检索结果-南通市图书馆

Chinese Chemical Letters 1999年第12期10卷 995-998页

作者： Zhen MA Ru Dong YANG Lan YAN(Department of Chemistry, lanzhou University, lanzhou, gansu 730000) Department of Chemistry Lanzhou University

The Schiff base cryptand and its cryptates were synthesized with the methods of [1+1] condensation of trialdehyde and tris(2-aminoethyl)amine and obtained in 60-65%, 5-25% and 70-80% yields respectively with or without some rare earth elements as templates. The polyoxa-aza cryptand was produced in 72% and 60-70% yields with reduction of Schiff base and its cryptates respectively.

关键词： Schiff base polyoxa-aza cryptand rare earth condensation

Synthesis of 6-aryl substituted 3-(5'-phenyl-2H-tetrazole-2'-methylene)-S-triazolo[3,4-b]-1,3,4-thiadiazoles

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 1995年第5期13卷 448-453页

作者： ZHANG, Zi-Yi ZOU, NingNational Laboratory of Applied Organic Chemistry, Department of Chemistry, lanzhou University, lanzhou, gansu 730000, China National Laboratory of Applied Organic Chemistry Department of Chemistry Lanzhou University Lanzhou Gansu 730000 China

In this paper , 10 novel 6-aryl-3-(5'-phenyl-2H-tetrazole-2'-methylene)-S-triazolo[3, 4-b]-1,3,4-thiadiazoles have been synthesized by the condensation of 3-(5'-phenyl-2H-tetrazole-2'-methylene)-4-amino-5-mercapto-1,2,4-triazole with various aromatic carboxylic acids in the presence of phosphorus oxychloride. The structure of these compounds was determined by elemental analysis , UV, IR, 1H NMR and MS. Their spectral properties were also discussed.

关键词： S-triazolo[3,4-b]-1,3,4-thiadiazole synthesis spectral analysis

CLASSIFICATION AND EXISTENCE OF POSITIVE SOLUTIONS OF SECOND ORDER NONLINEAR DIFFERENTIAL EQUATIONS WITH DELAY DEPENDING ON THE UNKNOWN FUNCTION

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2004年第3期24卷 403-411页

作者： LiWantong DongZhongqi DepartmentofMathematics LanzhouUniversityLanzhouGansu730000China

A class of second order nonlinear differential equations with delay depenging on the unknown function of the fromin the case where ∫0∞ ds/r(s) < ∞ is studied. Various classifications of their eventually positive solutions are given in terms of their asymptotic magnitudes, and necessary as well as sufficient conditions for the existence of these solutions are also obtained.

关键词： Nonlinear differential equation with delay eventually positive solution asymptotic behavior fixed point theorem

A Facile Synthesis of (-)-5_αH,7β,10_α-Eudesmane-3,1 1-diene

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1996年第12期7卷 1081-1082页

作者： Ning ZOU Dong Liang CHENG Xin Fu PAN Yao Zu CHEN(Department of Chemistry, lanzhou University, lanzhou, gansu 730000) Department of Chemistry Lanzhou University Lanzhou Gansu 730000

s: The convenient synthesis of (-)-5αH.7β 10α-eudesmane-3. 11-dielle 1 has been achieved in four steps starting from R-(-)-carvone. The key step is the reductive deoxygenation of α,β-unsaturated tosylhydrazone to... 详细信息

关键词： A Facile Synthesis of Eudesmane-3,1 1-diene H,7

SIMULATION ON SITE ERRORS'ESTIMATION

在线全文

学校读者我要写书评

暂无评论

高原气象 1992年第3期11卷 285-293页

作者： Chen Mingli Guo Changming(lanzhou Institute of Plateau Atmospheric Physics, Chinese Academy of Sciences, lanzhou, gansu 730000) 中科院兰州高原大气物理所甘肃兰州

In this paper, using the same simulated conditions that Lopez and Passi (1989) used, the method of Chen et a1.(1991) (CLG’s algorithm) for site error estimation has been performed. The results show that the CLG works well for a four-DF network but still has some shortcomings for a three-DF system. The reason why there is a big difference between a four-DF network and a three-DF network is also discussed and several measures to improve the performance of CLG’s algorithm are suggested. For practice, we have also done the simulated experiment for the Beijing local three-DF network. This is helpful for us to use the data obtained in this network.

关键词： Lightning location system Site errors Cloud-to-ground lightning.

