全文获取类型
收费全文 | 73篇 |
免费 | 2篇 |
专业分类
化学 | 42篇 |
力学 | 1篇 |
数学 | 4篇 |
物理学 | 28篇 |
出版年
2021年 | 3篇 |
2020年 | 1篇 |
2017年 | 2篇 |
2015年 | 1篇 |
2013年 | 1篇 |
2012年 | 2篇 |
2011年 | 5篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 5篇 |
2007年 | 5篇 |
2006年 | 4篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 2篇 |
1998年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1981年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有75条查询结果,搜索用时 31 毫秒
51.
Roberta Bernini 《Tetrahedron letters》2010,51(31):4113-487
Less reactive hydroxyls, such as those present in secondary alcohols and in some primary alcohols, phenols and carboxylic acids, were easily tritylated with the homogeneous assistance of equimolar quantities of chlorides of di- and trivalent metals in aprotic solvents. The metal ions allowed both high concentration of the effective reagent triphenylmethylcarbenium ion and mobilisation of the hydroxyl proton, thus giving rise to rapid, room temperature substitution reactions. The experimental conditions were so mild that other protected groups, such as alkyl- or trityl-protected carboxyls and (9-fluorenylmethoxycarbonyl)- or trityl-protected amino groups, remained unaffected. 相似文献
52.
A very sensitive interferometric technique is presented. It allows direct measurement of optical and thermal properties. The experimental set-up is very simple and acts essentially as an unfocused Fabry-Perot interferometer giving rise only to a central fringe. Measurement of (∂n/∂T)p up to 10-7 K-1 is possible. Determination of (∂n/∂T)p for some liquids, particularly for water and deuterium oxide, has been already performed and others, for ionic crystals, are under way. 相似文献
53.
We present an integrated tunable liquid-core/liquid-cladding (L2) optical fiber, based on a novel three-dimensional hydrodynamic focusing scheme that enables the production of a tunable circular liquid core located in the center of the channel, regardless of the flow-rate ratio of the cladding and core liquids. 相似文献
54.
María C. Bernini Felipe Gándara Marta Iglesias Dr. Natalia Snejko Dr. Enrique Gutiérrez‐Puebla Prof. Elena V. Brusau Dr. Griselda E. Narda Dr. M. Ángeles Monge Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(19):4896-4905
The novel Yb succinate metal–organic framework exhibits a reversible single‐crystal to single‐crystal polymorphic transformation (see figure) when it is heated above 130 °C, returning to its initial form when back at room temperature. This transformation produces a change in the coordination sphere of the Yb atoms, which influences the catalytic activity of the material.
55.
A novel approach to distributed fiber-optic Brillouin sensing is presented and numerically analyzed. An integral equation that directly relates the Brillouin gain to the Brillouin signal is derived in the frequency domain, and from this result a new technique for the quantitative reconstruction of temperature-strain profiles along an optical fiber is developed. We achieve the reconstruction by minimizing a cost function that represents the error between the measured and the model data. We effectively perform such a minimization by representing the unknown (temperature-strain) profile with a finite number of parameters. Numerical results confirm the effectiveness of the proposed approach and its stability against noise in the data. 相似文献
56.
57.
58.
59.
Roberta Bernini Enrico Mincione Maurizio Barontini Giancarlo Fabrizi Sabrina Tempesta 《Tetrahedron》2006,62(33):7733-7737
Alkylated phenol and methoxytoluene derivatives were catalytically and selectively oxidized to the corresponding 1,4-benzoquinones in good conversions and yields. Reactions were performed with hydrogen peroxide (H2O2)/methyltrioxorhenium (CH3ReO3) in 1-butyl-3-methylimidazolium tetrafluoroborate [bmim]BF4, a neutral ionic liquid. Compounds were tested in vitro for their antifungal activity against the growth of several widespread soil fungi. Some of them were proved to be potent inhibitors of Fusarium sp. than ketoconazole, a commercially available and expensive antifungal agent. 相似文献
60.
Cacchi S Fabrizi G Goggiamani A Parisi LM Bernini R 《The Journal of organic chemistry》2004,69(17):5608-5614
The palladium-catalyzed reaction of sulfinic acid salts with a wide variety of aryl and vinyl halides or triflates provides unsymmetrical diaryl sulfones and aryl vinyl sulfones in good to excellent yields. The reaction is strongly influenced by the presence of nBu4NCl, and the use of Xantphos, a rigid bidentate ligand with a wide natural bite angle, was found to be crucial for the success of the reaction. With neutral, electron-rich, and electron-poor aryl iodides best results were obtained by using Pd2(dba)3, Xantphos, Cs2CO3, and nBu4NCl, in toluene at 80 degrees C. Two general procedures were employed with aryl bromides and triflates: sodium p-toluenesulfinate, Pd2(dba)3, Xantphos, Cs2CO3, 120 degrees C, in toluene with nBu4NCl (procedure A: neutral, electron-rich, and slightly electron-poor aryl bromides or triflates) and without nBu4NCl (procedure B: electron-poor aryl bromides or triflates). With vinyl triflates best results were obtained at 60 degrees C omitting nBu4NCl. 相似文献