全文获取类型
收费全文 | 550篇 |
免费 | 1篇 |
国内免费 | 2篇 |
专业分类
化学 | 292篇 |
晶体学 | 7篇 |
力学 | 15篇 |
数学 | 33篇 |
物理学 | 206篇 |
出版年
2020年 | 3篇 |
2018年 | 4篇 |
2014年 | 5篇 |
2013年 | 22篇 |
2012年 | 9篇 |
2011年 | 17篇 |
2010年 | 14篇 |
2009年 | 9篇 |
2008年 | 20篇 |
2007年 | 19篇 |
2006年 | 15篇 |
2005年 | 21篇 |
2004年 | 25篇 |
2003年 | 10篇 |
2002年 | 17篇 |
2001年 | 15篇 |
2000年 | 14篇 |
1999年 | 11篇 |
1998年 | 12篇 |
1997年 | 3篇 |
1996年 | 11篇 |
1995年 | 9篇 |
1994年 | 12篇 |
1993年 | 10篇 |
1992年 | 10篇 |
1991年 | 11篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 28篇 |
1984年 | 15篇 |
1983年 | 7篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1976年 | 10篇 |
1975年 | 13篇 |
1974年 | 11篇 |
1973年 | 9篇 |
1972年 | 7篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1969年 | 3篇 |
1968年 | 3篇 |
1937年 | 3篇 |
排序方式: 共有553条查询结果,搜索用时 15 毫秒
81.
The key step of a new approach to the total synthesis of the structurally and physiologically interesting sesquiterpenoid (±)-quadrone (1) involves thermal (Cope) rearrangement of the highly functionalized divinylcyclopropane derivative 8. The product 9 of this process is converted into 19, thus completing a formal total synthesis of (±)-1. 相似文献
82.
83.
Roger Bolton W.K. Adrian Moss John P.B. Sandall Gareth H. Williams 《Journal of fluorine chemistry》1975,5(1):61-65
The thermolyses of a number of aroyl peroxides in hexafluorobenzene, and of benzoyl peroxide in octafluorotoluene, gave the corresponding biaryls which were isolated by steam distillation. Mass spectrometry of the residues showed evidence of biphenylyl radicals arising from the arylation of the peroxides themselves or, possibly, of the derived aroic acids. Terphenyls, and the corresponding σ-intermediate radicals, could be found, and the relative molecular masses of the latter components showed that subsequent arylation of the main binuclear products was not the main source of terphenyls. 相似文献
84.
85.
86.
87.
Moss JA Lillo A Kim YS Gao C Ditzel H Janda KD 《Journal of the American Chemical Society》2005,127(2):538-539
The internalization mechanism of a cell-penetrating peptide has been explored through combinatorial selection of a phage-displayed peptide dimer library, chemical synthesis, and biophysical characterization. Both energy-dependent and energy-independent modes for peptide uptake by the target mammalian cells were observed, suggesting a role for higher-order structure in modulating the action of this novel cell-penetrating peptide. 相似文献
88.
The reaction of p-nitrophenoxychlorodiazirine with tetrabutylammonium fluoride follows three channels: (1) approximately 17% of p-nitrophenoxide/fluoride exchange to chlorofluorodiazirine and p-nitrophenol, (2) approximately 28% of Cl/F exchange to p-nitrophenoxyfluorodiazirine, and (3) approximately 55% of ipso fluoride attack, affording p-nitrofluorobenzene and the previously unknown diazirinone (diazacyclopropenone). 相似文献
89.
Recent experiments have demonstrated that the (13)C NMR spectra of iodoalkynes exhibit a strong solvent effect because of complexation with Lewis-basic solvents. This paper describes DFT NMR calculations (B3LYP-GIAO with LanL2DZ or Sadlej pVTZ basis set) of iodoalkynes and their Lewis acid-base complexes, interpreted by using Natural Chemical Shift (NCS) analysis within the framework of the Ramsey formalism for chemical shift. In particular, the paper presents calculations on diiodoethyne and its complexes with one and two ammonia molecules. Examination of the orbital changes upon forming the mono- and bisammonia complexes indicates that mixing of the nitrogen lone pair with the C-I antibonding orbital increases the paramagnetic deshielding at C1. Further increases can be attributed to increased polarization of the iodine lone-pair orbitals onto C1. The haloiodoalkyne series XCCI (X = F, Cl, Br, I) offers additional support for this model of the solvent effect. 相似文献
90.