全文获取类型
收费全文 | 600188篇 |
免费 | 4473篇 |
国内免费 | 1650篇 |
专业分类
化学 | 290452篇 |
晶体学 | 8307篇 |
力学 | 32274篇 |
综合类 | 17篇 |
数学 | 98017篇 |
物理学 | 177244篇 |
出版年
2021年 | 5035篇 |
2020年 | 5477篇 |
2019年 | 6222篇 |
2018年 | 18175篇 |
2017年 | 18063篇 |
2016年 | 17266篇 |
2015年 | 6937篇 |
2014年 | 10687篇 |
2013年 | 23721篇 |
2012年 | 21754篇 |
2011年 | 31413篇 |
2010年 | 21597篇 |
2009年 | 21880篇 |
2008年 | 26671篇 |
2007年 | 28498篇 |
2006年 | 18774篇 |
2005年 | 17769篇 |
2004年 | 16835篇 |
2003年 | 15792篇 |
2002年 | 14768篇 |
2001年 | 14920篇 |
2000年 | 11583篇 |
1999年 | 8870篇 |
1998年 | 7749篇 |
1997年 | 7583篇 |
1996年 | 7107篇 |
1995年 | 6367篇 |
1994年 | 6335篇 |
1993年 | 6107篇 |
1992年 | 6425篇 |
1991年 | 6924篇 |
1990年 | 6626篇 |
1989年 | 6541篇 |
1988年 | 6378篇 |
1987年 | 6186篇 |
1986年 | 5926篇 |
1985年 | 7453篇 |
1984年 | 7810篇 |
1983年 | 6569篇 |
1982年 | 6856篇 |
1981年 | 6364篇 |
1980年 | 6047篇 |
1979年 | 6545篇 |
1978年 | 6773篇 |
1977年 | 6647篇 |
1976年 | 6602篇 |
1975年 | 6315篇 |
1974年 | 6139篇 |
1973年 | 6448篇 |
1972年 | 4723篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
A.D. Bykov V.N. Saveliev C. Camy-Peyret A. Valentin 《Journal of Molecular Spectroscopy》2004,224(2):164-175
Forty-seven N2 broadened water vapor line-widths have been measured in the 1845-2140 cm−1 spectral range with a Fourier Transform spectrometer in the 258-330 K temperature range at a spectral resolution of 0.005 cm−1 for the lines with upper state rotational quantum number up to 16. The measured exponents of the temperature dependence of the width exhibit a large range of values from 1.60 to −0.86. Theoretical calculations were made using a semi-empirical technique based on the Anderson theory. The calculated broadening coefficients as well as the temperature exponents for the half-width agree satisfactory with measured values. 相似文献
952.
Bahraminasab A. Tabei S. M. A. Masoudi A. A. Shahbazi F. Reza Rahimi Tabar M. 《Journal of statistical physics》2004,116(5-6):1521-1544
The joint probability distribution function (PDF) of the height and its gradients is derived for a zero tension d + 1-dimensional Kardar-Parisi-Zhang (KPZ) equation. It is proved that the height's PDF of zero tension KPZ equation shows lack of positivity after a finite time t c . The properties of zero tension KPZ equation and its differences with the case that it possess an infinitesimal surface tension is discussed. Also potential relation between the time scale t c and the singularity time scale t c.v→0 of the KPZ equation with an infinitesimal surface tension is investigated. 相似文献
953.
A. V. Burenin 《Optics and Spectroscopy》2004,97(6):867-875
A noninvariant geometrical group characterizing the internal dynamics of the tetrahydrofuran molecule C4H8O with allowance for the clearly pronounced pseudorotation effect is constructed. On this basis, some qualitative features of the energy spectrum of the molecule following from the analysis of high-resolution spectroscopic data are explained. 相似文献
954.
The phenomenon of plasmon resonance in a nanosphere and a nanospheroid is considered. As is known, this phenomenon does not depend explicitly on the size of these nanoparticles. However, it is shown that, actually, the resonance conditions are determined by the diameter of the nanosphere and by the length of the major axis of the nanospheroid. 相似文献
955.
956.
The Kα to Lα and Kβ to Lβ intensity ratios of seven elements have been measured following photoionization at 59.5 keV by using a Si (Li) detector
(FWHM=155 eV at 5.96 keV). The intensity ratios were determined by measuring K and L x-rays emitted from a standard target of a given element. The theoretical values of the Kα to Lα and Kβ to Lβ intensity ratios were calculated using theoretically tabulated values of shell/subshell photoionization cross sections,
fluorescence yields, Coster-Kronig transition probabilities, and radiative decay rates for ηKLi≠ and ηKLi=0. The measured values are in good agreement with theoretical results.
From Optika i Spektroskopiya, Vol. 97, No. 2, 2004, pp. 186–189.
Original English Text Copyright ? 2004 by A. Kü?ük?nder, S?ğüt, E. Kü?ük?nder, Büyükkasap.
This article was submitted by the authors in English. 相似文献
957.
The kinetics of decay of a phase hologram in a semiconductor CdF2 crystal with bistable In centers is studied. Kinetic constants of the hologram decay are found, and the potential relief of the bistable center is plotted. The resolving power of the crystal is evaluated and recording of a transparency is demonstrated. 相似文献
958.
959.
The cross section of absorption of electromagnetic radiation by an inhomogeneous spherical particle is calculated. The general case of an arbitrary value of the ratio of the particle radius to the radius of the dielectric core is considered. The condition of diffuse reflection of electrons from the inner and outer surfaces of the metal layer of the particle is taken as the boundary condition of the problem. The limiting cases are considered and the results obtained are discussed. 相似文献
960.
N. A. Borisevich S. L. Dziarzhytski V. A. Povedailo D. L. Yakovlev 《Optics and Spectroscopy》2004,96(6):819-823
The spectra of the fluorescence excitation within the rotational contours of the bands of the pure electronic long-wavelength S 0-S 1 transitions of jet-cooled indole and carbazole molecules and their complexes with water are measured. For the carbazole-water complex, a contour with three maxima is registered, which is possibly related to the occurrence of two isomers, differing in a slight displacement of hydrogen between the nitrogen atom of the imine group of carbazole and the oxygen atom of the water molecule. The degrees of polarization of integral fluorescence upon excitation within the rotational contours of the S 0-S 1 electronic transition bands of the above molecules and their complexes with water are determined for the first time. The coincidence of the calculated (7.7%) and measured (7.3%) values of the degree of polarization upon excitation in the rotational Q branch of the b L 1-A electronic transition of indole confirms the accepted intramolecular orientation of the transition dipole moment at an angle of 38.3° with respect to the principal axis of inertia A. Upon excitation of indole, its complex with water, and carbazole into the P and R branches, the measured and calculated degrees of polarization are also close to each other and amount to 2–3%. This confirms the occurrence of contributions to the fluorescence polarization due to the rotations of the indole molecules around the principal axes of inertia A and C. 相似文献