全文获取类型
收费全文 | 883篇 |
免费 | 31篇 |
国内免费 | 3篇 |
专业分类
化学 | 485篇 |
晶体学 | 9篇 |
力学 | 12篇 |
数学 | 85篇 |
物理学 | 191篇 |
无线电 | 135篇 |
出版年
2023年 | 6篇 |
2022年 | 7篇 |
2021年 | 8篇 |
2020年 | 7篇 |
2019年 | 22篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 28篇 |
2015年 | 15篇 |
2014年 | 8篇 |
2013年 | 27篇 |
2012年 | 36篇 |
2011年 | 44篇 |
2010年 | 25篇 |
2009年 | 35篇 |
2008年 | 70篇 |
2007年 | 57篇 |
2006年 | 63篇 |
2005年 | 45篇 |
2004年 | 35篇 |
2003年 | 30篇 |
2002年 | 40篇 |
2001年 | 35篇 |
2000年 | 15篇 |
1999年 | 10篇 |
1998年 | 7篇 |
1997年 | 14篇 |
1996年 | 11篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 11篇 |
1992年 | 20篇 |
1991年 | 17篇 |
1990年 | 12篇 |
1989年 | 14篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 15篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 10篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1971年 | 2篇 |
1930年 | 2篇 |
排序方式: 共有917条查询结果,搜索用时 15 毫秒
861.
Santiago Diaz Lech Drewnowski Antonio Fernandez Miguel Florencio Pedro J. Paul 《Results in Mathematics》1992,21(3-4):289-298
Let S(μ, E) be the space of (classes of μ-a.e. equal) simple functions defined on a (non-trivial) measure space with values in a locally convex space E. The following results hold: S(μ,E) is quasi-barrelled (resp. bornological) if and only if E is quasi-barrelled (resp. bornological) and E′(β(E′,E)) has the property (B) of Pietsch; S(μ, E) is barrelled if and only if S(μ,K) is barrelled and E is barrelled and nuclear; S(μ, E) is never ultrabornological; and S(μ, E) is a DF-space if and only if E is a DF-space. 相似文献
862.
Christiansen C.F. Battaiotto R. Fernandez D. Tacconi E. 《Industrial Electronics, IEEE Transactions on》1989,36(1):79-83
A digital method to measure angular velocity for machine control applications is described. The method uses a phase-locked loop to multiply the frequency and reject the jitter. The process for measurement is completed in a very short time, providing not only quick readouts, but also information on transient velocity. Since the sampling intervals are fixed, measurement of angular acceleration can be obtained almost immediately 相似文献
863.
Jonathan Raz Erik J. Fernandez John Gillespie 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1997,127(2):173-183
Distortions in the FID and spin echo due to magnetic field inhomogeneity are proved to have a representation as the characteristic function of some probability distribution. In the special case that the distribution is Cauchy, the model reduces to the conventional Lorentzian model. A more general and flexible representation is presented using the Fourier transform of a logspline density. An algorithm for fitting the model is described, the performance of the model and algorithm is investigated in applications to real and simulated data sets, and the logspline approach is compared to a previous Hermitian spline approach and to the Lorentzian model. The logspline model is more parsimonious than the Hermitian spline model, provides a better fit to real data, and is much less biased than the Lorentzian model. 相似文献
864.
The loss spectra of several ordered/disordered parent and polytypic crystals of CdI2 have been studied. The region of interest is seen to lie in the frequency range 0.1–3 kHz where several peaks are found to occur. While, in general, three prominent peaks occur in the region ~ 1 to ~ 3 kHz, disordered structures exhibit additional larger peaks below 1 kHz. The peaks occuring in the 1–3 kHz region arise due to inherent point defects present in the crystals and those occuring below 1 kHz and singular to the disordered structures are attributed to a resonance absorption effect embodying interfacial polarization which arises due to the occurence of dislocation dipoles which are responsible for the creation of the disorder. 相似文献
865.
