全文获取类型
收费全文 | 642篇 |
免费 | 11篇 |
国内免费 | 4篇 |
专业分类
化学 | 240篇 |
晶体学 | 1篇 |
力学 | 43篇 |
数学 | 232篇 |
物理学 | 141篇 |
出版年
2022年 | 5篇 |
2019年 | 6篇 |
2018年 | 10篇 |
2017年 | 15篇 |
2016年 | 9篇 |
2015年 | 7篇 |
2014年 | 21篇 |
2013年 | 19篇 |
2012年 | 23篇 |
2011年 | 42篇 |
2010年 | 26篇 |
2009年 | 18篇 |
2008年 | 28篇 |
2007年 | 17篇 |
2006年 | 15篇 |
2005年 | 14篇 |
2004年 | 15篇 |
2003年 | 22篇 |
2002年 | 18篇 |
2001年 | 7篇 |
2000年 | 11篇 |
1999年 | 11篇 |
1997年 | 10篇 |
1996年 | 10篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1986年 | 6篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 13篇 |
1981年 | 14篇 |
1980年 | 7篇 |
1979年 | 11篇 |
1978年 | 13篇 |
1977年 | 14篇 |
1976年 | 8篇 |
1975年 | 15篇 |
1974年 | 9篇 |
1973年 | 13篇 |
1972年 | 8篇 |
1971年 | 9篇 |
1970年 | 7篇 |
1967年 | 4篇 |
排序方式: 共有657条查询结果,搜索用时 281 毫秒
1.
The steel ASTM A213 P22 is used for superheater outlet header in power plants. During duty cycles lasting over tens of years the temperature is of the order of 545°C and the pressure 125 atm. The microscopic changes in these steels are hard to analyze under working conditions, but they are believed to be responsible for the appearance of creeps in such devices. Investigation of the microscopic modifications will help to predict future failures due to creeps, increasing the reliability and saving a lot of money.We report the investigation of such changes in ASTM A213 P22 steel in use for 30 years as a Superheater header at Haifa power station. The analysis has been carried out using Mössbauer Spectroscopy, X-ray diffraction and optical microscopy. As a result it seems that the morphology and phase change of the carbide phases M3C/M7C3 and M23C6 are the most prominent changes leading to the material failures. 相似文献
2.
Shmuel Yariv 《Journal of Thermal Analysis and Calorimetry》2003,71(3):685-687
Journal of Thermal Analysis and Calorimetry - 相似文献
3.
S. A. Klimin M. N. Popova E. P. Chukalina B. Z. Malkin A. R. Zakirov E. Antic-Fidancev Ph. Goldner P. Aschehoug G. Dhalenne 《Physics of the Solid State》2005,47(8):1425-1430
The absorption spectra of Yb2Ti2O7 single crystals and the luminescence and luminescence excitation spectra of Y2Ti2O7: Yb (1%) polycrystals were studied in the temperature range 4.2–300 K. The spectra were analyzed in terms of the crystal-field
theory and the exchange-charge model. Based on the set of crystal-field parameters found for Yb2Ti2O7, analogous sets of parameters were determined for other rare-earth titanates and proved to be in reasonable agreement with
all available experimental data.
__________
Translated from Fizika Tverdogo Tela, Vol. 47, No. 8, 2005, pp. 1376–1380.
Original Russian Text Copyright ? 2005 by Klimin, Popova, Chukalina, Malkin, Zakirov, Antic-Fidancev, Goldner, Aschehoug,
Dhalenne. 相似文献
4.
Bassan Bruno Gossner Olivier Scarsini Marco Zamir Shmuel 《International Journal of Game Theory》2003,32(1):17-31
We exhibit a general class of interactive decision situations in which all the agents benefit from more information. This class includes as a special case the classical comparison of statistical experiments à la Blackwell.
AMS 2000 Subject Classification:Primary 91A35.The work of Bruno Bassan and Marco Scarsini was partially supported by MIUR-COFIN. The authors express their thanks to Sylvain Sorin for enlightening comments. 相似文献
5.
6.
E. D. Skakovskii S. V. Rykov L. Yu. Tychinskaya Ya. N. Malkin 《Russian Chemical Bulletin》1987,36(8):1753-1755
Conclusions Negative polarization of the protons of aniline and other compounds is observed upon the photoexcitation of aniline solutions. This effect is a consequence of optical nuclear polarization in short-lived donor-acceptor complexes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1890–1892, August, 1987. 相似文献
7.
Light-dependent oxygen uptake was observed and studied in thylakoids from early greening barley in comparison to oxygen uptake in chlorophyll solutions and in thylakoids from fully green leaves. Substantial oxygen uptake was observed in chlorophyll solutions supplemented with tryptophan, histidine, ascorbic acid or linoleic acid. This uptake was diminished by adding azide, beta-carotene and alpha-tocopherol, which are specific singlet-oxygen quenchers. Illuminated thylakoids from greening barley also exhibited marked oxygen uptake that, likewise, was strongly quenched by azide. In comparison, azide was found not to affect oxygen uptake that is associated with the methyl viologen-catalyzed Mehler reaction. It is reasoned that in the first two cases the oxygen uptake arises from chlorophyll-photosensitized activation of oxygen to the singlet state and its consumption by exogenous or endogenous substrates. In greening, we propose that disorganized chlorophyll photo-sensitizes the oxygen uptake. 相似文献
8.
9.
10.
Shmuel Zaks 《BIT Numerical Mathematics》1984,24(2):196-204
A new algorithm for generating permutations is presented, that generates the next permutation by reversing a certain suffix of its predecessor. The average size of this suffix is less thane 2.8. It is shown how to find the position of a given permutation and how to construct the permutation of a given position, where the position refers to the order in which the permutations are generated, and is also new.On leave from the Department of Computer Science, Technion, Haifa, Israel. This work was supported by NSF grant MCS-8302391. 相似文献