全文获取类型
收费全文 | 295篇 |
免费 | 14篇 |
国内免费 | 2篇 |
专业分类
化学 | 242篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 13篇 |
物理学 | 53篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 15篇 |
2015年 | 9篇 |
2014年 | 10篇 |
2013年 | 24篇 |
2012年 | 22篇 |
2011年 | 26篇 |
2010年 | 14篇 |
2009年 | 13篇 |
2008年 | 16篇 |
2007年 | 12篇 |
2006年 | 15篇 |
2005年 | 16篇 |
2004年 | 11篇 |
2003年 | 10篇 |
2002年 | 16篇 |
2001年 | 9篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 7篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
排序方式: 共有311条查询结果,搜索用时 15 毫秒
101.
102.
Katsufumi Tanaka Yuichiro Tanabe Takatoshi Morina Ryuichi Akiyama 《Liquid crystals》2008,35(3):253-264
Solid cast films with polydomain textures were prepared on a glass substrate with transparent interdigitated electrodes from an isotropic aqueous solution of hydroxypropyl cellulose via its liquid crystalline phase under the sinusoidal electric field with small amplitude and frequency of 0.05 V µm-1 and 105 Hz, respectively. The process was monitored using microdielectrometry as well as polarised optical microscopy. The apparent dielectric constant εr' and loss factor εr' sensitively changed with time depending on the process conditions. On the other hand, the logarithmic relation between εr' and εr' showed a single curve, when they were normalised by an effective portion of the electrostatic energy density estimated using each solid-film thickness. The conversion to the solid film was estimated during the process based on the concentration dependences of εr' and εr'. Characteristic times were reported for the onset of the biphasic phase, fully developed cholesteric phase and termination of the process. 相似文献
103.
Masuyuki Sugiyama Hideki Hasegawa Yuichiro Hashimoto 《Rapid communications in mass spectrometry : RCM》2009,23(18):2917-2922
We have developed a new mass‐selective axial ejection method from a linear ion trap (LIT). In this method, a set consisting of a trap wire lens and an extraction wire lens positioned orthogonally to each other was placed between quadrupole rods. The trap wire lens confines the ions inside the trap, and the extraction wire axially extracts ions from the trap. Ions introduced into the LIT are trapped between the inlet lens and the trap wire lens. In addition to the wire lenses, a set of excitation lenses, which are aligned orthogonally to the trap wire lens, are inserted between rods. The ions are resonantly excited in the direction perpendicular to the trap wire lens by applying a supplemental alternating current (AC) to the excitation lenses. Excited ions with a large motion pass over the trap wire lens, while unexcited ions remain trapped inside. Ions that have passed over the trap wire lens are then extracted by the extraction wire lens. The characteristics of the mass‐selective ejection with a direct current (DC) extraction field were investigated by both simulation and experiment. A mass resolving power of m/Δm = 1300 was achieved at a scan rate of 500 Th/s. The dependence of the ejection efficiency on trap wire lens bias was measured, and an ejection efficiency of 20% at a scan rate of 500 Th/s was achieved by optimizing the DC bias on the trap wire lens. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
104.
Reduction of dichlorodiphenylstannane with lithium followed by treatment with methyl iodide gave methyltriphenylstannane, dimethyldiphenylstannane and 1,2‐dimethyldistannane. 1,2‐Dilithiodistannane and triphenylstannyllithium were intermediates of this reaction. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
105.
Axinelloside A, an unprecedented highly sulfated lipopolysaccharide inhibiting telomerase, from the marine sponge, Axinella infundibula 总被引:1,自引:0,他引:1
Warabi K Hamada T Nakao Y Matsunaga S Hirota H van Soest RW Fusetani N 《Journal of the American Chemical Society》2005,127(38):13262-13270
Axinelloside A was isolated from the lipophilic extract of the Japanese marine sponge Axinella infundibula as a strong human telomerase inhibitor (IC(50) 2.0 microg/mL). It has the molecular weight of 4780.4 as the monoisotopic mass of the 19 sodium salt. The chemical structure was elucidated mainly by spectroscopic methods (2D NMR and MS). Axinelloside A consists of twelve sugars, e.g., a scyllo-inositol, a D-arabinose, 5 D-galactoses, and 5 L-fucoses, together with an (R)-3-hydroxy-octadecanoic acid, 3 (E)-2-hexadecenoic acids, and 19 sulfates. 相似文献
106.
107.
p‐Toluoyl 9‐triptycyl diselenide ( 9 ) was prepared by reaction of Se‐9‐triptycyl triptycene‐9‐selenoseleninate ( 7 ) with p‐toluenecarboselenoic acid ( 8 ) and by reaction of triptycene‐9‐selenenoselenolate salt with p‐toluoyl chloride. Acetyl 9‐triptycyl diselenide ( 13 ) was prepared by reaction of triptycene‐9‐selenenoselenolate salt with acetyl chloride. Hydrolysis of the two diselenides, 9 and 13 , provided triptycene‐9‐selenol ( 10 ) and di‐9‐triptycyl triselenide ( 12 ), suggesting the generation of triptycene‐9‐selenenoselenoic acid ( 3 ). © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:525–528, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20155 相似文献
108.
109.
110.