全文获取类型
收费全文 | 72807篇 |
免费 | 2478篇 |
国内免费 | 270篇 |
专业分类
化学 | 45316篇 |
晶体学 | 447篇 |
力学 | 1502篇 |
综合类 | 1篇 |
数学 | 12177篇 |
物理学 | 16112篇 |
出版年
2022年 | 481篇 |
2021年 | 700篇 |
2020年 | 1053篇 |
2019年 | 906篇 |
2018年 | 839篇 |
2017年 | 799篇 |
2016年 | 1904篇 |
2015年 | 1612篇 |
2014年 | 1882篇 |
2013年 | 3730篇 |
2012年 | 3676篇 |
2011年 | 4330篇 |
2010年 | 2281篇 |
2009年 | 1955篇 |
2008年 | 4075篇 |
2007年 | 3857篇 |
2006年 | 3660篇 |
2005年 | 3348篇 |
2004年 | 2772篇 |
2003年 | 2318篇 |
2002年 | 2214篇 |
2001年 | 1272篇 |
2000年 | 1167篇 |
1999年 | 889篇 |
1998年 | 820篇 |
1997年 | 851篇 |
1996年 | 976篇 |
1995年 | 795篇 |
1994年 | 863篇 |
1993年 | 917篇 |
1992年 | 795篇 |
1991年 | 646篇 |
1990年 | 655篇 |
1989年 | 539篇 |
1988年 | 563篇 |
1987年 | 577篇 |
1986年 | 492篇 |
1985年 | 855篇 |
1984年 | 810篇 |
1983年 | 721篇 |
1982年 | 801篇 |
1981年 | 744篇 |
1980年 | 709篇 |
1979年 | 633篇 |
1978年 | 659篇 |
1977年 | 626篇 |
1976年 | 576篇 |
1975年 | 541篇 |
1974年 | 488篇 |
1973年 | 464篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
We consider Markov processes built from pasting together pieces of strong Markov processes which are killed at a position
dependent rate and connected via a transition kernel. We give necessary and sufficient conditions for local absolute continuity
of probability laws for such processes on a suitable path space and derive an explicit formula for the corresponding likelihood
ratio process. The main tool is the consideration of the process between successive jumps – what we call ‘elementary experiments’
– and criteria for absolute continuity of laws of the process there. We apply our results to systems of branching diffusions
with interactions and immigrations.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
62.
Norbert Auner Larissa Zherlitsyna Michael Bolte 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(5):m199-m200
The title compound, [Cu8(C8H24O2Si)2(C3H7NO)8]·C4H4N2·C3H7NO, features a sandwich‐like cage enclosing a pyrazine molecule, both situated on a centre of inversion. In addition, the crystal structure contains one dimethylformamide molecule which is disordered over a centre of inversion. The copper layer, containing eight atoms, is located between two siloxanolate fragments. The whole structure of Cu atoms and siloxanolate rings is distorted by the pyrazine molecule, leading to an oval form. As a result, the angles between the Cu atoms differ at the copper layer. The difference in the angles could lead to some deviations in the Cu–Cu exchange interactions within the copper ring, which is of interest for molecular magnetism. 相似文献
63.
A new method is presented for the determination of Ricci Collineations (RC) and Matter Collineations (MC) of a given spacetime, in the cases where the Ricci tensor and the energy momentum tensor are non-degenerate and have a similar form with the metric. This method reduces the problem of finding the RCs and the MCs to that of determining the KVs whereas at the same time uses already known results on the motions of the metric. We employ this method to determine all hypersurface homogeneous locally rotationally symmetric spacetimes, which admit proper RCs and MCs. We also give the corresponding collineation vectors. These results conclude a long due open problem, which has been considered many times partially in the literature. 相似文献
64.
For more than 25 yearsJΨ production has helped to sharpen our understanding of QCD. In proton induced reaction some observations are rather well understood
while others are still unclear. The current status of the theory ofJΨ production will be sketched, paying special attention to the issues of formation time andJΨ re-interaction in a nuclear medium. 相似文献
65.
66.
I. M. Kolthoff S. R. Cooper V. J. Tulane F. Reimers H. A. J. Pieters K. Höppner V. H. Matula C. B. Macek W. N. Skworzow J. S. Schepelewa F. Čuta K. Kámen S. Cohen R. E. Oesper D. S. Narayanamurthi T. R. Seshadri H. M. State A. W. Kirssanow W. M. Tscherkassow D. M. Mukherjee T. Akiyama Y. Mine S. Yabe Y. Volmar M. Déribéré 《Analytical and bioanalytical chemistry》1937,111(5-6):192-197
67.
68.
C. Michael 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):257-260
Lattice QCD can give direct information on OZI-violating contributions to mesons. Here we explore the contributions that split flavour singlet and non-singlet meson masses. I discuss in detail the spectrum and decays for scalar mesons (i.e. including glueball effects). I also review the status of hybrid mesons and their decays.Received: 30 September 2002, Published online: 22 October 2003PACS:
12.38.Gc Lattice QCD calculations - 12.39.Mk Glueball and nonstandard multi-quark/gluon states 相似文献
69.
70.
Michael T. Jury David W. Kribs 《Proceedings of the American Mathematical Society》2005,133(1):213-222
Given a row contraction of operators on a Hilbert space and a family of projections on the space that stabilizes the operators, we show there is a unique minimal joint dilation to a row contraction of partial isometries that satisfy natural relations. For a fixed row contraction the set of all dilations forms a partially ordered set with a largest and smallest element. A key technical device in our analysis is a connection with directed graphs. We use a Wold decomposition for partial isometries to describe the models for these dilations, and we discuss how the basic properties of a dilation depend on the row contraction.