全文获取类型
收费全文 | 1094篇 |
免费 | 10篇 |
国内免费 | 9篇 |
专业分类
化学 | 725篇 |
晶体学 | 5篇 |
力学 | 11篇 |
数学 | 140篇 |
物理学 | 232篇 |
出版年
2022年 | 7篇 |
2021年 | 9篇 |
2020年 | 15篇 |
2019年 | 9篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 18篇 |
2015年 | 13篇 |
2014年 | 11篇 |
2013年 | 51篇 |
2012年 | 54篇 |
2011年 | 61篇 |
2010年 | 39篇 |
2009年 | 20篇 |
2008年 | 57篇 |
2007年 | 66篇 |
2006年 | 60篇 |
2005年 | 65篇 |
2004年 | 37篇 |
2003年 | 44篇 |
2002年 | 33篇 |
2001年 | 24篇 |
2000年 | 16篇 |
1999年 | 10篇 |
1998年 | 16篇 |
1997年 | 12篇 |
1996年 | 16篇 |
1995年 | 15篇 |
1994年 | 17篇 |
1993年 | 16篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 15篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 13篇 |
1981年 | 18篇 |
1980年 | 15篇 |
1979年 | 13篇 |
1978年 | 15篇 |
1977年 | 16篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1974年 | 18篇 |
1973年 | 9篇 |
排序方式: 共有1113条查询结果,搜索用时 31 毫秒
61.
George E. Andrews 《Annals of Combinatorics》1999,3(2-4):115-130
We study the number of solutions of the Diophantine equationn=x
1
x
2+x
2
x
3+x
3
x
4+...+x
k
x
k+1 The combinatorial interpretation of this equation provides the name stacked lattices boxes. The study of these objects unites three separate threads in number theory: (1) the Liouville methods, (2) MacMahon's partitions withk different parts, (3) the asymptotics of divisor sums begun by Ingham.Partially supported by National Science Foundation Grant DMS-9206993, USA. 相似文献
62.
The adsorption and decomposition of monoethylgermane (GeH3Et) on the Si(100)-(2×1) surface was investigated with the intent of elucidating the surface processes leading to the deposition of germanium. The low-temperature adsorption of the molecule was explored, as well as its thermal decomposition. H2 and C2H4 are observed as the desorption products in temperature-programmed desorption experiments. The ethylene is produced by a hydride elimination reaction within the adsorbed ethyl groups. The amount of Ge which can be deposited in a reaction cycle is correlated with the number of sites occupied by the ethyl groups upon the dissociation of GeH3Et. 相似文献
63.
64.
Optical and resonance Raman spectra of the reaction products of Mg, Ca, Sr, and Ba with ozone were observed in argon and nitrogen matrices. The visible spectra were characterized by strong, vibronically structured absorptions between 540 and 350 nm, and are assigned to the alkaline earth metal ozonides, . Vibrational analysis yielded ω1′ and ω1x1 values of about 900 and 6 cm?1, respectively, with only slight variation from metal to metal. Resonance Raman spectra consisted of a strong fundamental near 1020 cm?1 and two overtones with decreasing intensity. Oxygen-18 substitution confirmed the vibrational assignments, which agree very well with the alkali metal ozonide spectra. These results suggest that the +1 oxidation state plays an important role in the chemistry of the alkaline earth metals under conditions where aggregation does not occur to favor the +2 state. A thorough search was made for absorptions due to the alkaline earth oxide species, but no bands were observed. 相似文献
65.
66.
67.
68.
Matrix reactions of Mg, Zn and Cd atoms and NO2 have been performed. Infrared absorptions in the 1220 cm?1 range show isotopic shifts appropriate for M+NO2? species. Bands near 950 cm?1 in the zinc experiments are attributed to a different ion-pair structural isomer. 相似文献
69.
Aharon Loewenschuss John C. Miller Lester Andrews 《Journal of Molecular Spectroscopy》1980,80(2):351-362
Absorption spectra of ClO, BrO, and IO and the emission spectrum of IO have been observed from argon matrix samples prepared by microwave discharging the reagent mixture before condensation. Vibronic progressions were observed for each system. The spectroscopic scopic constants Te, ω′e, ωex′e, ω″e, and ωex″e were evaluated from the absorption and emission data for comparison with gas-phase constants. Very good agreement is found for ClO. The argon matrix observations dictate a revision of the gas-phase vibronic assignments for BrO. The ground-state vibrational fundamental and Te for argon matrix isolated IO are similar to the gas-phase values, but a lower excited-state spacing is found in the matrix. 相似文献
70.