全文获取类型
收费全文 | 345篇 |
免费 | 21篇 |
国内免费 | 24篇 |
专业分类
化学 | 27篇 |
晶体学 | 1篇 |
力学 | 103篇 |
数学 | 25篇 |
物理学 | 89篇 |
综合类 | 145篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 5篇 |
2020年 | 10篇 |
2019年 | 6篇 |
2018年 | 5篇 |
2017年 | 10篇 |
2016年 | 17篇 |
2015年 | 8篇 |
2014年 | 16篇 |
2013年 | 21篇 |
2012年 | 14篇 |
2011年 | 20篇 |
2010年 | 5篇 |
2009年 | 11篇 |
2008年 | 19篇 |
2007年 | 21篇 |
2006年 | 18篇 |
2005年 | 19篇 |
2004年 | 14篇 |
2003年 | 14篇 |
2002年 | 22篇 |
2001年 | 14篇 |
2000年 | 15篇 |
1999年 | 13篇 |
1998年 | 12篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有390条查询结果,搜索用时 15 毫秒
31.
利用剪贴定片条纹设计制作不同直线方向动感的条纹动感片 总被引:1,自引:1,他引:0
王洪录 《东北师大学报(自然科学版)》1996,(1):40-43
给出运用条纹动感片迭加条纹运动规律,由测定的剪贴定片条纹数据,计算求解能产生各种不同直线方向动感的定片条纹数据的方法。 相似文献
32.
In the paper a procedure is described whereby the characterization of isotropic and anisotropic laminae is carried out by full-field measurement of the surface rotations under proper flexural loads. The analytic formulation does not necessarily imply a numerical calibration and the elastic constants are determined by integrating the whole experimental data on the surface of the specimen. Measurements were carried out by phase-stepped speckle interferometry using a shearometer based on Michelson design. The experimental instrumentation, including the loading device, and the procedures for the manipulation of experimental data are detailedly described; experimental results obtained on a steel specimen and a composite laminate are also reported. 相似文献
33.
Thin Co/Fe multilayers were e-beam evaporated in ultra-high vacuum, keeping constant the Co layer thickness and varying that
of Fe in the 0.5÷15 nm range. By increasing the Fe layer thickness, a component of magnetization perpendicular to the film
plane rises up, and long and parallel magnetic domains (stripe domains) appear. The phenomenon is explained on the basis of
the competition between the magnetoelastic anisotropy induced by stresses at the interfaces, and the shape anisotropy constraining
the magnetization in the film plane.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
34.
层合板热后屈曲分析中的Lagrangian方法 总被引:3,自引:0,他引:3
从研究层合板热后屈曲路径出发,阐述了板(梁)几何非线性有限元分析中的TL方法和UL方法,基于Von-Karman大挠度理论,分析了两种方法的差异和适用范围;通过算例指出对于层合板的热后屈曲路径的研究,只有采用UL方法才能保证在较大变形范围内正确求解。 相似文献
35.
以感水稻条纹叶枯病品种"日本晴"、高抗品种"kasalath"以及14个目前在我国长三角地区水稻生产中被认为在抵抗条纹叶枯病方面具有较好效果的水稻品种为材料,分析比较了14对分子标记引物扩增16个水稻品种基因组获得的DNA产物.结果显示:在14对分子标记引物中,有8对在扩增感病品种"日本晴"和高抗品种"Kasalath"水稻基因组时可获得多态性条带.因此推断这8个标记可在以这两个品种为亲本的抗条纹叶枯病选育中使用;并且,本研究结果还将为利用本试验收集的14个水稻品种为亲本的分子标记辅助育种提供重要的背景信息. 相似文献
36.
A mathematical formalism related to the approximate as well as the accurate interferometric data reduction schemes is briefly outlined and subsequently applied in the reconstruction of the assumed (Luneburg) axisymmetric refractive index distribution. The presented comparative analysis confirms the generally held opinion that the approximate methods (“straight-line” and Kokubun-Iga approaches) may provide quite reasonable results in the examination of refractively inhomogeneous disturbances characterized by weak gradient and moderate index variation. On the other hand, the accurate scheme for transverse interferometric data interpretation and reduction, based on the close-form correlation between the fringe shift and the deflection function, [1] remains the only method for reliable reconstruction of strongly refracting index profiles, independently of magnitude of refraction and ambiguity of the fringes. This fact is of considerable importance for transverse interferometry of fibers (preform rods) and/or GRIN-rod lenses characterized by high numerical apertures. 相似文献
37.
针对组合楼板的主要破坏模式——纵向剪切破坏,本文发现在一种新型叠合楼板中存在的连锁咬合效应,以之作为一种新的叠合面水平抗剪机制,并阐述了其作用机理.通过进行6块3类不同形式预制底板叠合成的叠合楼板的单向拟静力试验,从极限承载力、滞回曲线、自复位性能等方面总结、对比了这3种叠合板的整体受力性能,验证了这种水平抗剪机制的有效性.结果表明:相比于传统的叠合板,本文提出的这种新型叠合板中存在的连锁咬合效应减少了叠合面的损伤累积,可在一定程度上增强叠合板的变形恢复性能,提高此类叠合楼板叠合层与预制底板的协同受力性能,保证叠合试件充分发挥其极限承载能力. 相似文献
38.
A.E. Elmughrabi 《Polymer Degradation and Stability》2008,93(10):1877-1883
A small-scale loading frame was used to apply tensile and compressive stresses to glass vinyl ester and glass polyester laminates in a cone calorimeter under a heat flux of 75 kW m−2. It was found, for the first time, that stress has a small but significant effect on the fire reaction properties. Increasing tensile stress increased heat release rate and smoke production while shortening the time-to-ignition. Compressive stress had the reverse effect. This was attributed to the fact that tensile stress promotes the formation of matrix microcracks, facilitating the evolution of flammable volatiles. This hypothesis is further supported by the observation that stress has the greatest effect on the early heat and smoke release peaks, with a lower effect on the final ‘run-out’ values.Stress rupture (time-to-failure) curves were produced for tension and compression. In tension, the behaviour was fibre dominated, with times-to-failure being roughly 10 times those in compression. Compressive failure involved resin dominated local fibre kinking, initiated near to the rear face of the specimen. The failure time was determined by a significant proportion of the specimen reaching its glass transition temperature. 相似文献
39.
带裂纹层合板能量释放率分析 总被引:1,自引:1,他引:0
为了进一步了解裂纹尖端应力场的特性,本文对复合材料层合板的界面裂纹作了分析.文中强调了能量释放率分量存在的条件,并给出能量释放率分量和应力强度因子间的关系式.结合经典板理论的分析结果,根据外荷作用及某些几何参数和材料多数,导出了一般复合材料层合板的应力强度因子的封闭形式解.为了得到在一般荷载条件下能量释放率的分量,必须分别确定模型混合参数Ω,文中讨论了确定参数Ω的方法,最后,应用本文方法于几种不同种类的复合材料层合板,证明其结果可应用于工程实践. 相似文献
40.
镧系超导体中,当掺杂空穴浓度等于1/8时出现的超导反常抑制现象一直是超导研究方面的一个焦点.J.M.Tranquada将La2-XSrXCuO4中出现的动态二唯无公度(incommensurate)自旋关联解释为电荷自旋相互分离的条纹相之后,人们对镧系超导体的电子-电子、电子-晶格、以及磁相互作用进行了系统的研究.但条纹相形成的驱动机制以及条纹相与超导电性的关系等基本问题仍没有得到充分的解释. 相似文献