全文获取类型
收费全文 | 184篇 |
免费 | 275篇 |
国内免费 | 6篇 |
专业分类
化学 | 8篇 |
力学 | 31篇 |
数学 | 25篇 |
物理学 | 401篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2014年 | 15篇 |
2013年 | 15篇 |
2012年 | 29篇 |
2011年 | 27篇 |
2010年 | 29篇 |
2009年 | 42篇 |
2008年 | 49篇 |
2007年 | 35篇 |
2006年 | 39篇 |
2005年 | 35篇 |
2004年 | 38篇 |
2003年 | 18篇 |
2002年 | 20篇 |
2001年 | 12篇 |
2000年 | 9篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 3篇 |
1978年 | 1篇 |
排序方式: 共有465条查询结果,搜索用时 62 毫秒
431.
References: 《理论物理通讯》2007,47(2):221-224
The unified symmetry of a nonholonomic system of non-Chetaev's type in event space under infinitesimal transformations of group is studied.Firstly,the differential equations of motion of the system are given.Secondly,the definition and the criterion of the unified symmetry for the system are obtained.Thirdly,a new conserved quantity,besides the Noether conserved quantity and the Hojman conserved quantity,is deduced from the unified symmetry of a nonholonomic system of non-Chetaev's type.Finally,an example is given to illustrate the application of the result. 相似文献
432.
DING Ning FANG Jian-Hui WANG Peng ZHANG Xiao-Ni 《理论物理通讯》2007,48(5):799-800
A new type of conserved quantity, which is induced from the Mei symmetry of Lagrange systems, is studied. The conditions for that the new type of conserved quantity exists and the form of the new type of conserved quantity are obtained. An illustrated example is given. The Noether conserved quantity induced from the Mei symmetry of Lagrange systems is a special case of the new type of conserved quantity given in this paper. 相似文献
433.
Symmetry of Tzénoff equations for
unilateral holonomic system under the infinitesimal transformations of
groups is investigated. Its definitions and discriminant equations of Mei
symmetry and Lie symmetry of Tzénoff equations are given. Sufficient and
necessary condition of Lie symmetry deduced by the Mei symmetry is also
given. Hojman conserved quantity of
Tzénoff equations for the system
above through special Lie symmetry and Lie symmetry in the condition of
special Mei symmetry respectively is obtained. 相似文献
434.
This paper studies a new type of conserved quantity which is directly
induced by Mei symmetry of the Lagrange system. Firstly, the
definition and criterion of Mei symmetry for the Lagrange system are
given. Secondly, a coordination function is introduced, and the
conditions of existence of the new conserved quantity as well as its
forms are proposed. Lastly, an illustrated example is given. The
result indicates that the coordination function can be selected
properly according to the demand for finding the gauge function, and
thereby the gauge function can be found more easily. Furthermore,
since the choice of the coordination function has multiformity, many
more conserved quantities of Mei symmetry for the Lagrange system
can be obtained. 相似文献
435.
The construction of conserved quantities for linearly coupled oscillators and study of symmetries about the conserved quantities 下载免费PDF全文
In this paper, the conserved quantities are constructed using two
methods. The first method is by making an ansatz of the conserved
quantity and then using the definition of Poisson bracket to obtain
the coefficients in the ansatz. The main procedure for the second
method is given as follows. Firstly, the coupled terms in Lagrangian
are eliminated by changing the coordinate scales and rotating the
coordinate axes, secondly, the conserved quantities are obtain in
new coordinate directly, and at last, the conserved quantities are
expressed in the original coordinates by using the inverse transform
of the coordinates. The Noether symmetry and Lie symmetry of the
infinitesimal transformations about the conserved quantities are
also studied in this paper. 相似文献
436.
Unified symmetry of the nonholonomic system of non-Chetaev type with unilateral constraints in event space 下载免费PDF全文
This paper studies the unified symmetry of a nonholonomic system of
non-Chetaev type with unilateral constraints in event space under
infinitesimal transformations of group. Firstly, it gives the
differential equations of motion of the system. Secondly, it obtains
the definition and the criterion of the unified symmetry for the
system. Thirdly, a new conserved quantity, besides the Noether
conserved quantity and the Hojman conserved quantity, is deduced from
the unified symmetry of a nonholonomic system of non-Chetaev type
with unilateral constraints. Finally, an example is given to
illustrate the application of the results. 相似文献
437.
XIA Li-Li LI Yuan-Cheng WANG Jing HOU Qi-Bao 《理论物理通讯》2006,46(3):415-418
This paper concentrates on studying the symmetries and a new type of conserved quantities called Mei conserved quantity. The criterions of the Mei symmetry, the Noether symmetry and the Lie symmetry are given. The conditions and the forms of the Mei conserved quantities deduced from these three symmetries are obtained. An example is given to illustrate the application of the result. 相似文献
438.
This paper focuses on studying the relation between a velocity-dependent symmetry and a generalized Lutzky conserved quantity for a holonomic system with remainder coordinates subjected to unilateral constraints. The differential equations of motion of the system are established, and the definition of Lie symmetry for the system is given.The conditions under which a Lie symmetry can directly lead up to a generalized Lutzky conserved quantity and the form of the new conserved quantity are obtained, and an example is given to illustrate the application of the results. 相似文献
439.
Based on the infinitesimal and one parameter transformation,
the problem of Lie symmetry of three-order Lagrangian equations has
been studied. Under Lie transformation, the sufficient and necessary
condition which keeps three-order Lagrangian equations to be unchanged
and the invariant are obtained in this paper. 相似文献
440.
In this paper, we have studied the unified symmetry of a nonholonomic
mechanical system in phase space. The definition and the criterion
of a unified symmetry of the nonholonomic mechanical system in
phase space are given under general infinitesimal transformations
of groups in which time is variable. The Noether conserved
quantity, the generalized Hojman conserved quantity and the Mei
conserved quantity are obtained from the unified symmetry. An
example is given to illustrate the application of the results. 相似文献