全文获取类型
收费全文 | 73篇 |
免费 | 13篇 |
国内免费 | 12篇 |
专业分类
化学 | 4篇 |
晶体学 | 1篇 |
力学 | 53篇 |
数学 | 6篇 |
物理学 | 34篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2014年 | 1篇 |
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 4篇 |
2010年 | 2篇 |
2009年 | 4篇 |
2008年 | 7篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
排序方式: 共有98条查询结果,搜索用时 15 毫秒
51.
集成马赫-曾德尔热光耦合器的可调谐振环优化设计 总被引:1,自引:1,他引:0
根据耦合模理论,推导出可调谐光波导谐振环的光强和相位传递函数的表达式,并分析了可调谐谐振环的传输特性.结果表明,谐振环中集成的马赫-曾德尔耦合器的参量设定和调谐方式直接影响谐振环的谐振频率移动范围和调制功率.通过改变耦合器参量对谐振环进行优化设计,在中心波长为1550 am附近,谐振环半径2 cm,传输损耗0.08 dB/cm的情况下,实现了清晰度和最佳谐振深度的调谐,谐振频率的移动范围低于0.027 GHz,降低了谐振环对频率调制器的调频要求,同时降低了耦合器的调制功率. 相似文献
52.
Effects of notches on the order of flux-closure state formation in bi-rings by micromagnetic simulation 下载免费PDF全文
The effects of the number and the location of notches on the formation of flux-closure states in bi-rings with fields applied in the x direction (i.e., along the short axis direction of bi-rings) and y direction (i.e., along the long axis direction of bi-rings) are investigated using micromagnetic simulation. For the bi-rings with one notch and the bi-rings with two notches symmetric about y axis, the order of flux-closure state formation in each ring can be controlled. But the flux-closure state forms simultaneously in each ring for the bi-rings with two notches symmetric about x axis. For the bi-rings with two notches that are symmetric neither about x axis nor about y axis, only one ring can form a flux-closure state in the y-direction field and no flux-closure state can be found in rings in the x-direction field. Therefore, logic states can be defined by controlling the order of flux-closure state formation, which can be utilized in future logic devices. 相似文献
53.
为解决托卡马克磁体电源系统中出现的低频谐波检测问题,研究了基于可调参数 Q 的 F42N150 单
频模拟陷波器和椭圆数字带通滤波器的混合检测算法。通过边界优化有效剔除干扰基波及 5 次谐波,实现有效的
频谱分离。利用 MATLAB 优化了为设计过程进行,使用基于 DSP 的数字分析系统进行了试验验证,验证了检测
算法的正确性和有效性。 相似文献
54.
In this paper, the eigenequation of notch in Reissner plate is derived by the eigenfunction method. Eigenvalues of different notches with different angles are calculated by Muller iteration method.The expression of stress and strain at the tip of notch in Reissner plate is obtained. 相似文献
55.
Based on the tranditional V-notched blasting, a technique of spirally V-notched blasting to loosen earth and rock was presented. Fracture mechanics and Westergaard stress function were adopted to build a complex stress function to derive the plane stress and strain fields at one tip of the crack under a quasi-static pressure. An expression was formulated to define the stress intensity factor of spiral V-notch loosen blasting. Factors that have effects on the stress intensity factor were studied. It is demonstrated that spiral V-notch loosen blasting is an extension of vertical V-notch blasting, straight cracking, and alike theories. 相似文献
56.
A TTF-type coaxial higher order modes (HOM) coupler has been used in a TESLA 9 cell cavity. It is impossible to measure the stop band characteristics of the HOM coupler with the cavity. A measurement device for the coaxial transmission line type for the HOM coupler has been designed at Peking University. Experimentally it was shown that the average voltage standing wave ratio of the coaxial transmission line is smaller than 1.08. The experimental results of the stop band characteristics of the TTF-type HOM coupler have been fitted for the simulation. This paper describes the design of the measurement device and discusses the experimental and simulation results of stop band characteristics of the HOM coupler. 相似文献
57.
Elastic analysis of an elliptic notch in quasicrystals of point group 10 subjected to shear loading 下载免费PDF全文
Based on the stress potential and complex variable
function method, this paper makes an elastic analysis of an
elliptic notch subjected to uniform shear stress at infinity in
quasicrystals with point group 10. With the aid of conformal
transformation, an exact solution for the elliptic notch of the
quasicrystals is obtained. The solution of the mode {\rm II}
Griffith crack as a special case is constructed. The stress
intensity factor and energy release rate have been also obtained as
a direct result of the crack solution. 相似文献
58.
以飞机螺旋桨叶常用材料LY11CZ铝合金锻件的材料试件、腐蚀试件和缺口试件的疲劳极限实验结果为依据,研究了腐蚀与缺口对疲劳极限的影响,给出腐蚀试件和缺口试件疲劳极限的关系,并建立起一种只用材料疲劳极限来确定严重腐蚀情况对应的疲劳极限分布的方法,以适应螺旋桨叶等按无限寿命准则设计的构件评估腐蚀后疲劳可靠性的工程需求. 相似文献
59.
60.
Yazhou Guo Yulong Li 《Acta Mechanica Solida Sinica》2012,25(3):299-311
Modifications were made on the traditional split Hopkinson pressure bar (SHPB) system to conduct dynamic shear tests. The shear response of Ti-6Al-4V was acquired at a shear strain rate of 10 4 s 1 by using this modified apparatus. The geometry as well as the clamping mode of the double-notch specimen was optimized by commercial FEM software ABAQUS, and the feasibility of the experiment set-up was validated. A shear stress calibration coefficient of τ = 1.03 and a shear strain calibration coefficient of Γ = 0.50 were obtained.We have employed high-speed photography to record the deformation process, especially the initiation and propagation of adiabatic shear band (ASB), during the dynamic shear test. The frames show that the time duration from ASB initiation to its completion is less than 2 μs, from which we can estimate that the propagation speed of ASB within Ti-6Al-4V is more than 1250 m/s under such loading conditions. The temperature rise within ASB is also estimated to be T 2 ≈ 1460℃ based on energy balance. Such high temperature has led to softening of the material within the ASBs, and has intensified the shear localization and finally resulted in fracture of the material. 相似文献