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排序方式: 共有1775条查询结果,搜索用时 593 毫秒
981.
982.
983.
Thin-film zeolite-filled silicone/PVDF composite membranes were fabricated by incorporating zeolite particles into PDMS(poly(dimethylsiloxane)) membranes.The morphology of zeolite particles and zeolite filled silicone composite membranes were characterized by SEM.The zeolite-filled PDMS/PVDF composite membranes were applied for the pervaporation of ethanol/water mixtures and showed higher flux compared with that reported in literatures.The effect of zeolite loading and Si/Al ratio of zeolite particles on... 相似文献
984.
A new flavonoid glucoside from Cassia angustifolia 总被引:1,自引:0,他引:1
A new flavonoid glucoside with a known one was isolated from the leaves of Cassia angustifolia.Based on the spectral analysis, including MS,~1H NMR,~(13)C NMR,DEPT,~1H-~1HCOSY,HMQC,HMBC and NOSEY,their chemical structures were determined as kaempferol-3-O-[(6′′′-O-trans-sinnapoyl)-β-D-glucopyranosyl(1→)]-β-D-glucopyranoside 1 and apigenin-6,8-di-C-glycoside 2. 相似文献
985.
GAO Yang JIANG Ru-zhi CHEN Ying-hong LUO Hao-ming XU Duo-duo GAO Qi-pin .Research Development Center Changchun University of Traditional Chinese Medicine Changchun P.R.China .Academy of Traditional Chinese Medicine Material Medica of Jilin Province Changchun 《高等学校化学研究》2009,25(1)
The water-soluble part(GS) of Ganoderma sinense Zhao,Xu et Zhang was divided into high molecu-lar(GS-H) and low molecular(GS-L) parts by Cellulose Super Filtration,and GS was also fractionated into four frac-tions,GS-1,2,3,and 4 by ethanol precipitation according to their molecular weights.Chemical analysis shows that GS and GS-1,2,3,4 were complexes of polysaccharide and peptide.The fractions with molecular weights over 4000,GS-1,2,3,and GS-H show anti-tumor activities,however,the fractions with molecular ... 相似文献
986.
WANG Hao-an LI Yu-xin LI Zheng-ming CHENG Hai-ying WANG Su-hua LIU Bin Elemento-Organic Chemistry Institute State Key Laboratory of Elemento-Organic Chemistry National Pesticide Engineering Research Center Nankai University Tianjin P.R.China 《高等学校化学研究》2009,(1)
A series of novel 2,3-dihydro-2-phenylsulfonylhydrazono-3-(2',3',4',6'-tetra-O-acetyl-β-D-glucopyranosyl) thiazoles were designed and synthesized via the reaction of thiosemicarbazide with chloroaldehyde.Their chemical structures were characterized by 1H and 13C NMR spectroscopy and elemental analysis.The bioassay results indicate that some of these compounds exhibit moderate fungicidal and herbicidal activities. 相似文献
987.
Measurement of Atrazine Adsorption onto Surficial Sediments (Natural Surface Coatings)——New Evidence for the Importance of Fe Oxides 总被引:1,自引:0,他引:1
LI Yu WANG Ao GAO Qian WANG Xiao-li .Energy Environmental Research Center North China Electric Power University Beijing P.R.China .College of Environment Resources Jilin University Changchun .Jilin Provincial Center for Sanitary Inspection Test Changchun 《高等学校化学研究》2009,25(1)
To reveal the relative contribution of the components, Fe, Mn oxides or organic materials(OMs) in the surficial sediments(SSs), and the natural surface coating samples(NSCSs) to adsorbing atrazine(AT), a selective chemical extraction technique was employed, to remove the different components, and the adsorption characteristics of AT on the SSs and the NSCSs were investigated. The observed adsorptions of AT on the original and extracted SSs and NSCSs were analyzed by nonlinear least squares fitting(NLSF) to estimate the relative contribution of the com-ponents. The results showed that the maximum adsorption of AT on the NSCSs was greater than that in the SSs, be-fore and after extraction treatments, implying that the NSCSs were more dominant than the SSs for organic pollutant adsorption. It was also found that the Fe oxides, OMs, and residues in SSs(NSCSs) facilitated the adsorption of AT, but Mn oxides directly or indirectly restrained the interaction of AT with SSs(NSCSs) particles. The contribution of the Fe oxides to AT adsorption was more than that of OMs; the greatest contribution to AT adsorption on a molar ba-sis was from the Fe oxides in the nonresidual fractions, indicating that the Fe oxides played an important role in con-trolling the environmental behavior of AT in an aquatic environment. 相似文献
988.
目的:研究叶下珠药材中的荧光活性物质及性质,为光敏剂的筛选提供资料。方法:采用50%乙醇提取、乙酸乙酯萃取,对叶下珠植物提取分离:采用荧光扫描确定提取液激发波长和发射波长。提取液经硅胶柱层析,氯仿:甲醇:磷酸(85:14:1)洗脱。结果:提取液最小激发波长和最大发射波长分别为418nm和667nm。硅胶柱层析获得6种组分,其中一种组分,经418nm光激发后,在667nm处具有较强的荧光发射峰。pH酸性、提高温度和光照均可提高其荧光强度,碱件条件会导致其荧光猝灭。通过液质测定,推断其为珠子草素。结论:该成分具有光敏剂开发前景。 相似文献
989.
990.
Some embedding inequalities in Hardy-Sobolev space are proved.Furthermore,by the improved inequalities and the linking theorem,in a new k-order Sobolev-Hardy space,we obtain the existence of sign-changing solutions for the nonlinear elliptic equation {-△(k)u:=-△u-(((N-2)2)/4)U/︱X︱2-1/4 sum from i=1 to(k-1) u/(︱x︱2(In(i)R/︱x︱2))=f(x,u),x ∈Ω,u=0,x ∈Ω,where 0 ∈ΩBa(0)RN,N≥3,ln(i)=i éj=1 ln(j),and R=ae(k-1),where e(0)=1,e(j) = ee(j-1) for j≥1,ln(1)=ln,ln(j)=ln ln(j-1) for j≥2.Besides,positive andnegative solutions are obtained by a variant mountain pass theorem. 相似文献