全文获取类型
收费全文 | 7155篇 |
免费 | 315篇 |
国内免费 | 79篇 |
专业分类
化学 | 4254篇 |
晶体学 | 221篇 |
力学 | 194篇 |
综合类 | 4篇 |
数学 | 1046篇 |
物理学 | 1830篇 |
出版年
2022年 | 60篇 |
2021年 | 66篇 |
2020年 | 93篇 |
2019年 | 141篇 |
2018年 | 100篇 |
2017年 | 98篇 |
2016年 | 142篇 |
2015年 | 122篇 |
2014年 | 187篇 |
2013年 | 560篇 |
2012年 | 311篇 |
2011年 | 353篇 |
2010年 | 239篇 |
2009年 | 211篇 |
2008年 | 246篇 |
2007年 | 254篇 |
2006年 | 220篇 |
2005年 | 176篇 |
2004年 | 173篇 |
2003年 | 201篇 |
2002年 | 171篇 |
2001年 | 100篇 |
2000年 | 95篇 |
1999年 | 66篇 |
1997年 | 70篇 |
1996年 | 79篇 |
1995年 | 85篇 |
1994年 | 82篇 |
1993年 | 85篇 |
1992年 | 98篇 |
1991年 | 88篇 |
1990年 | 77篇 |
1989年 | 111篇 |
1988年 | 76篇 |
1987年 | 70篇 |
1986年 | 82篇 |
1985年 | 126篇 |
1984年 | 119篇 |
1983年 | 93篇 |
1982年 | 98篇 |
1981年 | 101篇 |
1980年 | 86篇 |
1979年 | 98篇 |
1978年 | 73篇 |
1977年 | 100篇 |
1976年 | 79篇 |
1975年 | 86篇 |
1974年 | 92篇 |
1973年 | 97篇 |
1972年 | 57篇 |
排序方式: 共有7549条查询结果,搜索用时 890 毫秒
991.
Stephen C. Hurlock Walter J. Lafferty K. Narahari Rao 《Journal of Molecular Spectroscopy》1974,50(1-3)
The rotational structure of the ν3 fundamental of 14N16O2 has been recorded by employing a vacuum grating infrared spectrograph. The analysis has led to the assignment of over 500 R- and P-branch transitions in the spectral region 1562–1650 cm−1. Molecular constants for the upper state, 001, have been presented. No Q-branch transitions were used in the evaluation of these constants. The presently obtained
and the band center ν0 = 1616.846 cm−1 differ significantly from previous determinations. Spin splitting was observed but no information was extracted about upper state spin splitting parameters. 相似文献
992.
993.
994.
995.
Nonlinear steady cellular convection in a fluid-saturated porous medium is investigated using the technique of spectral analysis. The effect of permeability is shown to contract the cell and to damp the convection process. The influence of Prandtl number, though small, is seen only in the fourth order term. The cross-interactions of the higher modes caused by nonlinear effects are considered through the modal Rayleigh number R
. The possibility of the existence of a steady solution with two self-excited modes in certain regions is predicted. A detailed discussion of the heat transport is made. The theoretical value of the Nusselt number is found to be in good agreement with the experimental results. The similarities and qualitative differences between the present analysis and that of the power integral technique are brought out. 相似文献
996.
The suitability of potassium dichromate as a standard oxidant has been examined by comparing direct oxidation of iron(II) solutions with alternative back-titration procedures. 相似文献
997.
V. Pandu Ranga Rao V. V. Sarma A. S. R. Krishna Murty 《Proceedings Mathematical Sciences》1976,84(4):150-156
Extraction of vanadium (IV) in the presence of perchlorate, nitrate, halides, and thiocyanate and neutral oxygen donors liken-butanol, TBP and antipyrine into various solvents is studied. Composition of the extracting species and the stability constants are determined. The effectiveness of the three neutral oxygen donors studied in the extraction of vanadium (IV)-anion systems is found to follow the order: antipyrine > TBP >n-butanol. 相似文献
998.
Saussurea lactone is identical with the product of pyrolysis of dihydrocostunolide. On cyclisation in the presence of p-nitrobenzoic acid followed by hydrogenation it gives santanolide C. Hence structure (V) is assigned to saussurea lactone. 相似文献
999.
1000.
Pramana - The absorption and fluorescence spectra of Ho3+:LaF3, in the wavelength region from 4000 Å to 7500 Å have been reinvestigated incorporating polarization features, for the first... 相似文献