J. C. Adloff R. Brandt V. S. Butsev M. Debeauvais F. Fernandez B. A. Kulakov M. I. Krivopustov M. Ochs A. N. Sosnin M. Zamani 《Radiation measurements》1997,28(1-6):313-316
Spallation neutrons produced from 12C ions at 18 and 44 GeV on Cu and Pb targets were studied as well as thermalization in appropriate moderators. The irradiation were performed at the Dubna LHE Synchrophasotron. Results are given for thermal and fast neutrons estimated and compared with different experimental methods. 相似文献
866.
S.E. Darden Sudhir Sen G. Murillo M. Fernandez J. Ramiez A. Galindo P.L. Jolivette B.P. Hichwa 《Nuclear Physics A》1984,429(2):218-258
Angular distributions of cross section and analyzing power for elastic scattering of protons from 15N have been measured for Ep = 2.7–7.0 MeV. A phase-shift analysis of the data yields spin-parity assignments and level parameters for seventeen states of 16O in the excitation energy region 14.8–18.6MeV. Three of the resonances have not previously been identified, among them being a broad Jπ = 2? level at Ep = 6.1 MeV which is almost certainly the analog of the 2? 1p1h state with configuration () at Ex ∽ 5.0 MeV in 16N. The broad level previously reported near Ep = 5.0 MeV has been observed and its parameters determined. A resonance analysis of the phase shifts yielded values of Er, Γ and Γp for all of the levels. The Jπ assignments are in agreement with previously reported values. For resonances having J = l, the data can usually be fit with a resonant phase shift corresponding to either J = l + 1 or J = l ? 1, in addition to the phase shift for J = l. Which of the two spurious-J solutions occurs seems to depend on whether the partial wave through which the resonant state is formed is . 相似文献
867.
A simple mechanical model permits to recover the main properties of adiabatically weakly damped solitons which may be described in terms of a particle in a potential well. The adiabatic damping rate and the tail amplitude are obtained. Three examples are chosen which cover a wide field of nonlinear physics. 相似文献
868.
M. Fernandez J. Tortajada L. M. Sesé 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1988,9(3):243-251
This paper reports an attempt to understand theoretically the red shifts seen in the benzene ultraviolet spectrum upon changing from gas to the liquid phase. The theoretical analysis is performed through a framework which brings together Quantum Chemistry and Classical Statistical Mechanics of molecular liquids. As it is discussed herein, the influence of the liquid phase on the individual molecular properties is taken into account by means of a perturbation term included in the effective molecular Hamiltonian. Such a perturbation depends explicitly on both the chemical nature and the static structure of the liquid surrounding the molecule under study. In order to simulate the vibronic couplings, which make the benzene |Ddforbidden|DD bands1 L a and1 L b have nonzero intensity, random displacements of the nuclei of benzene have been employed in this introductory work. The calculations involve the CNDO/S procedure and the atom-atom radial distribution functions of the liquid sample. The results account for the large red shift (?20 nm) undergone by the band1 L a . 相似文献
869.
870.
Chang Liu Norbert Neumeister Nicola Amapane Cristina Fernandez Bedoya Riccardo Bellan Philipp Biallass Sara Bolognesi Gianluca Cerminara Mary-Cruz Fouz Iglesias Marina Giunta Luigi Guiducci Kerstin Hoepfner Stefano Lacaprara Gianni Masetti Anna Meneguzzo Pierluigi Paolucci Jesus Puerta Pelayo Riccardo Travaglini Marco Zanetti Carlos Villanueva 《The European Physical Journal C - Particles and Fields》2008,56(3):449-460
The powerful muon and tracker systems of the CMS detector together with dedicated reconstruction software allow precise and
efficient measurement of muon tracks originating from proton-proton collisions. The standard muon reconstruction algorithms,
however, are inadequate to deal with muons that do not originate from collisions. This note discusses the design, implementation,
and performance results of a dedicated cosmic muon track reconstruction algorithm, which features pattern recognition optimized
for muons that are not coming from the interaction point, i.e., cosmic muons and beam-halo muons. To evaluate the performance
of the new algorithm, data taken during Cosmic Challenge phases I and II were studied and compared with simulated cosmic data.
In addition, a variety of more general topologies of cosmic muons and beam-halo muons were studied using simulated data to
demonstrate some key features of the new algorithm. 相似文献