全文获取类型
收费全文 | 32529篇 |
免费 | 4598篇 |
国内免费 | 15745篇 |
专业分类
化学 | 33205篇 |
晶体学 | 702篇 |
力学 | 1470篇 |
综合类 | 1058篇 |
数学 | 6441篇 |
物理学 | 9996篇 |
出版年
2024年 | 275篇 |
2023年 | 1029篇 |
2022年 | 1188篇 |
2021年 | 1255篇 |
2020年 | 1005篇 |
2019年 | 1355篇 |
2018年 | 861篇 |
2017年 | 1270篇 |
2016年 | 1448篇 |
2015年 | 1555篇 |
2014年 | 2394篇 |
2013年 | 2516篇 |
2012年 | 2588篇 |
2011年 | 2546篇 |
2010年 | 2475篇 |
2009年 | 2655篇 |
2008年 | 3099篇 |
2007年 | 2826篇 |
2006年 | 3087篇 |
2005年 | 2671篇 |
2004年 | 2909篇 |
2003年 | 1957篇 |
2002年 | 1114篇 |
2001年 | 1105篇 |
2000年 | 988篇 |
1999年 | 1066篇 |
1998年 | 787篇 |
1997年 | 594篇 |
1996年 | 499篇 |
1995年 | 513篇 |
1994年 | 508篇 |
1993年 | 475篇 |
1992年 | 524篇 |
1991年 | 492篇 |
1990年 | 397篇 |
1989年 | 384篇 |
1988年 | 234篇 |
1987年 | 100篇 |
1986年 | 46篇 |
1985年 | 34篇 |
1984年 | 17篇 |
1983年 | 17篇 |
1982年 | 6篇 |
1979年 | 2篇 |
1959年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
汪更生 《数学物理学报(B辑英文版)》2005,25(1):7-22
This paper deals with maximum principle for some optimal control problem governed by some elliptic variational inequalities. Some state constraints are discussed. The basic techniques used here are based on those in [1] and a new penalty functional defined in this paper. 相似文献
102.
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
103.
104.
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
105.
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
106.
107.
108.
通过紫外-可见吸收光谱、压力-面积等温线、二次谐波的测量,研究了不同活性分子混合聚集体的形成对LB膜光学性质的影响。分子极性基团间的相互作用,使激发态能量及平均偶极矩发生变化,导致LB膜的光学非线性明显地增强或减弱。 相似文献
109.
A Fixed Point Theorem for Multi-valued Composite Increasing OperatorsLiFengyou(李凤友)(DepartmentofMathematics,Tianjin'NormalUni... 相似文献
110.
1978年,D,Quillen证明了:若群G有非平凡的正规p-子群,则由p-子群组成的半序集是可缩的。同时,他还猜想逆定理也成立。1993年,M.Aschbacher和S.D.Smith证明了若群G不包含某种酉分支的话,则Quillen猜想的确成立,在他们的证明中,Quillen所证明的下述定理起着很重要的作用:由基本阿贝耳P-子群组成的半序集到所有P-子群组成的半序集的包含映射导出对应下同调的同构。以Buchsbaum条件为重要的工具,本文将重新叙述此定理的证明。 相似文献