全文获取类型
收费全文 | 548篇 |
免费 | 27篇 |
国内免费 | 1篇 |
专业分类
化学 | 441篇 |
晶体学 | 5篇 |
力学 | 5篇 |
数学 | 22篇 |
物理学 | 103篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 10篇 |
2020年 | 7篇 |
2019年 | 15篇 |
2018年 | 9篇 |
2017年 | 6篇 |
2016年 | 20篇 |
2015年 | 10篇 |
2014年 | 19篇 |
2013年 | 35篇 |
2012年 | 30篇 |
2011年 | 30篇 |
2010年 | 15篇 |
2009年 | 11篇 |
2008年 | 31篇 |
2007年 | 37篇 |
2006年 | 26篇 |
2005年 | 26篇 |
2004年 | 25篇 |
2003年 | 20篇 |
2002年 | 20篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 3篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1982年 | 6篇 |
1981年 | 12篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1973年 | 6篇 |
1972年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有576条查询结果,搜索用时 0 毫秒
81.
Masaaki Kubota Yoshimasa Fujishiro Ryohei Ishida 《Spectrochimica Acta Part B: Atomic Spectroscopy》1981,36(7):697-710
A strict, comparative investigation of published transition probabilities for thermometric lines and an experimental study of determinations of plasma temperatures were made for improving the accuracy in temperature measurements by the well-known slope method. Four sets of FeI lines which satisfy the requirements for the thermometric lines were selected in the wavelength region of 200–400 nm. A statistical method was used to evaluate degrees of agreement among different sets of transition probabilities. In the experimental study, excitation temperatures of a stabilized arc plasma were determined from relative line-intensities recorded by photoelectric scanning spectrometry. In conclusion, two recommended combinations of lines and transition probability data are presented for the slope temperature measurement. Line pairs used in combination of selected transition probabilities suitable for the two-line method are also given. 相似文献
82.
The reduction of Chandrasekhar's planetary problem to the standard problem has been made by several authors (cf. Chandrasekhar(1); Sobolev;(2)Van de Hulst;(3)Coulsonet al.; (4)Ueno; (5)Kagiwada and Kalaba;(6). However, the diffuse reflection and transmission problem in a finite anisotropically scattering atmosphere bounded by a specular reflector has not been reduced to the standard problem. In the present paper, starting with an integral equation governing the source function for Chandrasekhar's planetary problem in the case of a specular reflector, we show how to express the required scattering and transmission functions in terms of the Chandrasekhar's scattering and transmission functions. So far as we know, the reduction formulae are new. They will be useful for the numerical study of Chandrasekhar's planetary problem in the case of a specular reflector with the aid of high-speed digital computer. 相似文献
83.
Takashi Toda Norihiko Shimazaki Toshio Mukai Chizuko Kabuto 《Tetrahedron letters》1980,21(41):4001-4004
The structure of a minor dimer () of 1-arylcycloheptatrienylidenethylene was determined by X-ray crystallography. Dehydration of and gave novel non-benzenoid aromatics---6,12-diarylazuleno[1,2-b]azulenes ( and ), whose electronic and NMR spectral properties were reported. 相似文献
84.
85.
In order to investigate unique behaviors in kinetics of the reaction of multiphoton excited BCl3 with H2S, two kinds of experiments were performed. The first, parallel beam experiment, gives the activation energy of the primary reaction pathway considerably smaller than the bond strength. The second, focussed beam experiment, shows that the isotope selectivity increase with incident pulse energy. Both results were found different from typical multiphoton dissociation experiments, showing its own characteristics. 相似文献
86.
Ken-ichi Kanno Shun-ichi Naoe Seiji Mukai Yoshio Nakai Takeshi Miyanaga 《Solid State Communications》1973,13(9):1325-1328
The absorption spectra of CdCl2 and CdBr2 single crystals doped with cuprous or cupric halides were measured. Optical bleaching of the absorption bands due to Cu+ gives rise to new absorption bands which suggest the conversion of Cu+→Cu2+. This was confirmed also by detecting the growth in ESR signals characteristic of Cu2+ centers. 相似文献
87.
Zuyi Zhang Yoshinori Tanigami Ryohei Terai 《Journal of Sol-Gel Science and Technology》1996,6(3):273-278
An oligomer solution was prepared from methyltriethoxysilane with HNO3 catalyst. Aluninum acetylacetonate was introudced into the solution to eliminate crystalline precipitates (CH3SiO3/2)8. Self-sustained film was attempted by dropping the solution onto an aqueous solution, into which NaCl was added to elevate the solution density. The film formation greatly depended both on the reaction time and on the supporting solution. The structure of the film thus obtained was investigated by FTIR attenuated total reflectance spectroscopy. 相似文献
88.
Reducing sugars are determined in the concentration range 10 ˜ 100 μg/ml using 3:6-dinitrophthalic acid as a colour developing agent. Individual pentoses, hexoses, and disaccharides give the same calibration curves, respectively. Sucrose is also determined in the presence of glucose or fructose. 相似文献
89.
The effect of solid-solution alloying on grain boundary sliding (GBS) was investigated using pure magnesium and six kinds of Mg–X (X?=?Ag, Al, Li, Pb, Y and Zn) dilute binary solid solutions with an average grain size of 10?µm. A sharp increase in damping capacity caused by GBS was observed above a certain temperature. The temperature at which a sharp increase in damping capacity occurred depended on the alloying element. The addition of Y and Ag markedly increased the onset temperature (more than 100?K) for a sharp increase in damping capacity, whereas the addition of Zn, Al and Li slightly increased the onset temperature (less than 50?K) as compared with that for pure magnesium. Tensile tests at a temperature of 423?K revealed that the higher the onset temperature, the lower the strain rate sensitivity of the flow stress. It is suggested that the former elements (Y and Ag) are more effective in suppressing GBS in magnesium alloys than the latter ones (Zn, Al and Li). The suppression of GBS was associated with low grain boundary energy, and the extent to which the energy is reduced depended on the alloying element. It was suggested that the change in the lattice parameter (the so-called c/a ratio) affects the grain boundary energy, and thus, the occurrence of GBS. 相似文献
90.
Self-phase modulation signatures of neuronal activity 总被引:1,自引:0,他引:1
Fischer MC Liu HC Piletic IR Escobedo-Lozoya Y Yasuda R Warren WS 《Optics letters》2008,33(3):219-221
We use phase-sensitive detection of spectral hole refilling to demonstrate strong novel intrinsic nonlinear signatures of neuronal activation in hippocampal brain slices. The ability to gain access to this fundamentally new intrinsic contrast with modest power levels suggests a new approach to in vivo neural imaging. We expect that we can extrapolate our method to high spatial and temporal resolution in deep tissue while retaining the noninvasive character. 相似文献