全文获取类型
收费全文 | 29327篇 |
免费 | 3976篇 |
国内免费 | 14956篇 |
专业分类
化学 | 32176篇 |
晶体学 | 607篇 |
力学 | 1078篇 |
综合类 | 907篇 |
数学 | 4629篇 |
物理学 | 8862篇 |
出版年
2024年 | 237篇 |
2023年 | 926篇 |
2022年 | 942篇 |
2021年 | 1079篇 |
2020年 | 974篇 |
2019年 | 1301篇 |
2018年 | 823篇 |
2017年 | 1199篇 |
2016年 | 1376篇 |
2015年 | 1444篇 |
2014年 | 2100篇 |
2013年 | 2354篇 |
2012年 | 2452篇 |
2011年 | 2317篇 |
2010年 | 2248篇 |
2009年 | 2433篇 |
2008年 | 2873篇 |
2007年 | 2631篇 |
2006年 | 2843篇 |
2005年 | 2517篇 |
2004年 | 2736篇 |
2003年 | 1866篇 |
2002年 | 1129篇 |
2001年 | 1043篇 |
2000年 | 898篇 |
1999年 | 1000篇 |
1998年 | 605篇 |
1997年 | 448篇 |
1996年 | 390篇 |
1995年 | 389篇 |
1994年 | 394篇 |
1993年 | 388篇 |
1992年 | 444篇 |
1991年 | 411篇 |
1990年 | 339篇 |
1989年 | 318篇 |
1988年 | 220篇 |
1987年 | 84篇 |
1986年 | 37篇 |
1985年 | 21篇 |
1984年 | 14篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1980年 | 1篇 |
1959年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
利用内部爆炸加载方法对U-Nb合金进行爆破试验,对爆破试验产生的破片进行回收,并对U-Nb合金破片进行一些微观检测分析,从而初步研究在爆炸加载下U-Nb合金的微观断裂机制。 相似文献
104.
Spin-Polarized Tunnelling Magnetoresistance Effects in La0.833K0.167MnO3/SrTiO3 Polycrystalline Perovskite Manganites 下载免费PDF全文
A sample of La0.833K0.167MnO3-SrTiO3 (LKMO/STO) is fabricated by the sol-gel method. The microstructure,magnetic and transportation properties have been studied. X-ray diffraction patterns indicate that the structure of LKMO/STO is a homogeneous solid solution phase. The resistivity of LKMO/STO shows the insulator behaviour, which is different from La0.833K0.167MnO3 (LKMO) whose resistivity shows metal-insulator transition with decreasing temperature. The low-field (moH = 0.02 T) magnetoresistance decreases from 11% to 0.2% with the increasing temperature from 4 K‘to 220K for the LKMO/STO sample. The magnitude of magnetoresistance in a strong field (μoH = 5.5 T) almost increases linearly with decreasing temperature and reaches the maximum of 65% at the low temperature of 4.2K, which is much higher than that oE LKMO (40%). The enhanced low-field magnetoresistance effects are quantitatively explained by the spin-polarized tunnelling at grain boundaries. 相似文献
105.
106.
We investigate magnetic and crystalline microstructures of melt-spun (Fe0.675Pt0.325)100-xBx (x=12, 14, 16, 18,20) nanocomposite ribbons after optimal thermal treatment using a magnetic force microscope. The magnetic microstructures are characterized by darker spots adjacent to brighter ones in a sub-micro scale and in random distribution. It is found that the strength of the exchange coupling interaction between the crystals in the 10-100 nm scale, implied by the maximum value (δM)max of the Henkel plot, could be roughly described by the ratio of the average width of the magnetic spots w^- to the average crystal size D^- for the ribbons. Moreover, we find that the intrinsic coercivity jHc of the ribbons is sensitive to their crystal sizes, and the smaller D^-, the higher jHc. Finally, by using roughness analysis, the curve of the root mean square values (δФ)rms of the phase shift of the magnetic force images versus the boron content x is obtained, which is qualitatively consistent with that of the magnetization σ12 kOe of the ribbons versus x. 相似文献
107.
Theoretical Study on the Rotational Bands and Shape Coexistence of^179,181,183Au in the Particle-Triaxial-Rotor Model 下载免费PDF全文
We perform a series of theoretical calculations and investigation for nuclei 179,181,183Au in the particle-triaxialrotor model with variable moment of inertia. The calculated energy spectra in^179,181,183Au agree well with the experimental data globally. The obtained results indicate that the nuclei^179,181,183Au have prolate deformation and involve shape coexistence with different deformation parameters in different bands. The main configuration of bands 1, 2, 3 and 5 in these nuclei are identified as [541]1/2^- (πh9/2, α = 1/2), [541]1/2- (πh9/2, α= -1/2),[530] 1/2- (πf7/2) and [660] 1/2^ (πi13/2), respectively. 相似文献
108.
109.
110.