Open metallocene: VIII. Electronic structure of PD2ML compounds

EHMO method has been used to calculate the electronic structure of PD₂ML compounds (PD—pentadienyl or methyl-substituted one, M—transition metal atom, L—Lewis base). Compared with CP₂M (CP—cyclopentadienyl), fragment orbitals of PD₂M serve as starting point for general account of the effects of forming M—L bonds on configuration, conformation and stability of PD₂-ML compounds.     

一类非线性奇摄动Robin问题解的渐近性态

利用渐近理论和微分不等式的方法,该文研究了一类非线性奇摄动Robin问题. 证明了其解的存在性,并得到了解的任意n 阶一致有效渐近展开式.     

Low valent tungsten reaction—Composition studies and reactions with sulfoxides and pyridine-N-oxides

Sulfoxides are converted to the corresponding sulfides in good yields by low valent tungsten agents derived from WCl₆—BuLi(1) and WCl₆—Zn (2). Pyridine-N-Oxides are also reduced easily with 1 to give the corresponding pyridines in almost quantitative yields. A yellow solid WCl₄ (THF)_n is isolated from the reaction of one mole of WCl₆ and two mole of n-BuLi in tetrahydrofuran (THF) at low temperature, and its composition is established by using ESCA. IR, ¹H and ¹²C NMR. Reaction of WCl₄ (THF)_n with excess of pyridine gives the known WCl₄(C₅H₅N)₂.     

On the problem of crack system with an elliptic hole

The problem of cracks with an elliptic hole in an infinite plane is investigated. By introducing the fictitious loads on the hole edge and using the Muskhelishvili method, the problem is reduced to solving a system of mixed-type integral equations in which some are Fredholm equations but others Cauchy-type singular ones. A numerical method is suggested and can be used for the treatment of other similar equations. The numerical results for some typical examples are given, showing that the method is really effective.     

Determination of serum catecholamine metabolites in neuroblastoma by high performance liquid chromatography with electrochemical detection

A method for determining serum catecholamine metabolites such as vanillylmandelic acid (VMA), 3-methoxy-4-hydroxyphenyl glycol (MHPG) and homovanillic acid (HVA) in neuroblastoma by using high performance liquid chromatography and electrochemical detector is described. The separation of catecholamine metabolites was performed on a reverse phase column with an eluting system containing citric acid-potassium hydrogen phosphate buffer and methanol as the organic modifier. The experimental results showed that VMA and HVA levels in the serum of neuroblastoma patients were 15-30 times higher than that of the normal control group. The same phenomenon also occurred in patients with stage II neuroblastoma. Serum VMA, MHPG and HVA levels reduced to normal in patients suffering from neuroblastoma after surgery. Serum catecholamine metabolites analysed by using HPLC/ECD is more simple, sensitive and reliable than that by usual urine assay and might be used for the diagnosis of neuroblastoma even in early stage.     

Systematical Synthesis of Distamycin Analogues and Their Interaction with Herring Sperm DNA

A simple procedure for the systematical synthesis of eight distamycin analogues containing N‐methylpyrrole (Py) and N‐methylimidazole (Im) has been developed by a chloroform reaction and DCC coupling reaction without amino protection and deprotection, and the interaction of the analogues with Herring Sperm DNA was investigated by fluorescence spectroscopy.