全文获取类型
收费全文 | 677581篇 |
免费 | 32522篇 |
国内免费 | 22369篇 |
专业分类
化学 | 358429篇 |
晶体学 | 9472篇 |
力学 | 36525篇 |
综合类 | 369篇 |
数学 | 91623篇 |
物理学 | 236054篇 |
出版年
2022年 | 5831篇 |
2021年 | 7426篇 |
2020年 | 8258篇 |
2019年 | 9590篇 |
2018年 | 11972篇 |
2017年 | 12558篇 |
2016年 | 16686篇 |
2015年 | 10791篇 |
2014年 | 15749篇 |
2013年 | 32320篇 |
2012年 | 27135篇 |
2011年 | 31609篇 |
2010年 | 26138篇 |
2009年 | 26381篇 |
2008年 | 27966篇 |
2007年 | 26909篇 |
2006年 | 24727篇 |
2005年 | 22434篇 |
2004年 | 21741篇 |
2003年 | 19179篇 |
2002年 | 19050篇 |
2001年 | 19801篇 |
2000年 | 15391篇 |
1999年 | 12604篇 |
1998年 | 10996篇 |
1997年 | 10475篇 |
1996年 | 10177篇 |
1995年 | 9500篇 |
1994年 | 9698篇 |
1993年 | 9440篇 |
1992年 | 9361篇 |
1991年 | 9477篇 |
1990年 | 8910篇 |
1989年 | 8869篇 |
1988年 | 8497篇 |
1987年 | 7696篇 |
1986年 | 7437篇 |
1985年 | 8834篇 |
1984年 | 9323篇 |
1983年 | 7609篇 |
1982年 | 8219篇 |
1981年 | 7550篇 |
1980年 | 7169篇 |
1979年 | 7569篇 |
1978年 | 7898篇 |
1977年 | 7786篇 |
1976年 | 8045篇 |
1975年 | 7193篇 |
1974年 | 7079篇 |
1973年 | 7439篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.
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
992.
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
993.
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
994.
V. L. Gilyarov A. I. Slutsker V. P. Volodin L. A. Laius 《Physics of the Solid State》1997,39(1):132-135
The dependence of the energy characteristics on an adiabatically slowly increasing external force is determined analytically
for an anharmonic oscillator. The analytical results are confirmed by a numerical calculation. The nature of the force dependences
of the energy characteristics are determined and discussed.
Fiz. Tverd. Tela (St. Petersburg) 39, 153–157 (January 1997) 相似文献
995.
N. I. Alekseev V. B. Kaplan A. M. Martsinovskii I. I. Stolyarov 《Technical Physics》1997,42(6):599-605
Results are presented from a systematic investigation of the conditions under which anomalously high rates of plasma generation
are observed in the anode region of a low-voltage Knudsen arc in grid plasma switch elements. The phenomenon develops over
a wide range of currents and switched voltages under conditions for which the plasma density in the cathode-grid region is
noticeably higher than the density in the anode region. and its onset is characterized by a pronounced pressure threshold
of ∼2×10−2 Torr. The results are analyzed from the standpoint of the possible mechanisms for anomalous plasma generation — collisional
nonresonance diffusion of electrons in velocity space, leading to enrichment of the distribution function in fast particles,
and the collapse of Langmuir waves in the gap at the high energies of the beam produced when the wires of the grid are bridged
by the quenching pulse and and the current is blocked.
Zh. Tekh. Fiz. 67, 15–21 (June 1997) 相似文献
996.
The dependence of the nonlinear reflection coefficient R of a mirror with a wavefront reversing surface on the intensity I
of the reference wave is analyzed in terms of a phenomenological model of a medium having a nonlinear Fresnel reflection amplitude
coefficient φ. Substantial differences are revealed for media having different signs of the nonlinearity coefficient β=(dφ/dI).
It is shown that R is related to the magnitude D of the dynamic range of the wavefront reversing mirror by the expression
RD=Qs' where Qs is a parameter which defines the “quality” of the nonlinear medium.
Far-Eastern State Academy of Communications. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 68–70,
August, 1997. 相似文献
997.
998.
999.
A. V. Vashkovskii É. G. Lokk V. I. Shcheglov 《Journal of Experimental and Theoretical Physics》1997,84(3):560-568
The propagation of surface and volume magnetostatic waves in unsaturated films of yttrium iron garnet is studied experimentally
for the case when the wavelength greatly exceeds the domain width, while the domain width is comparable to the film thickness.
The characteristics of these waves are examined for symmetric linear, asymmetric linear, and symmetric zigzag strip domain
structures in the films. These characteristics cannot be explained by a theory based on averaging the magnetization over all
the domains.
Zh. éksp. Teor. Fiz. 111, 1016–1031 (March 1997) 相似文献
1000.
The yield and energy distributions of potassium and cesium atoms emitted in electron-stimulated desorption (ESD) from a molybdenum
surface, oxidized to different extent and maintained at 300 K, have been measured by the time-of-flight technique with a surface
ionization detector. The ESD threshold for potassium and cesium atoms lies around 25 eV, irrespective of molybdenum oxidation
state. In the case of molybdenum coated by an oxygen monolayer, secondary thresholds at ∼40 and ∼70 eV have been observed,
as well as atomic energy distribution tailing down to very low energies. The most probable kinetic energies of the atoms are
a few tenths of one eV. The results are explained within a model involving Auger neutralization of the adsorbed alkali metal
ions after the filling of the 2s O, 4s Mo, and 4p Mo core holes. The possibility of ESD of a neutral species as a result of oxide-cation core-level ionization has been demonstrated
for the first time.
Fiz. Tverd. Tela (St. Petersburg) 39, 758–761 (April 1997) 相似文献