全文获取类型
收费全文 | 792篇 |
免费 | 11篇 |
国内免费 | 2篇 |
专业分类
化学 | 428篇 |
晶体学 | 3篇 |
力学 | 15篇 |
数学 | 209篇 |
物理学 | 150篇 |
出版年
2020年 | 7篇 |
2017年 | 8篇 |
2016年 | 13篇 |
2015年 | 15篇 |
2014年 | 11篇 |
2013年 | 31篇 |
2012年 | 39篇 |
2011年 | 26篇 |
2010年 | 27篇 |
2009年 | 24篇 |
2008年 | 25篇 |
2007年 | 23篇 |
2006年 | 20篇 |
2005年 | 30篇 |
2004年 | 24篇 |
2003年 | 19篇 |
2002年 | 10篇 |
2000年 | 16篇 |
1999年 | 12篇 |
1998年 | 14篇 |
1997年 | 10篇 |
1996年 | 13篇 |
1995年 | 14篇 |
1994年 | 21篇 |
1993年 | 15篇 |
1992年 | 18篇 |
1991年 | 14篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 17篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 14篇 |
1983年 | 11篇 |
1982年 | 15篇 |
1981年 | 17篇 |
1980年 | 8篇 |
1979年 | 22篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1976年 | 7篇 |
1975年 | 17篇 |
1974年 | 7篇 |
1973年 | 5篇 |
1971年 | 5篇 |
1969年 | 7篇 |
1966年 | 5篇 |
1965年 | 8篇 |
1960年 | 6篇 |
排序方式: 共有805条查询结果,搜索用时 15 毫秒
71.
72.
73.
Summary Disilane derivatives undergo disproportionation reactions to polysilanes. Investigated were 1,2-dimethyldisilane and 1,2-dimethyltetrachlorodisilane with catalysts like NH4Cl, AgCN, and Nacyanamide. In case of 1,2-dimethyldisilane, with more than catalytic amounts of NH4Cl, a nitrogen containing polysilane is formed. Two new compoundsMeSiH(NCO)2 andMe
2Si2(NCO)4 were synthesized and characterized. The last one leads to a polymer at heating. Additionally an electrochemical formation of polydimethylsilane is described. 相似文献
74.
75.
76.
Complexity measures for sequences over finite fields, such as the linear complexity and the k-error linear complexity, play an important role in cryptology. Recent developments in stream ciphers point towards an interest in word-based stream ciphers, which require the study of the complexity of multisequences. We introduce various options for error linear complexity measures for multisequences. For finite multisequences as well as for periodic multisequences with prime period, we present formulas for the number of multisequences with given error linear complexity for several cases, and we present lower bounds for the expected error linear complexity. 相似文献
77.
We continue the study of the linear complexity of binary sequences, independently introduced by Sidel’nikov and Lempel, Cohn,
and Eastman. These investigations were originated by Helleseth and Yang and extended by Kyureghyan and Pott. We determine
the exact linear complexity of several families of these sequences using well-known results on cyclotomic numbers. Moreover,
we prove a general lower bound on the linear complexity profile for all of these sequences. 相似文献
78.
79.
F. Brenscheidt E. Wieser W. Matz A. Mücklich W. Möller 《Applied Physics A: Materials Science & Processing》1997,65(3):281-286
3 N4 ceramic after chromium implantation were investigated for the dependence on implantation energy between 200 keV and 3 MeV
at a fixed fluence of 1017 ions/cm2. The wear of the modified material is reduced for a load of 2 N independent of ion energy accompanied by a slight increase
of the friction coefficient. At higher loads only high-energy implantations result in improved wear behaviour. Structural
investigations show the absence of any new phases formed by ion implantation. All energies result in an amorphous layer. For
lower energies this amorphous layer reaches up to the surface whereas at higher energies it is covered by still-crystalline
but damaged material. The observed wear behaviour can be explained with the amorphization of the near surface region and the
stress generated by the volume swelling of the amorphous layer.
Received: 25 November 1996/Accepted: 29 April 1997 相似文献
80.
In this work, an efficient analytical model for the stress analysis of single lap joints with a functionally graded adhesive bondline is proposed which considers peel as well as shear stresses in the adhesive. The model takes into account the nonlinear geometric characteristics of a single lap joint under tensile loading and allows for the analysis of various adhesive Young's modulus variations. The obtained stress distributions are compared to results of detailed Finite Element analyses and show a good agreement for several single lap joint configurations. In addition, different adhesive Young's modulus distributions and their effect on the peel and shear stresses are studied and discussed in detail. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献