全文获取类型
收费全文 | 56篇 |
免费 | 1篇 |
专业分类
化学 | 38篇 |
力学 | 1篇 |
数学 | 9篇 |
物理学 | 9篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2018年 | 1篇 |
2016年 | 4篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 1篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1926年 | 1篇 |
排序方式: 共有57条查询结果,搜索用时 4 毫秒
1.
Haishan Bu Yanwan Pang Dandan Song Tongyin Yu T. M. Voll George Czornyj B. Wunderlich 《Journal of Polymer Science.Polymer Physics》1991,29(2):139-152
Various approaches to the preparation and verification of single-molecule single crystals are discussed for polyethylene and poly (oxyethylene). Analytic tools are electron microscopy, electron diffraction, and differential scanning calorimetry. The main difficulty in producing a single-molecule single crystal is to keep crystals from joining during growth. 相似文献
2.
J. Voll T. Kerscher D. Geppert R. de Vivie-Riedle 《Journal of photochemistry and photobiology. A, Chemistry》2007,190(2-3):352-358
The technological needs imposed by the exponential miniaturization trend of conventional electronic devices has drawn attention towards the development of smaller and faster devices like ultrafast molecular switches. In recent years molecular switches emerge again in the focus of active and innovative research with state-of-the-art optical tools recording their dynamics in real time. Still many questions about the underlying microscopic mechanism are left open, including potential factors that effect the switching process in either way, improve or worsen it. Due to the complexity of such molecules it is difficult to obtain a global answer from experiment alone. On the other side molecular switches are generally too large for a complete quantum chemical and quantum dynamical calculation. In our group we therefore developed an ab initio based modular model to handle the laser induced quantum dynamics in molecular switches like fulgides. It enables us to study the effect of internal molecular coupling and of the molecular response to external fields. We can investigate the related wave packet dynamics, the switching efficiency and the controllability. Our results focus on the laser induced ring opening in fulgides, which equals one direction of the switching process. Presented are the influence of a conical intersection seam and of time-dependent potentials, mimicking the mean interaction with the environment. Furthermore the relation of controllability and the wave packet's momentum is studied and the influence of potential barriers on the switching dynamics is shown. 相似文献
3.
Christoph Herfurth Dominik Voll Jens Buller Jan Weiss Christopher Barner‐Kowollik André Laschewsky 《Journal of polymer science. Part A, Polymer chemistry》2012,50(1):108-118
We report on the controlled free radical homopolymerization of 1‐ferrocenylethyl acrylate as well as of three new ferrocene bearing monomers, namely 4‐ferrocenylbutyl acrylate, 2‐ferrocenylamido‐2‐methylpropyl acrylate, and 4‐ferrocenylbutyl methacrylate, by the RAFT technique. For comparison, the latter monomer was polymerized using ATRP, too. The ferrocene containing monomers were found to be less reactive than their analogues free of ferrocene. The reasons for the low polymerizability are not entirely clear. As the addition of free ferrocene to the reaction mixture did not notably affect the polymerizations, sterical hindrance by the bulky ferrocene moiety fixed on the monomers seems to be the most probable explanation. Molar masses found for 1‐ferrocenylethyl acrylate did not exceed 10,000 g mol?1, while for 4‐ferrocenylbutyl (meth)acrylate molar masses of 15,000 g mol?1 could be obtained. With PDIs as low as 1.3 in RAFT polymerization of the monomers, good control over the polymerization was achieved. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
4.
5.
6.
M. Merschdorf W. Pfeiffer A. Thon S. Voll G. Gerber 《Applied Physics A: Materials Science & Processing》2000,71(5):547-552
Two-photon photoemission spectroscopy using femtosecond laser pulses is used to investigate the excitation and decay mechanisms
of the surface plasmon resonance in Ag nanoparticles grown on graphite. The resonant excitation of this collective excitation
leads to a two-orders-of-magnitude-enhanced two-photon photoemission yield from a graphite surface with Ag nanoparticles compared
to the yield from pure graphite. From the shape of the photoemission spectra, the polarization dependence of the photoemission
yield and the excitation probabilities for different excitation pathways we conclude that excitation with 400-nm femtosecond
laser pulses leads to the coherent multiple excitation of the surface plasmon in the Ag nanoparticles. This multiply excited
plasmon mode can decay via the coupling to a single-particle excitation leading to the emission of an electron if its final
state is located in the continuum. The surface plasmon in metallic nanoparticles is a model system to investigate collective
excitations in multiphoton processes.
