全文获取类型
收费全文 | 4016篇 |
免费 | 119篇 |
国内免费 | 10篇 |
专业分类
化学 | 2364篇 |
晶体学 | 57篇 |
力学 | 60篇 |
数学 | 633篇 |
物理学 | 1031篇 |
出版年
2021年 | 40篇 |
2020年 | 50篇 |
2019年 | 56篇 |
2018年 | 45篇 |
2017年 | 33篇 |
2016年 | 80篇 |
2015年 | 75篇 |
2014年 | 77篇 |
2013年 | 154篇 |
2012年 | 145篇 |
2011年 | 151篇 |
2010年 | 112篇 |
2009年 | 100篇 |
2008年 | 143篇 |
2007年 | 122篇 |
2006年 | 123篇 |
2005年 | 124篇 |
2004年 | 109篇 |
2003年 | 81篇 |
2002年 | 99篇 |
2001年 | 67篇 |
2000年 | 97篇 |
1999年 | 77篇 |
1998年 | 58篇 |
1997年 | 63篇 |
1996年 | 65篇 |
1995年 | 54篇 |
1994年 | 80篇 |
1993年 | 79篇 |
1992年 | 63篇 |
1991年 | 57篇 |
1990年 | 57篇 |
1989年 | 42篇 |
1988年 | 42篇 |
1987年 | 46篇 |
1986年 | 60篇 |
1985年 | 64篇 |
1984年 | 51篇 |
1983年 | 56篇 |
1982年 | 49篇 |
1981年 | 43篇 |
1980年 | 67篇 |
1979年 | 45篇 |
1978年 | 57篇 |
1977年 | 59篇 |
1976年 | 55篇 |
1975年 | 58篇 |
1974年 | 45篇 |
1973年 | 52篇 |
1972年 | 35篇 |
排序方式: 共有4145条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
45.
Abstract—Applying criteria used for higher plants, phytochrome mediation of uredospore germination in the stem-rust fungus, Puccinia graminis f. sp. tritici (Eriks & Henn) Guyot is established. A 1 min red irradiation at 660 nm promotes uredospore germination and this potentiation of promotion is photoreversible by a 1 min far-red irradiation at 730 nm. 相似文献
46.
K. Jungmann P. E. G. Baird J. R. M. Barr C. Bressler P. F. Curley R. Dixson G. H. Eaton A. I. Ferguson H. Geerds V. W. Hughes J. Kenntner S. N. Lea F. Maas M. A. Persaud G. zu Putlitz P. G. H. Sandars W. Schwarz W. T. Toner M. Towrie G. Woodman L. Zhang Z. Zhang 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,21(3):241-243
The 12 S 1/2(F=1)?22 S 1/2(F=1) energy interval in muonium has been investigated by Doppler-free two-photon laser spectroscopy. The transition was observed by uniquely identifying and counting the muons released after the photoionization of the 2S state by the same laser field. The measured transition frequency of 2455 528016(58)(43) MHz is in good agreement with QED calculations. The experiment can be interpreted as a test of the Lamb shift contributions at the 1% level. The method is also well suited for a precise determination of the mass of the positive muon in a muoniumhydrogen isotope shift measurement. 相似文献
47.
48.
49.
M. Schneider A. Hinz A. Groh K. M. Evenson W. Urban 《Applied physics. B, Lasers and optics》1987,44(4):241-245
Frequency stabilization of the CO laser using a CO lamb-dip is achieved in the range from 5.0–6.3 m. The CO saturation signal is obtained from a low-pressure discharge in absorption and is detected using optogalvanic, detection. The frequency stability and reproducibility has been verified to be better than 100 kHz; this is an improvement of more than one order of magnitude compared with locking techniques using CO laser gain profiles.Alexander von Humboldt Awardee from National Bureau of Standards, Boulder, Colorado, USA 相似文献
50.
N. K. Hansen P. Pattison J. R. Schneider 《Zeitschrift für Physik B Condensed Matter》1987,66(3):305-315
A method of reconstructing the electron momentum density (p), and its Fourier transform,B(t), from a series of directional Compton profiles is described. It is based on a double Fourier inversion technique and an expansion in lattice harmonic functions. The effect of random errors has been analysed, and the implications for the data collection discussed. We have used the reconstruction technique to obtain (p) andB(t) for silicon from six directional Compton profiles measured with 412 KeV gamma-radiation. The experimental result is in good agreement with earlier measurements and with available solid state theories. A recent Wannier function calculation for silicon using orthogonalised bond orbitals provides a useful tool for identifying the physical origins of the observed anisotropies. A comparison between the information presented in position and momentum space shows that the ease of interpretation depends upon the degree to which the various interactions give rise to localised features in each representation. 相似文献