全文获取类型
收费全文 | 108篇 |
免费 | 12篇 |
专业分类
化学 | 95篇 |
力学 | 1篇 |
数学 | 3篇 |
物理学 | 21篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 6篇 |
2013年 | 7篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 6篇 |
2007年 | 6篇 |
2006年 | 7篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1997年 | 3篇 |
1995年 | 1篇 |
1994年 | 7篇 |
1991年 | 2篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1981年 | 3篇 |
1908年 | 1篇 |
1906年 | 1篇 |
排序方式: 共有120条查询结果,搜索用时 31 毫秒
1.
2.
Jess H. Brewer 《Hyperfine Interactions》1991,65(1-4):1137-1148
In this paper I speculate upon the potential of muon spin rotation/relaxation/resonance (μSR) for future refinement and/or
exploitation at large accelerators like KAON, which might generate muon beams a hundred times more intense than today's best.
Several schemes for efficient utilisation of such beams might be well worth implementing on existing muon channels.
Work supported by NRC and NSERC. 相似文献
3.
4.
5.
Dale R. Harshman Ralph Eric Turner Jess H. Brewer David P. Spencer 《Hyperfine Interactions》1986,32(1-4):527-533
Muonium (μ
+
e
−) in bulk fused quartz is a unique system in that theμ
+ spin polarization (in the muonium state) relaxes almost entirely via random anisotropic hyperfine distortions (RAHD). As
such, this system provides an excellent test case for a new RAHD spin relaxation theory. This theory is quantitatively compared
to static zero field data and the functional characteristics in both the high field and dynamic limits are considered as well. 相似文献
6.
7.
Bollermann T Schwedler I Molon M Freitag K Gemel C Seidel RW Fischer RA 《Dalton transactions (Cambridge, England : 2003)》2011,40(46):12570-12577
The reactions of heteroleptic GaCp*/CO containing transition metal complexes of iron and cobalt, namely [(CO)(3)M(μ(2)-GaCp*)(m)M(CO)(3)] (Cp* = pentamethylcyclopentadienyl; M = Fe, m = 3; M = Co, m = 2) and [Fe(CO)(4)(GaCp*)], with ZnMe(2) in toluene and the presence of a coordinating co-solvent were investigated. The reaction of the iron complex [Fe(CO)(4)(GaCp*)] with ZnMe(2) in presence of tetrahydrofurane (thf) leads to the dimeric compound [(CO)(4)Fe{μ(2)-Zn(thf)(2)}(2)Fe(CO)(4)] (1). Reaction of [(CO)(3)Fe(μ(2)-GaCp*(3))Fe(CO)(3)] with ZnMe(2) and stoichiometric amounts of thf leads to the formation of [(CO)(3)Fe{μ(2)-Zn(thf)(2)}(2)(μ(2)-ZnMe)(2)Fe(CO)(3)] (2) containing {Zn(thf)(2)} as well as ZnMe ligands. Using pyridine (py) instead of thf leads to [(CO)(3)Fe{μ(2)-Zn(py)(2)}(3)Fe(CO)(3)] (3) via replacement of all GaCp* ligands by three{Zn(py)(2)} groups. In contrast, reaction of [(CO)(3)Co(μ(2)-GaCp*)(2)Co(CO)(3)] with ZnMe(2) in the presence of py or thf leads in both cases to the formation of [(CO)(3)Co{μ(2)-ZnL(2)}(μ(2)-ZnCp*)(2)Co(CO)(3)] (L = py (4), thf (5)) via replacement of GaCp* with {Zn(L)(2)} units as well as Cp* transfer from the gallium to the zinc centre. All compounds were characterised by NMR spectroscopy, IR spectroscopy, single crystal X-ray diffraction and elemental analysis. 相似文献
8.
9.
Vancouver, Canada March 30, 1994 相似文献
10.
Jia-Pei Du Dr. Alexander Wilting Prof. Dr. Inke Siewert 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(21):5555-5564
Here, the reduction chemistry of mono- and binuclear α-diimine-Re(CO)3 complexes with proton responsive ligands and their application in the electrochemically-driven CO2 reduction catalysis are presented. The work was aimed to investigate the impact of 1) two metal ions in close proximity and 2) an internal proton source on catalysis. Therefore, three different Re complexes, a binuclear one with a central phenol unit, 3 , and two mononuclear, one having a central phenol unit, 1 , and one with a methoxy unit, 2 , were utilised. All complexes are active in the CO2-to-CO conversion and CO is always the major product. The catalytic rate constant kcat for all three complexes is much higher and the overpotential is lower in DMF/water mixtures than in pure DMF (DMF=N,N-dimethylformamide). Cyclic voltammetry (CV) studies in the absence of substrate revealed that this is due to an accelerated chloride ion loss after initial reduction in DMF/water mixtures in comparison to pure DMF. Chloride ion loss is necessary for subsequent CO2 binding and this step is around ten times faster in the presence of water [ 2 : kCl(DMF)≈1.7 s−1; kCl(DMF/H2O)≈20 s−1]. The binuclear complex 3 with a proton responsive phenol unit is more active than the mononuclear complexes. In the presence of water, the observed rate constant kobs for 3 is four times higher than of 2 , in the absence of water even ten times. Thus, the two metal centres are beneficial for catalysis. Lastly, the investigation showed that the phenol unit has no impact on the rate of the catalysis, it even slows down the CO2-to-CO conversion. This is due to an unproductive, competitive side reaction: After initial reduction, 1 and 3 loose either Cl− or undergo a reductive OH deprotonation forming a phenolate unit. The phenolate could bind to the metal centre blocking the sixth coordination site for CO2 activation. In DMF, O−H bond breaking and Cl− ion loss have similar rate constants [ 1 : kCl(DMF)≈2 s−1, kOH≈1.5 s−1], in water/DMF Cl− loss is much faster. Thus, the effect on the catalytic rate is more pronounced in DMF. However, the acidic protons lower the overpotential of the catalysis by about 150 mV. 相似文献