全文获取类型
收费全文 | 1490篇 |
免费 | 45篇 |
国内免费 | 7篇 |
专业分类
化学 | 1037篇 |
晶体学 | 14篇 |
力学 | 17篇 |
数学 | 158篇 |
物理学 | 316篇 |
出版年
2022年 | 9篇 |
2021年 | 7篇 |
2020年 | 12篇 |
2019年 | 13篇 |
2018年 | 5篇 |
2017年 | 20篇 |
2016年 | 30篇 |
2015年 | 24篇 |
2014年 | 27篇 |
2013年 | 77篇 |
2012年 | 52篇 |
2011年 | 88篇 |
2010年 | 40篇 |
2009年 | 60篇 |
2008年 | 81篇 |
2007年 | 101篇 |
2006年 | 88篇 |
2005年 | 107篇 |
2004年 | 90篇 |
2003年 | 69篇 |
2002年 | 71篇 |
2001年 | 24篇 |
2000年 | 24篇 |
1999年 | 24篇 |
1998年 | 14篇 |
1997年 | 18篇 |
1996年 | 17篇 |
1995年 | 8篇 |
1994年 | 16篇 |
1993年 | 14篇 |
1992年 | 28篇 |
1991年 | 11篇 |
1990年 | 13篇 |
1989年 | 12篇 |
1988年 | 10篇 |
1987年 | 11篇 |
1986年 | 5篇 |
1985年 | 22篇 |
1984年 | 19篇 |
1983年 | 14篇 |
1982年 | 23篇 |
1981年 | 13篇 |
1980年 | 23篇 |
1979年 | 20篇 |
1978年 | 10篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1975年 | 15篇 |
1974年 | 12篇 |
1973年 | 9篇 |
排序方式: 共有1542条查询结果,搜索用时 15 毫秒
31.
32.
Y. Obi H. Hiroyoshi K. V. Rao H. Fujimori 《Applied Physics A: Materials Science & Processing》1996,62(5):429-435
Magnetic properties of amorphous Mn
x
B100–x
alloys ranging fromx = 30 to 70 under high magnetic fields and low ac magnetic fields in the temperature range from 4.2 K to room temperature have been investigated. Samples which have Mn concentrations of aboutx = 40–60 show spin-glass-like properties in the low-temperature region. This spin-glass characteristics result from a frustration in the spin system which is caused by the competition of ferromagnetic and antiferromagnetic interactions between randomly distributed Mn atoms. Both magnetization at 4.2 K and paramagnetic momentP
eff as a function of Mn concentration show a peak aroundx 44 which drops rapidly towards both sides of the Mn content. 相似文献
33.
Inoue IH Watanabe M Kinoshita T Kakizaki A Kato R Kobayashi A Kobayashi H Fujimori A 《Physical review. B, Condensed matter》1993,47(19):12917-12920
34.
35.
36.
The triphenyl phosphite-palladium complex was found to effect catalytic substitution reactions of allylic alcohols via a direct C-O bond cleavage. The dehydrative etherification proceeded efficiently without any cocatalysts and bases to give allylic ethers in good to excellent yields. 相似文献
37.
Tawada Y Tsuneda T Yanagisawa S Yanai T Hirao K 《The Journal of chemical physics》2004,120(18):8425-8433
We apply the long-range correction (LC) scheme for exchange functionals of density functional theory to time-dependent density functional theory (TDDFT) and examine its efficiency in dealing with the serious problems of TDDFT, i.e., the underestimations of Rydberg excitation energies, oscillator strengths, and charge-transfer excitation energies. By calculating vertical excitation energies of typical molecules, it was found that LC-TDDFT gives accurate excitation energies, within an error of 0.5 eV, and reasonable oscillator strengths, while TDDFT employing a pure functional provides 1.5 eV lower excitation energies and two orders of magnitude lower oscillator strengths for the Rydberg excitations. It was also found that LC-TDDFT clearly reproduces the correct asymptotic behavior of the charge-transfer excitation energy of ethylene-tetrafluoroethylene dimer for the long intramolecular distance, unlike a conventional far-nucleus asymptotic correction scheme. It is, therefore, presumed that poor TDDFT results for pure functionals may be due to their lack of a long-range orbital-orbital interaction. 相似文献
38.
The sequential Sonogashira reaction and the cyclization reaction of various 2-iodoanilines and terminal alkynes in the presence of a palladium catalyst and tetrabutylammonium fluoride (TBAF) gave the corresponding 2-substituted indoles in good yields. 相似文献
39.
Zenjiro Osawa Takao Kimura Takao Kasuga 《Journal of polymer science. Part A, Polymer chemistry》1969,7(7):2007-2014
Two series of polymerization of methyl methacrylate with Grignard reagent in dioxane—tetrahydrofuran mixed solvent was carried out under ultrasonic irradiation. In series A, catalyst was added to the mixture of monomer and solvent, and in series B, catalyst was previously mixed with solvent. The effect of ultrasonic irradiation on Grignard catalyst and the microstructure in reacting sites were discussed on the basis of the stereoregularity of the polymers produced. The stereoregularity of the polymers in series A was higher than that in series B. The effect of ultrasonic irradiation on the stereoregularity was completely reversed in series A and B and it increased in the former and decreased in the latter. It was, therefore, assumed that ultrasonic irradiation affected the microstructure in the reacting sites in series A, while it increased the relative amount of R2Mg which gave polymers with poor stereoregularity in series B. 相似文献
40.
Electrophoretic mobilities of red blood cells (RBCs) were measured in microgravity using a home-made capillary electrophoresis unit, which consisted of two small reservoirs of 0.6 mL and a fused-silica capillary tubing with 2 cm in length and 50 num in inner diameter. Migration of RBCs was observed by a microscope at 1000 times magnification and recorded on a videotape. The experiments were performed during stays in microgravity (about 0.01 G), which lasted 20 s and were attained by parabolic flights of an aircraft. On average, the electrophoretic mobilities of RBCs determined in microgravity were about 30% higher than those measured at 1-G condition irrespectively whether the cells were suspended in saline or serum during measurements. This difference might be explained as being mainly due to the cell floating in microgravity. Morphological changes of RBCs may contribute partly to the difference, while the variation in viscosity of the medium under microgravity could play only a minor role. 相似文献