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991.
992.
The Bose-Einstein distribution is used to investigate Landau's hydrohynamical model with viscosity. In case the viscosity dependence on the temperature isT 3, the correction to the multiplicity behaves like 1/E and is found to be negligible for thepp data. A discussion is presented on a possibility of reconcilingE 1/2 and logE dependence of the multiplicity law. 相似文献
993.
利用△E-E望远镜及北京Q3D磁谱仪系统.在HI-13串列加速器提供的35MeVα离子轰击下,测量了56Fe(аd)58Co核反应的精细能谱和微分截面角分布.借助全微观DEBA理论分析,相应于核反应俘获的p-n核子对具有(lg9/2)2组态,观测到迄今所能看到的最高拉长态(lg9/2,lg9/2)_9.还对6.4 MeV高激发能级核反应截面的反常增强,而p-n核子对耦合成最小角动量的实验证据进行了讨论,并且确认了6.4MeV能级为非自然宇称态,自旋字称值Jл=1+. 相似文献
994.
995.
996.
997.
Feng Dang Kazumi Kato Hiroaki Imai Satoshi Wada Hajime Haneda Makoto Kuwabara 《Ultrasonics sonochemistry》2010,17(2):310-314
A new effect of ultrasonic irradiation on the formation of BaTiO3 particles was identified. Ultrasonication caused the aggregation of the original 5–10 nm BaTiO3 particles in the same crystal axis and accelerated the formation of BaTiO3 particles significantly. Furthermore, narrow size distribution was obtained for the aggregated particles under ultrasonic irradiation. 相似文献
998.
Jian Quan Qi Li Sun Peng Du Wan Ping Chen You Guo Xu Long Tu Li 《Journal of nanoparticle research》2010,12(7):2605-2609
Barium titanate nanoparticles with various nominal Ba/Ti ratios were prepared through direct synthesis from solution (DSS)
and further annealed at different temperatures. Their deviation from stoichiometry was studied through XRD analysis, and a
large deviation from stoichiometry has been observed. The grain size we studied ranges from 50 nm to 1 μm. For the as-prepared
particles, the grain size is about 50 nm, and the maximum excess of Ti is over 15%. For the samples annealed at 800 °C, the
grain size is increased to 100 nm, and the maximum excesses of Ba and Ti are 8 and 9%, respectively. The defects formed during
synthesis and surface effect of nanoparticles are both estimated for their contributions to the deviation from stoichiometry,
and the defects have been found to be mainly responsible for the large deviation observed. 相似文献
999.
Hahn FE Le Van D Paas M Fröhlich R 《Dalton transactions (Cambridge, England : 2003)》2006,(6):860-864
A versatile synthesis of unsymmetrically N,N'-substituted saturated carbenes is described. The novel racemic imidazolidin-2-ylidenes rac-5 have been synthesized by reductive desulfurization of the corresponding imidazolidin-2-thiones rac-4. The thiones were prepared in two reaction steps from aldimines and secondary amines. Three different substituents at N1, N3 and C4 of the five-membered N-heterocyclic ring can be introduced by choice of suitable aldimines and secondary amines. The dimerization behaviour (diaminocarbene/enetetramine equilibrium) for the unsymmetrically N,N'-substituted imidazolidin-2-ylidenes has been investigated by NMR spectroscopy. Unsymmetrically N-iPr and N-iBu substituted N-heterocyclic carbenes undergo a slow dimerization, whereas N-tBu substituted derivatives are stable as monomeric carbenes indefinitely. The carbene ligand rac-5d has been coordinated to rhodium(I) to give the square-planar rhodium carbene complex [Cl(cod)Rh(rac-5d)]rac-6d which has been characterized by an X-ray diffraction analysis. 相似文献
1000.
Petriellin A is a novel cyclic depsipeptide antifungal compound consisting of nine l-configured residues, one d-phenyllactic acid (PhLac) and three unknown chiral centres: two N-methyl-threonines (MeThr1 & MeThr2) and one N-methyl-isoleucine (MeIle). NMR experiments including 2D ROESY, NOESY along with structural and energy calculations predicted that the unknown chiral centres were all l-configured, which was later verified chemically. Simulated annealing, dynamics calculations and minimisation processes showed Petriellin A to have a folded "C-shaped" structure. 相似文献