Photooxidation of α-Tocopherol in Micelles. A New Singlet Oxygen Oxidation Product

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1998年第9期9卷 823-826页

作者： Wei YU Li YANG Zhong Li LIU (National Laboratory of Applied Organic Chemistry, lanzhou Universitylanzhou, gansu 730000) Natl. Lab. of Appl. Organ. Chemistry Lanzhou University Lanzhou Gansu 730000 China

Methylene blue sensitized singlet oxygen oxidation of dl-α-tocopherol in dodecylsulfate (SDS) or cetyl trimethyl ammonium brondde (CTAB) ndcelles led to the formation, besidesα-tocopherol quinone and its epoxide, of a hitherto unknown spiro compound 6-hydroxy-2,6,8,9-tetramethyl-2-phytyl- 1-oxaspiro [4, 5] dec -8 - en - 7, 10-dione.

关键词： α-tocopherol singlet oxygen 6-hydroxy-2,6,8,9-tetramethyl-2-phytyl-1-oxaspiro-dec-8-en-7,10-dione

Photoinduced self-substitution of haloquinones

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 1994年第5期12卷 456-463页

作者： LIU, Zhong-Li ZHANG, Mao-Xi CHEN, Yi-Wen YANG, Li LIU, You-ChengNational Laboratory of Applied Organic Chemistry, lanzhou University, lanzhou, gansu 730000, China National Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou Gansu 730000 China

A series of novel oligo(halobenzoquinoid) compounds have been obtained from the photoinduced self-substitution of 2,5-dibromo-1,4-benzoquinone (1a), 2,6-dibromo-1,4-benzoquinone (1b), 2-chloro-1,4-benzoquinone (1c), 2-bromo-5-chloro-1,4-benzoquinone (1d), 2,3,5,6-tetrachloro-1,4-benzoquinone (1e) and 1,4-benzoquinone (1f) in the presence of N,N-dimethyl-t-butylamine (2) in acetonitrile. Dimers, trimers and/or pentamers of these haloquinones were found to be the major products.

关键词： PhotoreEtction haloquinones oligomers.

Oxyfunctionalization of ketones bearing α-methylene group with piperidine oxoammonium *** of α-diketones from monoketones

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 1996年第3期14卷 252-258页

作者： LIU, You-Cheng REN, Tan GUO, Qing-Xiang National Laboratory of Applied Organic Chemistry, lanzhou University,lanzhou, gansu 730000, China Department of Modern Chemistry, University of Science and Technology of China,Hefei, Anhui 230026, China National Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou Gansu 730000 China Department of Modern Chemistry University of Science and Technology of China Hefei Anhui 230026 China

A facile method for the title transformation is described. The reaction of 2,2,6,6-tetramethyl-4-methoxypiperidine oxoammonium chloride (1b) and ketones bearing a-methylene group in acetonitrile proceeded smoothly to give the a-oxyfunctionalized coupling products (6a-h). These coupling products decomposed upon heating in acidic medium to produce a-diketones (7a-h) in good to excellent yields.

关键词： Piperidine oxoammonium salt monoketones,α-diketones synthesis

NEW TAXANES FROM TAXUS CHINENSIS.2

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1990年第1期1卷 91-92页

作者： Zong Ping ZHANG Zhong Jian JIA Institute of Organic Chemistry,lanzhou University,lanzhou 730000,gansu,P.R.of China

Tow new taxane diterpenes were isolated from the leaves and stems of Taxus *** structures were established as 2-deacctyl-5-decinnamatetaxagifine and taxagifinc Ⅲ on the basis of spectroscopic analysis.

关键词： ppm HNMR NEW TAXANES FROM TAXUS CHINENSIS.2 Miller

REACTION OF CARBON MONOXIDE AND HYDROGEN ON M-Zr CATALYSTS—VERY HIGH SELECTIVITY TO ETHYLENE

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 1992年第4期 304-314页

作者： ZHANG Wen-Zhong SU Gui-Qin GAO Run-Xiong YIN Yuan-Qi lanzhou Institute of Chemical Physics,Academia Sinica,lanzhou,gansu 730000

Hydrogenation of carbon monoxide over M-Zr catalysts selectivelyproduces ethylene（>90%）in a short time at 360℃,in the stream of 0.8MPa syngas（H/CO=4.5/1）with a space velocity of 345 *** distribution of formed hydrocarbons does not obey the *** of the catalysts makes them be deactivated in 3 *** and Ncan recover CO conversion of catalysts（the former even en-hance it greatly）,but can not recover their selectivity to *** be-haviour of M-Zr catalysts seems to be controlled by their acidity and basici-ty.

关键词： Zr VERY HIGH SELECTIVITY TO ETHYLENE REACTION OF CARBON MONOXIDE AND HYDROGEN ON M-Zr CATALYSTS