How to estimate the effect of an intense meteor shower on human space activities

In the present age, the potential threat to space projects coming from some intense meteor storms has been noticed. Especially, the increasing activities of mankind in space for scientific, commercial and military purposes have led to an increase in safety-related problems about the satellites, space stations and astronauts. Several new techniques for observing meteors and meteor showers have been developed. However, how to estimate even predict the effect of an intense meteor shower should be further studied. The initial definition about a meteor storm based on visual observations with a Zenithal Hourly Rate of over one thousand seems insufficient, since it only means a storm or burst of meteors in numbers. In 2006 the author suggested a synthetical index of the potential threats about intense activities of meteors; however, it is too complex to determine several parameters. In this paper, the author suggests a Special True Number Flux Density (STNFD). Set a certain energy-limit, or a certain electric-charge-limit, and then calculate the number flux density. Through the comparison between two of the 10 strong meteor showers in recent years it is found that the important factor affecting the space flight security is not only the number of meteoroids, but also their velocities, their average energy and the population index r. Calculations show that Giacobinids, even June Bootids, should be one of the most hazardous meteor showers.     

方剂的化学成分及药效物质

方剂是中医临床用药的主要形式,是中医理论整体观和辨证施治的最佳体现,在整个中医药体系中占有举足轻重的地位;由于化学成分不清楚,作用机理不明确,方剂的国际化在很大程度上受到了限制。方剂的化学成分和药效物质研究是中医药现代化研究的两个重要组成部分。近年来,多种生物技术和分析化学方法为方剂化学成分和药效物质研究提供了新的方法和技术。本文在总结方剂化学成分和药效物质基础研究现状的基础上,提出了进一步深入研究的基本思路。     

Four New Taxoids from the Barks of Taxus yunnanensis

The ongoing study of our previous work1-4 led to the isolation of four new taxoids from the barks of Taxus yunnanensis. One of them belonged to a paclitaxel analogue named 7-xylosyl-taxol D, the others were 11(15?1)-abeotaxoids with an opened D-ring system, named taxuyunnanines P-R respectively. Their structures were determined by means of spectral method s including 1D and 2D NMR spectroscopy.7-Xylosyl-taxol D (1), white powder, has a molecular formula, C49H61NO18, from its positive HR…     

A New 24, 30-Dinortriterpenoid from Paeonia delavayi

We reported some constituents from the plant of Paeonia delavayi Franch1. Further investigation on the chemical constituents of the same plant resulted in the isolation and determination of a new triterpenoid, 3(, 4(, 23-trihydroxy-24, 30-dinorolean-12, 20(29)-dien-28-oic acid 1, in addition to five known compounds, 2(, 3(, 23-trihydroxy-12-oleanen-28-oic acid-(-D-glucopyranosyl ester2, palbinone3, 2-hydroxy-benzoic acid4, vanillic acid4, syringic acid5. In this paper we describe the structur…     

Measurement of Orotic Acid in Urine by Supercritical Fluid Chromatography

Orotic acid is an intermediate in the pathway of pyrimidine synthesis. It is an important substance but difficult to analyze in biological samples because it is present in trace amount in normal human urine, but greatly increased in inherited metabolic diseases and drug treatment. The methods used to determine orotic acid in urine were mainly high performance liquid chromatography (HPLC)1 and capillary zone electrophoresis (CZE)2. To date, the analysis of orotic acid in urine with SFC h…     

New Diterpenoid Alkaloids from Spiraea japonica var. Ovalifolia

In the investigation of the chemical constituents of Spireae japonica L. f. var. ovalifolia (Rosaceae), a shrub originated in Songming, Yunnan, five new diterpenoid alkaloids, 19-O-deethylspiramine N (1), deacetylspiramine S (2), spiramidine A (3), spiramidine B (4) and deacetylspiramine F (5), were isolated from aerial parts of the plant and structurally elucidated. Compound 1, a white amorphous powder with [(]+17.99 (c, 0.26, MeOH ), was determined to have the molecular formula of C20H…     

Paired-permanent approach for VB theory (Ⅱ)——An ab initio spin-free VB program

Paired-permanent approach for VB theory is extensively developed. Canonical expansion of a paired-permanent is deduced. Furthermore, it is shown that a paired-permanent may be expressed in terms of the products of sub-paired-permanents of any given order and their corresponding minors. An ab initio spin-free valence bond program, called Xiamen, is implemented by using paired-permanent approach. Test calculation shows that Xiamen package is more efficient than some other programs based on the traditional VB algorithm, and it provides a new practical tool for quantum chemistry.     

Paired-permanent approach for VB theory (II)

Paired-permanent approach for VB theory is extensively developed. Canonical expansion of a paired-permanent is deduced. Furthermore, it is shown that a paired-permanent may be expressed in terms of the products of sub-paired-permanents of any given order and their corresponding minors. Anab initio spin-free valence bond program, called Xiamen, is implemented by using paired-permanent approach. Test calculation shows that Xiamen package is more efficient than some other programs based on the traditional VB algorithm, and it provides a new practical tool for quantum chemistry.     

ICP-AES雾化法氢化法联合同时测定人血清中三十种元素

本文探讨了用ICP-AES雾化法氢化法联合同时测定人血清中三十种元素的方法。本法最低检出量基本满足血清样品的测定要求。方法回收率在95—105%之间,重复测定的相对误差小于5%。对于探索血清元素含量与疾病的关系及临床诊断有一定价值。     

火焰原子吸收法测定血清中三种元素的三种前处理方法比较

本文就火焰原子吸收法测定血清中K、Fe、Mg三种元素常用的三种前处理方法,即用去离子水稀释、用1%硝酸稀释、用硝酸-高氯酸消化进行了比较,并用数理统计方法进行差异显著性测验,证明三种前处理方法所得结果一致。其中1%硝酸稀释法操作简便快速,适于批量样品的分析。