全文获取类型
收费全文 | 257篇 |
免费 | 6篇 |
国内免费 | 5篇 |
专业分类
化学 | 107篇 |
晶体学 | 4篇 |
力学 | 8篇 |
数学 | 49篇 |
物理学 | 100篇 |
出版年
2021年 | 3篇 |
2019年 | 3篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 9篇 |
2013年 | 14篇 |
2012年 | 11篇 |
2011年 | 13篇 |
2010年 | 11篇 |
2009年 | 8篇 |
2008年 | 7篇 |
2007年 | 10篇 |
2006年 | 12篇 |
2005年 | 11篇 |
2004年 | 15篇 |
2003年 | 2篇 |
2002年 | 12篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1993年 | 2篇 |
1991年 | 2篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 10篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1980年 | 5篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1970年 | 1篇 |
1955年 | 1篇 |
1936年 | 1篇 |
1917年 | 1篇 |
1915年 | 1篇 |
1905年 | 1篇 |
1902年 | 2篇 |
1899年 | 2篇 |
1897年 | 2篇 |
1891年 | 1篇 |
排序方式: 共有268条查询结果,搜索用时 0 毫秒
91.
Nau D Schönhardt A Bauer Ch Christ A Zentgraf T Kuhl J Klein MW Giessen H 《Physical review letters》2007,98(13):133902
We analyze the influence of correlations on the optical properties of disordered metallic photonic crystal slabs experimentally and theoretically. Different disorder models with different nearest-neighbor correlations are considered. We present a theory that allows us to quantitatively calculate the optical properties of the different samples. We find that different kinds of correlations produce characteristic spectral features such as peak reduction and inhomogeneous broadening. These features are caused by reduced excitation efficiencies and the excitation of multiple resonances. 相似文献
92.
Philipp-M. Hilgendorff Andrei Grigorescu Martina Zimmermann Claus-P. Fritzen Hans-J. Christ 《力学快报》2014,4(5):051004
The monitored resonant behavior of fatigue specimens of metastable austenitic stainless steel (AISI304) is correlated with its damage accumulation in the very high cycle fatigue (VHCF) regime. The resonant behavior is studied experimentally and shows a distinct transient characteristic. Microscopic examinations indicate that during VHCF a localized plastic deformation in shear bands arises on the specimen surface. Hence, this work focuses on the effect of damage accumulation in shear bands on the resonant behavior of AISI304 in the VHCF regime. A microstructural simulation model is proposed that takes into account specific mechanisms in shear bands proven by experimental results. The simulation model is solved numerically using the two-dimensional boundary element method and the resonant behavior is characterized by evaluating the force-displacement hysteresis loop. Simulation of shear bands agrees well with microscopic examinations and plastic deformation in shear bands influences the transient characteristic of the resonant behavior. 相似文献
93.
94.
The nature of the critical behavior in the refractive index n is revisited in the framework of the complete scaling formulation. A comparison is made with the critical behavior of n as derived from the Lorentz-Lorenz equation. Analogue anomalies to those predicted for the dielectric constant ε, namely, a leading |t|(2β) singularity in the coexistence-curve diameter in the two-phase region and a |t|(1-α) along the critical isopleth in the one phase region, are expected in both cases. However, significant differences as regards the amplitudes of both singularities are obtained from the two approaches. Analysis of some literature data along coexistence in the two-phase region and along the critical isopleth in the one-phase region provide evidence of an intrinsic effect, independent of the density, in the critical anomalies of n. This effect is governed by the shift of the critical temperature with an electric field, which is supposed to take smaller values at optical frequencies than at low frequencies in the Hz to MHz range. 相似文献
95.
