全文获取类型
收费全文 | 1997篇 |
免费 | 14篇 |
国内免费 | 2篇 |
专业分类
化学 | 887篇 |
晶体学 | 48篇 |
力学 | 136篇 |
数学 | 112篇 |
物理学 | 830篇 |
出版年
2022年 | 20篇 |
2021年 | 20篇 |
2020年 | 23篇 |
2019年 | 37篇 |
2018年 | 65篇 |
2017年 | 53篇 |
2016年 | 66篇 |
2015年 | 35篇 |
2014年 | 63篇 |
2013年 | 65篇 |
2012年 | 97篇 |
2011年 | 96篇 |
2010年 | 83篇 |
2009年 | 65篇 |
2008年 | 82篇 |
2007年 | 96篇 |
2006年 | 96篇 |
2005年 | 73篇 |
2004年 | 72篇 |
2003年 | 45篇 |
2002年 | 78篇 |
2001年 | 52篇 |
2000年 | 49篇 |
1999年 | 34篇 |
1998年 | 20篇 |
1997年 | 16篇 |
1996年 | 18篇 |
1995年 | 15篇 |
1994年 | 21篇 |
1993年 | 17篇 |
1992年 | 19篇 |
1991年 | 22篇 |
1990年 | 17篇 |
1989年 | 22篇 |
1988年 | 20篇 |
1987年 | 21篇 |
1985年 | 16篇 |
1984年 | 25篇 |
1983年 | 14篇 |
1982年 | 17篇 |
1981年 | 15篇 |
1979年 | 20篇 |
1977年 | 21篇 |
1976年 | 12篇 |
1975年 | 20篇 |
1974年 | 13篇 |
1973年 | 17篇 |
1972年 | 14篇 |
1971年 | 15篇 |
1970年 | 13篇 |
排序方式: 共有2013条查询结果,搜索用时 15 毫秒
1.
We use the adiabatic hyperspheric expansion and the Faddeev decomposition of the wave function with only s-waves. We derive for a fixed hyperradius an integro-differential equation for the angular eigenvalue and wave function. The
correlations lower the interaction energy for N = 20 by about a factor of 5.
Received October 22, 2001; accepted for publication November 5, 2001 相似文献
2.
Some possible errors in determining the gravity anomalies are discussed. Such errors may be caused by an inaccurate calibration of the gravimeter used in an airborne survey system. An approach based on wavelet decompositions is proposed for its additional calibration with the use of flight data obtained during repeated flights. 相似文献
3.
A. R. Kuznetsov S. G. Lunter S. I. Nikitina A. G. Plyukhin Yu. K. Fedorov 《Journal of Applied Spectroscopy》1992,56(1):68-72
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 56, No. 1, pp. 90–95, January, 1992. 相似文献
4.
N. V. Vysotina N. N. Rozanov V. E. Semenov V. A. Smirnov S. V. Fedorov D. N. Christodoulides 《Optics and Spectroscopy》2005,98(6):895-903
The polarization structure of nonparaxial spatial solitons in a transparent medium with the electronic mechanism of Kerr nonlinearity is studied theoretically. It is demonstrated analytically in the weak nonparaxiality approximation that the regime of polarization locking, in which all the field components have the same propagation constant, is the only stable regime. Estimates of the rate of transition of the initial metastable regime of rotation of the polarization ellipse to the regime of polarization locking are presented. Based on a numerical solution of the nonlinear Maxwell equations, the presence of the nonparaxial regime of polarization locking is confirmed and the main characteristics of the corresponding spatial solitons are obtained. 相似文献
5.
The properties of high-energy ion beams (beamlets) observed in the boundary layer of the plasma sheet of the Earth’s magnetotail during short time intervals (1–2 min) have been considered. Beamlets are induced by nonlinear impulse accelerating processes occurring in the current sheet of the far regions of the geomagnetic tail. Then, moving toward the Earth along the magnetic field lines, they are detected in the magnetotail (in the plasma sheet boundary layer) and in the high-latitude part of the auroral zone in the form of short bursts of high-energy ions (with energies of several tens of keVs). The size of the localization region of the beamlets in the magnetotail and auroral zone has been determined by the epoch-superposition method, and it has been shown that beamlets are concentrated in a narrow region near the plasma sheet boundary, whose latitude size is no more than 0.8δ. This conclusion corroborates the theoretical prediction that the nonadiabatic resonant acceleration of ions occurs in a spatially localized region near the separatrix separating the open magnetic field lines and closed field lines, which contain the hot and isotropic plasmas of the plasma sheet. Based on the CLUSTER multisatellite measurements, the spatial structure of beamlets is analyzed and it has been found that the Alfvén wave arises due to the excitation of fire-hose instability at the instant of the exit of the ion beam from the current sheet to the high-latitude region of the far tail of the Earth’s magnetosphere. The longitudinal (along the magnetic field) and transverse sizes of a beamlet are estimated. It has been found that the beamlet is a dynamic plasma structure whose longitudinal size is several hundred times larger than its transverse size. 相似文献
6.
P. V. Pavlov I. V. Babushkin N. A. Loiko N. N. Rosanov S. V. Fedorov 《Radiophysics and Quantum Electronics》2004,47(10-11):898-904
We consider spatial dissipative solitons arising in the system of two nonlinear thin films which interact resonantly with light. Symmetric and nonsymmetric solitons and methods of their exciting and switching are studied. 相似文献
7.
Transversely one-dimensional moving and oscillating solitons in a wide-aperture laser with saturable absorber with fast (inertialess) nonlinearity are found by numerical simulation. The regions of existence of such solitons and of their complexes are presented. 相似文献
8.
Magnetism of Fe/Cr/Sn/Cr multilayers have been studied by the first-principles density-functional theory. Calculations by the full-potential linearized augmented plane waves (FP LAPW) and screened Korringa–Kohn–Rostoker (SKKR) methods have shown that two types of solutions may be found in these systems: a high-spin (HS) and a low-spin (LS) ones in accordance with the Cr magnetic moment magnitudes. In this work, we have concentrated our attention on the LS solution. The calculation has shown that the LS solution has a phase slip of antiferromagnetic ordering in Cr and is classified as an incommensurate spin density wave (ISDW). The dependence of the ISDW solution on the thickness of Cr, lattice parameter and boundary conditions has been investigated. 相似文献
9.
10.
A. N. Vasiliev V. N. Grishin A. M. Davidenko A. A. Derevschikov Yu. A. Matulenko Yu. M. Melnik A. P. Meschanin V. V. Mochalov L. V. Nogach S. B. Nurushev A. F. Prudkoglyad P. A. Semenov L. F. Soloviev V. L. Solovianov V. Yu. Khodyrev K. E. Shestermanov A. E. Yakutin N. S. Borisov V. N. Matafonov A. B. Neganov Yu. A. Plis Yu. A. Usov A. N. Fedorov A. A. Lukhanin 《Physics of Atomic Nuclei》2004,67(8):1487-1494
Results are presented that were obtained by measuring single-spin asymmetry in the inclusive production of neutral pions in the reaction p+p ↑→ π 0+X at x F≈0. A beam of 70-GeV protons was extracted directly from the vacuum chamber of the accelerator by means of a bent single crystal. For transverse momenta in the range 1.0<p T<3.0 GeV/c, the single-spin asymmetry independently measured by two detectors is zero within the errors. This result is in agreement with Fermilab data obtained at 200 GeV, but it is at odds with CERN data measured at 24 GeV. 相似文献