全文获取类型
收费全文 | 23800篇 |
免费 | 775篇 |
国内免费 | 21篇 |
专业分类
化学 | 15730篇 |
晶体学 | 167篇 |
力学 | 430篇 |
数学 | 4020篇 |
物理学 | 4249篇 |
出版年
2023年 | 159篇 |
2022年 | 156篇 |
2021年 | 252篇 |
2020年 | 352篇 |
2019年 | 365篇 |
2018年 | 486篇 |
2017年 | 445篇 |
2016年 | 909篇 |
2015年 | 690篇 |
2014年 | 771篇 |
2013年 | 1555篇 |
2012年 | 1550篇 |
2011年 | 1552篇 |
2010年 | 927篇 |
2009年 | 859篇 |
2008年 | 1352篇 |
2007年 | 1372篇 |
2006年 | 1224篇 |
2005年 | 1141篇 |
2004年 | 1042篇 |
2003年 | 798篇 |
2002年 | 695篇 |
2001年 | 518篇 |
2000年 | 472篇 |
1999年 | 345篇 |
1998年 | 244篇 |
1997年 | 233篇 |
1996年 | 300篇 |
1995年 | 210篇 |
1994年 | 239篇 |
1993年 | 195篇 |
1992年 | 192篇 |
1991年 | 182篇 |
1990年 | 171篇 |
1989年 | 151篇 |
1988年 | 144篇 |
1987年 | 139篇 |
1986年 | 135篇 |
1985年 | 209篇 |
1984年 | 201篇 |
1983年 | 126篇 |
1982年 | 133篇 |
1981年 | 144篇 |
1980年 | 140篇 |
1979年 | 100篇 |
1978年 | 97篇 |
1977年 | 106篇 |
1976年 | 86篇 |
1975年 | 88篇 |
1973年 | 72篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
José A. Anquela Teresa Cortés Miguel Gómez-Lozano Mercedes Siles-Molina 《Acta Mathematica Hungarica》2004,103(3):177-196
We investigate the basic properties of the different socles that can be considered in not necessarily semiprime associative
systems. Among other things, we show that the socle defined as the sum of minimal (or minimal and trivial) inner ideals is
always an ideal. When trivial inner ideals are included, this inner socle contains the socles defined in terms of minimal
left or right ideals.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
23.
We derive the incompressible and compressible k–ε model for locally homogeneous turbulence. The model is rigorously derived on formal mathematical grounds using the MPP modelling technique. This lets us calculate by either analytical or numerical means the closure constants of the model. To cite this article: T. Chacón Rebollo, D. Franco Coronil, C. R. Acad. Sci. Paris, Ser. I 337 (2003). 相似文献
24.
We consider toy cosmological models in which a classical, homogeneous, spinor field provides a dominant or sub-dominant contribution to the energy-momentum tensor of a flat Friedmann-Robertson-Walker universe. We find that, if such a field were to exist, appropriate choices of the spinor self-interaction would generate a rich variety of behaviors, quite different from their widely studied scalar field counterparts. We first discuss solutions that incorporate a stage of cosmic inflation and estimate the primordial spectrum of density perturbations seeded during such a stage. Inflation driven by a spinor field turns out to be unappealing as it leads to a blue spectrum of perturbations and requires considerable fine-tuning of parameters. We next find that, for simple, quartic spinor self-interactions, non-singular cyclic cosmologies exist with reasonable parameter choices. These solutions might eventually be incorporated into a successful past- and future-eternal cosmological model free of singularities. In an Appendix, we discuss the classical treatment of spinors and argue that certain quantum systems might be approximated in terms of such fields. 相似文献
25.
W. Królas A. Maj P. Bednarczyk B. Fornal W. Mceczynski J. Styczeń M. Zicebliński 《Zeitschrift für Physik A Hadrons and Nuclei》1992,344(2):145-147
High-energy gamma-rays emitted in the decay of the giant dipole resonance built on excited states of55Mn nucleus were measured with a bismuth germanate detector. Resonance parameters were extracted from the fits to the experimental spectra. Two new high-energy calibration points originating from slow-neutron capture in germanium isotopes of bismuth germanate crystal are proposed for large-volume BGO detectors. 相似文献
26.
D. Kast A. Jungclaus K.P. Lieb M. Górska G. de Angelis P.G. Bizzeti A. Dewald C. Fahlander H. Grawe R. Peusquens M. De Poli H. Tiesler 《The European Physical Journal A - Hadrons and Nuclei》1998,3(2):115-128
In the neutron deficient isotopes 104,105In lifetimes of high spin states in the range from 0.5 ps to 600 ps have been measured in a coincidence recoil distance Doppler
shift (RDDS) experiment. By combining the Doppler shift attenuation (DSA) and RDDS methods at few μm flight distances, the
problem of delayed feeding has been avoided and very short lifetimes in the range 0.5–0.8 ps have been determined. Shell model
calculations with strong restrictions for the neutron orbitals reveal good agreement with experimental level energies and
still fair agreement for most measured B(M1) and B(E2) values.
Received: 30 June 1998 相似文献
27.
S. Ramos-Bernal A. Negrón-Mendoza 《Journal of Radioanalytical and Nuclear Chemistry》1992,160(2):487-492
This research addresses itself to the study of the mechanism of the acetic acid decarboxylation in Na-Montmorillonite exposed to ionizing radiation. The results obtained indicated that the decarboxylation reaction is enhanced several times by the irradiation. This behavior is probably due to an oxidation reaction at the edges of the clay. Also it is by energy transfer from the clay to adsorbed molecules by an interaction of non-equilibrium charge carriers with the adsorbed molecules. 相似文献
28.
To Professor Guillermo Torres on the occasion of his 70th birthday. 相似文献
29.
M. T. Viciosa J. Quiles Hoyo M. Dionísio J. L. Gómez Ribelles 《Journal of Thermal Analysis and Calorimetry》2007,90(2):407-414
Temperature modulated differential scanning calorimetry (TMDSC) is used to study the kinetics of the free radical isothermal polymerization of triethyleneglycol dimethacrylate (TEGDMA). Azo-bis-isobutironitrile was used as initiator. The polymerization’s temperature is lower than the final glass transition temperature of the polymer network. The measurement of the average heat flow released and the heat capacity during the reaction allows identifying the different stages of the reaction. The presence of double peaks in the heat flow is ascribed to the autoacceleration. The influence of temperature, measuring conditions and oxygen are described. Vitrification is detected by the drop in heat capacity. It occurs at increasing conversion rates for increasing temperatures. After vitrification, the diffusion-controlled reaction continues. 相似文献
30.
We study in this Note the continuum (macroscopic) limit for some atomistic models for crystals. The purpose is to derive densities of mechanical energies from microscopic models. In contrast to the setting of a previous study, where the microscopic structure was assumed to be periodic, it is modelled here by a stochastic lattice, which enjoys some stationarity and ergodicity properties, following notions previously introduced elsewhere. To cite this article: X. Blanc et al., C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献