全文获取类型
收费全文 | 332篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
化学 | 213篇 |
晶体学 | 5篇 |
力学 | 2篇 |
数学 | 28篇 |
物理学 | 93篇 |
出版年
2021年 | 3篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 9篇 |
2013年 | 15篇 |
2012年 | 6篇 |
2011年 | 6篇 |
2010年 | 20篇 |
2009年 | 9篇 |
2008年 | 14篇 |
2007年 | 12篇 |
2006年 | 13篇 |
2005年 | 13篇 |
2004年 | 27篇 |
2003年 | 14篇 |
2002年 | 14篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1986年 | 10篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1973年 | 6篇 |
1972年 | 2篇 |
1969年 | 2篇 |
1968年 | 4篇 |
1967年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有341条查询结果,搜索用时 15 毫秒
41.
We theoretically investigated laser trimming to adjust grating offset in phase-shifted fiber grating coupler (FGC) for all-optical switching application. It was clarified that the trimming made the extinction ratio higher in all-optical FGC switch. 相似文献
42.
The molecular structure of SR-90 and CR-39 is very similar except that the average length of carbonate linkages in SR-90 is 1.6 times longer than in CR-39. However, the effect of vacuum and carbon dioxide (CO2) on the track registration of these two detectors is very different: 1) the sensitivity of CR-39 becomes very low in vacuum; the sensitivity of SR-90 does not go down to zero even after storage in vacuum for a long time; 2) the sensitivity of SR-90 decreases both in air and in vacuum but the original sensitivity can be restored by storing it in CO2 of 13 atm for several days. We also found that the sensitization of latent tracks by oxygen (O2) is effective only at the time of irradiation but the sensitization by CO2 is effective after irradiation. 相似文献
43.
Hirohisa Yokota Jun-ichi Igarashi Yoshitaka Satoda Satoru Ohuchi Yutaka Sasaki 《Optical Review》2002,9(3):94-99
A new all-fiber optical add-drop multiplexer (ADM) using a pair of fiber grating couplers (FGCs) was proposed and first demonstrated. It was theoretically and experimentally shown that both drop and add efficiencies could be maximized in the proposed ADM. It was also clarified that the crosstalk between dropped and added signals could be improved in the proposed ADM compared with that in the single FGC. Drop and add operations in the ADM for 3-channel WDM signals with 1.6 nm wavelength spacing were confirmed. The ADM with signal amplification ability, which consists of a pair of FGCs, an EDF, and a pump-LD, was proposed and demonstrated. It was confirmed that the dropped and transmitted optical signals could be amplified in the ADM, and would be able to expand fiber routing spans. 相似文献
44.
45.
46.
When two waves are coupled in Bi12SiO20 crystals, the polarization states of the signal wave are affected by the self-diffraction. We have theoretically studied the influence of the self-diffraction on the polarization of the signal wave. The change of polarization states are strongly affected by the self-diffraction effect when the external field is applied. We present a new method that converts the change of polarization into an intensity signal. 相似文献
47.
The rotating-sector method has been applied to the photoinitiated radical-chain decomposition of formamide at 300°C to measure the rate constant for the bimolecular disappearance of NH2 radicals. The decomposition is propagated by the reactions (1) (2) Conditions were chosen so that reaction (1) was rate controlling and NH2 the terminating radical. A flow system was employed with C2F6 as a carrier gas at a pressure of 300 Tort, and the chain reaction was initiated by the photolysis of either formamide or NH3. A value of 4.7(±2.0) × 1010 (M ·sec)?1 was estimated for the termination reaction (3) and a value of 8.4 × 106 (M ·sec)?1 for reaction (1) in the same system, both at 300°C. 相似文献
48.
49.
50.
Tsunetoshi Kobayashi Katsuyuki Yokota Saburo Nagakura 《Journal of Electron Spectroscopy and Related Phenomena》1973,2(5):449-454
The photoelectron spectra of styrene and its methyl derivatives were measured and interpreted. The vinyl group twisted by the steric hindrance of the α- or orthomethyl group was found to play an important role in the interpretation of the photoelectron spectra of these compounds. The dependence of the higher occupied π orbital energies of styrene upon the twist angle of the vinyl group was estimated from the experimental data. 相似文献