全文获取类型
收费全文 | 381篇 |
免费 | 10篇 |
国内免费 | 3篇 |
专业分类
化学 | 180篇 |
晶体学 | 1篇 |
力学 | 30篇 |
数学 | 121篇 |
物理学 | 62篇 |
出版年
2022年 | 10篇 |
2021年 | 14篇 |
2020年 | 10篇 |
2019年 | 6篇 |
2018年 | 14篇 |
2017年 | 10篇 |
2016年 | 17篇 |
2015年 | 12篇 |
2014年 | 14篇 |
2013年 | 39篇 |
2012年 | 22篇 |
2011年 | 33篇 |
2010年 | 21篇 |
2009年 | 16篇 |
2008年 | 21篇 |
2007年 | 15篇 |
2006年 | 15篇 |
2005年 | 19篇 |
2004年 | 13篇 |
2003年 | 10篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1940年 | 2篇 |
排序方式: 共有394条查询结果,搜索用时 0 毫秒
91.
New functionalized isoxazolines were effeciently and easily prepared from limonene. The procedure involves a peri‐ and regioselective 1,3‐dipolar cycloaddition of nitrile oxides on the monoterpene external double bond, followed by a highly chemoselective RuCl3‐NaIO4 oxidative cleavage of the internal one. All the newly prepared isoxazolyl‐ketoacids were fully characterized from their spectroscopic data. 相似文献
92.
93.
94.
This paper deals with the study of behaviour of an idealized 2D hydroelastic system involving two inviscid liquids with an
elastic rectangular container. The main objective is to investigate the influence of the physical parameters on eigenfrequencies
and eigenmodes of the system. The study extends the previous results obtained for hydroelastic systems with one fluid. The
governing equations describing the behaviour of the system are analyzed by using the concept of normal modes and their solutions
presented in the form of infinite series. The expansion coefficients for the velocity potentials are calculated by employing
a new inner product that allows the orthogonalisation of the normal modes. An eigenfrequency equation is then derived from
the existence condition of a nontrivial solution. The numerical calculations are performed by varying only some relevant parameters. 相似文献
95.
96.
97.
98.
Mohammed Debiane Christian Kharif Mustapha Amaouche 《European Journal of Mechanics - B/Fluids》2000,19(6):855
This paper presents a method for the calculation of steady periodic capillary-gravity waves on water of arbitrary uniform depth. The method developed by Debiane and Kharif in 1997 for infinite depth is extended to finite depth. The water-wave problem is reduced to a system of nonlinear algebraic equations which is solved using Newton's method. For the resonant configurations, the method does not suffer from the Wilton's failures and is valid for all depths. In addition, it is shown that the method allows the computation of solitary waves and generalized solitary waves. 相似文献
99.
H. Raissi A. F. Jalbout M. Yoosefian Mustapha Fazli A. Nowroozi M. Shahinin A. De Leon 《International journal of quantum chemistry》2010,110(4):821-830
The molecular structure and intramolecular hydrogen bond energies of 44 conformers of 2‐Amino methylene malonaldehyde were investigated at MP2 and B3LYP levels of theory using the standard 6‐311++G** basis set and AIM and NBO analysis. The calculated geometrical parameters and conformational analysis in gas phase show that the closed ring via intramolecular hydrogen bonded conformers of this compound are more stable than the other ones. Hydrogen bond energies for H‐bonded conformers were obtained from the related rotamers method (RRM) and Schuster method, and also the nature of H‐bonding of them has been investigated by means of the Bader theory of atoms in molecules, which is based on topological properties of the electron density. Delocalization effects can be identified from the presence of off diagonal elements of the Fock matrix in the NBO basis. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献
100.
Mustapha Lahyane 《Journal of Pure and Applied Algebra》2010,214(7):1217-1240
We give a numerical criterion for ensuring the finite generation of the effective monoid of the surfaces obtained by a blowing-up of the projective plane at the supports of zero dimensional subschemes assuming that these are contained in a degenerate cubic. Furthermore, this criterion also ensures the regularity of any numerically effective divisor on these surfaces. Thus the dimension of any complete linear system is computed. On the other hand, in particular and among these surfaces, we obtain ringed rational surfaces with very large Picard numbers and with only finitely many integral curves of strictly negative self-intersection. These negative integral curves except two (−1)-curves are all contained in the support of an anticanonical divisor. Thus almost all the geometry of such surfaces is concentrated in the anticanonical class. 相似文献