全文获取类型
收费全文 | 617篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
化学 | 424篇 |
晶体学 | 7篇 |
力学 | 6篇 |
数学 | 19篇 |
物理学 | 171篇 |
出版年
2021年 | 4篇 |
2019年 | 9篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 15篇 |
2014年 | 6篇 |
2013年 | 41篇 |
2012年 | 16篇 |
2011年 | 21篇 |
2010年 | 14篇 |
2009年 | 9篇 |
2008年 | 33篇 |
2007年 | 19篇 |
2006年 | 29篇 |
2005年 | 32篇 |
2004年 | 11篇 |
2003年 | 10篇 |
2002年 | 22篇 |
2001年 | 13篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 9篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 8篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 15篇 |
1984年 | 23篇 |
1983年 | 8篇 |
1982年 | 21篇 |
1981年 | 28篇 |
1980年 | 28篇 |
1979年 | 19篇 |
1978年 | 15篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1975年 | 9篇 |
1974年 | 11篇 |
1973年 | 5篇 |
1972年 | 5篇 |
1970年 | 3篇 |
1968年 | 3篇 |
排序方式: 共有627条查询结果,搜索用时 0 毫秒
1.
2.
3.
Takanari Yasui Takeshi Ohtsuka Tetsu Suzuki Shigeki Okajima Kazuya Nakayama Mitsuru Tomioka Katsuhiro Kamimura Takeo Namekata Hiroaki Minamide Hiromasa Ito 《International Journal of Infrared and Millimeter Waves》2006,27(2):199-210
A new, wide-band, high-speed and high-sensitivity THz detector has been developed. The prototype detector consists of a parabolic
cylindrical mirror, a long wire antenna and a Schottky barrier diode. Direct detection measurements have shown a stable sensitivity
of 150 ± 50 V/W for 1–2 THz without any adjustments. The long wire antenna was fixed at the focus of parabolic cylindrical
mirror then it has been realized less operation steps, easy coupling to the external THz signals and a dramatic enhancement
in the practicality of this system. The optically polished mirror and frosted surface one showed comparable sensitivities,
thus easy polishing and less cost mirror fabrication can be applied for this system. The radiation pattern showed a maximum
radiation angle of approximately 23° with its dominant main lobe, which was attributed to the wire antenna character and confirmed
good agreements with classical antenna theory. 相似文献
4.
5.
H. Kawaguchi S. Kataiwa T. Mita Y. Ohtsuka T. Takeuchi S. Kobayashi 《Colloid and polymer science》1990,268(12):1167-1173
Dichlorophene was used as a model drug. Drug-carrying latex particles were prepared by soap-free emulsion copolymerization of dichlorophene acrylate with some hydrophilic methacrylate comonomers. The comonomers used affected not only the structure and colloidal stability of particles, but also the drug-activity of particles. Preliminary study of the drug activity revealed that highly hydrophilic latex particles were very stable and too inactive to be engulfed by amoebae and kill them. On the contrary, less hydrophilic particles carrying a large amount of drug can be an effective device to release drugs at a moderate rate to fight against extracelluar targets such as parasites. 相似文献
6.
7.
Infrared and Raman spectra of 1,2-dibromoethane CH2BrCH2Br and CD2BrCD2Br were observed in the liquid state, and the fundamental frequencies were determined by comparison with those of related molecules. Infrared absorption intensities of fundament bands were measured in the liquid state, and the intensity data were interpreted on the basis of the valence-optical theory. From the converged value of a population ratio, the energy difference between the trans and gauche isomers was determined, which was in good agreement with the value obtained from the temperature effect of the IR spectrum. 相似文献
8.
Treatment of alkyl allyl carbonates derived from various alcohols with a palladium catalyst in MeCN affords ketones and aldehydes in high yields. This new method of oxidation of alcohols can be applied to various alcohols except simple primary alcohols. 相似文献
9.
Isotropie Raman spectra of the symmetric C—H stretching bands of several organic molecules are measured in the neat liquid and in solvents including water. The linewidths are interpreted on the basis of the vibrational dephasing model, and intermolecular interactions between the solutes and solvents are discussed. 相似文献
10.
Allylation of carbonucleophiles with allylic carbamates under neutral conditions has been studied. The C-allylation of carbonucleophile is competitive with the N-allylation of amines, and the structure of amines is crucial for the selectivity. Bulky secondary amines gave the best results. Also a new method of protection-deprotection of amines as carbamates has been developed. Smooth deprotection is possible by the palladium-catalyzed reaction of allyl carbamates with formic acid. This method is particulary useful for primary amines, including optically active amino acids. 相似文献