A Novel Protoiiludane Sesquiterpene from the Wood of Xanthoceras sorbifolia

A protoilludane sesquiterpene (named xanthocerapene) was isolated from the wood of Xanthoceras sorbifolia Bunge. Its structure, including the relative configuration was established by spectroscopic and chemical methods.     

Crystal Structure and Conformation of [1-(β-D-lyxofuranosyl)uracil]- 2''''-spiro-5"-[4"-(S)-(diethoxyphosphinyl)-2"-oxazoline]

1 INTRODUCTION It is well known that natural and modified nucleosides have potential antiviral and anticancer activities[1,2]. These observations prompted us to synthesize the title compound －a new kind of spironucleoside, whose structure was determined by 1HNMR, 31PNMR and elemental analysis. The configuration was assigned by means of nuclear Overhauser effect. To further confirm the structure and configuration unambiguously, the title compound was subjected to X-ray diffractio…     

Analysis of Influential Factors of Konjac Glucomannan（KGM） Molecular Structure on Its Activity

Biological activity of konjac glucomannan is closely related to its structure,in particular to its high-level structure.Researches on the activity mechanism of konjac glucomannan are significant for revealing the mysteries of participation in life activity.In this paper,analysis of the effects of konjac glucomannan configuration and various factors on its structure and activity was conducted,mechanism of biological activity of konjac glucomannan was explored,and the hot research topic of konjac glucomannan was given.     

Atemoyacin A: A new bis-tetrahydrofuranyl annonaceous acetogenin from Annona atemoya H.

Atemoyacin A, a new annonaceous acetogenin was isolated from the alcoholic extract of the seeds of Annona atemoya Hort (Annonaceae). Its structure and relative configuration were elucidated on the basis of the spectral analysis.     

THE STRUCTURE OF ARMILLARIZIN,A NEW PROTOILLUDANE SESQUITERPENOID AROMATIC ESTER FROM ARMILLARIA MELLEA(VAHL.EX FR)QUEL.

A new protoilludane sesquiterpenoid aromatic ester,named armillarizin(1)has been isolated from the artificially cultured mycelium of Armillaria me-llea(Vahl.ex Fr)Quel.(Tricholomataceae).Its structure was deduced on the ba-sis of spectral analyses.The relative configuration was established from thenuclear Overhauser effects and from the values of ~1H-~1H coupling constants.     

A new alkaloid from Stemona sessilifolia

A new alkaloid, named sessilistemonamine D, was isolated from the roots of Stemona sessilifolia and the structure and relative configuration were determined on the basis of NMR and MS spectrometric data analysis.     

Study on the reaction of triple helix poly(A:2I) with Cu~(2+)

The effect of Cu2+ on the triple-stranded helical structure of poly(A:2I) was studied by means of circular dichroism spectral method with the help of ultraviolet spectral and ethidium bromide fluorescence probe methods. It was found that Cu2+ destabilizes the structure of the triple helix poly(A:2I) and induces its structural transformations, meanwhile, the transformations can be partially reversed by a higher NaCl concentration. The structural transformations may be expressed by the following scheme: poly(A:2I) - poly(A:I) + poly(I)- poly(A) + 2poly(I)     

THE ABSOLUTE CONFIGURATION OF S-(+)-1-p-CHLOROPHENYL-4-ETHYL-2,8,9-TRIOXA-5-AZA-1-SILATRANE(3.3.3.01.5) UNDBCANE

<正> The title compound crystallized in orthorhombic system with space group P212121 and cell dimensions a=9.805(2),b=11.381(4), c=13.865(4) A,V= 1547.0A3, Z=4,Dc=1.345 g.cm-3,λ=1.5418A,μ=13.067 cm-1.The structure was solved by direct methods and refined by block-diagonal least-squares method to the final discrepancy factors R=0.042 and Rw=0.042 for 1101 reflections with I>2.50σ(I). The absolute configuration was determined by utilizing the anomalous scattering of the Si and Cl atoms.It has the S configuration. The Si←N bond length is 2.146(5)A.     

Palcernuine,the first [5/6/6/6]-cernuane-type alkaloid from Palhinhaea cernua f. sikkimensis

One novel(named palcernuine, 1) and five known cernuane-type(2–6) alkaloids were isolated from the whole plant of Palhinhaea cernua f. sikkimensis. The structure of 1, possessing an unprecedented [5/6/6/6]-tetracyclic ring system containing two nitrogen atoms, was established on the basis of spectroscopic methods, and its absolute configuration was determined by comparison of the experimental and calculated electronic circular dichroism(ECD) spectra. A plausible biosynthetic pathway to 1 is proposed.     