Received: 26 June 2000 / Accepted: 2 September 2000 / Published online: 12 October 2000 相似文献
7.
Jürgen M. Kolos Sebastian Pomplun Sascha Jung Benedikt Rieß Patrick L. Purder Andreas M. Voll Stephanie Merz Monika Gnatzy Thomas M. Geiger Ingrid Quist-Lkken Jerome Jatzlau Petra Knaus Toril Holien Andreas Bracher Christian Meyners Paul Czodrowski Vera Krewald Felix Hausch 《Chemical science》2021,12(44):14758
Methyl groups can have profound effects in drug discovery but the underlying mechanisms are diverse and incompletely understood. Here we report the stereospecific effect of a single, solvent-exposed methyl group in bicyclic [4.3.1] aza-amides, robustly leading to a 2 to 10-fold increase in binding affinity for FK506-binding proteins (FKBPs). This resulted in the most potent and efficient FKBP ligands known to date. By a combination of co-crystal structures, isothermal titration calorimetry (ITC), density-functional theory (DFT), and 3D reference interaction site model (3D-RISM) calculations we elucidated the origin of the observed affinity boost, which was purely entropically driven and relied on the displacement of a water molecule at the protein–ligand–bulk solvent interface. The best compounds potently occupied FKBPs in cells and enhanced bone morphogenic protein (BMP) signaling. Our results show how subtle manipulation of the solvent network can be used to design atom-efficient ligands for difficult, solvent-exposed binding pockets.Enhancement by displacement. A single methyl group displaces a water molecule from the binding site of FKBPs, resulting in the most potent binders known, outperforming the natural products FK506 and rapamycin in biochemical and cellular assays. 相似文献
8.
C. Kennerknecht H. Hövel M. Merschdorf S. Voll W. Pfeiffer 《Applied physics. B, Lasers and optics》2001,73(4):425-429
The resonant multiple excitation of collective modes in metallic nanoparticles using ultrashort laser pulses leads to an enhanced
multiphoton photoemission from the particles. This effect is here demonstrated for the surface-plasmon resonance of Au nanoparticles
on graphite. The shape of the photoemission spectra is explained by multiphoton photo-assisted thermionic emission from the
nanoparticles and resonant emission via the image-potential state on graphite. Tuning the photon energy between 1.7 eV and
3.2 eV allows the identification of an enhancement of the photoemission yield at 2.1±0.1-eV photon energy that is attributed
to the resonant excitation of the surface plasmon in the Au nanoparticles. This identification of the surface-plasmon excitation
in this energy range is also supported by electron energy loss spectroscopy.
Received: 8 August 2001 / Revised version: 13 September 2001 / Published online: 10 October 2001 相似文献
9.
Günter Voll 《Zeitschrift für Physik B Condensed Matter》1993,90(4):455-466
It is our goal to obtain a reliable prediction of the rotational tunnelling spectrum to be expected for a long chain of coupled one-dimensional quantum rotors. The problem is intractable by the simple methods used so far for up to three coupled methyl groups. Therefore, an efficient, nevertheless sufficiently precise method for solving the stationary Schrödinger equation of interacting methyl groups is developed first; it proves to be valid for a broad range of not too weak potential strengths. Then, three scenarios are investigated: they differ with respect to the relative strength of the single-rotor potential and the interaction potential. For each scenario, we illustrate the dependence of the energy level scheme on the number of coupled groups. For strong coupling and weak single-particle potential, the characteristic features of the energy level scheme of interacting methyls are most clearly observable: For as few as four coupled methyl groups we predict tunnelling spectra which are hardly distinguishable from single-methyl spectra. However, the collective behaviour is still important for the value of the tunnelling splitting. Therefore, the interpretation of such a spectrum in terms of single-methyl tunnelling is obvious but misleading with respect to the potential seen by a methyl group in the crystal. 相似文献
10.
Holba Vladislav Benko Ján Grančičová Ol'ga Vollárová Ol'ga 《Transition Metal Chemistry》1985,10(3):84-89
Summary The kinetics of oxidation of [Co(NH3)5(NCS)]2+ by peroxodisulphate and periodate were investigated at different ionic strengths, and at different temperatures and concentrations
of perchloric acid. Rate constants and activation parameters are also reported in mixed water-organic solvents. It was shown
that the acid-base equilibria involving S2O
8
−2
, and IO
4
−
ions are important in the reactions studied. Solvent effects on the oxidation are interpreted in terms of the solvation of
both the initial state and the activated complex. 相似文献