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61.
Carbon nitride thin films were prepared by electron-beam evaporation
assisted with nitrogen ion bombardment and TiN/CNx composite films were by
unbalanced dc magnetron sputtering, respectively. It was found that the
sputtered films were better than the evaporated films in hardness and
adhesion. The experiments of atomic oxygen action, cold welding, friction
and wearing were emphasized, and the results proved that the sputtered
TiN/CNx composite films were suitable for space application. 相似文献
62.
黄民海 《应用数学和力学(英文版)》1999,20(7):812-818
IntroductionUptonow,therehavebenmanyresearchesontheplaneweldingproblemofisotropicmaterials.e.g.[1]and[2]etc.However,forthepla... 相似文献
63.
双周期裂纹场平面弹性焊接的数学问题 总被引:3,自引:0,他引:3
本文讨论双周期胞腔中含任意形状裂纹的不同材料的弹性平面焊接(焊线为任意形状的封闭光滑曲线)的第二基本问题.运用Мусхелишвили复变函数方法,对这类弹性平面问题建立起了数学模型,将求解弹性平衡问题化归为寻求复应力函数满足一定边界条件的边值问题,然后构造其解的形式,再将其转化为正则型的奇异积分方程,数学上严格证明其解的存在与唯一. 相似文献
64.
两个各向异性半平面的焊接问题 总被引:3,自引:1,他引:2
本文利用复变函数方法,研究了两个各向异性半平面的焊接问题,得到了应力分布的封闭形式解. 相似文献
65.
Tong Wu Haoxuan Li Jiajia Xue Xiumei Mo Younan Xia 《Angewandte Chemie (International ed. in English)》2019,58(46):16416-16421
We report a simple method for the photothermal welding of nonwoven mats of electrospun nanofibers by introducing a near‐infrared (NIR) dye such as indocyanine green. By leveraging the strong photothermal effect of the dye, the nanofibers can be readily welded at their cross points or even over‐welded (i.e., melted and/or fused together) to transform the porous mat into a solid film upon exposure to a NIR laser. While welding at the cross points greatly improves the mechanical strength of a nonwoven mat of nanofibers, melting and fusion of the nanofibers can be employed to fabricate a novel class of photothermal papers for laser writing or printing without chemicals or toner particles. By using a photomask, we can integrate photothermal welding with the gas foaming technique to pattern and then expand nonwoven mats into 3D scaffolds with well‐defined structures. This method can be applied to different combinations of polymers and dyes, if they can be co‐dissolved in a suitable solvent for electrospinning. 相似文献
66.
Dmitry G. Luchinsky Halyna Hafiychuk Vasyl Hafiychuk Kenta Chaki Hiroya Nitta Taku Ozawa Kevin R. Wheeler Tracie J. Prater Peter V. E. McClintock 《Journal of polymer science. Part A, Polymer chemistry》2020,58(15):2051-2061
We consider an atomistic model of thermal welding at the polymer-polymer interface of a polyetherimide/polycarbonate blend, motivated by applications to 3D manufacturing in space. We follow diffusion of semiflexible chains at the interface and analyze strengthening of the samples as a function of the welding time tw by simulating the strain–stress and shear viscosity curves. The time scales for initial wetting, and for fast and slow diffusion, are revealed. It is shown that each component of the polymer blend has its own characteristic time of slow diffusion at the interface. Analysis of strain–stress demonstrates saturation of the Young's modulus at tw = 240 ns, while the tensile strength continues to increase. The shear viscosity is found to have a very weak dependence on the welding time for tw > 60 ns. It is shown that both strain–stress and shear viscosity curves agree with experimental data. 相似文献
67.
The microstructural evolution of pure copper during friction-stir welding was found to be principally influenced by welding temperature. At temperatures below ~0.5 Tm (where Tm is melting point), the microstructure was shown to be essentially determined by continuous recrystallization, leading to significant grain refinement and related material strengthening in the stir zone. In contrast, grain structure development at temperatures above ~0.5 Tm was dominated by discontinuous recrystallization producing a relatively coarse grain structure in the stir zone and giving rise to material softening. 相似文献
68.
硬质WC粒子增强镍基合金喷熔层耐磨粒磨损性能的研究 总被引:15,自引:1,他引:15
WC粒子增强镍基合金复合材料具有良好的耐磨性能和广阔的应用前景.为了更好地利用这种复合材料,研究了硬质WC粒子的尺寸、含量、几何形状和镍基合金的化学组成等因素对喷熔层耐磨粒磨损性能的影响.结果表明,在给定的试验条件下,当WC粒子为球形,质量分数为50%,粒子的平均尺寸为200μm和镍基合金为Ni60时,喷熔层的耐磨粒磨损性能最好 相似文献
69.
爆炸焊接驻点近区应变率分布规律计算 总被引:4,自引:0,他引:4
为了认识爆炸焊接驻点近区材料的力学和热学行为 ,分析波状界面和绝热剪切带生成 ,采用理想流体对称碰撞模型沿流线研究了驻点近区的应变率分布规律 ,并推导出了驻点应变率的理论计算公式。通过数值与理论计算对爆炸焊接碰撞角、界面距离等因素对应变率的影响进行了讨论。计算结果表明 ,爆炸焊接中强烈变形集中在驻点附近区域 ,其应变率高达 10 6~ 10 7s-1,拉压应变率的绝对值在驻点处达到最大 ;而剪应变在焊接界面上为零 ,其最大值出现在驻点的前方 ,为拉压应变率的约二倍。 相似文献
70.