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排序方式: 共有137条查询结果,搜索用时 17 毫秒
1.
用强子–弦级联模型JPCIAE及相应的Monte Carlo事例产生器研究相对论性核–核碰撞中带电粒子多重数的赝快度密度对能量和中心度的依赖关系.无需另调任何模型参数的条件下,此模型可以同时较好地描述相对论性pp实验数据及PHOBOS和PHENIX实验组的Au+Au实验数据.本文指出:因〈Npart〉并非严格定义的物理量,致使实验上和理论上确定〈Npart〉有一定任意性,从而使得每参加者核子对的带电粒子赝快度密度随着〈Npart〉的增加可能逐渐增大,也可能逐渐减小,因此用它来区分粒子产生机制是欠妥的. 相似文献
2.
S. G. Yunusova S. D. Gusakova A. I. Glushenkova U. K. Nadzhimov Sh. Turabekov SA. Musaev 《Chemistry of Natural Compounds》1991,27(2):147-150
A comparative analysis has been made of the amounts of lipids and their fatty-acid compositions in the seeds of the lines of agenetic collection of cotton plants of the speciesGossypium hirsutum and their hybrids and the variety Tashkent-1. The results obtained on the fatty-acid compositions of some hybrids make it possible to recommend the use of individual lines of cotton plants as donors for improving the food-value indices of cottonseed oil.Institute of Chemsitry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 173–176, March–April, 1991. 相似文献
3.
4.
G.R. Clark C.M. Cochrane W.R. Roper L.J. Wright 《Journal of organometallic chemistry》1980,199(2):C35-C38
The osmium carbyne complex, Os(CR)Cl(CO)(PPh3)2, (R p-tolyl) reacts with Group I halides to form the mixed dimetallocyclopropene species, R)Cl(CO)(PPh3)2, R)Cl(CO)(PPh3)2, R)Cl(CO)(PPh3)2, and [R)Cl(CO)(MeCN)(PPh3)2] ClO4 X-ray crystal structure determination of R)Cl(CO)(PPh3)2 confirms the presence of a three-membered ring and the structure can be viewed as the “acetylene-like” interaction of an osmium—carbon triple bond with AgCl. In acid solution AgCl is precipitated and an alkylidene complex results from proton addition to the carbyne ligand. 相似文献
5.
We give numerical and theoretical evidence in support of the conjecture of Dressler that between any two positive integers having the same prime factors there is a prime. In particular, it is shown that the abc conjecture implies that the gap between two consecutive such numbers is , and it is shown that this lower bound is best possible. Dressler's conjecture is verified for values of and up to .
6.
We obtain upper bounds for mixed exponential sums of the type
where pm is a prime power with m⩾ 2 and X is a multiplicative character (mod pm). If X is primitive or p⫮(a, b) then we obtain |S(χ,f,p
m)| ⩽2np
2/3 m. If X is of conductor p and p⫮( a, b) then we get the stronger bound |S(χ,f,p
m)|⩽np
m/2.
This paper is dedicated to Prof. Wang Yuan on the occasion of his 70th birthday. 相似文献
7.
Role of structure in amorphous magnetic materials: Dense random packing of hard spheres of two sizes
We investigate the structure of amorphous rare-earth transition-metal alloys and its influence on their magnetic properties in the context of a simple model. The packing fraction of the alloys is discussed using both ball-bearing assemblies and also computer-generated clusters of randomly close-packed hard spheres, and the latter clusters are used to discuss the radial distribution functions (RDF's) and the magnetic anisotropy. The computer-generated RDF's are compared with published neutron diffraction results on amorphous TbFe2. 相似文献
8.
利用溶液聚合和成酰胺反应合成了多功能梳状两亲性共聚物,聚(甲基丙烯酸-co-甲基丙烯酸十八酯)-(乙醇胺-乙二胺叶酸)(PSM-EE-FA).用红外光谱(FTIR),核磁共振(1H-NMR)及凝胶渗透色谱(GPC)表征了该聚合物的结构及分子量分布.实验结果证明合成了该聚合物,其数均分子量(Mn)为28600,多分散性为1.375.用该两亲梳状聚合物包覆油溶性CdSe/ZnS量子点,通过相转移作用,得到水溶性靶向量子点(PSM-EE-FA-QDs).该水溶性量子点溶液具有较好的稳定性.通过紫外-可见(UV-Vis)及荧光发射光谱分析对该量子点的光学性质进行研究.结果表明,PSM-EE-FA-QDs的紫外-可见光谱及荧光发射光谱峰形与原量子点基本一致.由于量子点表面聚合物层的形成,峰位发生少量红移.该量子点水溶液的荧光强度是原量子点氯仿溶液的98%,荧光产率是原量子点氯仿溶液的95%.动态光散射(DLS)及透射电镜(TEM)测试结果表明水溶性量子点分布均匀.合成的水溶性量子点不但光学性能稳定,而且聚合物及水溶性量子点的合成方法较为简便. 相似文献
9.
Sonier JE Huang W Kaiser CV Cochrane C Pacradouni V Sabok-Sayr SA Lumsden MD Sales BC McGuire MA Sefat AS Mandrus D 《Physical review letters》2011,106(12):127002
It is shown that attempts to accurately deduce the magnetic penetration depth λ of overdoped BaFe(1.82)Co(0.18)As? single crystals by transverse-field muon spin rotation (TF μSR) are thwarted by field-induced magnetic order and strong vortex-lattice disorder. We explain how substantial deviations from the magnetic field distribution of a nearly perfect vortex lattice by one or both of these factors is also significant for other iron-arsenic superconductors, and this introduces considerable uncertainty in the values of λ obtained by TF μSR. 相似文献
10.