全文获取类型
收费全文 | 415篇 |
免费 | 14篇 |
国内免费 | 1篇 |
专业分类
化学 | 248篇 |
晶体学 | 5篇 |
力学 | 11篇 |
数学 | 85篇 |
物理学 | 81篇 |
出版年
2023年 | 1篇 |
2022年 | 10篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 21篇 |
2013年 | 14篇 |
2012年 | 26篇 |
2011年 | 26篇 |
2010年 | 26篇 |
2009年 | 14篇 |
2008年 | 18篇 |
2007年 | 24篇 |
2006年 | 25篇 |
2005年 | 17篇 |
2004年 | 9篇 |
2003年 | 16篇 |
2002年 | 18篇 |
2001年 | 12篇 |
2000年 | 15篇 |
1999年 | 5篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有430条查询结果,搜索用时 0 毫秒
101.
The effects of several metallic ions on the oxidation of natural rubber were studied by differential scanning calorimetry (DSC). The activation energy of oxidation was evaluated from DSC curves. Cobalt, manganese, iron and copper ions decreased the activation energy of oxidation. Nickel, zinc and tin ions did not affect the activation energy. The effective ions are those which are able to undergo one-electron transfer redox reaction with hydroperoxide. Based on the activation energy values, the catalytic activities of metallic ions are: Co > Mn > Cu ? Fe > Ni ? Zn ? Sn. 相似文献
102.
A new approach to the controlled synthesis of multicomponent dendrimers is presented, in which three oligonucleotide-dendron conjugates were synthesized using solid phase techniques and hybridized to create a second generation polyester dendrimer with DNA as a core and bearing two types of peripheral functional groups. 相似文献
103.
Aldol reaction under solvent-free conditions: highly stereoselective synthesis of 1,3-amino alcohols
[formula: see text] A method for the highly stereoselective synthesis of 1,3-amino alcohols based on the indium trichloride-catalyzed Mukaiyama aldol reaction of keto ester (R,S)-1 under solvent-free conditions has been developed. The high selectivity observed can be explained on the basis of the shielding of one face by a remote substituent. 相似文献
104.
An unexpected reduction of indolic double bond of mitragynine was described by using n-butyl silane and tris(pentafluorophenyl)triborane. 相似文献
105.
106.
107.
Glen B. Deacon Prof. Dr. Lai Yoong Goh Prof. Dr. W. Roy Jackson Brian W. Skelton Wei Chen Allan H. White 《无机化学与普通化学杂志》2010,636(8):1478-1483
Monomeric manganese(II) complexes of bulky alkyl/ aryl‐substituted phenoxides, [Mn{C6HnRmO}2(DME)] [ 1 : R = C6H5, n = 3, m = 2 (2,6); 2 : R = Me3C, n = 3, m = 2 (2,6); 3 : R = Me3C, n = 2, m = 3 (2,4,6)] were prepared in yields of 37, 44 and 72 %, respectively, from the reaction of manganese powder, Hg(C6F5)2 and the corresponding phenol in the presence of a little mercury in dimethoxyethane (DME). The compounds were characterized spectroscopically and by magnetic measurements. The single crystal structures of 1 and 3 and also of the mixed phenoxide complex [Mn{(C6H3(C6H5)2‐2,6‐O}{C6H3(Me3C)2‐2,6‐O}(DME)] 4 are reported. 相似文献
108.
109.
The lifting scheme has been found to be a flexible method for constructing scalar wavelets with desirable properties. Here it is extended to the construction of multiwavelets. It is shown that any set of compactly supported biorthogonal multiwavelets can be obtained from the Lazy matrix filters with a finite number of lifting steps. As an illustration of the general theory, compactly supported biorthogonal multiwavelets with optimum time–frequency resolution are constructed. In addition, experimental results of applying these multiwavelets to image compression are presented. 相似文献