全文获取类型
收费全文 | 98篇 |
免费 | 3篇 |
专业分类
化学 | 75篇 |
数学 | 13篇 |
物理学 | 13篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 6篇 |
2018年 | 2篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 5篇 |
2013年 | 3篇 |
2012年 | 4篇 |
2011年 | 7篇 |
2010年 | 4篇 |
2009年 | 1篇 |
2008年 | 9篇 |
2007年 | 4篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1995年 | 7篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有101条查询结果,搜索用时 15 毫秒
61.
Toshiyasu Inuzuka Keita Yamamoto Arihiro Iwasaki Osamu Ohno Kiyotake Suenaga Yoshinori Kawazoe Daisuke Uemura 《Tetrahedron letters》2014
Three novel compounds, yoshinones A, B1, and B2, were isolated from the marine cyanobacterium Leptolyngbya sp., and their structures were elucidated by NMR spectral analysis. Yoshinone A, but not yoshinone B1 or B2, inhibited the differentiation of 3T3-L1 cells into adipocytes. In addition, yoshinone A did not exhibit cytotoxicity, suggesting that yoshinone A may be useful in studies on the treatment of obesity. 相似文献
62.
Total synthesis of the title compounds is described which includes, as the key step, regioselective Dieckmann reaction for constructing the 2-oxo-carbapenam ring system. 相似文献
63.
Iwamoto T Watanabe Y Sakamoto Y Suzuki T Yamago S 《Journal of the American Chemical Society》2011,133(21):8354-8361
[n]Cycloparaphenylenes (n = 8-13, CPPs) were synthesized, and their physical properties were systematically investigated. [8] and [12]CPPs were selectively prepared from the reaction of 4,4'-bis(trimethylstannyl)biphenyl and 4,4'-bis(trimethylstannyl)terphenyl, respectively, with Pt(cod)Cl(2) (cod = 1,5-cyclooctadiene) through square-shaped tetranuclear platinum intermediates. A mixture of [8]-[13]CPPs was prepared in good combined yields by mixing biphenyl and terphenyl precursors with platinum sources. Products were easily separated and purified by using gel permeation chromatography. In (1)H NMR spectra, the proton of the CPPs shifts to a lower field as n increased due to an anisotropic effect from the nearby PP moieties. Although the UV-vis spectra were rather insensitive to the size of the CPPs, the fluorescence spectra changed significantly in relation to their size. A larger Stokes shift was observed for the smaller CPPs. Redox properties of the CPPs were measured for the first time by using cyclic voltammetry, and the smaller CPPs had lower oxidation potentials. The results are consistent with the HOMO energies of CPPs, of which the smaller CPPs had higher energies. 相似文献
64.
65.
66.
Toshiyasu Arai 《Archive for Mathematical Logic》2002,41(2):123-153
We formulate epsilon substitution method for theories (H)α0 of absolute jump hierarchies, and give two termination proofs of the H-process: The first proof is an adaption of Mints M,
Mints-Tupailo-Buchholz MTB, i.e., based on a cut-elimination of a specially devised infinitary calculus. The second one is
an adaption of Ackermann Ack. Each termination proof is based on transfinite induction up to an ordinal θ(α0+ ω)0, which is best possible.
Received: 19 April 1999 / Published online: 20 December 2001 相似文献
67.
68.
Iwamatsu Si S Vijayalakshmi PS Hamajima M Suresh CH Koga N Suzuki T Murata S 《Organic letters》2002,4(7):1217-1220
[reaction: see text] Photorearrangement of tetraalkoxycarbonyl-substituted cyclohexadiene derivatives of C(60) yields not only well-known bis(fulleroid) but also bis(methano)fullerene. Existence of a labile and structurally new intermediate is observed in the reaction mixture. The discovery of the compound suggests the existence of another possible pathway giving those two products other than the widely accepted [4 + 4]/[2 + 2 + 2] mechanism. 相似文献
69.
Shizuaki Murata Toshiyasu Suzuki Akira Yanagisawa Seiji Suga 《Journal of heterocyclic chemistry》1991,28(2):433-438
Reaction of 2,2′-dilithio-1,1′-binaphthyl with selenium followed by air oxidation gives a mixture of dinaph-thoselenophene and dimer and oligomers of 2,2′-diseleno-1,1′-binaphthyl. 2,2′-Dilithio-1,1′-biphenyl reacts with selenium to afford dibenzo[c,e][1,2]diselenin. Structures of the dimeric 2,2′-diseleno-1,1′-binaphthyl and dibenzo[c,e][1,2]diselenin have been confirmed by X-ray crystallographic analyses. Similar reaction of 2,2′-dilithio-1,1′-binaphthyl with sulfur or tellurium gives a mixture of dinaphthothiophene and dinaphtho[2,1-c:-1′,2′-e][1,2]dithiin or a mixture of dinaphthotellurophene and oligomer of 2,2′-ditelluro-1,1′-binaphthyl, respectively. Dibenzotellurophene and oligomer of 2,2′-ditelluro-1,1′-biphenyl are obtained from reaction of 2,2′-dilithio-1,1′-biphenyl with tellurium. 相似文献
70.
Koch N Gerlach A Duhm S Glowatzki H Heimel G Vollmer A Sakamoto Y Suzuki T Zegenhagen J Rabe JP Schreiber F 《Journal of the American Chemical Society》2008,130(23):7300-7304
The interfaces formed between pentacene (PEN) and perfluoropentacene (PFP) molecules and Cu(111) were studied using photoelectron spectroscopy, X-ray standing wave (XSW), and scanning tunneling microscopy measurements, in conjunction with theoretical modeling. The average carbon bonding distances for PEN and PFP differ strongly, that is, 2.34 A for PEN versus 2.98 A for PFP. An adsorption-induced nonplanar conformation of PFP is suggested by XSW (F atoms 0.1 A above the carbon plane), which causes an intramolecular dipole of approximately 0.5 D. These observations explain why the hole injection barriers at both molecule/metal interfaces are comparable (1.10 eV for PEN and 1.35 eV for PFP) whereas the molecular ionization energies differ significantly (5.00 eV for PEN and 5.85 eV for PFP). Our results show that the hypothesis of charge injection barrier tuning at organic/metal interfaces by adjusting the ionization energy of molecules is not always readily applicable. 相似文献