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41.
(黄家寅)(秦圣立)THEPROBLEMSOFNONLINEARBENDINGFORORTHOTROPICRECTANGULARPLATEWITHFOURCLAMPEDEDGES¥HuangJiayin;QinShengli(QufuNormalUn... 相似文献
42.
基于Reissner-Mindlin一阶剪切变形板理论,讨论在预加面内机械荷载或温度场作用下,点支撑中厚矩形板的弯曲问题。温度场假定沿板表面为均布,沿板厚方向为线性分布的。利用考虑剪切变形影响的Timoshenko梁函数,采用Rayleigh-Ritz法给出不同边界条件下点支撑中厚板在横向荷载作用下的挠度和弯矩分布。结果表明,均匀温度场与预加面内压力将使板的挠度和弯矩增加。支撑点位置的变化、边界约束条件和横向剪切变形效应都对板的内力大小和分布有显著影响。 相似文献
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骨具有力电性质,这一性质可促进骨组织生长。骨既是生理器官又是介电材料,在交变电场作用下,其表现行为可能有生理作用。为此,本文测量了骨悬臂梁试样在交变电场下的表面温升与顶端挠度。发现在电压70V,频率为10~70kHz的交流电场下,最大表面温升达到2~4℃,最大挠度变化为9.0~78.7μm;在频率10kHz,电压为70~175V的交流电场下,最大表面温升达到4~6℃,最大挠度变化为13.0~114.3μm。同时测量了两种经典介电材料有机玻璃和聚乙烯在交变电场下的温升与顶端挠度,最大温升低于0.5℃,但是挠度与骨试样相当,所以相对高温升是骨特有的性质。将交流电压有效值替换成相同幅值的直流电压时,最大温升也低于0.5℃,基本没有挠度变化,所以相对的高温升反映了骨的交流性质。分析后认为,骨在交变电场作用下的温升由胶原的介电损耗引起。实验数据显示,骨在交变电场下,表面温度变化与加载电压的平方成正比,且在实验加载的10~70kHz频段内,骨的介电常数随频率的变化明显。 相似文献
45.
流动环是一款魔术玩具,具有丰富的力学行为。制作流动环时应用了预应力储存技术,使得环内部储存了弹性弯曲变形能。一经外界扰动,流动环会迅速张开,进入一种新的稳定平衡状态;若给张开的流体环输入某种形式的能量,环会合拢,恢复原有的稳定平衡状态。本文从能量的角度对流动环张开与合拢等现象进行力学分析。 相似文献
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Ebtisam A. Aldaais Scott Crittenden 《Journal of Polymer Science.Polymer Physics》2019,57(24):1684-1691
We incorporate the Boltzmann factors for inter‐monomer bending energy into the monomer growth direction choice in Rosenbluth's algorithm to model chains of arbitrary nearest‐neighbor rigidity. This allows for the consideration of compact (bent state lower in energy), free (straight and bent state equal in energy), or extended chains (bent state higher). We validate against, and compare to, various other results, showing very good agreement with known results for short chains and demonstrate the ability to model chains up to 500 segments long, far beyond the length at which the normal Rosenbluth method becomes unstable for reasonable nonzero bending energies. This approach is easily generalizable both to other energies determinable during chain growth, for example, polymers composed of more than one type of monomer with differing monomer interaction energies, as well as to other chain production algorithms. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1684–1691 相似文献
48.
Dr. Jiang Peng Jiakun Bai Xiumian Cao Jieting He Prof. Weiqing Xu Dr. Junhui Jia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(64):16036-16042
Elastic organic single crystals with light-emitting and multi-faceted bending properties are extremely rare. They have potential application in optical materials and have attracted the extensive attention of researchers. In this paper, we reported a structurally simple barbituric derivative DBDT , which was easily crystallized and gained long needle-like crystals (centimeter-scale) in DCM/CH3OH (v/v=2/8). Upon applying or removing the mechanical force, both the (100) and (040) faces of the needle-like crystal showed reversible bending behaviour, showing the nature of multi-faceted bending. The average hardness (H) and elastic modulus (E) were 0.28±0.01 GPa and 4.56±0.03 GPa for the (040) plane, respectively. Through the analysis of the single crystal data, it could be seen that the van der waals (C−H⋅⋅⋅π and C−H⋅⋅⋅C), H-bond (C−H⋅⋅⋅O) and π⋅⋅⋅π interactions between molecules were responsible for the generation of the crystal elasticity. Interestingly, elastic crystals exhibited optical waveguide characteristics in straight or bent state. The optical loss coefficients measured at 627 nm were 0.7 dBmm−1 (straight state) and 0.9 dBmm−1 (bent state), while the optical loss coefficient (α) were 1.5 dBmm−1 (straight state) and 1.8 dBmm−1 (bent state) at 567 nm. Notably, the elastic organic molecular crystal based on barbituric derivative could be used as the candidate for flexible optical devices. 相似文献
49.
E. Lambruschi I. Aliatis L. Mantovani M. Tribaudino D. Bersani G. J. Redhammer P. P. Lottici 《Journal of Raman spectroscopy : JRS》2015,46(6):586-590
The Raman spectra of Ge‐clinopyroxenes CaM2+Ge2O6 (M2+ = Mg, Mn, Fe, Co, Ni, Zn), general formula M2M1T2O6, are reported for the first time. Their spectral features are discussed in comparison with corresponding Si‐pyroxenes. The vibrational wavenumbers of germanates may be roughly obtained by a scale factor of about ~0.8 by those of the corresponding silicates, due to the Ge‐Si mass difference. The main peaks in the germanate Raman spectra at ~850 and ~540 cm−1 may be related to Ge‐O tetrahedral stretching and chain bending, respectively; minor peaks between 200 and 400 cm−1 are ascribed to bending and stretching of the non‐tetrahedral cations. Within Ge‐pyroxenes, possible correlations between crystallographic parameters and the vibrational wavenumbers are investigated. The main stretching mode at ~850 cm−1 shows wavenumber changes with M2+ substitutions, but no simple correlation can be found with M2+ cation mass or size. On the other hand, the chain bending wavenumber linearly decreases with increasing ionic radius of the M2+ cation: the expansion of the M1 polyhedron reduces the chain kinking angle and the Ge‐Ge distances correspondingly increase. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
50.
In this research, the experimental tests of quasi-static three-point bending and three-point bending fatigue were carried out for a ±25° biaxial braided carbon fibre reinforced polymer (CFRP) manufactured using vacuum assisted resin transfer moulding (VARTM). A finite element (FE) model was also set up for quasi-static testing and the prediction results revealed that local fibre volume fraction (FVF) is a primary source affecting the mechanical properties of braided CFRP. The fatigue of the braided CFRP was defined as three different stages according to the flexural modulus results. The damage modes of the test specimens were observed via a digital microscope and scanning electron microscope (SEM) and the process-induced defects were summarised. With compiled results and observations, this study provides a better understanding of failure and fatigue behaviour of biaxial braided composites and their flexural properties which offers a good basis for any further research in fibre volume fractions, structure design and manufacturing for braided CFRP. 相似文献