全文获取类型
收费全文 | 576篇 |
免费 | 18篇 |
国内免费 | 14篇 |
专业分类
化学 | 131篇 |
晶体学 | 4篇 |
力学 | 5篇 |
综合类 | 6篇 |
数学 | 61篇 |
物理学 | 401篇 |
出版年
2023年 | 1篇 |
2022年 | 8篇 |
2021年 | 10篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 10篇 |
2015年 | 8篇 |
2014年 | 23篇 |
2013年 | 43篇 |
2012年 | 14篇 |
2011年 | 38篇 |
2010年 | 31篇 |
2009年 | 41篇 |
2008年 | 51篇 |
2007年 | 58篇 |
2006年 | 29篇 |
2005年 | 17篇 |
2004年 | 14篇 |
2003年 | 33篇 |
2002年 | 27篇 |
2001年 | 31篇 |
2000年 | 20篇 |
1999年 | 13篇 |
1998年 | 15篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 1篇 |
排序方式: 共有608条查询结果,搜索用时 15 毫秒
441.
D. W. Boukhvalov M. I. Katsnelson 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,68(4):529-535
Based on the ab initio electronic structure calculations the
picture of ferromagnetism in polimerized C60 is proposed
which seems to explain the whole set of controversial experimental
data. We have demonstrated that, in contrast with cubic
fullerene, in rhombohedral C60 the segregation of iron atoms
is energetically unfavorable which is a strong argument in favor
of intrinsic character of carbon ferromagnetism which can be
caused by vacancies with unpaired magnetic electrons. It is shown
that: (i) energy formation of the vacancies in the rhombohedral
phase of C60 is essentially smaller than in the cubic phase,
(ii) there is a strong ferromagnetic exchange interactions between
carbon cages containing the vacancies,
(iii) presence of iron impurities can diminish essentially
the formation energy of intrinsic defects, and (iv) the fusion of the
magnetic single vacancies into nonmagnetic bivacancies is energetically
favorable. The latter can explain a fragility of the ferromagnetism. 相似文献
442.
Fabrizio Esposito Adriana Aragri Tommaso Piccoli Gioacchino Tedeschi Rainer Goebel Francesco Di Salle 《Magnetic resonance imaging》2009
Functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) represent brain activity in terms of a reliable anatomical localization and a detailed temporal evolution of neural signals. Simultaneous EEG-fMRI recordings offer the possibility to greatly enrich the significance and the interpretation of the single modality results because the same neural processes are observed from the same brain at the same time. Nonetheless, the different physical nature of the measured signals by the two techniques renders the coupling not always straightforward, especially in cognitive experiments where spatially localized and distributed effects coexist and evolve temporally at different temporal scales. 相似文献
443.
S. W. Tang L. L. Sun J. D. Feng H. Sun R. S. Wang Y. F. Chang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(2):197-204
A systematic investigation of D3 C32 fullerene and its derivatives C32Xn (X = H and Cl) has been performed using B3LYP/6-31G(d) method based on the density functional theory. The geometry structures,
reaction energies, relative stabilities, and electronic properties have been studied. By investigating the possible C32Xn (X = H and Cl) molecules, C32H2 and C32Cl2 behave more thermodynamically accessible with respect to other derivatives. The frontier molecular orbitals and electronic
density of states calculations of C32X2 system indicate that H and Cl passivation have less contribution to the electronic structures, but significantly improve
the stability of D3 C32 fullerene. Finally, the 13C NMR chemical shifts of C32H2 and C32Cl2 have been simulated to provide helpful information for further experiment identification. 相似文献
444.
A. Peralta Conde P. Tzallas D. Charalambidis 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(2):289-294
The population dynamics induced in an atomic system by XUV-attosecond radiation have been investigated within the electric
dipole approximation. The main characteristics of the dynamics are explained in simple terms, extending our previous work
on coherent laser-atom interactions in the XUV spectral region. Attosecond beating appearing in a second-order autocorrelation
of a coherent superposition of high order harmonics, is investigated from the perspective of a superposition of Rabi oscillations,
as well as of coherent population return (CPR). The work reveals the strength of attosecond radiation as a tool for time domain
studies of coherent manipulations of quantum systems. 相似文献
445.
Salim Lahmiri 《Physics letters. A》2018,382(34):2326-2333
The purpose of the current work is to study nonlinear dynamics in neuronal activity within human brain visual cortex based on blood-oxygen-level dependent (BOLD) contrast imaging. In particular, based on functional magnetic resonance imaging (fMRI) signals, measures of fractality, complexity, and state disorder are estimated from central and peripheral eccentricity bands across three visual areas. Statistical results from analysis of 48750 resting-state fMRI signals show evidence that nonlinear dynamics of neuronal activity in resting-state in central and peripheral eccentricity bands of human visual cortex are persistent. However, they exhibit heterogeneous variability across eccentricity bands and visual areas. Also, information content in first visual area is more ordered than in the second one, whilst information content in the third visual area is the least ordered. These interesting nonlinear statistical properties are a further step toward understanding neuronal activity and nonlinear dynamics in human brain visual cortex. 相似文献
446.
