全文获取类型
收费全文 | 207篇 |
免费 | 46篇 |
国内免费 | 9篇 |
专业分类
化学 | 31篇 |
力学 | 62篇 |
综合类 | 16篇 |
数学 | 67篇 |
物理学 | 86篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 17篇 |
2013年 | 11篇 |
2012年 | 10篇 |
2011年 | 17篇 |
2010年 | 19篇 |
2009年 | 15篇 |
2008年 | 14篇 |
2007年 | 17篇 |
2006年 | 13篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 8篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 10篇 |
1996年 | 5篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1984年 | 1篇 |
排序方式: 共有262条查询结果,搜索用时 252 毫秒
71.
72.
平面杆系结构静力分析的统一模型 总被引:1,自引:0,他引:1
从平面杆单元的经典刚度方程出发,在引入基本假定的基础上由严格的数学方法得到了平面杆系结构的统一计算模型.当该模型中的有关参数取特殊值时可直接得到理想的衍架模型和刚性连接模型,而且可用于具有任意半刚性连接和混合结点的一般杆系结构的静力分析. 相似文献
73.
ZHAO Guang-ming 《应用数学和力学(英文版)》2005,26(8):982-988
IntroductionMeshless methods, as a special numerical method, originated from1970s. Since thediffuse element method was proposed by Nayroleset al.[1]in1992, the meshless methodshave received wide attentions in the mechanics area, and have shown obvious adv… 相似文献
74.
An electromagnetically induced grating in a four-level tripod-type atomic system is studied theoretically. By virtue of a weak standing-wave signal field, the phase modulation effectively diffracts a weak probe field into the first-order direction. By changing the weak signal field, the diffraction of the weak probe field can be modulated in real time, and a first-order diffraction efficiency of more than 32% can be obtained with proper parameters. Such a system has a potential application in an all-optical switch controlled by a weak optical signal. 相似文献
75.
A compact all-solid-state continuous-wave (CW) laser at 1047 nm is developed based on Nd:LuLF, which is grown through the Czochralski technique. From the laser system, 1.3-W laser can be obtained, which corresponds to the slope efficiencies of 20.1% and 49.5% with respect to the incident and absorbed pump powers, respectively. To the best of our knowledge, this is the highest power level achieved at 1047 nm based on the Nd:LuLF crystal. 相似文献
76.
77.
Time integration algorithm is a key issue in solving dynamical system. An unconditionally stable Hamel generalized α method is proposed to solve the instability issue arising in the time integration of dynamic equations and to eliminate the pseudo high order harmonics incurred by the spatial discretization of finite element simultaneously. Therefore, the development of numerical integration algorithm to solve the above-mentioned problems has important theoretical and application value. The algorithm proposed in this paper is developed based on the moving frame method and Hamel’s field variational integrators along with the strategy to construct an unconditionally stable Hamel generalized α method. It is shown that a new numerical formalism with higher accuracy can be derived under the same framework of the unconditional stable algorithm established through a special variational formalism and variational integrators. The above-mentioned formalism can be extended from general linear space to Lie group by utilizing the moving frame method and the Lie group formalism of the Hamel generalized α method has been obtained. Both the convergence and stability of the algorithm are discussed, and some numerical examples are presented to verify the conclusion. It is demonstrated by the theoretical analysis that the Hamel generalized α method proposed in the paper is unconditionally stable, second-order accurate and can quickly filter out pseudo high-frequency harmonics. Both conventional and proposed methods have been applied to numerical examples respectively. Comparisons between results of numerical examples show that the aforementioned advantages of the proposed method in terms of accuracy, dissipation and stability are tested and verified. At the same time, it can be developed that new numerical integration algorithms with even higher order accuracy. The scheme can also be proposed, which is suitable for both general linear space and Lie group space. A new way for constructing variational integrators is also obtained in this paper. 相似文献
78.
Cladding-Pumped Tm^3+-Doped Large-Mode-Area Fibre Laser Highly Efficient Output at Approximately 2μm 下载免费PDF全文
A cladding-pumped Tm^3+-doped fibre laser is carried out to generate continuous-wave output power up to 8.4 W at approximately 2 μm with a slope efficiency of 57% compared to the launched pump power. When the fibre is cooled by water, the slope efficiency increases greatly and the output laser spectrum has a blue shift. 相似文献
79.
80.
借助转动物体的力学知识, 对溜溜球的运动过程进行了分析和解释, 证明其满足机械能守恒, 且与圆盘
沿斜坡滚动的过程具有相似性 相似文献