S. Removille R. Dubessy Q. Glorieux S. Guibal T. Coudreau L. Guidoni J.-P. Likforman 《Applied physics. B, Lasers and optics》2009,97(1):47-52
This paper reports on the use of ultrafast pulses for photoionisation loading of singly-ionised strontium ions in a linear
Paul trap. We take advantage of an autoionising resonance of Sr neutral atoms to form Sr+ by two-photon absorption of femtosecond pulses at a wavelength of 431 nm. We compare this technique to electron-bombardment
ionisation and observe several advantages of photoionisation. It actually allows for the loading of a pure Sr+ ion cloud in a low radio-frequency voltage amplitude regime. In these conditions, up to 4×104 laser-cooled Sr+ ions were trapped. 相似文献
96.
97.
Results of kinetic investigations on the basis of isothermal DSC measurements by means of defined pressure changes are presented and interpreted for the Mg/MgH2 system. From an evaluation of the experimentally obtained DSC-signals, the dependence of reaction rate on hydrogen pressure p0, temperature and sample morphology could be described. Under certain conditions, it is possible to visualise individual rate-determining steps and, thus, to arrive at conclusions on the reaction mechanism. 相似文献
98.
Benzothiazoles containing 2-perfluoroalkylether as well as perfluoroaryl substituents have been synthesized by two methods: (1) direct acylation of 2-aminobenzenethiol with perfluoroacyl halides, and (2) the reduction of N, Nt?-diacy1-2, 2t?-diaminodiphenyldisulfides followed by dehydrative cyclization. The intermediates formed in the direct acylation procedure are the N-acylaminobenzenethiols rather than the S-acyl derivatives. 相似文献
99.
Alfred Zeman Peter Bartl Albert Schaaff und Volker Christ 《Fresenius' Journal of Analytical Chemistry》1978,290(1):21-28
Zusammenfassung Synthetische Flugturbinenöle auf Basis von FettsÄuretetraestern des Pentaerythrits wurden mittels Gaschromatographie — Massenspektrometrie untersucht. Die Entstehung strukturspezifischer Ionen bei der elektronensto\induzierten Fragmentierung wird anhand einiger Modellester diskutiert. Werden FettsÄuregemische mit Pentaerythrit verestert, dann entstehen komplexe Gemische, die gas-chromatographisch nach der Molmasse der Esterkomponenten getrennt werden können. Die Auftrennung isomerer Esterkomponenten gelingt nicht. Die Identifizierung dieser Komponenten kann massenspektrometrisch erfolgen. Es wird gezeigt, da\ durch direkte GC-MS der öle die Struktur der vorliegenden Esterkomponenten weitgehend ermittelt werden kann. ZusÄtzliche Informationen werden durch Bestimmung der quantitativen FettsÄurezusammensetzung der öle und Berechnung der möglichen Esterkombinationen erhalten. Die Methode wird an einem handelsüblichen Flugturbinenöl erlÄutert.
Analysis of synthetic aviation turbine oils by gas chromatography—mass spectrometryPart I. Pentaerythritol ester oils
Summary Synthetic aviation turbine oils based on fatty acid tetraesters of pentaerythritol were investigated by gc-ms. The formation of specific ions by electron impact induced fragmentation is discussed using model compounds. Esterification of pentaerythritol with mixtures of fatty acids yields complex ester mixtures which can be separated by gas chromatography according to molecular size of the ester components. The separation of isomers is not successful. The identification of these components is possible by mass spectrometry. It is shown that the structure of the ester components can be determined extensively by direct gc-ms of the oils. Additional information is obtained by determination of the quantitative fatty acid composition of the oils and calculation of the possible ester combinations. The method is illustrated using a commercial aviation turbine oil.相似文献
100.
E. Stachowska M. Fabiszisky M. Christ A. Scholz U. Sterr W. Ertmer 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,27(4):303-306
Using two-step laser spectroscopy with the sideband technique the hyperfine structure (hfs) splittings of the levels (3d 4)3 G 4,5 in47Ti have been measured. These are the first hfs measurements of the levels belonging to the 3d N+2 configuration of the system (3d+4s) N+2. The experimental results indicate a strong increase of the core polarization effect due to excitation of both 4s-electrons to the open 3d-shell. 相似文献