Synthesis of maximally entangled mixed states and disentanglement in
coupled Josephson charge qubits 总被引:1,自引:0,他引:1
Mahmoud Abdel-Aty 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(3):537-543
We analyze a controllable generation of maximally entangled mixed states of
a circuit containing two-coupled superconducting charge qubits. Each qubit
is based on a Cooper pair box connected to a reservoir electrode through a
Josephson junction. Illustrative variational calculations were performed to
demonstrate the effect on the two-qubits entanglement. At sufficiently
deviation between the Josephson energies of the qubits and/or strong
coupling regime, maximally entangled mixed states at certain instances of
time is synthesized. We show that entanglement has an interesting subsequent
time evolution, including the sudden death effect. This enables us to
completely characterize the phenomenon of entanglement sharing in the
coupling of two superconducting charge qubits, a system of both theoretical
and experimental interest. 相似文献
447.
R. Kofman M. Allione F. Celestini Z. Barkay Y. Lereah 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,50(3):279-284
Solid/liquid two-components Ga–Pb structures in isolated nanometer sized
particles have been produced and studied by electron microscopy. Production
is based on the breath figure technique and we investigate the way the two
components are distributed. We clearly identify two growth regimes
associated with the two different ways a Pb atom incorporates into a Ga
nanodrop. Using TEM and SEM, the shape and microstructure of the
nanoparticles are studied and the results obtained are in good agreement
with the proposed model. The experimental technique used appears to be
appropriate to produce Pb nanocrystals in liquid Ga nano-containers. 相似文献
448.
T. Biben C. Misbah 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):311-316
We study dynamics of a deformable entity (such as a vesicles under hydrodynamical constraints). We show how the problem can
be solved by means of Green's functions associated with the Stokes equations. A gauge-field invariant formulation makes the
study of dynamics efficient. However, this procedure has its short-coming. For example, if the fluids are not Newtonian, then
no Green's function is available in general. We introduce a new approach, the advected field one, which opens a new avenue
of applications. For example, non-Newtonian entities can be handled without additional deal. In addition problems like budding,
droplet break-up in suspensions, can naturally be treated without additional complication. We exemplify the method on vesicles
filled by a fluid having a viscosity contrast with the external fluid, and submitted to a shear flow. We show that beyond
a viscosity contrast (the internal fluid being more viscous), the vesicle undergoes a tumbling bifurcation, which has a saddle-node
nature. This bifurcation is known for blood cells. Indeed red cells either align in a shear flow or tumble according to whether
haematocrit concentration is high or low.
Received 19 December 2001 / Received in final form 31 May 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: chaouqi.misbah@ujf-grenoble.fr 相似文献
449.
Y. Pavlyukh W. Hübner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(2):239-246
We present a method for the numerical investigation of the electron dynamics in small metallic clusters in intense laser fields.
We obtain information about collective excitations and relaxation processes in the Na
9
+
and Pt3 clusters analyzing the power spectrum of the dipole moment within a mean-field approach. The power spectrum is computed for
various laser pulse parameters as well as for the limit of an infinitely short laser pulse. Due to the basis set expansion
of the wave function our method is capable to follow the dynamics not only of the whole electron cloud, but of any particular
molecular orbital.
Received 28 March 2002 / Received in final form 31 May 2002 Published online 24 September 2002
RID="a"
ID="a"e-mail: pavlyukh@mpi-halle.de 相似文献
450.
Michelle Alexandra Chinelatti Thais Helena Andreolli do Amaral Regina Guenka Palma-Dibb 《Applied Surface Science》2007,253(11):4866-4871
The purpose of this study was to analyse, by scanning electron microscopy (SEM), the morphology of enamel and dentin/adhesive interfaces in cavities prepared by air-abrasion at different working distances. Thirty sound third human molars were selected and, on both their buccal and lingual surfaces, class V cavities were prepared by air-abrasion, at 2-, 4-, 6-, 8- and 10-mm working distances, or high-speed bur (control group). After preparation, all cavities were etched with 35% phosphoric acid gel and restored with Single Bond/Filtek Z-250. Buccal and lingual surfaces were separated and restorations sectioned in a buccolingual direction, providing two sections of each cavity, which were analysed by scanning electron microscopy. It was observed that the distances of 6 and 8 mm promoted more homogeneous dentin/adhesive interfaces, with tags formation, and more uniform for enamel, which were similar to the control group. It may be concluded that the air-abrasion working distance can influence the morphology of enamel and dentin/adhesive interfaces, and the intermediate distances provided better adhesive interfaces. 相似文献