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  • Author or Editor: Li Zhang x
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Abstract  

Many academic journals of China began to be published in English when China opened door to the world more than 20 years ago. Tsinghua University started to publish an academic journal, the Tsinghua Science and Technology since 1996. We made statistical analyses on the regional distribution on the authors and of the references cited by the articles of Tsinghua Science and Technology from 1996 to 2002. The results show that although the authors are mainly from the Tsinghua University, the number of authors from other regions, especially the number of overseas authors, are increasing in recent years; the average number of references cited by every article are increasing from 6.9 in 1996 to 13.4 in 2002. The results suggest that we must learn the successful experiences from well-known journals. Attracting high-level articles and realizing the internationalization of the journal will help us to develop the journal.

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Abstract  

Two sufficient conditions for a finite group G to be p-supersolvable have been obtained. For example (Theorem 1.1), let N be a normal subgroup of G such that G/N is p-supersolvable for a fixed odd prime p and let N p be a Sylow p-subgroup of N. Suppose that N is p-solvable and Ω1(N p) is generated by the subgroups of order p of N p which are normal in N G(N p). Then G is p-supersolvable.

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SOFM (self-organizing feature map) clustering is powerful in analyzing and solving complicated and non-linear problems. This method was used and compared with fuzzy C-means clustering and TWINSPAN, the most common classification methods, in analysis of plant communities in the Guancen Mts., China. The dataset consisted of importance values of 112 species in 53 quadrats of 10 m × 20 m. All the three methods classified the 53 quadrats into eight groups, representing eight associations of vegetation. They were all effective in the analysis of ecological data. The consistency of SOFM clustering with fuzzy C-means clustering (FCM) and TWINSPAN classification was 81.1% and 94.3%, respectively. SOFM clustering has some advantages and more potentiality in application to studies of ecology.

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Abstract  

By using 188Re as a radiotracer, the extraction behavior of Re(VII) by a tertiary amine extractant N-235 from HCl and the back-extraction behavior of Re(VII) by HNO3 and ammonia were studied. A chemical separation procedure, which combined the acid alumina column and solvent extraction was established. The procedure was rapid and efficient for the separation of 186Re from 186W irradiated by 16 MeV deuterons. No-carrier-added 186ReO4 saline solution with high specific volume activity was obtained. The overall recovery yield of 186Re was about 85%.

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Authors: Li Yuguo, Zhang Xiaodong, Li Qingnuan and Li Wenxin

Abstract  

In this paper water-soluble fullerene derivative C60(OH)xOy was radioiodinated with the iodogen method. The labeling yield was determined by radio-TLC. The effects of pH value, reaction time, temperature and amount of the iodogen on the labeling yield were studied. The labeled product was purified by Sephadex G-25 column chromatography and then the stability of 125I-C60(OH)xOy was examined . The results showed that the radiochemical purity of 125I-C60(OH)xOy solution with benzylalcohol remained 82.7% after 43 hours.

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Authors: Yan Shuheng, Lin Fa, Zhang Hongdi, Li Xueliang and Zhang Shulan

Abstract  

In order to determine the fission yields of lanthanides precisely, lanthanides with carriers of 1–2 mg per element are separated from each other by means of pressurized cation exchange chromatography-HIBA concentration gradient elution: The effects of initial loading technique, concentration gradient, flow rate, and temperature on separation were investigated in detail. Under the optimum conditions adopted according to the results given in this work, all the lanthanides can be completely separated within about 90 minutes with a recovery of more than 95% and purity higher than 99%.

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