全文获取类型
收费全文 | 372篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
化学 | 317篇 |
数学 | 11篇 |
物理学 | 54篇 |
出版年
2023年 | 6篇 |
2022年 | 4篇 |
2021年 | 10篇 |
2020年 | 5篇 |
2019年 | 9篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 9篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 10篇 |
2012年 | 16篇 |
2011年 | 18篇 |
2010年 | 15篇 |
2009年 | 11篇 |
2008年 | 22篇 |
2007年 | 34篇 |
2006年 | 22篇 |
2005年 | 21篇 |
2004年 | 18篇 |
2003年 | 11篇 |
2002年 | 7篇 |
2001年 | 5篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1987年 | 3篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 4篇 |
1977年 | 7篇 |
1974年 | 3篇 |
1937年 | 2篇 |
1934年 | 2篇 |
1925年 | 2篇 |
1921年 | 2篇 |
1911年 | 2篇 |
1910年 | 2篇 |
1908年 | 2篇 |
1906年 | 2篇 |
1904年 | 2篇 |
1890年 | 2篇 |
1881年 | 1篇 |
排序方式: 共有382条查询结果,搜索用时 15 毫秒
31.
Birgit Krimmel Friederike Swoboda Sonja Solar Gottfried Reznicek 《Radiation Physics and Chemistry》2010,79(12):1247-1254
The OH-radical induced degradation of hydroxybenzoic acids (HBA), hydroxycinnamic acids (HCiA) and methoxylated derivatives, as well as of chlorogenic acid and rosmarinic acid was studied by gamma radiolysis in aerated aqueous solutions. Primary aromatic products resulting from an OH-radical attachment to the ring (hydroxylation), to the position occupied by the methoxyl group (replacement –OCH3 by ?OH) as well as to the propenoic acid side chain of the cinnamic acids (benzaldehyde formations) were analysed by HPLC–UV and LC–ESI–MS. A comparison of the extent of these processes is given for 3,4-dihydroxybenzoic acid, vanillic acid, isovanillic acid, syringic acid, cinnamic acid, 4-hydroxycinnamic acid, caffeic acid, ferulic acid, isoferulic acid, chlorogenic acid, and rosmarinic acid. For all cinnamic acids and derivatives benzaldehydes were significant oxidation products. With the release of caffeic acid from chlorogenic acid the cleavage of a phenolic glycoside could be demonstrated. Reaction mechanisms are discussed. 相似文献
32.
33.
34.
Ohne Zusammenfassung 相似文献
35.
G. S. Jamieson R. Wrenshall Ericson V. Lenher W. G. Crawford J. W. Mellor B. Neumann R. K. Murphy Kaiser A. J. Rossi E. Knecht P. W. Shimer E. B. Shimer F. A. Gooch H. D. Newton W. M. Thornton Jr. F. Bourion K. Schröder J. Bellucci L. Grassi C. R. Mc Cabe und A. R. Scott 《Fresenius' Journal of Analytical Chemistry》1915,54(12):606-617
Ohne Zusammenfassung 相似文献
36.
Victor Meyer C. Gräbe Knecht Carl Meyer Heinrich Züblin Crafts F. Meier Watson Smith Lothar Meyer J. Piccard O. Pettersson G. Ekstrand und Heinrich Goldschmidt 《Fresenius' Journal of Analytical Chemistry》1881,20(1):394-399
Ohne Zusammenfassung 相似文献
37.
K. Someya J. Knop S. B. Jatar E. Knecht und Eva Hibbert 《Fresenius' Journal of Analytical Chemistry》1927,70(12):466-467
Ohne Zusammenfassung 相似文献
38.
Jester SS Idelson A Schmitz D Eberhagen F Höger S 《Langmuir : the ACS journal of surfaces and colloids》2011,27(13):8205-8215
Shape-persistent rigid phenylene-ethynylene-butadiynylenes form lamellar self-assembled monolayers (SAMs) at the HOPG/TCB interface, which were studied by scanning tunneling microscopy (STM) with submolecular resolution. Substitution of the terminating acetylene functions with polar cyanopropyldimethylsilyl groups leads to 2D phase separation and defined rod-rod interactions, which determine the packing distances between the rigid rods. The results stimulated the connection of rigid rods via septiarylene clamp units. They covalently link two rigid rod units and define the intramolecular rod-rod distance that matches the alkoxy substituent chain lengths. The systems can be described as half-ring structures of two rigid rods connected via a rotatable joint unit. These acetylene-terminated half-ring structures were also oligomerized under Cu and Pd catalysis to yield defined acyclic and cyclic oligomers. Detailed STM studies decoded the molecular origin of the surface patterning of such systems. The dodecyloxy side chains are adsorbed along the HOPG main axes and, together with the alkoxy backbone angle, determine the adsorption direction of the adlayers. 相似文献
39.
40.
Coppage R Slocik JM Briggs BD Frenkel AI Heinz H Naik RR Knecht MR 《Journal of the American Chemical Society》2011,133(32):12346-12349
The ability to control the size, shape, composition, and activity of nanomaterials presents a formidable challenge. Peptide approaches represent new avenues to achieve such control at the synthetic level; however, the critical interactions at the bio/nano interface that direct such precision remain poorly understood. Here we present evidence to suggest that materials-directing peptides bind at specific time points during Pd nanoparticle (NP) growth, dictated by material crystallinity. As such surfaces are presented, rapid peptide binding occurs, resulting in the stabilization and size control of single-crystal NPs. Such specificity suggests that peptides could be engineered to direct the structure of nanomaterials at the atomic level, thus enhancing their activity. 相似文献