全文获取类型
收费全文 | 435528篇 |
免费 | 3942篇 |
国内免费 | 871篇 |
专业分类
化学 | 198859篇 |
晶体学 | 5779篇 |
力学 | 24459篇 |
综合类 | 8篇 |
数学 | 84854篇 |
物理学 | 126382篇 |
出版年
2021年 | 3961篇 |
2020年 | 4368篇 |
2019年 | 5188篇 |
2018年 | 17162篇 |
2017年 | 17040篇 |
2016年 | 15796篇 |
2015年 | 6121篇 |
2014年 | 9052篇 |
2013年 | 16603篇 |
2012年 | 17460篇 |
2011年 | 25307篇 |
2010年 | 17772篇 |
2009年 | 18063篇 |
2008年 | 20956篇 |
2007年 | 22580篇 |
2006年 | 13136篇 |
2005年 | 12620篇 |
2004年 | 12189篇 |
2003年 | 11661篇 |
2002年 | 10772篇 |
2001年 | 9259篇 |
2000年 | 7587篇 |
1999年 | 5569篇 |
1998年 | 5203篇 |
1997年 | 4946篇 |
1996年 | 4802篇 |
1995年 | 4056篇 |
1994年 | 4159篇 |
1993年 | 4123篇 |
1992年 | 4102篇 |
1991年 | 4423篇 |
1990年 | 4434篇 |
1989年 | 4356篇 |
1988年 | 4082篇 |
1987年 | 4146篇 |
1986年 | 3825篇 |
1985年 | 4479篇 |
1984年 | 4711篇 |
1983年 | 3956篇 |
1982年 | 4171篇 |
1981年 | 3856篇 |
1980年 | 3603篇 |
1979年 | 4006篇 |
1978年 | 4065篇 |
1977年 | 4238篇 |
1976年 | 4283篇 |
1975年 | 3971篇 |
1974年 | 3814篇 |
1973年 | 4023篇 |
1972年 | 3363篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Francesc Carreras M. Dolors Llongueras Antonio Magaña 《Annals of Operations Research》2005,137(1):67-89
A partnership in a cooperative game is a coalition that possesses an internal structure and, simultaneously, behaves as an
individual member. Forming partnerships leads to a modification of the original game which differs from the quotient game
that arises when one or more coalitions are actually formed.
In this paper, the Shapley value is used to discuss the convenience to form either coalitions or partnerships. To this end,
the difference between the additive Shapley value of the partnership in the partnership game and the Shapley alliance value
of the coalition, and also between the corresponding value of the internal and external players, are analysed. Simple games
are especially considered.
Research partially supported by Grant BFM 2003-01314 of the Science and Technology Spanish Ministry and the European Regional
Development Fund. 相似文献
992.
Rie Natsui 《Acta Mathematica Hungarica》2005,108(4):299-318
Summary Let Fq be a finite field with q elements. We consider formal Laurent series of Fq -coefficients with their continued fraction expansions by Fq -polynomials. We prove some arithmetic properties for almost every formal Laurent series with respect to the Haar measure. We construct a group extension of the non-archimedean continued fraction transformation and show its ergodicity. Then we get some results as an application of the individual ergodic theorem. We also discuss the convergence rate for limit behaviors. 相似文献
993.
994.
995.
A. L. Goldenberg V. N. Manuilov M. Yu. Glyavin 《Radiophysics and Quantum Electronics》2005,48(6):461-465
We describe a nonadiabatic electron gun operated in the mode of a currentconfined by spatial charge and intended for producing
helical electron beams for high-power gyroresonantdevices.Results of numerical simulation of electron trajectories and electron-beam
parameters arepresented. It is shown that for a high operating current, the pitch factor and the electronvelocity spread can
be significantly better than in the conventional adiabatic systems.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48,No. 6, pp. 517–522, June 2005 相似文献
996.
The ferromagnetic shape memory alloy with nominal composition Ni54Fe19Ga27 is investigated by Ac susceptibility and resistivity measurements. The alloy shows long-range ferromagnetic order below 290 K. The anomaly due to the martensitic transition is observed in the susceptibility and resistivity data in the temperature range around 220 K, which is associated with clear thermal hysteresis. Minor hysteresis loop technique was used to investigate the phase coexistence across the martensitic transition, and our analysis indicate that both martensite and austenite phases mutually coexist in the region of hysteresis. 相似文献
997.
V. Boutou M. A. Lebeault-Dorget A. R. Allouche C. Bordas J. Chevaleyre 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,40(1):448-453
In this article, we present results obtained on structures of small bare and oxygenated barium clusters produced by the laser vaporization technique. Contrary to the very weak Ba—Ba binding (0.202 eV), the Ba—O binding is rather strong (5.8 eV). As a consequence, extremely small amounts of oxygen in the cluster source are sufficient to induce the nucleation of oxygenated barium clusters. Surprisingly, at least for substoechiometric systems, BanOm clusters exhibit the same icosahedral structure as bare clusters do. Mass spectra seem to indicate that replacing a barium atom with a strongly polar BaO molecule does not affect the geometrical structure of the cluster. This aspect is more easily understandable if we assume that the oxygen atom takes place inside the structure of the Ban cluster without significant distortions. Ab-initio calculations have been undertaken in order to give a satisfactory account of this hypothesis. 相似文献
998.
A matrix formalism is introduced here for the analytical calculation of the thermo-elastic response of one-dimensional optically inhomogeneous layered structures exposed to the periodic laser heating. The multilayer structure consists of thermally and mechanically homogeneous solid layers which can be interleaved by liquid ot galore interlayers. The method enables the modelling of photoacoustic and photothermal measurements in a variety of engineering applications. 相似文献
999.
V. A. Isupov 《Physics of the Solid State》1997,39(1):116-117
The values of the Curie temperatures of bismuth-containing layered ferroelectrics and deformations of the pseudoperovskite
cell, distinguished in the perovskite-like layer of these compounds, are discussed. It is shown that the perovskite-like layers
play an important role in the appearance of the ferroelectric state.
Fiz. Tverd. Tela (St. Petersburg) 39, 135–136 (January 1997) 相似文献
1000.
The acoustoelectromagnetic interaction is examined in a regime where three mechanisms must be taken into account simultaneously:
photoelasticity, quadratic photoelasticity, and elastic nonlinearity. It is shown that beyond the critical conditions, acoustic
solitary waves are formed at harmonic and subharmonic frequencies in a crystal. Including damping and nonideal reflection
at the boundaries does not lead to the establishment of any sort of stationary state: a soliton spatial-temporal dynamic develops.
Fiz. Tverd. Tela (St. Petersburg) 39, 1101–1104 (June 1997) 相似文献