全文获取类型
收费全文 | 10770篇 |
免费 | 1955篇 |
国内免费 | 967篇 |
专业分类
化学 | 7073篇 |
晶体学 | 84篇 |
力学 | 675篇 |
综合类 | 86篇 |
数学 | 1207篇 |
物理学 | 4567篇 |
出版年
2024年 | 43篇 |
2023年 | 257篇 |
2022年 | 415篇 |
2021年 | 450篇 |
2020年 | 430篇 |
2019年 | 428篇 |
2018年 | 367篇 |
2017年 | 345篇 |
2016年 | 535篇 |
2015年 | 513篇 |
2014年 | 572篇 |
2013年 | 782篇 |
2012年 | 937篇 |
2011年 | 1018篇 |
2010年 | 636篇 |
2009年 | 665篇 |
2008年 | 664篇 |
2007年 | 571篇 |
2006年 | 524篇 |
2005年 | 437篇 |
2004年 | 340篇 |
2003年 | 281篇 |
2002年 | 256篇 |
2001年 | 207篇 |
2000年 | 217篇 |
1999年 | 204篇 |
1998年 | 212篇 |
1997年 | 191篇 |
1996年 | 149篇 |
1995年 | 195篇 |
1994年 | 166篇 |
1993年 | 125篇 |
1992年 | 101篇 |
1991年 | 85篇 |
1990年 | 90篇 |
1989年 | 64篇 |
1988年 | 43篇 |
1987年 | 33篇 |
1986年 | 35篇 |
1985年 | 21篇 |
1984年 | 18篇 |
1983年 | 21篇 |
1982年 | 12篇 |
1981年 | 6篇 |
1980年 | 10篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Luo S 《Physical review letters》2003,91(18):180403
The Wigner-Araki-Yanase theorem puts a limitation on the measurement of observables in the presence of a conserved quantity, and the notion of Wigner-Yanase skew information quantifies the amount of information on the values of observables not commuting with the conserved quantity. We demonstrate that the statistical idea underlying the skew information is the Fisher information in the theory of statistical estimation. A quantum Cramér-Rao inequality and a new uncertainty relation in terms of the skew information are established, which shed considerable new light on the relationships between quantum measurement and statistical inference. The result is applied to estimating the evolution speed of quantum states. 相似文献
132.
Brandon Wilfong Muhtar Ahart Stephen A. Gramsch Chris Stock Xiaomin Li H. Luo Russell J. Hemley 《Journal of Raman spectroscopy : JRS》2016,47(2):227-232
The vibrational and structural properties of Pb(Fe0.5Nb0.5)O3 have been investigated using Raman spectroscopy up to 40 GPa at 300 K and from 300 to 415 K at selected pressures. The measurements reveal three phase transitions, at 5.5, 8.7, and 24 GPa at room temperature. The temperature dependences of the spectra indicate transitions at 1.5 GPa, at 335 and 365 K. The results are consistent with the appearance of an intermediate tetragonal P4mm phase between the ferroelectric R3m and paraelectric Pm‐3m phases. A P–T phase diagram is proposed that allows further insight into the magnetoelectric coupling present in this material. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
133.
电磁学的知识是高中物理教学的重要内容,学过的学生会对麦克斯韦电磁场理论深深着迷,“变化的电场产生磁场,变化的磁场产生电场”的规律充分体现了物理规律的对称美、和谐美. 相似文献
134.
Pearlescent coatings become highly popular to the modern generation of color rendering materials due to their unique color effect. However, it is quite challenging to evaluate its color appearance by traditional color measurement. A low-cost camera is a highly efficient device for multi-geometry color appearance estimation for pearlescent bottles, which has been achieved through the camera characterization, sample image capturing, and then mathematical transforming from RGB (red, green, and blue) values to color appearance attributes based on the color appearance model of CIECAM02. A tele-spectroradiometer for physical measurement together with visual assessment is applied for comparison with the camera method to evaluate the accuracy of camera predictions and discuss the applicability of CIECAM02. The experimental results indicate that the camera data have strong correlation with the physical measurement and also fit well with visual data except for a slight slope shift existing in lightness due to a divinable psychophysical magnitude variation for spatial-dependent color samples. Hence it is feasible to estimate the color appearance of pearlescent bottles using a digital camera. 相似文献
135.
Xu Chun Song E. Yang Rong Ma Hai Fang Chen Zhong Li Ye Min Luo 《Applied Physics A: Materials Science & Processing》2009,94(1):185-188
ZnWO4 nanorods with a bundle-like structure were synthesized at 180°C for 12 h by a hydrothermal technology from Na2WO4⋅2H2O and ZnSO4⋅7H2O in the presence of sodium dodecyl sulfate (SDS). The as-synthesized bundle-like structure of ZnWO4 nanorods was characterized by various techniques: TEM, XRD and EDS. The luminescence properties of the bundle-like structure
of the ZnWO4 nanorods were investigated by photoluminescence (PL) spectroscopy. 相似文献
136.
137.
In this Letter, we report single-mode fibers made of chalcogenide glasses with low loss in the 5-12μm range. Glasses from the Ge-As-Te-Se system were optimized to prevent nucleation and to exhibit low density of charge carriers. Single-mode fibers were obtained through the rod-in-tube method by substituting 2% Te/Se between the core and cladding glasses. The resulting single-mode fibers had a core diameter of 30μm and exhibited losses of ~6 dB/m at 10.6μm, and as low as 3-4dB/m in the 6-10μm range. 相似文献
138.
Deng L Hagley EW Cao Q Wang X Luo X Wang R Payne MG Yang F Zhou X Chen X Zhan M 《Physical review letters》2010,105(22):220404
We report the first experimental observation of strong suppression of matter-wave superradiance using blue-detuned pump light and demonstrate a pump-laser detuning asymmetry in the collective atomic recoil motion. In contrast to all previous theoretical frameworks, which predict that the process should be symmetric with respect to the sign of the detuning of the pump laser from the one-photon resonance, we find that for condensates the symmetry is broken. With high condensate densities and red-detuned pump light the distinctive multiorder, matter-wave scattering pattern is clearly visible, whereas with blue-detuned pump light superradiance is strongly suppressed. However, in the limit of a dilute atomic gas symmetry is restored. 相似文献
139.
Jiaowan Luo 《Journal of Mathematical Analysis and Applications》2009,351(1):147-326
In this paper, we study the existence and uniqueness of the solution to a class of doubly perturbed jump-diffusion processes with non-Lipschitz coefficients. Some well-known results are improved and generalized. 相似文献
140.
The electronic structure and magnetic properties of B-based Heusler alloys Fe2YB (Y=Ti, V, Cr and Mn) have been studied theoretically. These alloys are all ferrimagnets except for Fe2VB. The latter has 24 valence electrons and is a paramagnetic semimetal. Fe2CrB is predicted to be half-metals at equilibrium lattice constant. The spin polarization of Fe2MnB is also quite high. The calculated total moments are 1.00 μB for Fe2CrB and 2.04 μB for Fe2MnB. In Fe2CrB and Fe2MnB, the total moments are mainly determined by the partial moment of Cr or Mn. The Fe moment is relatively small and antiparallel to that of Cr or Mn. Under uniform lattice distortion, the half-metallicity of Fe2CrB is more stable than Fe2MnB, which is related to the detailed DOS structure of them near EF. 相似文献