Studies on the Relationship Between the Structure and Anticonvulsant Activity of Cinnamamides and Their Analogs

On the basis of systematic modification of the structure of componds of antiepilepsirine type, more than 200 cinnamamides were synthesized and tested by animal assay (maximal electroshock seizure, MES). Pharmacological evaluation showed that the configuration and the substituents on the phenyl ring and the nitrogen of amides, and substituents on the double bond displayed an important effect on the anticonvulsant activity.For studying the effect of the modification of structure to anticonvulsant activity, Hansch approach was employed to study the QSAR among 38 cinnamamides, and Hopfinger' s MSA was employed to study the MSA-QSAR among 26 cinnamamides.     

电位溶出分析法的理论和验证

本文推导了电位溶出分析法的过渡时间和电位-时间曲线方程式,并成功地进行了验证,理论和实验结果十分符合。     

流动注射在线吸附预富集原子光谱联用技术在痕量 (形态)分析中的应用

深入系统地讨论了以编结反应器(KR)为吸附介质的流动注射(FI)在线预富集分离与原子光(质)谱联用技术及其在环境和生物样品中(超)痕量元素(形态)分析中的应用。与常用的FI在线C18微柱预富体系相比,KR体系不需填料作吸附剂、反压低、可用较大样品流速以补偿其富集效率低的缺点,并且使用寿命几乎无限长。KR吸附体系具有经济、简便和易操作等优点,是替代常用的FI在线C18微柱预富集的比较理想的体系。     

气体流动注射分析和连续流动分析系统的研究-二氧化硫气体的电化学测定

本文以电化学气体传感器为检测器, 将流动注射技术直接用于二氧化硫气体分析。详细研究了气体流动体系的连接方式、气体流速以及体系中压强的变化对分析信号的影响, 得到最佳连接方式, 比较了载气流速对气体流动注射分析和连续流动分析的影响。气体流动注射分析法重现性较好, 测定2890×10^-^6mol/mol SO2的相对标准偏差为0.7%(n=12), 测定速度快, 可达50样/时。连续流动分析能达到气体传感器的稳态响应信号, 灵敏度较高。     

倒数示波计时电位法的研究: 新线路的研制及应用

本文研制了获得倒数示波计时电位图的新线路, 并加上电流反馈装置。这套装置具有灵敏度高、稳定性好等特点, 应用此线路, 我们用新的方法进行了峰电位的测量、痕量物质的分析及药品含量测定。     

逐级电子转移过程的0.5次微分电分析法

卷积伏安法(新极谱法)是近十年发展起来的一种新电化学分析方法, 本文报导了逐级电子转移过程的0.51次微分电分析法的理论和实验结果, 用计算机模拟了理论极谱图, 讨论了标准分离电位和电子转移数对极谱的影响 。并选择0.1M的NH~4Cl-NH~4OH作为缓冲溶液中铜(II)的还原作为检验理论和实验之间的关系。     

催化动力学分析法测定痕量汞(II)的新方法研究:

本文应用多目标罚函数单纯形法对汞I(II)催化亚铁氰化钾与硫脲配体置换反应测定汞(II)的实验条件优化,并对其机理进行了较深入的研究。本法用于标准水样中痕量(II)的测定,得到满意结果。     

线性变位极谱法研究XX. 卷积和去卷积配位吸附不可逆波理论

本文提出线性变位极谱卷积和去卷积配位吸附不可逆波理论, 并进行了验证,实验结果与理论相符。     

以meso-四(N-甲基-3-吡啶基)卟啉荧光光度测定痕量锌的研究

研究了以meso-四(N-甲基-3-吡啶基)卟啉测定锌痕量锌的荧光光度法, 其灵敏度较其它水溶性卟啉衍生物测定锌的分光光度法要高, 检出量为1ppb, 线性范围为0-1.0μg/25mL. 方法已用于测定自来水和头发中的微量锌, 结果满意.     

Nafion修饰电极还原计时电位溶出法的理论和验证

本文推导了Nafion修饰电极还原计时电位溶出法的过渡时间和电位-时间曲线方程式。经过验证,实验结果与理论相符。     

溶液中溶菌酶的荧光光谱研究

本文采用荧光分析法(荧光光谱、荧光偏振度)结合内源荧光探针色氨酸残基对溶菌酶及其在不同条件下的构象变化进行了研究。结果表明,利用荧光光谱可对溶菌酶溶液构象进行有效的分析,能够较直观地表征色氨酸残基在溶菌酶分子中的微环境及其在不同条件下构象的变化,得出了一些较有价值的结果。