全文获取类型
收费全文 | 1157篇 |
免费 | 102篇 |
国内免费 | 94篇 |
专业分类
化学 | 67篇 |
晶体学 | 7篇 |
力学 | 242篇 |
综合类 | 3篇 |
数学 | 9篇 |
物理学 | 1025篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 11篇 |
2021年 | 15篇 |
2020年 | 7篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 27篇 |
2016年 | 31篇 |
2015年 | 35篇 |
2014年 | 40篇 |
2013年 | 32篇 |
2012年 | 41篇 |
2011年 | 54篇 |
2010年 | 49篇 |
2009年 | 59篇 |
2008年 | 55篇 |
2007年 | 72篇 |
2006年 | 66篇 |
2005年 | 59篇 |
2004年 | 70篇 |
2003年 | 55篇 |
2002年 | 53篇 |
2001年 | 61篇 |
2000年 | 62篇 |
1999年 | 37篇 |
1998年 | 26篇 |
1997年 | 51篇 |
1996年 | 36篇 |
1995年 | 25篇 |
1994年 | 25篇 |
1993年 | 29篇 |
1992年 | 23篇 |
1991年 | 13篇 |
1990年 | 19篇 |
1989年 | 15篇 |
1988年 | 19篇 |
1987年 | 17篇 |
1986年 | 7篇 |
1985年 | 10篇 |
1984年 | 11篇 |
1983年 | 7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1353条查询结果,搜索用时 31 毫秒
51.
An interferometer having accuracy in displacement measurement of <1 nm is necessary in nanometrology. To meet the requirement, the periodic nonlinearity mainly caused by polarization and frequency mixings should be less than deep sub-nanometer. In this paper, two spatial-separated polarization beams are used to avoid mixings and then the periodic nonlinearity. The developed interferometer demonstrates a periodic nonlinearity of about 25 pm and a 2 pm/Hz in displacement noise level. 相似文献
52.
Feedback interferometers are described with specific reference to potential applications in micro-machines. A theoretical analysis is developed to determine the linearity, stability, and noise performance of this type of interferometer. The theoretical analysis was tested using a prototype high-precision feedback interferometer which showed that, at a feedback loop gain which enabled the system to track 6 fringes, the linearity of the interferometer was better than λ/100 and single phase measurements could be made with an accuracy of λ/80. 相似文献
53.
M. Lawrence 《Optics & Laser Technology》1984,16(3):137-140
The general design, operating principles, and accuracy limitations of cw laser wavemeters based on the Michelson interferometer are discussed. Device construction and operating practicalities are illustrated by reference to an automatic system built to monitor the wavelength of a Coherent 599-21 single-mode dye laser. 相似文献
54.
55.
R. S. Sirohi 《Optics & Laser Technology》1984,16(5):251-254
A number of speckle shear methods and their applications to ndt are discussed. Experiments using multiple apertures with custom-made optical elements have shown that in-plane displacement, slope and curvature patterns can be obtained by filtering through appropriate haloes. 相似文献
56.
We present applications of polar plots for analyzing fluorescence lifetime data acquired in the frequency domain. This graphical,
analytical method is especially useful for rapid FLIM measurements. The usual method for sorting out and determining the underlying
lifetime components from a complex fluorescence signal is to carry out the measurement at multiple frequencies. When it is
not possible to measure at more than one frequency, such as rapid lifetime imaging, specific features of the polar plot analysis
yield valuable information, and provide a diagnostic visualization of the participating fluorescent species underlying a complex
lifetime distributions. Data are presented where this polar plot presentation is useful to derive valuable, unique information
about the underlying component distributions. We also discuss artifacts of photolysis and how this method can also be applied
to samples where each fluorescence species shows a continuous distribution of lifetimes. Polar plots of frequency-domain data
are commonly used for analysis of dielectric relaxation experiments (Cole–Cole plots), which have proved to be exceptionally
useful in that field for decades. We compare this analytical tool that is well developed and extensively used in dielectric
relaxation and chemical kinetics to fluorescence measurements. 相似文献
57.
Yande Xu 《Optical Review》2004,11(5):303-307
This paper proposes a new measuring method called two-period interference fringe interferometry, for a step-profile altitude difference measurement. The principle of the method is different from that of the two-wavelength interferometry which is widely known. The two interference fringes with only slight difference between their spatial periods are obtained by turning a binary step-grating, and they produce a synthetic equivalent period much longer than either of the two periods alone. The interference fringes are produced by the ±1st-order beams diffracted from the grating. The intensity distribution of the interference pattern is independent of the wavelength of the laser-diode light source used. The measuring range of this method is much larger than that of the two-wavelength interferometery. Sinusoical phase modulating technique is easily applied to detect the phase distribution of the interference pattern by vibrating the grating sinusoidally. A plane reflector of 3mm thickness is measured to verify this novel method. 相似文献
58.
59.
Measurement Accuracy in Phase-Shifting Point Diffraction Interferometer with Two Optical Fibers 总被引:1,自引:0,他引:1
Toshiaki Matsuura Satoru Okagaki Takaaki Nakamura Yasushi Oshikane Haruyuki Inoue Motohiro Nakano Toshihiko Kataoka 《Optical Review》2007,14(6):401-405
A phase-shifting point diffraction interferometer (PS/PDI) with point sources of two single mode optical fibers has been developed,
which will be appropriate for the surface figure measurement of large aperture optics on a sub-nanometer scale. To reduce
the measurement error factors, a fiber optic plate (FOP) is used as a projection plane for interference pattern. Errors caused
by imperfection of optical alignment, such as position of point sources and tilt of FOP, are minimized by analyzing the measured
phase data with an original method. Measurement accuracy in the PS/ PDI is estimated with the interference pattern produced
by the two optical fiber sources. If inhomogeneity of the FOP and a systematic error of the PS/PDI are eliminated, the measurement
accuracy of the present system is estimated to be less than 4nm P-V and 0.7nm rms, respectively, at a measurement wavelength
of 632.8 nm. 相似文献
60.
Ping Sun 《Optics Communications》2007,275(2):305-310
A fringe carrier method for separating out-of-plane displacement from in-plane components based on large image-shearing electronic speckle pattern interferometry (ESPI) is presented. If the test object is respectively illuminated by two expanded symmetric illuminations in large image-shearing ESPI, two interferometers are formed. Carrier fringe patterns can be introduced by tilting reference surface a small angle. The carrier fringe patterns are demodulated after deformation of the object. Two phase maps, which include out-of-plane and in-plane displacement, can be obtained by using Fourier transform. Then out-of-plane displacement can be easily separated from in-plane displacement by simple operation between two unwrapped phase distributions. The principle of spatial carrier frequency modulation in large image-shearing ESPI is discussed. A typical three-point-bending experiment is completed. Experimental results are offered. The results show that the method offers high visibility of carrier fringes. And the system presented does not need a special beam as a reference light and has simple optical setup. 相似文献