全文获取类型
收费全文 | 74288篇 |
免费 | 16094篇 |
国内免费 | 84篇 |
专业分类
化学 | 72824篇 |
晶体学 | 369篇 |
力学 | 2587篇 |
综合类 | 1篇 |
数学 | 7931篇 |
物理学 | 6754篇 |
出版年
2024年 | 384篇 |
2023年 | 4186篇 |
2022年 | 1593篇 |
2021年 | 2712篇 |
2020年 | 4925篇 |
2019年 | 2697篇 |
2018年 | 2892篇 |
2017年 | 1219篇 |
2016年 | 6581篇 |
2015年 | 6271篇 |
2014年 | 5828篇 |
2013年 | 7126篇 |
2012年 | 4919篇 |
2011年 | 2870篇 |
2010年 | 4495篇 |
2009年 | 4301篇 |
2008年 | 2723篇 |
2007年 | 2404篇 |
2006年 | 1584篇 |
2005年 | 1424篇 |
2004年 | 1269篇 |
2003年 | 963篇 |
2002年 | 827篇 |
2001年 | 643篇 |
2000年 | 586篇 |
1999年 | 424篇 |
1998年 | 327篇 |
1997年 | 348篇 |
1996年 | 430篇 |
1995年 | 399篇 |
1994年 | 358篇 |
1993年 | 438篇 |
1992年 | 324篇 |
1985年 | 391篇 |
1984年 | 406篇 |
1982年 | 311篇 |
1981年 | 361篇 |
1980年 | 393篇 |
1979年 | 330篇 |
1978年 | 318篇 |
1977年 | 442篇 |
1976年 | 479篇 |
1975年 | 577篇 |
1974年 | 558篇 |
1973年 | 386篇 |
1972年 | 414篇 |
1971年 | 399篇 |
1970年 | 580篇 |
1969年 | 442篇 |
1968年 | 474篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Günter Graumann Prof. Dr. 《ZDM》2005,37(3):190-198
Problem fields with one or two generating problems and possibilities of varying existing problems give a good chance for self-activities of students and can be used for reaching different general aims. In this paper some topics concerning quadrilaterals will be presented. I hope they will animate teachers for more problem orientation in mathematics education. First we will reflect about different types of convex and non-convex quadrilaterals and possibilities of ordering them. Then we focus on middle-quadrilaterals and types of quadrilaterals with special middle-quadrilaterals as well as their logical ordering. Finally we investigate the analogies in space to the parallelogram and its sub-types and order them in the “house of parallelepipeds”. 相似文献
32.
33.
Tomás Chacón Rebollo Antonio Domı́nguez Delgado Enrique D. Fernández Nieto 《Comptes Rendus Mathematique》2004,338(1):85-90
In this work we introduce a class of balanced numerical schemes, up to second order, for the solution of general non-homogeneous hyperbolic systems of conservation laws. We give a general technique to build such schemes. We also prove that they balance up to second order a large class of steady solutions in the whole domain but some subset whose measure tends to zero as the grid size decreases to zero. We finally present an application to Shallow Water equations that exhibit the good performances of some of the schemes introduced. To cite this article: T. Chacón Rebollo et al., C. R. Acad. Sci. Paris, Ser. I 338 (2004). 相似文献
34.
Juan A. Barceló Jonathan Bennett Alberto Ruiz 《Journal of Fourier Analysis and Applications》2003,9(6):541-562
We study the continuity properties of a projection derived from a recent characterization of Herglotz Wave Functions in the plane. Herglotz Wave Functions are the entire solutions of the Helmholtz equation which have L2-Far-Field-Pattern. The behavior of this projection is reminiscent of the Disc Multiplier Operator on both Lp and mixed Lp-normed spaces. In particular a Kakeya type set plays a central role in our analysis. As a consequence we answer a question posed by Alvarez, Folch-Gabayet and Pérez-Esteva. 相似文献
35.
36.
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
37.
38.
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
39.
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
40.
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