全文获取类型
收费全文 | 2964篇 |
免费 | 56篇 |
国内免费 | 9篇 |
专业分类
化学 | 1926篇 |
晶体学 | 18篇 |
力学 | 82篇 |
数学 | 304篇 |
物理学 | 699篇 |
出版年
2021年 | 19篇 |
2020年 | 26篇 |
2019年 | 27篇 |
2018年 | 22篇 |
2017年 | 20篇 |
2016年 | 38篇 |
2015年 | 35篇 |
2014年 | 34篇 |
2013年 | 92篇 |
2012年 | 129篇 |
2011年 | 159篇 |
2010年 | 77篇 |
2009年 | 47篇 |
2008年 | 128篇 |
2007年 | 132篇 |
2006年 | 158篇 |
2005年 | 139篇 |
2004年 | 137篇 |
2003年 | 94篇 |
2002年 | 110篇 |
2001年 | 76篇 |
2000年 | 87篇 |
1999年 | 45篇 |
1998年 | 45篇 |
1997年 | 31篇 |
1996年 | 68篇 |
1995年 | 38篇 |
1994年 | 54篇 |
1993年 | 76篇 |
1992年 | 54篇 |
1991年 | 33篇 |
1990年 | 35篇 |
1989年 | 37篇 |
1988年 | 30篇 |
1987年 | 39篇 |
1986年 | 28篇 |
1985年 | 48篇 |
1984年 | 30篇 |
1983年 | 23篇 |
1982年 | 49篇 |
1981年 | 31篇 |
1980年 | 45篇 |
1979年 | 29篇 |
1978年 | 44篇 |
1977年 | 36篇 |
1976年 | 27篇 |
1975年 | 43篇 |
1974年 | 29篇 |
1973年 | 35篇 |
1972年 | 19篇 |
排序方式: 共有3029条查询结果,搜索用时 250 毫秒
71.
Kubota Y Lattery M Nelson JK Patton S Perticone D Poling R Savinov V Schrenk S Wang R Alam MS Kim IJ Nemati B O'Neill JJ Severini H Sun CR Zoeller MM Crawford G Daubenmier CM Fulton R Fujino D Gan KK Honscheid K Kagan H Kass R Lee J Malchow R Morrow F Skovpen Y Sung M White C Butler F Fu X Kalbfleisch G Ross WR Skubic P Snow J Wang PL Wood M Brown DN Fast J McIlwain RL Miao T Miller DH Modesitt M Payne D Shibata EI Shipsey IP Wang PN Battle M Ernst J Kwon Y Roberts S Thorndike EH Wang CH 《Physical review letters》1994,72(13):1972-1976
72.
73.
74.
75.
W. M. Reiff B. D. James M. Bakalova J. Liesegang A. H. White B. W. Skelton D. C. R. Hockless 《Hyperfine Interactions》1994,94(1):2081-2086
Iron-57 Mössbauer spectroscopic results for a new series of related chloroferrate salts of complex ammonium cations are presented. In particular, spectra of materials based on FeCl
4
–
, FeCl
5
2–
, FeCl
6
–
, [FeCl5(H2O)]2–, and [FeCl5(CH3OH)]2– anions are discussed relative to the systematics of their isomer shifts, coordination numbers, and low temperature 3D critical ordering temperatures. The following specific systems have been studied by Mössbauer spectroscopy and definitively characterized by single-crystal X-ray analysis: [CH3NH
3
+
]4[FeCl6]3–[Cl–](A), [Me2N(-CH2CH2)2NMe
2
+
][FeCl
5
2–
] (B), [H3NCH2CH2NH
3
2+
][FeCl5·H2O2–], (C), and [NH3(CH2)6NH
3
2+
]4[(FeCl
6
3–
)(FeCl
4
–
)ClCl
4
–
] (D). The spectral data for these complexes are considered in the light of results of previous studies for systems such as [K2FeCl5·H2O], [Co(NH3)6][FeCl6], diamethyltriethylenediammoniumpentachloroferrate (E), and the related [FeCl5·CH3OH]2– salt (F). The critical 3D ordering temperatures are 1.45, 6.80, 3.45, and 1.22K forA, B, C, andD, respectively. 相似文献
76.
J. E. A. Whiteaway A. P. Wright B. Garrett G. H. B. Thompson J. E. Carroll L. M. Zhang C. F. Tsang I. H. White K. A. Williams 《Optical and Quantum Electronics》1994,26(7):S817-S842
This paper describes the first general large-signal dynamic multiple-mode laser model that incorporates all the main mechanisms known to influence the dynamic behaviour of DFB laser structures with the exception of thermal effects: longitudinal mode spatial hole burning, carrier transport effects, nonlinear gain, and laser and submount parasitics. The time evolution of the output power and wavelength of all modes is predicted, and full spectra can be plotted as a function of time. The model has been extended to include an approximation to the effects of propagation down dispersive fibre, thereby allowing the simulation of filtered received eye diagrams. Detailed comparison of the model with the experimental performance of 2×/8 DFB lasers has shown good agreement, allowing the performance to be optimized, particularly with respect to longitudinal hole burning and carrier transport. The model is also applied to gain-switched operation of 2×/8 DFB structures, fast pulsing of three-section /4 DFB lasers, and the dynamic behaviour of complex coupling coefficient DFB laser structures. 相似文献
77.
Ammar R Ball S Baringer P Bean A Besson D Coppage D Copty N Davis R Hancock N Kelly M Kwak N Lam H Kubota Y Lattery M Nelson JK Patton S Perticone D Poling R Savinov V Schrenk S Wang R Alam MS Kim IJ Nemati B O'Neill JJ Severini H Sun CR Zoeller MM Crawford G Daubenmier CM Fulton R Fujino D Gan KK Honscheid K Kagan H Kass R Lee J Malchow R Morrow F Skovpen Y Sung M White C Butler F Fu X Kalbfleisch G Ross WR Skubic P Snow J Wang PL Wood M Brown DN Fast J McIlwain RL Miao T Miller DH Modesitt M 《Physical review D: Particles and fields》1994,49(11):5701-5704
78.
Alam MS Kim IJ Nemati B O'Neill JJ Severini H Sun CR Zoeller MM Crawford G Daubenmier CM Fulton R Fujino D Gan KK Honscheid K Kagan H Kass R Lee J Malchow R Morrow F Skovpen Y Sung M White C Butler F Fu X Kalbfleisch G Ross WR Skubic P Snow J Wang PL Wood M Brown DN Fast J McIlwain RL Miao T Miller DH Modesitt M Payne D Shibata EI Shipsey IP Wang PN Battle M Ernst J Kwon Y Roberts S Thorndike EH Wang CH Dominick J Lambrecht M Sanghera S Shelkov V Skwarnicki T Stroynowski R Volobouev I Wei G 《Physical review D: Particles and fields》1994,50(1):43-68
79.
80.
Belz J Cousins RD Diwan MV Eckhause M Ecklund KM Hancock AD Highland VL Hoff C Hoffmann GW Irwin GM Kane JR Kettell SH Klein JR Kuang Y Lang K Martin R May M McDonough J Molzon WR Riley PJ Ritchie JL Schwartz AJ Trandafir A Ware B Welsh RE White SN Witkowski MT Wojcicki SG Worm S 《Physical review letters》1996,76(18):3277-3280