全文获取类型
收费全文 | 1156篇 |
免费 | 27篇 |
国内免费 | 11篇 |
专业分类
化学 | 740篇 |
晶体学 | 6篇 |
力学 | 34篇 |
数学 | 241篇 |
物理学 | 173篇 |
出版年
2023年 | 6篇 |
2022年 | 18篇 |
2021年 | 22篇 |
2020年 | 18篇 |
2019年 | 10篇 |
2018年 | 21篇 |
2017年 | 13篇 |
2016年 | 40篇 |
2015年 | 27篇 |
2014年 | 21篇 |
2013年 | 47篇 |
2012年 | 71篇 |
2011年 | 75篇 |
2010年 | 50篇 |
2009年 | 40篇 |
2008年 | 61篇 |
2007年 | 71篇 |
2006年 | 61篇 |
2005年 | 45篇 |
2004年 | 34篇 |
2003年 | 33篇 |
2002年 | 42篇 |
2001年 | 10篇 |
2000年 | 13篇 |
1999年 | 15篇 |
1998年 | 13篇 |
1997年 | 6篇 |
1996年 | 13篇 |
1995年 | 14篇 |
1994年 | 17篇 |
1993年 | 7篇 |
1992年 | 10篇 |
1991年 | 13篇 |
1990年 | 14篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1987年 | 14篇 |
1986年 | 18篇 |
1985年 | 17篇 |
1984年 | 25篇 |
1983年 | 21篇 |
1982年 | 15篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 13篇 |
1978年 | 5篇 |
1976年 | 10篇 |
1975年 | 5篇 |
1972年 | 3篇 |
1933年 | 3篇 |
排序方式: 共有1194条查询结果,搜索用时 0 毫秒
101.
Stefano De Leo Pietro Rotelli 《The European Physical Journal C - Particles and Fields》2009,62(4):793-797
We develop the potential scattering of a spinor within the context of perturbation field theory. As an application, we reproduce,
up to second order in the potential, the diffusion results for a potential barrier of quantum mechanics. An immediate consequence
is a simple generalization to arbitrary potential forms, a feature not possible in quantum mechanics. 相似文献
102.
Domenico Alfieri Giuseppe Coppola Pietro Ferraro Giovanni Pierattini 《Optics Communications》2006,260(1):113-116
A method for allowing direct perfect superimposition and comparison of Fresnel-transform reconstructions of digital holograms recorded of the same object at different distances and wavelengths is proposed and demonstrated. The method takes into account the dependence of the reconstruction pixel on the distance and the wavelength by the Fresnel-transform algorithm. The method avoids the need for image scaling at the end of the reconstruction process that usually is performed in multi-wavelength digital holography. Demonstration is given by superposing the numerical reconstructions of holograms recorded at different distances and wavelengths. The method can be potentially very useful for real-time monitoring in biological processes or for recognition and ranging by multiple wavelengths of a target with fast movements or finally for very fast investigation and study of very fast processes. 相似文献
103.
Arfè Andrea Peluso Stefano Muliere Pietro 《Statistical Inference for Stochastic Processes》2021,24(1):1-15
The literature on Bayesian methods for the analysis of discrete-time semi-Markov processes is sparse. In this paper, we introduce the semi-Markov beta-Stacy process, a stochastic process useful for the Bayesian non-parametric analysis of semi-Markov processes. The semi-Markov beta-Stacy process is conjugate with respect to data generated by a semi-Markov process, a property which makes it easy to obtain probabilistic forecasts. Its predictive distributions are characterized by a reinforced random walk on a system of urns.
相似文献104.
M. Papa F. Amorini M. Cabibbo G. Cardella A. Di Pietro P. Figuera A. Musumarra G. Pappalardo F. Rizzo S. Tudisco 《The European Physical Journal A - Hadrons and Nuclei》1999,4(1):69-82
Recent experimental results on particles-γ coincidence measurements on the systems 12C +64Ni and 35Cl +64Ni at about 8 MeV/nucleon are interpreted as due to the effect of a Dipole pre-equilibrium emission produced during the damping
of the proton-neutron relative collective motion in very deformed intermediate systems formed in the first instants of the
collision. The pre-equilibrium effects are evaluated through semiclassic kinetic theories and through modified statistical
approach to include non-stationary effects in Fusion processes, Massive Transfer reactions (in the 12C +64Ni system) and in Binary Dissipative reactions (in the 35Cl +64Ni system). In particular the study performed on the dipole molecular component allows to establish a link between the above
phenomenon and the charge and mass transfer process in quasi-peripheral reactions.
Received: 15 April 1998 / Revised version: 8 June 1998 相似文献
105.
106.
107.
Archimede Rotondo Giuseppe Bruno Francesco Nicol Giuseppe Tresoldi Santo Di Pietro 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(1):o15-o19
The structure of 2,6‐bis(2‐pyridyltsulfanylmethyl)pyridine (pytmp), (I), C17H15N3S2, presents a twisted conformation, with the three planar moieties almost perpendicular to each other. The structures of two related derivatives, namely 2,6‐bis(6‐methyl‐2‐pyridylsulfanylmethyl)pyridine (mpytmp), (II), C19H19N3S2, and 2,6‐bis(4‐methyl‐2‐pyrimidylsulfanylmethyl)pyridine (mprtmp) n‐pentane hemisolvate, (III), C17H17N5S2·0.5C5H12, present extended planar fragments with just one quasi‐perpendicular arylsulfanylmethyl side arm, such that the molecules are folded in an L‐shaped conformation. All three conformations appear different from those adopted by similar compounds, demonstrating the great flexibility of such species, although such differences in conformational behaviour might drive specific coordination modes. 相似文献
108.
Andrei V. Grafov Eugene A. Mazurenko Giovanni A. Battiston Pierino Zanella Francesco Tisato Franco Braga Pietro Traldi 《应用有机金属化学》1995,9(3):259-266
The first three representatives of a new family of volatile organohafnium compounds suitable as metallo-organic chemical vapour deposition precursors were synthesized. A combination of cyclopentadienyl and alkoxo-ligands with a bicyclo[2.2.1]heptanc framework was used. Volatility at relatively low temperatures for hafnium compounds was found and the precursors were characterized by elemental analysis and spectroscopic methods (IR, 1H and 13C NMR, mass spectrometry and mass-analysed ion kinetic energy spectroscopy). The outlook for use in hafnium functional materials synthesis was derived from the fragmentation data. 相似文献
109.
Pietro Aiena Maria Luisa Colasante Manuel Gonzá lez 《Proceedings of the American Mathematical Society》2002,130(9):2701-2710
We find several conditions for the quasi-nilpotent part of a bounded operator acting on a Banach space to be closed. Most of these conditions are established for semi-Fredholm operators or, more generally, for operators which admit a generalized Kato decomposition. For these operators the property of having a closed quasi-nilpotent part is related to the so-called single valued extension property.
110.