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 359 毫秒
71.
ZHANG Xiao-Ni FANG Jian-Hui LIN Peng PANG Ting 《理论物理通讯》2008,49(5):1145-1147
In this paper, a new type of conserved quantity directly deduced from the Mei symmetry for relativistic variable mass system in phase space is studied. The definition and the criterion of the Mei symmetry for the system are given. The conditions for existence and the form of the new conserved quantity are obtained. Finally, an example is given to illustrate the application of the results. 相似文献
72.
ZHANG Xiao-Ni FANG Jian-Hui PANG Ting LIN Peng 《理论物理通讯》2009,51(2):205-208
For a nonholonomic mechanical system, the generalized Mei conserved quantity and the new generalized Hojman conserved quantity deduced from Noether symmetry of the system are studied. The criterion equation of the Noether symmetry for the system is got. The conditions under which the Noether symmetry can lead to the two new conserved quantities are presented and the forms of the conserved quantities are obtained. Finally, an example is given to illustrate the application of the results. 相似文献
73.
XIA Li-Li LI Yuan-Cheng WANG Xian-Jun 《理论物理通讯》2009,51(6):1073-1077
The Mei symmetries and the Lie symmetries for nonholonomic controllable mechanical systems with relativistic rotational variable mass are studied. The differential equations of motion of the systems are established. The definition and criterion of the Mei symmetries and the Lie symmetries of the system are studied respectively. The necessary and sufficient condition under which the Mei symmetry is Lie symmetry is given. The condition under which the Mei symmetries can be led to a new kind of conserved quantity and the form of the conserved quantity are obtained. An example is given to illustrate the application of the results. 相似文献
74.
Mei symmetry and Mei conserved quantity for a non-holonomic system of non-Chetaev's type with unilateral constraints in the Nielsen style are studied. The differential equations of motion for the system above are established. The definition and the criteria of Mei symmetry, conditions, and expressions of Mei conserved quantity deduced directly from the Mei symmetry are given. An example is given to illustrate the application of the results. 相似文献
75.
Two new types of conserved quantities deduced by Noether-Mei symmetry of nonholonomic mechanical system are studied. The definition and criterion of Noether-Mei symmetry for the system are given. A coordination function is introduced, and the conditions under which the Noether-Mei symmetry leads to the two types of conserved quantities and the forms of the two types of conserved quantities are obtained. An illustrative example is given. The coordination function can be selected according to the demand for finding the gauge function, and the choice of the coordination function has multiformity, so more conserved quantities deduced from Noether-Mei symmetry of mechanical system can be obtained. 相似文献
76.
This paper studies a new type of conserved quantity which
is directly induced by Lie symmetry of the Lagrange system. Firstly, the
criterion of Lie symmetry for the Lagrange system is given. Secondly,
the conditions of existence of the new conserved quantity as well as
its forms are proposed. Lastly, an example is given to illustrate
the application of the result. 相似文献
77.
Mei symmetry and Mei conserved quantity of Appell equations for a variable mass holonomic system 下载免费PDF全文
Mei symmetry and Mei conserved quantity of Appell
equations for a variable mass holonomic system are investigated.
Appell equations and differential equations of motion for a variable
mass holonomic system are established. A new expression of the total
first derivative of the function with respect of time t along the
systematic motional track curve, and the definition and the
criterion of Mei symmetry for Appell equations under the
infinitesimal transformations of groups are given. The expressions
of the structural equation and Mei conserved quantity for Mei
symmetry in Appell are obtained. An example is given to illustrate
the application of the results. 相似文献
78.
This paper discusses the weak Noether symmetry for a nonholonomic controllable mechanical system of Chetaev type, and presents expressions of three kinds of conserved quantities obtained by using weak Noether symmetry. Finally, the application of these new results is illustrated by an example. 相似文献
79.
After a Birkhoff system is restricted by constraints, the determining equations, the Lie symmetries, the structure equation and the form of conserved quantities corresponding to the Lie symmetries will change. Some Lie symmetries will disappear and under certain conditions some Lie symmetries will still remain present. The condition under which Lie symmetries and conserved quantities of the system will remain is given. 相似文献
80.
The form invariance of Appell equations of holonomic mechanical systems under the infinitesimal transformations of groups is studied. The definition and the criterion of the form invariance of Appell equations are given. This form invariance can lead to a conserved quantity under certain conditions. 相似文献