全文获取类型
收费全文 | 72篇 |
免费 | 1篇 |
专业分类
化学 | 47篇 |
数学 | 1篇 |
物理学 | 25篇 |
出版年
2021年 | 1篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有73条查询结果,搜索用时 15 毫秒
41.
L. Gonzalez-Sanchez E. Bodo E. Yurtsever F. A. Gianturco 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(1):75-82
Rotationally superelastic collisions are computed from quantum
dynamical calculations for the two title systems, down to the very
low collision energies of interest in cold trap experiments. The
results are obtained via ab initio interaction potentials, the one
for the MgH-He system being given here for the first time and
discussed in details in the present paper.
The calculations show marked differences in behaviour for both
cooling efficiency rates at vanishing temperatures and individual
cross sections between levels, and their origin is related to target
structural properties and with specific features of the two
potentials. 相似文献
42.
An efficient basis set for use with the Harris, Engerholm and Gwinn solution of one-dimensional vibrational potentials has been derived from centrosymmetric sturmian Laguerre functions using the l = 0 condition. Six-figure accuracy is achieved for n bound levels of the Morse and Fues potentials using 4n sturmian functions. With simple formulas and sparse arrays, convergence to all bound levels is achieved. 相似文献
43.
A class of integral transform functions previously applied to He and Li has been extended to the ground state of Be where an energy of −14.567553 au was obtained. Although the function is slightly less than double-zeta quality and requires numerical integration techniques, it is shown how the parameters of the function can be related to single-zeta screening constants while obtaining much improved minimal basis energies. 相似文献
44.
Research on Chemical Intermediates - In this study, phthalocyanine (Pc)–TiO2 nanocomposites were prepared via in situ hydrothermal method. The metal-free, zinc(II), cobalt(II), nickel(II) and... 相似文献
45.
The solvation of Buckminsterfullerene \(\hbox {C}_{60}\) by para-hydrogen and ortho-deuterium clusters has been modeled using a dedicated potential and path-integral molecular dynamics simulations at low temperature (2 K). The solvation shell obtained from the distribution of radial distances is found to be complete near 50 molecules, in agreement with recent mass spectrometry measurements. Deuteration increases the shell size by one, indicating a denser shell owing to less prominent vibrational delocalization for this heavier isotope. 相似文献
46.
Allylic onium salts with different hetero‐atoms and various substituent groups at the allylic double bond have been shown to be very efficient initiators for cationic polymerization. When attacked by a radical, they become radical cations, which are highly unstable species, and undergo fragmentation into smaller radical cations called onium radical cations. The reaction mechanism involves radical formation, addition and fragmentation. In our previous work, radical initiators generated in the same way and under the same conditions are studied experimentally for their ability to affect the polymerization efficiency. Here, the factors affecting the polymerization efficiency are discussed theoretically using semi‐empirical quantum mechanical techniques. The type of radical species, substituent group at the allylic side, the heteroatom at the onium side and the onium group itself are analyzed separately. For this purpose, the geometries of different onium radical cations to be fragmented are optimized and the strength of the C–heteroatom bond to be broken and the size of the radical cations after fragmentation are considered. 相似文献
47.
The energy landscapes of ion clouds confined in isotropic quadrupolar and octupolar traps are characterized for several representative cluster sizes. All clusters exhibit stable multishell structures that belong to separate funnels. Quadrupolar confinement leads to more homogeneous clusters and denser distributions of isomers than octupolar confinement. Statistical analysis of the transition states indicates that the barriers associated with intrashell motion are lower but more asymmetric and more cooperative compared to intershell motion. The relaxation between low-energy funnels with different arrangements of shells mostly exhibits Arrhenius kinetics, with a weak variation of the activation energy at higher temperatures. 相似文献
48.
The mechanism of formation of dithieno[3,2-b:2′,3′-d]thiophene (DTT) through the reaction of 1,8-diketone, 4,5-bis(benzoylmethylthio)thiophene with P4S10 was examined in detail by employing DFT method at B3LYP/6-311+G(d,p) level. Two mechanisms were considered. The first one included two parts (i) transformation of the 1,8-diketone, 4,5-bis(benzoylmethylthio)thiophene to the dithione by the reaction of P4S10 with the carbonyl groups and (ii) cyclization of the dithione to the final product, DTT, through an intramolecular reaction of the thiophene with thiones. The second mechanism consists of an initial attack of the carbonyl oxygen to the phosphorus atom of P4S10 followed by cyclization via an intramolecular attack from the thiophene ring to the highly electrophilic carbons connected to the oxygens to form DTT. According to the calculated Gibbs free energies of the studied paths, the second mechanism is more favorable than the first one and both pathways proceed in a stepwise manner. 相似文献
49.
50.
Dialkyl (3,4-dicyanophenyl)propargylmalonates were prepared by the reaction of propargyl bromide and the potassium salt of dialkyl-3,4-dicyanophenylmalonates. A cyclotetramerization reaction was achieved in pentanol in the presence of DBU without protective/deprotective chemistry, affording the peripherally tetrasubstituted alkynyl phthalocyanines. Subsequently, in situ metallation and ‘clicking’ were employed for the first time as an efficient and quantitative route to tetratriazole-functionalized phthalocyanines. 相似文献