全文获取类型
收费全文 | 11966篇 |
免费 | 328篇 |
国内免费 | 15篇 |
专业分类
化学 | 6368篇 |
晶体学 | 84篇 |
力学 | 251篇 |
数学 | 2558篇 |
物理学 | 3048篇 |
出版年
2022年 | 100篇 |
2021年 | 134篇 |
2020年 | 187篇 |
2019年 | 164篇 |
2018年 | 206篇 |
2017年 | 215篇 |
2016年 | 459篇 |
2015年 | 418篇 |
2014年 | 449篇 |
2013年 | 811篇 |
2012年 | 592篇 |
2011年 | 724篇 |
2010年 | 464篇 |
2009年 | 385篇 |
2008年 | 450篇 |
2007年 | 421篇 |
2006年 | 316篇 |
2005年 | 189篇 |
2004年 | 226篇 |
2003年 | 216篇 |
2002年 | 208篇 |
2001年 | 169篇 |
2000年 | 187篇 |
1999年 | 174篇 |
1998年 | 157篇 |
1997年 | 142篇 |
1996年 | 147篇 |
1995年 | 135篇 |
1994年 | 128篇 |
1993年 | 117篇 |
1992年 | 120篇 |
1991年 | 100篇 |
1990年 | 118篇 |
1989年 | 96篇 |
1988年 | 94篇 |
1987年 | 96篇 |
1986年 | 93篇 |
1985年 | 134篇 |
1984年 | 149篇 |
1983年 | 97篇 |
1982年 | 119篇 |
1981年 | 118篇 |
1980年 | 101篇 |
1979年 | 112篇 |
1978年 | 115篇 |
1977年 | 99篇 |
1976年 | 119篇 |
1975年 | 113篇 |
1974年 | 109篇 |
1968年 | 102篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
151.
I. Muzyčenková V. Kellnerová M. Koneracká P. Kopčanský M. Antalík J. Ďurišin 《Czechoslovak Journal of Physics》1995,45(9):727-734
The encapsulation of fine magnetite particles of 10 nm size and marker ANS within asolectin vesicles has been made by sonication of the mixture in water. For the proof of encapsulation of magnetite in vesicles the electron microscope and spectrofluoriphotometer technique were used. The theory for the calculation of the magnetic force acting on the system consisted of non-capsulated magnetic particles dispersed in water and magnetic vesicles was developed.This work was supported by the Slovak Academy of Sciences within the framework of Project GAV No. 1361. 相似文献
152.
In this paper large-scale properties of developed magnetohydrodynamic turbulence have been investigated by using double expansion method in the frame of quantum field renormalization group. It has been shown that universal kinetic scaling regime exists, but the double expansion in general leads to qualitatively different results than those provided by the usual -expansion treatment.This work was supported by Slovak Grant Agency for Science. 相似文献
153.
Anton Marcinčin Marcela Hricová Arun Aneja Alexandra Andrejková Eva Körmendyová 《Journal of Macromolecular Science: Physics》2013,52(5):945-956
Polypropylene (PP)/polyester (PES)–blend fibers were prepared by extruder melt spinning. The polymer blend consisted of PP and a “master batch” (MB) based on polytrimethylene terephthalate (PTT) or polyethylene terephthalate (PET), binary PTT/PET or PP/PTT blends, and also on a ternary PP/(PTT/PET) blend. The phase structure of PP/PES–blend fibers was examined. PES microfibers showed separation from the PP matrix in blend fibers. The impact of MB composition and rheological characteristics on phase structure parameters indicate a significant contribution of the PTT in the binary MB on the length of dispersed PES microfibers in the PP matrix. However, the blends of PP and ternary MB (PP/PTT/PET) have a lower diameter and length of the PES microfibers. The presence of PTT/PET (PES) enhances the structural and mechanical properties of the blend PP/PES fibers. In addition, PTT increases the tensile strength of the PP/PES–blend fibers if a binary MB is used, while the fiber nonuniformity is reduced in the presence of a ternary MB. 相似文献
154.
The Kirkwood-Buff statistical mechanical theory of surface tension γ for monatomic fluids is extended to molecular fluids. A rigorous expression for γ is derived in terms of the angular pair distribution function f(z 1 R 12θ1θ2) of an equilibrium fluid-fluid system (liquid-gas, liquid-liquid, or gas-gas). The Fowler approximation is applied for the liquid-gas case, and a simple expression for γ is derived in terms of the bulk liquid angular pair correlation function g(R 12θ1θ2). Thermodynamic perturbation theory for g(R 12θ1θ2) is also used to calculate γ theoretically. The theoretical results are compared with experimental values. 相似文献
155.
