A New ent-Kaurane Diterpenoid from Isodon enanderianus

Isodon enanderianus (Hand. -Mazz.) H. W. Li, has been used in folk medicine as anti-inflammatory and detoxified agent1. The Isodon genus is known to be rich in ent-kaurane diterpenoids, a series of new ent-kaurane diterpenoids have been isolated from the dried leaves of I. enanderianus2-4. In order to find more biologically active substances, we have carefully investigated the chemical constituents of I. enanderianus collected in Shiping county of Yunnan province, and as a result, enanderi…     

Retention Behaviors of Uronic Acid-containing Polysaccharides and Neutral Polysaccharides in HPGPC

The determination of molecular weights (Mw) of polysaccharides has served as an important process since the physical properties of the polysaccharides are closely related to their Mw and/or molecular weights distribution (MWD). For Mw and MWD determinations, high performance gel permeation chromatography (HPGPC) has gained wide acceptance as a preferred method due to its high sensitivity, speed and reproducibility. In chromatography, it is well known that the molecular weights are determ…     

Synthesis and Structure of E-2-(2,4,6-tri tert butylphenylphosphinyl)-2-〔N-(tert-butyldimethylsilyl)-N-(p-chrolophenyl)〕amino-1-(2,4,6-tri tert-butyl-phenyl)phosphacthylene

1　INTRODUCTIONItwaswellknown thatelementsofthesecondary and higherrow are in generaldifficulty to form multiplebondsin which apπ hybridized stateisinvolved〔1〕.Thus,simple compounds containing multiple phosphorus carbon bonds,such as methyl dynephosphine( HC≡P) 〔2 - 3〕 and methylenephosphine( H2 C=PH〔4〕,are notstableat room temperature.Three methods to stabilize compounds containing double ormultiple bond involving phosphorusatom in the pπ hybridized state are often used.The f…     

Two New Compounds from Goniothalamus Cheliensis Hu

Goniothalamus cheliensis Hu (Annonaceace) is a small tree or shrub in Yunnan Province, southwest of China. Acetogenins, styryllactones and alkaloids1-3 from the genus were reported in the previous literature and many of them showed strong cytotoxic activities against a number of human cancer cell lines4. The titled plant has been the subject of our investigation due to the impressive cytotoxicity of its organic extract against mouse lymphocytic leukemia cells in preliminary pharmacological s…     

Cosolvent Effect on the Tautomerism of Ethyl Acetoacetate in Supercritical CO_2

There are some unique advantages for chemical reactions in SCFs. For example, reaction rates, yields, and selectivity can be tuned by pressure or small amount of cosolvent. SCFs can be used to replace environmentally undesirable solvents. It is not surprised that in recent years the use of SCFs as solvents for chemical reaction media has received much attention. However, mechanism for the effect of pressure and cosolvents on chemical reactions is not very clear. Tautomeric reactions are id…     

工业多用途工具：微波激励KW级CO2激光器

提高气体放电的功率注入密度，是进一步发展工业用高功率ＣＯ２激光器的关键．为此，我们采用自制的变形 Ｍａｇｉｃ Ｔ型微波放电腔，克服了由于高频趋肤效应引起的放电不均匀，实现了大体积的均匀的微波辉光放电．在用于激励高功率ＣＯ２激光的原理性实验中，获得大于１ｋｗ的激光输出功率，光电效率优于２５％，首次达到商用水平．     

Photochemical Reduction of Aromatic Imines by 2-Phenyl-N, N-dimethylbenzimidazoline

Reduction of C=N double bonds has been recognized as an important reaction both in organic chemistry and bio-chemistry1. Hantzsch 1,4-dihydropyridine (HEH, one of NADH model compounds) has been reported as a reductive reagent for imines2. However, application of dihydropyridines as practical reducing reagents in organic synthesis is limited because of their instability3. Like NADH models, 2-phenyl-N, N-dimethylbenzimidazoline (PDMBI) is an efficient electron and hydrogen donor (Eox = 0…     

基于SAM-ED光谱匹配的绝缘子污秽类型检测方法研究

污闪是威胁电网安全可靠运行的重要原因之一，污秽类型差异将直接影响闪络电压大小。因此，及时掌握绝缘子污秽类型信息对预防污闪有重要作用。为此提出了一种基于SAM-ED光谱匹配的绝缘子污秽类型检测方法。采集不同污秽类型样本高光谱数据，经黑白校正及多元散射校正(MSC)去除噪声等干扰因素；利用竞争自适应重加权采样法(CARS)对光谱数据进行特征选取，分别在特征波段和全波段范围内通过SAM-ED光谱匹配法将测试组样本光谱与参考光谱进行匹配，根据匹配结果对样本进行分类；实验结果表明：相比于光谱角匹配法和最小距离法，SAM-ED光谱匹配法检测效果更好；基于全波长数据进行SAM-ED光谱匹配准确率可达95%,基于特征波长数据进行SAM-ED光谱匹配准确率可达98.33%。     

New conversion of Friendlnder reaction of 3-amino-1H-benzo[f]chromene-2-carbonitriles with cyclohexanone

Two different skeletons of heterocyclic compounds,quinoline and quinazolinone analogs could be obtained by a novel one-pot synthesis from substituted 3-amino-1 H-benzo[f]chromene-2-carbonitrile derivatives and cyclohexanone in DMF in the catalyst of anhydrous zinc chloride under reflux.A plausible mechanism was proposed.     

Novel preparation of NaA/carbon nanocomposite thin films with high permeance for CO2/CH4 separation

Novel NaA/carbon nanocomposite thin films were successfully prepared on a porous a-Al2O3 substrate by incorporatingnanosized NaA zeolite into novolak-type phenolic resin.The prepared films were characterized by XRD,SEM and single gaspermeation tests.The NaA zeolite/carbon nanocomposite thin films exhibited that the ideal separation factor of CO2/CH4 was 28.4and the carbon dioxide flux was 3.39*10-7mol/(Pa m2s)at room temperature and under a pressure difference of 100 kPa,whichwas two orders of magnitude higher than that of pure carbon membrane prepared at the same procedures and conditions as those ofcomposite films.From the SEM images,the films were continuous and highly intergrown.Compared with carbon membranes,thethickness of nanocomposite films was drastically decreased,which was helpful to reduce the diffusion resistance and increase theflux of gas permeance.