全文获取类型
收费全文 | 220篇 |
免费 | 6篇 |
专业分类
化学 | 103篇 |
晶体学 | 6篇 |
力学 | 8篇 |
数学 | 34篇 |
物理学 | 75篇 |
出版年
2023年 | 2篇 |
2020年 | 2篇 |
2019年 | 6篇 |
2016年 | 8篇 |
2015年 | 4篇 |
2013年 | 14篇 |
2012年 | 14篇 |
2011年 | 16篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 9篇 |
2007年 | 8篇 |
2006年 | 7篇 |
2005年 | 12篇 |
2004年 | 7篇 |
2003年 | 4篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 11篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 5篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1967年 | 1篇 |
1963年 | 1篇 |
1960年 | 1篇 |
1954年 | 1篇 |
1943年 | 1篇 |
1940年 | 2篇 |
1938年 | 2篇 |
1863年 | 2篇 |
排序方式: 共有226条查询结果,搜索用时 46 毫秒
31.
Parker SF Bennington SM Taylor JW Herman H Silverwood I Albers P Refson K 《Physical chemistry chemical physics : PCCP》2011,13(17):7789-7804
In this paper we exploit the complementarity of inelastic neutron scattering (INS), infrared and Raman spectroscopies with ab initio calculations to generate an updated assignment of the vibrational modes of C(60). We have carried out periodic-DFT calculations of the high temperature face centred cubic phase modelled as the standard structure and also of the low temperature simple cubic phase, the latter for the first time. Our assignment differs from all previous work, however, it is the only one that is able to successfully reproduce the INS spectrum in terms of both transition energies and intensities. In addition to the INS spectrum we are also able to quantitatively simulate the major features of the infrared and Raman spectra in the high temperature phase and the infrared spectrum in the low temperature phase. 相似文献
32.
Zusammenfassung Für die chromatographische Trennung hydrophober Substanzen werden aus Zellulosepapier unter Erhaltung der Faserstruktur Butyrylzellulose-, Benzoyl-zellulose- und Phthaloyl-zellulose-Papiere hergestellt. Sie zeichnen sich gegenüber dem früher beschriebenen Acetyl-zellulose-Papier bei verschiedenen Substanzen durch deren höhereR
f
-Werte aus. Im Phthaloylpapier ist nur eine Carboxylgruppe der Phthalsäure verestert. Es eignet sich deshalb auch gut zur Basenaustauschchromatographie und ist dem Carboxyl-zellulose-Papier wegen seiner Unlöslichkeit in Lauge überlegen.
Summary Butyrylcellulose-, benzoylcellulose-, and phthaloylcellulose papers were prepared for the Chromatographic separation of hydrophobic substances, with retention of the fiber structure of the paper. As compared with the earlier acetylcellulose paper, they are distinguished by their higherR f values in the case of various substances. Only one of the carboxyl groups of the phthalic acid is esterified in the phthaloyl paper. Consequently, it is also well suited for base exchange chromatography, and because of its insolubility in alkalies it is superior to the carboxylcellulose paper.
Résumé Pour la séparation chromatographique de substances hydrophobes, on a préparé des papiers à structure fibreuse, de butyrylcellulose, benzoylcellulose, phtaloylcellulose à partir de papier à la cellulose. Ils se distinguent des papiers déjà décrits à l'acétylcellulose par les valeurs duR f plus élevées pour des substances diverses. Dans le papier phtaloyle, il n'y a qu'un groupement carboxyle de l'acide phtalique estérifié. Par conséquent, il convient aussi très bien pour la Chromatographie d'échange des bases et, à cause de son insolubilité dans les lessives alcalines, il est supérieur au papier à la carboxylcellulose.相似文献
33.
Limiting-point radio-frequency size effect measurements have been performed in potassium to measure the anisotropy and magnitude of the electron-phonon scattering rate. The anisotropy is too small to be resolved by the method, and is estimated to be less than 10 per cent at low temperatures. Theoretical calculations confirm the small anisotropy, but yield a rate at least 40 per cent larger than that observed. 相似文献
34.
35.