Stefano Carli Wouter Dekeyser Reinart Coosemans Renaud Dejarnac Michael Komm Miglena Dimitrova Jiří Adámek Petra Bílková Petr Böhm 《等离子体物理论文集》2020,60(5-6):e201900155
Mean-field plasma edge transport codes such as SOLPS-ITER heavily rely on ad-hoc radial diffusion coefficients to approximately model anomalous transport. Such coefficients are experimentally determined and vary between different machines, and also depend on the operational regime and plasma location within the same device. Therefore, to match experimental data the modeller is required to manually tune several free parameters in expensive simulations, and the code's predictive capabilities are significantly downgraded. As a solution, a new model has been developed for SOLPS-ITER, solving an additional transport equation for the turbulent kinetic energy k, derived by consistently time-averaging the Braginskii equations, and including a diffusive closure for the anomalous particle flux. This closure model relates the anomalous diffusion coefficient to the local k value. The resulting equation structure and its closure are inspired by TOKAM2D isothermal interchange turbulence simulation results. Within this model, fewer and hopefully more universal free parameters are retained, thus improving the code's predictive capabilities. The new model has been tested on a COMPASS case for which upstream plasma profiles were available. Experimental data and a reference solution, obtained by matching the profiles through manual tuning of radial diffusivities, have been used to estimate the parameters of our new transport model. A ballooned particle diffusivity profile is retrieved by the new radial transport model, thanks to the proposed interchange drive. The obtained upstream profiles qualitatively agree with the experiment and prove the new model is a promising first attempt to be further refined. 相似文献
156.
We explain the (non-)validity of close-to-equilibrium entropy production principles in the context of linear electrical circuits.
Both the minimum and the maximum entropy production principles are understood within dynamical fluctuation theory. The starting
point are Langevin equations obtained by combining Kirchoff’s laws with a Johnson-Nyquist noise at each dissipative element
in the circuit. The main observation is that the fluctuation functional for time averages, that can be read off from the path-space
action, is in first order around equilibrium given by an entropy production rate.
That allows to understand beyond the schemes of irreversible thermodynamics (1) the validity of the least dissipation, the
minimum entropy production, and the maximum entropy production principles close to equilibrium; (2) the role of the observables’
parity under time-reversal and, in particular, the origin of Landauer’s counterexample (1975) from the fact that the fluctuating
observable there is odd under time-reversal; (3) the critical remark of Jaynes (1980) concerning the apparent inappropriateness
of entropy production principles in temperature-inhomogeneous circuits. 相似文献
157.
V. Wagner A. Krása M. Majerle F. Křížek O. Svoboda A. Kugler J. Adam V. M. Tsoupko-Sitnikov M. I. Krivopustov I. V. Zhuk W. Westmeier 《Pramana》2007,68(2):297-306
The set-up ‘energy plus transmutation’, consisting of a thick lead target and a natural uranium blanket, was irradiated by
relativistic proton beams with the energy from 0.7 GeV up to 2 GeV. Neutron field was measured in different places of this
set-up using different activation detectors. The possibilities of using the obtained data for benchmark studies are analyzed
in this paper. Uncertainties of experimental data are shown and discussed. The experimental data are compared with results
of simulation with MCNPX code.
相似文献
158.
Jan ?echal Jind?ich Mach Stanislav Voborný Petr Kostelník Petr Bábor Ji?í Spousta Tomáš Šikola 《Surface science》2007,601(9):2047-2053
Results for deposition and thermal annealing of gallium on the Si(1 0 0)-(2 × 1) surface achieved by synchrotron radiation photoelectron spectroscopy (SR-PES) and low energy electron diffraction (LEED) are presented. In addition to deposition of Ga on a clean surface, the influence of water adsorption on the arrangement of gallium atoms was also studied. The results on Ga deposition at a higher temperature (490 °C) are consistent with a Ga ad-dimer model showing equivalent bond arrangement of all Ga atoms for coverages up to 0.5 ML. The deposition onto a surface with adsorbed water at room temperature led to a disordered gallium growth. In this case gallium atoms bind to silicon dimers already binding fragments of adsorbed water. A subsequent annealing of these layers leads to a surface structure similar to the Ga-(2 × 2), however, it is less ordered, probably due to the presence of silicon oxides formed from water fragments. 相似文献
159.
This paper attempts to develop a theory of sufficiency in the setting of non-commutative algebras parallel to the ideas in
classical mathematical statistics. Sufficiency of a coarse-graining means that all information is extracted about the mutual
relation of a given family of states. In the paper sufficient coarse-grainings are characterized in several equivalent ways
and the non-commutative analogue of the factorization theorem is obtained. As an application we discuss exponential families.
Our factorization theorem also implies two further important results, previously known only in finite Hilbert space dimension,
but proved here in generality: the Koashi-Imoto theorem on maps leaving a family of states invariant, and the characterization
of the general form of states in the equality case of strong subadditivity.
Supported by the EU Research Training Network Quantum Probability with Applications to Physics, Information Theory and Biology
and Center of Excellence SAS Physics of Information I/2/2005.
Supported by the Hungarian grant OTKA T032662 相似文献
160.
For the fast characteristics of mixtures of Aluminium, Gallium and Indium the fluorimetric evaluation in the form of complexes
with 8-Hydroxyquinoline-5-sulphonic acid is described at selected pH. The highly collinear correlated fluorescent spectra
and their first derivation were evaluated under various experimental conditions with the Multiple Linear Regression (MLR),
Partial Least Squares (PLS) methods and Kalman filtering. When comparing the results, the PLS gives the least relative prediction
errors under optimal conditions, 5.6–15.9% for the concentration range of Al 0.025–0.2 μg cm−3, Ga 0.1–0.8 μg cm−3 and In 0.1–0.8 μg cm−3 in the mixture. 相似文献