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101.
以氰尿酸、二苯甲烷双马耒酰亚胺、环氧树脂和潜伏性固化剂为原料,合成了一种新型耐热性树脂,并压制了相应的玻璃布层压板。由于加入了适宜的固化剂,树脂溶液贮存稳定性好,易于成型加工。采用IR、DSC、DTA、TG和凝胶化时间测定等方法研究了树脂的固化过程和热稳定性。该树脂在150°以上固化迅速,固化热焓达-42.88卡/克。该树脂在170°固化5小时与在210℃固化4小有完全相同的热失重(TG)曲线。在170℃下压制的玻璃布层压板具有优良的高温介电性能和力学性能,180℃时的弯曲强度和介质损耗角正切值(工频)分别为346MPa和0.0212。 相似文献
102.
Three-dimensional solution for a hybrid cylindrical shell under axisymmetric thermoelectric load 总被引:2,自引:0,他引:2
S. Kapuria S. Sengupta P. C. Dumir 《Archive of Applied Mechanics (Ingenieur Archiv)》1997,67(5):320-330
Summary An exact axisymmetric piezothermoelastic solution is presented for a simply-supported hybrid cylindrical shell made of cross-ply
composite laminate and piezoelectric layers. Numerical results for hybrid shells are presented for sinusoidal and central
band thermal and electrical loads. The effect of the loading, the radius-to-thickness ratio, the span-to-radius ratio and
the number of layers of the substrate on the response is investigated. The interface between the substrate and the actuated
piezoelectric layer has been found to be subjected to high shear stress. It has been shown that the maximum values of the
deflection and the stresses, due to thermal load, can be appreciably reduced by appropriate application of actuation potential.
Accepted for publication 13 October 1996 相似文献
103.
The roll bonding technique is one of the most widely used methods to produce metal laminate sheets. Such sheets offer interesting research opportunities for both scientists and engineers. In this paper, we report on an experimental investigation of the ‘thickness effect’ during laminate rolling for the first time. Using a four-high multifunction rolling mill, Cu/Al/Cu laminate sheets were fabricated with a range of thicknesses (16, 40, 70 and 130 μm) of the Al layer. The thickness of the Cu sheets was a constant 300 μm. After rolling, TEM images show good bonding quality between the Cu and Al layers. However, there are many nanoscale pores in the Al layer. The fraction of nanoscale pores in the Al layer increases with a reduction in the Al layer thickness. The finite element method was used to simulate the Cu/Al/Cu rolling process. The simulation results reveal the effect of the Al layer thickness on the deformation characteristics of the Cu/Al/Cu laminate. Finally, we propose that the size effect of the Al layer thickness during Cu/Al/Cu laminate rolling may offer a method to fabricate ‘nanoporous’ Al sandwich laminate foils. Such foils can be used in electromagnetic shielding of electrical devices and noisy shielding of building. 相似文献
104.
Two approaches to the investigation of the stress-strain state and of free vibration frequencies of laminate panels with gently curved orthotropic layers are elaborated. The first approach is based on the analytical separation of variables, and in the second one the variables are approximated with respect to the transverse coordinate by the polynomials obtained from the Ambartsumyan iteration approach. Since the unknown functions in this approximation are related to the front surfaces of the structure, the panel can be divided, if necessary, into separate strips across the thickness with a rigid or sliding contact between them. The displacements on the lower surface can be excluded.Ukrainian Transport University, Kiev, Ukraine. Translated from Mekhanika Kompozitnykh Materialov, Vol. 35, No. 4, pp. 423–434, 1999. 相似文献
105.
磁致伸缩/压电复合材料通过磁致伸缩和压电效应的乘积而可以获得大的磁电效应.用磁控溅射方法制备了TbDyFe/PZT层状复合材料,实验测试了TbDyFe/PZT两层及TbDyFe/PZT/TbDyFe三层复合材料的磁电电压系数随周期磁场频率的变化关系,并采用有限元数值计算方法对两种材料的磁电电压系数进行了计算.研究结果表明,实验测试曲线与数值计算结果符合很好,所制备的层状复合材料在共振频率处存在最大的磁电电压系数值,由于两层板与三层板的振动模式不同,三层复合板的共振频率远高于两层复合板的共振频率.在非共振频率下,三层复合板的磁电转换效应高于两层复合板.有限元计算结果还显示,磁电层状复合材料的磁电电压系数随磁致伸缩层厚度的增加而增大.
关键词:
磁电效应
层合板
TbDyFe
有限元分析 相似文献
106.
107.
基于纵向极化压电材料及纵向磁化磁致伸缩材料的压电和压磁方程与磁电元件运动方程,给出磁电元件开路电压表达式;鉴于压电材料高输出阻抗的特点,考虑测试仪器的有限输入阻抗和传输信号引线电缆电容,通过建立等效电路模型推出了非开路情况下磁电电压计算式,取不同材料参数对磁电电压进行了数值计算.研究表明,材料参数、电路参数对输出电压均产生影响.对磁伸材料两端面受非均匀偏置磁场产生外力的非自由边界磁电效应进行研究发现,恒外力作用使压电元件产生不可检测的稳恒电压.
关键词:
纵向极化
磁电效应
磁电元件
层叠材料 相似文献
108.
Air-coupled transducers can be employed for generation and reception of Lamb waves in composite laminates. To generate and receive a particular Lamb mode, the transducers are oriented in a particular angle. The orientations of transducers also determine amplitude of a particular Lamb mode of interest. Any deviation (misalignment) from the right orientation results in a reduction in the amplitude. Therefore, an attempt has been made to establish variation in amplitude of the fundamental anti-symmetric Lamb mode (Ao) when misalignments were purposefully introduced in the air-coupled probes. In the present work, three different misalignments – linear, orientation and synchronized orientation were envisaged. Experiments were performed on two laminates – unidirectional ([03]s) and cross-ply ([0/902/0]s) of GFRP (Glass Fiber Reinforced Plastic) material. Curves were fitted on experimental data to characterize variation in amplitude of Ao mode in each misalignment. Moreover, wave splitting and merging was observed when the probe(s) was (were) rotated in a particular direction in orientation and synchronized orientation misalignments. 相似文献
109.
Tetsuya Matsuda Dai Okumura Nobutada Ohno Masamichi Kawai 《International Journal of Solids and Structures》2007,44(25-26):8274-8284
In this study, a method for three-dimensional microscopic interlaminar analysis of cross-ply laminates is developed based on a homogenization theory to analyze microscopic interactions between unidirectional long fiber-reinforced laminae. For this, a unit cell of a cross-ply laminate, which includes interlaminar areas, is defined under the assumption that each lamina in the laminate has a transversely square fiber array. Then, showing that the laminate has a point-symmetric internal structure, the symmetry is utilized to introduce half of the unit cell as the domain of analysis. Moreover, the domain of analysis is divided into substructures using a substructure method combined with the homogenization theory, significantly reducing the computational costs. The present method is then applied to the analysis of interlaminar stress distributions in a carbon fiber/epoxy cross-ply laminate subjected to in-plane uniaxial tension. It is shown that microscopic shear stress noticeably occurs at the interface between the 0°- and 90°-plies. It is also shown that the microscopic interaction between the two plies is observed only in the vicinity of the interface. 相似文献
110.