全文获取类型
收费全文 | 155154篇 |
免费 | 6880篇 |
国内免费 | 3721篇 |
专业分类
化学 | 90014篇 |
晶体学 | 2343篇 |
力学 | 6719篇 |
综合类 | 141篇 |
数学 | 15052篇 |
物理学 | 51486篇 |
出版年
2022年 | 1603篇 |
2021年 | 1851篇 |
2020年 | 2018篇 |
2019年 | 1970篇 |
2018年 | 1781篇 |
2017年 | 1601篇 |
2016年 | 2844篇 |
2015年 | 2477篇 |
2014年 | 3238篇 |
2013年 | 7127篇 |
2012年 | 6155篇 |
2011年 | 7165篇 |
2010年 | 4549篇 |
2009年 | 4245篇 |
2008年 | 5856篇 |
2007年 | 5660篇 |
2006年 | 5609篇 |
2005年 | 5193篇 |
2004年 | 4386篇 |
2003年 | 3890篇 |
2002年 | 3783篇 |
2001年 | 4125篇 |
2000年 | 3120篇 |
1999年 | 2777篇 |
1998年 | 2390篇 |
1997年 | 2348篇 |
1996年 | 2286篇 |
1995年 | 2194篇 |
1994年 | 1883篇 |
1993年 | 1809篇 |
1992年 | 2023篇 |
1991年 | 1963篇 |
1990年 | 1873篇 |
1989年 | 1826篇 |
1988年 | 1773篇 |
1987年 | 1752篇 |
1986年 | 1691篇 |
1985年 | 2208篇 |
1984年 | 2296篇 |
1983年 | 1931篇 |
1982年 | 2240篇 |
1981年 | 2049篇 |
1980年 | 2080篇 |
1979年 | 2062篇 |
1978年 | 2186篇 |
1977年 | 2090篇 |
1976年 | 2116篇 |
1975年 | 2054篇 |
1974年 | 1895篇 |
1973年 | 2102篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
The room temperature structure of perovskite CeAlO3 has been reinvestigated by X-ray powder diffraction. The Rietveld refinement has confirmed the tetragonal symmetry; but revealed a super cell, a=5.32489(6) Å and c=7.58976(10) Å, with the space group I4/mcm. In CeAlO3, the distortion from the ideal cubic perovskite is caused by the cooperative tilting of the AlO6 octahedra around the primitive cubic [001]p-axis. 相似文献
62.
63.
64.
65.
66.
67.
A novel super-hydrophobic stearic acid (STA) film with a water contact angle of 166o was prepared by chemical adsorption on aluminum wafer coated with polyethyleneimine (PEI) film. The micro-tribological behavior
of the super-hydrophobic STA monolayer was compared with that of the polished and PEI-coated Al surfaces. The effect of relative
humidity on the adhesion and friction was investigated as well. It was found that the STA monolayer showed decreased friction,
while the adhesive force was greatly decreased by increasing the surface roughness of the Al wafer to reduce the contact area
between the atomic force microscope (AFM) tip and the sample surface to be tested. Thus the friction and adhesion of the Al
wafer was effectively decreased by generating the STA monolayer, which indicated that it could be feasible and rational to
prepare a surface with good adhesion resistance and lubricity by properly controlling the surface morphology and the chemical
composition. Both the adhesion and friction decreased as the relative humidity was lowered from 65% to 10%, though the decrease
extent became insignificant for the STA monolayer.
The project supported by the National Natural Science Foundation of China (50375151, 50323007, 10225209) and the Chinese Academy
of Sciences (KJCX-SW-L2) 相似文献
68.
69.
Kosuke Morita Kouji Morimoto Daiya Kaji Yu Liang Zhao Atsushi Yoshida Toshimi Suda Akira Yoneda Tetsuya Ohnishi Hiromitsu Haba Eiji Ideguchi Hu Shan Xu Tao Zheng Hisaaki Kudo Keisuke Sueki Kenji Katori Isao Tanihata 《Acta Physica Hungarica A》2004,19(1-2):53-60
A gas-filled type of recoil separator for heavy element research was installed at an experimental hall of RIKEN Linear Accelerator facility to realize getting higher intensity of primary beam and long beam time. Performance of the separator was studied using target recoils and various nuclear reactions. The results show the high performance of the separator for heave element research. As an application of the GARIS, production and identification of an isotope of the 110th element 271[110] have been performed using the 208Pb(64Ni,1n)271[110] reaction. Three decay chains coincide well both in decay times and energies with the ones reported by the group of SHIP experiment at GSI, Germany. Our results provide a confirmation of the synthesis of an isotope 271[110] of element 110. 相似文献
70.
J. R. Lindle W. W. Bewley I. Vurgaftman J. R. Meyer J. L. Johnson M. L. Thomas W. E. Tennant 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):558
A self-referencing, optical modulation technique was used to measure the negative luminescence efficiencies of an array of mid-wave infrared HgCdTe photodiodes with cutoff wavelength 4.6 μm as a function of sample temperature. The internal efficiency at a wavelength of 4 μm was 93% at 295 K, and nearly independent of temperature in the 240–300 K range. This corresponds to an apparent temperature reduction >50 K at room temperature and >30 K at 240 K. Moreover, the reverse-bias saturation current density was only 0.13 A/cm2. The measured transmission and emission spectra were simulated using empirical HgCdTe absorption formulas from the literature. 相似文献