全文获取类型
收费全文 | 664090篇 |
免费 | 6377篇 |
国内免费 | 2517篇 |
专业分类
化学 | 343027篇 |
晶体学 | 9477篇 |
力学 | 32110篇 |
综合类 | 78篇 |
数学 | 87034篇 |
物理学 | 201258篇 |
出版年
2021年 | 5869篇 |
2020年 | 6472篇 |
2019年 | 7192篇 |
2018年 | 9579篇 |
2017年 | 9711篇 |
2016年 | 13569篇 |
2015年 | 7707篇 |
2014年 | 12460篇 |
2013年 | 29152篇 |
2012年 | 23089篇 |
2011年 | 27666篇 |
2010年 | 20429篇 |
2009年 | 20175篇 |
2008年 | 26079篇 |
2007年 | 25944篇 |
2006年 | 23839篇 |
2005年 | 21421篇 |
2004年 | 19656篇 |
2003年 | 17564篇 |
2002年 | 17471篇 |
2001年 | 18591篇 |
2000年 | 14380篇 |
1999年 | 11042篇 |
1998年 | 9491篇 |
1997年 | 9336篇 |
1996年 | 8844篇 |
1995年 | 7930篇 |
1994年 | 8001篇 |
1993年 | 7669篇 |
1992年 | 8225篇 |
1991年 | 8613篇 |
1990年 | 8186篇 |
1989年 | 8069篇 |
1988年 | 7852篇 |
1987年 | 7563篇 |
1986年 | 7330篇 |
1985年 | 9508篇 |
1984年 | 9868篇 |
1983年 | 8306篇 |
1982年 | 8709篇 |
1981年 | 8136篇 |
1980年 | 7714篇 |
1979年 | 8252篇 |
1978年 | 8630篇 |
1977年 | 8525篇 |
1976年 | 8525篇 |
1975年 | 8072篇 |
1974年 | 7990篇 |
1973年 | 8317篇 |
1972年 | 6163篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
The Al2O3−CdSe interface of a thin-film transistor is investigated in the frequency range 30 Hz-30 kHz under weak depletion and accumulation.
The surface states are, most likely, located in the insulator Al2O3 with a concentration varying from 4·1018 to 1019 cm−3 eV−1. The surface states have a negligible influence on the thin-film transistor operation. 相似文献
42.
The problem of the vector and axial-vector dominance of weak interactions within the framework of the quark model of superconductivity type is discussed. 相似文献
43.
The theory of tree-growing (RECPAM approach) is developed for outcome variables which are distributed as the canonical exponential family. The general RECPAM approach (consisting of three steps: recursive partition, pruning and amalgamation), is reviewed. This is seen as constructing a partition with maximal information content about a parameter to be predicted, followed by simplification by the elimination of ‘negligible’ information. The measure of information is defined for an exponential family outcome as a deviance difference, and appropriate modifications of pruning and amalgamation rules are discussed. It is further shown how the proposed approach makes it possible to develop tree-growing for situations usually treated by generalized linear models (GLIM). In particular, Poisson and logistic regression can be tree-structured. Moreover, censored survival data can be treated, as in GLIM, by observing a formal equivalence of the likelihood under random censoring and an appropriate Poisson model. Three examples are given of application to Poisson, binary and censored survival data. 相似文献
44.
45.
V. L. Topunov 《Acta Appl Math》1989,16(2):191-206
In this paper, an application of the Riquer-Thomas-Janet theory is described for the problem of transforming a system of partial differential equations into a passive form, i.e., to a special form which contains explicitly both the equations of the initial system and all their nontrivial differential consequences. This special representation of a system markedly facilitates the subsequent integration of the corresponding differential equations. In this paper, the modern approach to the indicated problem is presented. This is the approach adopted in the Knuth-Bendix procedure [13] for critical-pair/completion and then Buchberger's algorithm for completion of polynomial ideal bases [13] (or, alternatively, for the construction of Groebner bases for ideals in a differential operator ring [14]). The algorithm of reduction to the passive form for linear system of partial differential equations and its implementation in the algorithmic language REFAL, as well as the capabilities of the corresponding program, are outlined. Examples illustrating the power and efficiency of the system are presented. 相似文献
46.
47.
A. Sebbar 《Mathematische Zeitschrift》1989,201(4):561-581
Sans résumé 相似文献
48.
G. L. Booth 《Acta Mathematica Hungarica》1989,54(3-4):201-208
49.
50.
L. A. Khalfin 《Journal of Mathematical Sciences》1987,36(5):616-626
The article surveys the main results of the statistical approach to the solution of ill-posed problems of mathematical physics, in application to specific ill-posed inverse problems in geophysics.Invited paper presented at the International Seminar on Mathematical Foundations of the Interpretation of Geophysical Fields, Moscow, May–June 1972.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 79, pp. 67–81, 1978. 相似文献