全文获取类型
收费全文 | 403篇 |
免费 | 7篇 |
国内免费 | 1篇 |
专业分类
化学 | 308篇 |
晶体学 | 4篇 |
力学 | 10篇 |
数学 | 34篇 |
物理学 | 55篇 |
出版年
2022年 | 5篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 4篇 |
2014年 | 12篇 |
2013年 | 33篇 |
2012年 | 18篇 |
2011年 | 18篇 |
2010年 | 5篇 |
2009年 | 21篇 |
2008年 | 25篇 |
2007年 | 26篇 |
2006年 | 16篇 |
2005年 | 14篇 |
2004年 | 11篇 |
2003年 | 15篇 |
2002年 | 15篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1973年 | 8篇 |
1972年 | 6篇 |
1971年 | 3篇 |
1970年 | 6篇 |
1964年 | 2篇 |
1957年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有411条查询结果,搜索用时 15 毫秒
51.
A simple and efficient synthesis of indolylidinethiazolidnediones (3) and indolylidinecyclic-1,3-diketones (5) has been developed by reaction of indole-3-aldehyde (1) with thiazolidinedione (2) or cyclic-1,3-diketones (4) using tetra butyl ammonium acetate (TBAA) melt as novel, cost-effective, and recyclable ionic liquid under solvent-free green conditions at 100 °C for 15–20 min without additional use of catalyst.
[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献
52.
Viscosities and molar volumes of binary solutions,viz., Toluene-Nitrobenzene, Toluene-Bromobenzene, Toluene-Cyclohexanone, Cyclohexane-Cyclohexanone, Cyclohexane-Nitrobenzene, Cyclohexane-Acetic acid, Cyclohexane-Propionic acid and Cyclohexane-Butyric acid have been measured. The experimental results have been discussed in terms of viscosity-composition relations developed for binary solutions by Grunberg and Nissan and Katti and Chaudhri. 相似文献
53.
Maller V. N. Naidu M. S. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1975,3(2):49-54
The sparking potentials and swarm coefficients (ionization and attachment coefficients) have been measured in sulphurhexafluoride- air and freon-nitrogen mixtures over the range of 110 ? E/p ? 240 V cm-1 torr-l and gas pressures varying between 1 and 20 torr, at 20°C. Addition of strongly attaching salphur-hexafluoride and freon gases increased the sparking potentials and the rate of increase of the attachment coefficient with increasing percentage of the strongly attaching gases in the mixtures was much larger than the rate of change of the first ionization coefficient. 相似文献
54.
Prabhakar S. Naidu 《Optics Communications》1975,15(3):361-365
The signal-to-noise (S/N) ratio in the reconstructed image from a binary hologram has been quantitatively related to the amplitude and phase quantization levels. The S/N ratio increases monotonically with increasing number of quantization levels. This observation is further supported by experimental results. 相似文献
55.
56.
57.
A series of the title compounds have been prepared and the structures assigned to them were confirmed by IR and mass spectra.
The existence of hydrogen bonding between the amidic hydrogens and the phosphoryl oxygen in these compounds is indicated by
theIR spectra. The benzodiazaphosphole ring system appears to be quite stable under electron impact. An interesting type of McLafferty
rearrangement occurred in many of these molecules resulting in the formation of ions of benzodiazaphosphinous acid along with
the ejection of cyclo-hexane moiety from the molecular ion. Cleavage of P-N bonds of the molecular ions leading to the formation
of theo-phenylene diamine cations is observed 相似文献
58.
Pyridinium chromate-on-silica gel, and chromic acid-on-silica gel are described and evaluated as convenient off-the-shelf reagents for efficient oxidation of a variety of secondary and primary alcohols. Pyridinium chromate-on-silica gel can be safely used for the oxidation of alcohols containing acid-labile functions. 相似文献
59.
60.