全文获取类型
收费全文 | 1394篇 |
免费 | 152篇 |
国内免费 | 153篇 |
专业分类
化学 | 72篇 |
晶体学 | 6篇 |
力学 | 328篇 |
综合类 | 7篇 |
数学 | 8篇 |
物理学 | 1278篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 11篇 |
2021年 | 17篇 |
2020年 | 9篇 |
2019年 | 5篇 |
2018年 | 12篇 |
2017年 | 34篇 |
2016年 | 31篇 |
2015年 | 40篇 |
2014年 | 61篇 |
2013年 | 42篇 |
2012年 | 51篇 |
2011年 | 68篇 |
2010年 | 60篇 |
2009年 | 71篇 |
2008年 | 68篇 |
2007年 | 86篇 |
2006年 | 81篇 |
2005年 | 71篇 |
2004年 | 76篇 |
2003年 | 71篇 |
2002年 | 63篇 |
2001年 | 74篇 |
2000年 | 78篇 |
1999年 | 48篇 |
1998年 | 38篇 |
1997年 | 73篇 |
1996年 | 45篇 |
1995年 | 39篇 |
1994年 | 35篇 |
1993年 | 35篇 |
1992年 | 30篇 |
1991年 | 16篇 |
1990年 | 28篇 |
1989年 | 21篇 |
1988年 | 26篇 |
1987年 | 27篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1699条查询结果,搜索用时 123 毫秒
21.
表面粗糙度测量的磁光位相调制和锁相干涉 总被引:1,自引:0,他引:1
提出了一种表面粗糙度测量的新方法,该方法采用了微分偏振干涉的原理,利用由法拉第磁光调制器所组成的调制系统对偏振干涉光路的位相进行调制,利用锁相干涉原理对位相进行探测,该方法可实现无参考面快速非接触测量,在普通实验条件下,也可保持良好的稳定恶性循环 ,实验装置即可给出表面的轮廓又可给出其它统计数据,其横向分辨率为1.2μm纵向为2nm。 相似文献
22.
An acoustic pulse propagating on a two-mode fiber can act as a beam splitter in a scanning interferometer. When this device
is employed in white-light interferometry, the effects of distributed coupling and dispersive interferometer arms need to
be considered. A theory suitable for treating acousto-optic interaction of partially coherent light in a moving interaction
region was developed. It was found that differential optical dispersion should be negligible and the acoustic pulse length
short. Also the coherence time should be short but long compared to the intermodal group delay difference over a pulse length.
Experiments with long acoustic pulses were performed, and fairly good agreement with theory was obtained. 相似文献
23.
Holographic interferometry is proposed to detect the change in the mechanical responses of reed stems growing in eutrophic, as compared with those in healthy, water bodies. The detection of the difference in behaviour could be a sensitive way to index the degree of eutrophication. An interferometric method based on holomicroscopic moiré is developed and preliminary results obtained are presented. 相似文献
24.
CHENG Chuanfu SONG Hongsheng LIU Chunxiang REN Xiaorong ZHANG Ningyu TENG Shuyun & XU Zhizhan . Shanghai Institute of Optics Fine Mechanics Chinese Academy of Sciences P. O. Box - Shanghai China . Department of Physics Shandong Normal University Jinan China . Shandong Institute of Architecture Engineering Jinan China 《中国科学G辑(英文版)》2004,47(3):365-380
Speckle fields are the random light wave distributions produced when the light fields are scattered from random surfaces or a random medium. They appear in many optical phenomena that are related to light propagations[1,2] and have found wide appli-cations in a variety of scientific and technical fields. The examples of the recent impor-tant applications of speckles include the analysis of the movement of the granules[3], the three-dimensional imaging for the microstructures of metal nanocryst… 相似文献
25.
26.
Mechanics of Composite Materials - A three-dimensional ply-level modeling of multiple matrix cracking near an open hole in a quasi-isotropic composite laminate was performed. A mesh-independent... 相似文献
27.
Applications of electronic speckle interferometry (ESI) techniques for spacecraft structural components 总被引:1,自引:0,他引:1
Laser-based electronic speckle interferometry (ESI) techniques, viz., electronic speckle pattern interferometry (ESPI) and electronic speckle shearographic interferometry (ESSI) are used for testing of spacecraft structural components. The combined ESPI and ESSI system developed in house was successfully used for the non-destructive evaluation (NDE) of honeycomb sandwich panels and propellant tanks of Indian Space Research Organization (ISRO). Debonds between face sheet and the honeycomb core were identified using (i) thermal and (ii) dual vacuum stressing methods. On-line NDE of the propellant tanks under internal pressure loading for identification of the minute cracks and thickness reduction areas were successfully implemented by ESI. 相似文献
28.
Yoshiaki Yasuno Yasunori Sutoh Shuichi Makita Masahide Itoh Toyohiko Yatagai 《Optical Review》2003,10(5):498-500
A spectral interferometric optical coherence tomography (OCT) system which has polarization sensitivity is developed. This system reduces the mechanical scanning dimension by employing the principle of spectral interferometry, and measures a two dimensional cross-sectional image of biological tissue with one dimensional mechanical scanning. Sixteen OCT images with different polarization conditions are measured, and two dimensional distributions of each element of the Müller matrix of a sample to be measured are calculated. 相似文献
29.
30.
This paper presents a fringe pattern normalization and noise-reduction algorithm. Locally the background noise is suppressed, the modulation normalized and the noise smoothed. An expression to calculate the cosine-only term is formulated. It is related to the directional derivatives of the intensity fringes. Two-dimensional Fourier series are used to calculate the parameters needed for the algorithm. Experimental work is presented using diffraction and ESPI images. The programming is relatively simple and involves mainly local convolutions. The processing time using a 2 GHz computer to normalize an image of 256 × 256 pixels is approximately one second. 相似文献