全文获取类型
收费全文 | 1773篇 |
免费 | 28篇 |
国内免费 | 19篇 |
专业分类
化学 | 1265篇 |
晶体学 | 27篇 |
力学 | 46篇 |
数学 | 151篇 |
物理学 | 331篇 |
出版年
2021年 | 10篇 |
2020年 | 16篇 |
2019年 | 15篇 |
2018年 | 10篇 |
2017年 | 9篇 |
2016年 | 21篇 |
2015年 | 29篇 |
2014年 | 23篇 |
2013年 | 73篇 |
2012年 | 82篇 |
2011年 | 88篇 |
2010年 | 49篇 |
2009年 | 52篇 |
2008年 | 88篇 |
2007年 | 90篇 |
2006年 | 95篇 |
2005年 | 103篇 |
2004年 | 89篇 |
2003年 | 85篇 |
2002年 | 90篇 |
2001年 | 53篇 |
2000年 | 39篇 |
1999年 | 25篇 |
1998年 | 20篇 |
1997年 | 17篇 |
1996年 | 24篇 |
1995年 | 19篇 |
1994年 | 18篇 |
1993年 | 25篇 |
1992年 | 22篇 |
1991年 | 24篇 |
1990年 | 18篇 |
1989年 | 20篇 |
1988年 | 22篇 |
1987年 | 18篇 |
1986年 | 12篇 |
1985年 | 30篇 |
1984年 | 29篇 |
1983年 | 23篇 |
1982年 | 21篇 |
1981年 | 23篇 |
1980年 | 18篇 |
1979年 | 23篇 |
1978年 | 22篇 |
1977年 | 26篇 |
1976年 | 16篇 |
1975年 | 14篇 |
1974年 | 17篇 |
1973年 | 13篇 |
1968年 | 9篇 |
排序方式: 共有1820条查询结果,搜索用时 140 毫秒
11.
Hyperfine interaction constants (HFICs) of dangling bonds for CN and SiN films were calculated by density-functional theory. The averaged 14N isotropic HFICs for C dangling bonds are almost equal to those for Si dangling bonds. The anisotropic 14N HFICs calculated for C dangling bonds are larger than those for Si dangling bonds by a factor 2. The calculated results were compared with experimental results obtained by electron spin resonance and electron nuclear double resonance. It was indicated that the carbon dangling bonds are located such that they avoid N atoms in CN films. 相似文献
12.
13.
14.
H. Sakuma T. Taniyama K. Ishii Y. Kitamoto Y. Yamazaki 《Journal of magnetism and magnetic materials》2006,300(2):284-292
The order parameter S of Fe–Pt nanoparticles is estimated from X-ray diffraction (XRD) patterns. The total intensity of a diffraction peak is obtained by Rietveld analysis as well as simply integrating the intensity. The Rietveld analysis is found to provide a plausible value of S even for a sample showing an XRD pattern with broad and overlapped peaks. Another order parameter Q, which is obtained from Mössbauer spectra, is introduced, and it is confirmed that Q is equivalent to the probability of Fe atoms being in the L10-type atomic arrangement. The coercivity of Fe–Pt nanoparticles is directly proportional to Q, while it vanishes at S=0.4, indicating that the magnetic property of Fe–Pt nanoparticles has a closer relationship to Q than S. 相似文献
15.
Structural and electronic properties of a new BEDT-TTF based radical cation salt, α-(BEDT-TTF)2CsCd(SCN)4, are presented. In the measurements of the electrical resistivity and the magnetic susceptibility, this new α-type salt shows metallic behavior down to low temperature. Measurements of the resistivity under in-plane c-axial strain reveal a newly observed insulating phase, suggesting that α-(BEDT-TTF)2CsCd(SCN)4 is placed near an insulating phase which might have close relationships with a superconducting phase realized in α-type salts. 相似文献
16.
By time-resolved electron paramagnetic resonance (TREPR), four (tetraphenylporphinato) zinc (ZnTPP) complexes coordinated by an axial ligand containing a nitroxide radical (NRX; X=4, 5, 8, and 10, denotes the bond number from zinc to nitroxide nitrogen) have been studied in terms of magnetic interactions between the photoexcited triplet state of ZnTPP and NRX. The TREPR spectrum of ZnTPP coordinated by NR10 is almost the same as the one of ZnTPP coordinated by pyridine, indicating that the electron exchange interaction,J, between ZnTPP and the doublet nitroxide is negligibly small. On the other hand, TREPR spectra of the NR4 and NR5 complexes are assigned to the Q1 state constituted by the ZnTPP and the nitroxide radical. In the case of the ZnTPP-NR8 complex, both T1 and Q1 TREPR signals are seen, which may originate from two conformations or degenerate T1 states of ZnTPP. This EPR study is useful for understanding the photophysical and photochemical properties of chromophores. 相似文献
17.
This paper newly designs the recursive least-squares (RLS) fixed-lag smoother and filter using the covariance information in linear continuous-time stochastic systems. It is assumed that the signal is observed with additive white observation noise and the signal is uncorrelated with the observation noise. The estimators require the covariance information of the signal and the variance of the observation noise. The auto-covariance function of the signal is expressed in the semi-degenerate kernel form. 相似文献
18.
19.
Adachi I Aihara H Dijkstra HB Enomoto R Fujii H Fujii K Fujii T Fujimoto J Fujiwara N Hayashii H Higashi S Iida N Imanishi A Ikeda H Ishii T Itoh R Iwasaki H Iwata S Kajikawa R Kamae T Kato S Kawabata S Kichimi H Kishida T Kobayashi M Kuroda S Kusuki N Maruyama A Maruyama K Masuda H Matsuda T Miyamoto A Morimoto T Nakamura K Nitoh O Noguchi S Ochiai F Okuno H Okusawa T Ohshima T Ozaki H Sato T Sai F Shimonaka J Shimozawa K Shirahashi A Sugahara R Sugiyama A Suzuki S Suwada T Takahashi K 《Physical review letters》1988,60(2):97-100
20.