their fusion rules.Supported by a Junior Fellowship from Harvard Society of Fellows and in part by NSF grant DMS-9205303.Supported in part by NSF grant DMS-9103792. 相似文献
957.
958.
959.
Using a coarse-grained bead-spring model of flexible polymer chains, the structure of a polymeric nanodroplet adsorbed on a chemically decorated flat wall is investigated by means of molecular dynamics simulation. We consider sessile drops on a lyophilic (attractive for the monomers) region of circular shape with radius R(D) while the remaining part of the substrate is lyophobic. The variation of the droplet shape, including its contact angle, with R(D) is studied, and the density profiles across these droplets also are obtained. In addition, the interaction of droplets adsorbed on two walls forming a slit pore with two lyophilic circular regions just opposite of one another is investigated, paying attention to the formation of a liquid bridge between both walls. A central result of our study is the measurement of the force between the two substrate walls at varying wall separation as well as the kinetics of droplet merging. Our results are compared to various phenomenological theories developed for liquid droplets of mesoscopic rather than nanoscopic size. 相似文献
960.
We consider a thin film consisting of two layers of immiscible liquids on a solid horizontal (heated) substrate. Both the free liquid-liquid and the liquid-gas interface of such a bilayer liquid film may be unstable due to effective molecular interactions relevant for ultrathin layers below 100-nm thickness, or due to temperature-gradient-caused Marangoni flows in the heated case. Using a long-wave approximation, we derive coupled evolution equations for the interface profiles for the general nonisothermal situation allowing for slip at the substrate. Linear and nonlinear analyses of the short- and long-time film evolution are performed for isothermal ultrathin layers, taking into account destabilizing long-range and stabilizing short-range molecular interactions. It is shown that the initial instability can be of a varicose, zigzag, or mixed type. However, in the nonlinear stage of the evolution the mode type, and therefore the pattern morphology, can change via switching between two different branches of stationary solutions or via coarsening along a single branch. 相似文献