全文获取类型
收费全文 | 230篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
化学 | 77篇 |
晶体学 | 4篇 |
力学 | 7篇 |
数学 | 109篇 |
物理学 | 37篇 |
出版年
2021年 | 3篇 |
2015年 | 4篇 |
2013年 | 7篇 |
2012年 | 8篇 |
2011年 | 11篇 |
2010年 | 7篇 |
2009年 | 8篇 |
2008年 | 10篇 |
2007年 | 14篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1975年 | 12篇 |
1974年 | 4篇 |
1973年 | 6篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1966年 | 3篇 |
1963年 | 5篇 |
1960年 | 2篇 |
1955年 | 1篇 |
1936年 | 1篇 |
1931年 | 1篇 |
1920年 | 3篇 |
排序方式: 共有234条查询结果,搜索用时 15 毫秒
231.
The structurally complex antifungal agent posaconazole has been well characterized by conventional 1H‐ and 13C‐NMR studies. In contrast, 15N resonance assignments have never been reported. We now wish to report the assignment of the eight 15N resonances of posaconazole using two‐dimensional long‐range 1H‐15N GHMBCAD NMR data. The 15N resonance assignments were undertaken to facilitate the evaluation of the impact of 1H‐15N heteronuclear shift correlation data in the Computer‐Assisted Structure Elucidation (CASE) of complex molecular structures. J. Heterocyclic Chem., (2011). 相似文献
232.
A. J. W. Hilton 《Journal of Graph Theory》1986,10(4):523-527
Let K denote the complete graph K2n+1 with each edge replicated r times and let χ′(G) denote the chromatic index of a multigraph G. A multigraph G is critical if χ′(G) > χ′(G/e) for each edge e of G. Let S be a set of sn – 1 edges of K. We show that, for 0 < s ≦ r, G/S is critical and that χ′ (G/(S ∪{e})) = 2rn + r – s for all e ∈ E(G/S). Plantholt [M. Plantholt, The chromatic index of graphs with a spanning star. J. Graph Theory 5 (1981) 5–13] proved this result in the case when r = 1. 相似文献
233.
King BT Kroulík J Robertson CR Rempala P Hilton CL Korinek JD Gortari LM 《The Journal of organic chemistry》2007,72(7):2279-2288
Guidelines for the application of the Scholl reaction were developed. Labeling experiments demonstrate that the Scholl reaction fails in small, unsubstituted oligophenylenes (e.g., o-terphenyl) due to oligomerization of the products (e.g., triphenylene). Incorporation of suitably placed blocking groups (e.g., t-butyl) suppresses oligomerization. The well-established directing group effects in electrophilic aromatic substitution predict the outcome of Scholl reactions of substituted substrates. Activating o,p-directing groups (e.g., MeO) direct bond formation o,p, either intramolecularly or intermolecularly. Deactivating o,p-directing groups (e.g., Br) also direct bond formation o,p but yields are lower. Deactivating m-directors (e.g., NO2) suppress reaction. MoCl5 and PhI(OOCCF3)2/BF3.Et2O are general and effective reagents for the Scholl oxidation. Calculations (B3LYP/6-31G(d)) predict the Scholl reaction in alkoxyarenes to proceed via arenium cations, not radical cations. Suzuki-Miyaura couplings were used to generate 12 substituted o-terphenyl derivatives. 相似文献
234.
A. J. W. Hilton 《Combinatorica》1982,2(1):37-51
A variety of results on edge-colourings are proved, the main one being the following: ifG is a graph without loops or multiple edges and with maximum degree Δ=Δ(G), and if ν is a given integer 1≦ν≦Δ(G), thenG can be given a proper edge-colouring with the coloursc
1, ...,c
Δ+1 with the additional property that any edge colouredc
μ with μ≧ν is on a vertex which has on it edges coloured with at least ν − 1 ofc
1, ...,c
v
. 相似文献