全文获取类型
收费全文 | 27688篇 |
免费 | 3636篇 |
国内免费 | 13001篇 |
专业分类
化学 | 28026篇 |
晶体学 | 518篇 |
力学 | 1178篇 |
综合类 | 952篇 |
数学 | 6008篇 |
物理学 | 7643篇 |
出版年
2024年 | 233篇 |
2023年 | 902篇 |
2022年 | 989篇 |
2021年 | 1052篇 |
2020年 | 907篇 |
2019年 | 1239篇 |
2018年 | 768篇 |
2017年 | 1144篇 |
2016年 | 1282篇 |
2015年 | 1372篇 |
2014年 | 2064篇 |
2013年 | 2207篇 |
2012年 | 2288篇 |
2011年 | 2188篇 |
2010年 | 2172篇 |
2009年 | 2307篇 |
2008年 | 2702篇 |
2007年 | 2545篇 |
2006年 | 2749篇 |
2005年 | 2408篇 |
2004年 | 2600篇 |
2003年 | 1651篇 |
2002年 | 752篇 |
2001年 | 748篇 |
2000年 | 757篇 |
1999年 | 828篇 |
1998年 | 486篇 |
1997年 | 325篇 |
1996年 | 263篇 |
1995年 | 252篇 |
1994年 | 239篇 |
1993年 | 351篇 |
1992年 | 351篇 |
1991年 | 360篇 |
1990年 | 259篇 |
1989年 | 240篇 |
1988年 | 182篇 |
1987年 | 79篇 |
1986年 | 32篇 |
1985年 | 19篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 6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 687 毫秒
81.
82.
符号空间的拟移位和Moebius带上的奇怪吸引子 总被引:1,自引:0,他引:1
给出了双边符号空间上的一种新的拟移位映射,得到了它与传统的移位映射拓扑共轭.类似Smale马蹄,对这种拟移位映射给出了一个模型,即在Moebius带上给出一类映射.同时刻划了这类映射的吸引子的结构及动力学行为. 相似文献
83.
84.
设X和y是无限维的复Banach空间,φ是从B(X)到B(y)保单位的线性满射.本文证明了φ双边保算子的拟仿射性当且仅当φ为同构或反同构;φ双边保算子的值域稠性当且仅当φ是同构. 相似文献
85.
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
86.
A Continuation Method of Parameter Inversion for Non-Equilibrium Convection-Dispersion Equation 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Based on the homotopy mapping, a globally convergent method of parameter inversion for non-equilibrium convection-dispersion equations (CDEs) is developed. Moreover, in order to further improve the computational efficiency of the algorithm, a properly smooth function, which is derived from the sigmoid function, is employed to update the homotopy parameter during iteration. Numerical results show the feature of global convergence and high performance of this method. In addition, even the measurement quantities are heavily contaminated by noises, and a good solution can be found. 相似文献
87.
Spin-Polarized Tunnelling Magnetoresistance Effects in La0.833K0.167MnO3/SrTiO3 Polycrystalline Perovskite Manganites
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
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
88.
89.
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
90.
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
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
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