Hyland B Svensson CE Ball GC Leslie JR Achtzehn T Albers D Andreoiu C Bricault P Churchman R Cross D Dombsky M Finlay P Garrett PE Geppert C Grinyer GF Hackman G Hanemaayer V Lassen J Lavoie JP Melconian D Morton AC Pearson CJ Pearson MR Phillips AA Schumaker MA Smith MB Towner IS Valiente-Dobón JJ Wendt K Zganjar EF 《Physical review letters》2006,97(10):102501
A high-precision branching ratio measurement for the superallowed beta+ decay of 62Ga was performed at the Isotope Separator and Accelerator radioactive ion beam facility. Nineteen gamma rays emitted following beta+ decay of 62Ga were identified, establishing the dominant superallowed branching ratio to be (99.861+/-0.011)%. Combined with recent half-life and Q-value measurements, this branching ratio yields a superallowed ft value of 3075.6+/-1.4 s for 62Ga decay. These results demonstrate the feasibility of high-precision superallowed branching ratio measurements in the A>or=62 mass region and provide the first stringent tests of the large isospin-symmetry-breaking effects predicted for these decays. 相似文献
36.
M. Sc. Patrik Tholen M. Sc. Zhaowen Dong Dr. Marc Schmidtmann Dr. Lena Albers Prof. Dr. Thomas Müller 《Angewandte Chemie (International ed. in English)》2018,57(40):13319-13324
The synthesis of two η5‐aminoborole complexes of germanium(II) from the reaction of a germole dianion with aminoboron dichlorides is reported. This reaction constitutes a remarkable example of a germole‐to‐borole transformation. The two aminoborole complexes of germanium(II) were fully characterized by multinuclear NMR spectroscopy, IR spectroscopy, HRMS, and, in one case, by X‐ray crystallography. The results of quantum‐mechanical calculations favor the electronic structure of a half‐sandwich complex of GeII over an ionic representation with a germanium dication stabilized by an aromatic aminoborole dianion. 相似文献
37.
Cationic Si−H−Si Bridges in Polysilanes: Their Detection and Targeted Formation in Stable Ion Studies
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Lena Albers Dr. Judith Baumgartner Prof. Christoph Marschner Prof. Thomas Müller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(23):7970-7977
The ionization of 1,1‐dihydridocyclopentasilane 7 has been found to yield the cyclic polysilanylsilyl cation 8 instead of the expected hydrogen‐substituted silylium ion 6 . The silyl cation 8 is stabilized by the formation of an intramolecular Si?H?Si bridge, which also provides the thermodynamic driving force for its formation. In general, the preference for the formation of Si?H?Si bridges can be used to scavenge and identify transient intermediates in the Lewis acid induced rearrangement of polysilanes. The validity of this concept has been demonstrated for one central step in this chemistry, the ring‐contraction reaction of cyclohexasilanes to form silylcyclopentasilanes. 相似文献
38.
We propose a model for unsaturated poro‐plastic flow derived from the thermodynamic principles. For the isothermal case, the problem consists of a degenerate coupled system of two PDEs with two independent hysteresis operators describing hysteresis phenomena in both the solid and the pore fluids. Under natural hypotheses, we prove the existence of a global strong solution for this system. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
39.
Monoamine Oxidase Reporters 1 and 2 (MR1 and MR2) are substrate-tethered activity probes that utilize a tandem amine oxidation/beta-elimination mechanism to detect MAO chemistry in vitro and in living cells directly and specifically without the need for additional enzymes or other activating reagents. 相似文献
40.
Bettina Albers 《PAMM》2009,9(1):507-508
By means of a macroscopic linear model for a poroelastic medium with three deformable components the acoustic behavior of four unconsolidated soil types, filled by water and air, is studied. Necessary material parameters are mainly gathered from the German standard DIN 4220. It provides some useful parameters, as for example, van Genuchten parameters, for thirty-one different soil types including sands, silts and clays. There appear four body waves: three longitudinal waves and one shear wave. The slowest compressional wave does only exist if at least two pore fluids appear and is driven by the capillary pressure between the pore fluids. The wave analysis yields the dependence of velocities and attenuations of these waves on the saturation and on the frequency. This is compared to the so far most frequently studied case of partially saturated sandstones. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献