全文获取类型
收费全文 | 571篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 426篇 |
晶体学 | 2篇 |
力学 | 3篇 |
数学 | 32篇 |
物理学 | 115篇 |
出版年
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 9篇 |
2018年 | 6篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 21篇 |
2012年 | 20篇 |
2011年 | 30篇 |
2010年 | 25篇 |
2009年 | 21篇 |
2008年 | 32篇 |
2007年 | 32篇 |
2006年 | 39篇 |
2005年 | 32篇 |
2004年 | 25篇 |
2003年 | 26篇 |
2002年 | 30篇 |
2001年 | 17篇 |
2000年 | 13篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1986年 | 7篇 |
1985年 | 13篇 |
1984年 | 9篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1970年 | 2篇 |
排序方式: 共有578条查询结果,搜索用时 31 毫秒
71.
72.
A 1-l water sample was concentrated to 20ml by freezing and analyzed for soluble, colloidal and insoluble silica by the spectrophotometric heteropoly blue method and by inductively coupled plasma/atomic emission spectrometry. High-purity water obtained from a vitreous-silica sub-boiling distillation still contained a few micrograms of insoluble silica per liter. 相似文献
73.
74.
In the oxidation of cyclohexanol to cyclohexanone and the further oxidation to adipic acid, a dodecamolybdo-heteropolyanion (HPA) functions catalytically in the presence of aqueous hydrogen peroxide, whereas the HPA without hydrogen peroxide reacts only stoichiometrically. Air- or oxygen-passing through the refluxing system of cyclohexanone and the HPA in the presence of active charcoal, without hydrogen peroxide, has also promoted the oxidation catalytically. Since both hydrogen peroxide and aeration in the presence of active charcoal convert the reduced-form (blue) of the HPA produced by the oxidation of substrate to the oxidized-form (yellow), they play a role as a promoter or a reoxidizing reagent for the oxidation by the HPA. The reoxidizing effect of the aqueous hydrogen peroxide is much the more effective. 相似文献
75.
76.
Presented here is the construction of solvable two-dimensional lattice models associated with the affine Lie algebraA
n
/(1)
and an arbitrary pair of Young diagrams. The models comprise two kinds of fluctuation variables; one lives on the sites and takes on dominant integral weights of a fixed level, the other lives on edges and assumes the weights of the representations ofsl(n+1, C) specified by Young diagrams. The Boltzmann weights are elliptic solutions of the Yang-Baxter equation. Some conjectures on the one point functions are put forth. 相似文献
77.
78.
The theory of structural stability, being based on the number of closed loops per MO6 octahedral unit in the polyanion-cage, has been applied to a variety of heteropoly- and isopoly-compounds with previously unreported structures. The discussion includes the prediction of the structure of lacunary Keggin heteropoly-compound, Cs7Na2[PW10O37]·8H2O, recently obtained by Knoth and Harlow, the reinvestigation of mixed-type Keggin polyanions, [SiW9Co3(H2O)3O37]10? and [SiW11CoO39]6?, recently prepared by Pope's group, the interpretation of chemical behaviours of some molybdo- and tungsto-vanadates, the structural stabilities of Jeannin-type [As2W21O69(H2O)]6? polyanion and its related compounds, and some remarks on Weakley-type [X(W5O18)2]n? polyanions and Flynn-Stucky-type [X(Nb6O19)2]n? complexes belonging to the hybrid-complex of polyanion. 相似文献
79.
80.
Motokura K Fujita N Mori K Mizugaki T Ebitani K Kaneda K 《Journal of the American Chemical Society》2005,127(27):9674-9675
A Ti4+-exchanged montmorillonite (Ti4+-mont) and a hydrotalcite (HT) are strong solid Br?nsted acid and base, and these two clay catalysts could be used in a single reactor without neutralization of active sites. Because the Ti4+-mont have active acid site in the narrow interlayers, the base sites of large HT particles show no interaction with the acid sites. A variety of acid and base reactions, such as esterification, acetalization, deacetalization, aldol reaction, Michael reaction, and epoxidation, proceeded using both the Ti4+-mont and the HT in a single reactor. 相似文献