首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
Scanningtunnelingmicroscope(STM)hasrecentlybeenappliedtothestudyoftheadsorptionoforganicandbiologicalmoleculesinvariousenvironments,includingliquidcrystal(LC),onsurface.Inparticular,4_n_alkyl4′cyanobiphenyls(mCB,wheremisthenumberofcarbonsinthealkylgroup)on…  相似文献   

2.
Epimedium, one of representatives of traditional Chinese herb, is mainly composed of flavones and polysaccharide. It is famous for its antioxidant, antineoplastic and antiaging activities and has been widely used in the field of invigorating kidney and st…  相似文献   

3.
A stack of natural copper was bombarded with -particles. Cumulative cross-sections for65Ga,66Ga and65Zn production, and the excitation functions for68Ga and67Ga production, were measured using high resolution gamma-ray spectroscopy. The data are compared with the theoretical result provided by equilibrium and pre-equilibrium reaction model, for this purpose we used the code ALICE of Blann. The overall agreement with theory is good. Besides, we present the experimental data obtained by other authors.  相似文献   

4.
The substitution effect of fluorine on ethylene is investigated by means of studyingthe properties of the charge distribution at the bond critical points with the theory of atomsin molecules.It is found that fluorine atom acts not only as a σ electron acceptor,but also asa π electron donor,and these double effects are reflected in the quantity of ellipticity,Lap-lacian and the charge density of charge distribution at the bond critical points.For C—C,C—Fbonds,the major axis of elliptical contours is perpendicular to the molecular plane,but forC—H bond,it is parallel to the molecular plane.Other effects originating from the substi-tution have also been discussed.  相似文献   

5.
A systematic measurement of H2 adsorption on activated carbon over a wide scope of conditions was completed for the first time using a novel cryostat developed by the present authors. The equilibrium temperatures covered 77-298 K with the space of about 20 K, and the equilibrium pressures increased from 0 to about 7MPa. A set of adsorption/desorption isotherms was obtained by a standard volumetric method. This set of experimental data was fitted to all the well-known models of type-I isotherms, and Dubinin-Astakhov (D-A) equation was found to be the best-fit one On the basis of D-A model one can predict adsorption with relative error of ±4%. A 3-dimensional adsorption surface was also constructed, and the isosteric heat of adsorption was analytically determined. Except in the low pressure area, the calculated values agreed well with the experimental ones. Finally, the troubles encountered in applying D-A equation to supercritical adsorption is discussed.  相似文献   

6.
In this work,the influence of heat treatment on Polyamide-1010 structure ofaggregation state was studied by using WAXD and SAXS techniques.The results showedthat the best crystallinity was obtained nearby T=175℃ for Polyamide-1010 samples withvarious annealing treatment.Through extrapolating method,the Tg obtained wasapproximately 58℃.Based on the one-dimensional electron density correlation function ofpartially crystalline polymers,some structural parameters of Polyamide-1010 weredetermined by SAXS.  相似文献   

7.
Synthesized macroporous cross-linked copolymers of methyl acrylate-divinyl benzene (MA-DVB), acrylamide-N,N'-methylenebisacrylamide (AAM-BIS) and their functionalized products were used for immobilization of aminoacylase from Aspergillus oryzae. Effects of the carrier properties on the activity of immobilized aminoacylase were investigated and effects of substrate concentration, pH, phosphate buffer concentration and temperature on the immobilized aminoacylase were compared with those of the soluble aminoacylase. A column of immobilized aminoaoylase was prepared and used for continuous resolution of N-acyl-DL-methionine; the operational stability of immobilized enzyme was also investigated.  相似文献   

8.
IntroductionGlycolethersareimportantindustrialderivativesofepoxides .Polyethylene glycolethylethersandpolypropyleneglycolethylethersaretwoimportantseriesofproducts .Glycolethersaregoodsolventsduetothepresenceof—O—and—OH groups.Asare sult ,theyarewidelyuse…  相似文献   

9.
A novel polyquaternaryammonium cationic sulphur black dye was synthesized and its dyeing behavior on silk was studied. The dye exhibited excellent dyeing fixation of up to 98.2 %,as well as excellent dyeing fastness on silk.  相似文献   

10.
11.
IwrR0DUCTl0NThedeveloPmentofllthjuxnrechargeablebatteneshasattratedagreatdeal0finterestinrecentyearsduet0advancesinmicrotechnologyandPOrtabIeeleCtromceewpmenLC0nunerciaiaPPllcallonofthistechn01ogr'hasaJreadybeenrealizedwiththeintredchonofliffoum-ionrechargcablecellsbySOW'JutiliamgcarbonanodesSndlarceUtechnologyhasbeenreportedbysomeresearchersI2]usingacarb0nanodeandadifferentmetaloxide(ie.LixCoO2,LixNO2,Li.Mn204)cathodematerial.ButthecaPamtyofthecarbonandthereversibility0flithiuminc…  相似文献   

12.
There is a common hypothesis for the presently popular mild-slope equations that wave particle motion is irrotational. In this paper, an attempt is made to abandon the irrotational assumption and to set up new sea wave packet equations on slowly varying topography by use of the WKBJ method. To simplify the deduction, the two-dimensional shallow water equations are used to describe the sea wave particle motion in the very shallow nearshore area. The established equations can give some characteristics of wave propagation near shore.  相似文献   

13.
Mononuclear copper phthalocyanine (CuPc) and binuclear copper phthalocyanine (Cu2Pc2) were synthesized by the phenylanhydride-urea route, and their catalytic oxidation activity on 2-mercaptoethanol was studied. Based on the experimental results, a catalytic mechanism of Cu2Pc2 on 2-mercaptoethanol has been proposed. Furthermore, the effects of pH, Cu2Pc2 concentration, and temperature on the catalytic oxidation activity were evaluated. The results showed that CuPc has no catalytic activity, while Cu2Pc2 has high catalytic oxidation activity towards 2-mercaptoethanol with the optimal activity at pH 11. The reaction can further be enhanced by increasing Cu2Pc2 concentration and temperature, due to its endothermic characteristics.  相似文献   

14.
15.
The adsorption and diffusion of N atoms on the three low-index Cu planes were studied using 5-parameter Morse potential (5-MP) method, and the best theory-experiment agreement was obtained. N atoms of Cu(100) surface sit on the fourfold hollow site with the vertical height of 0.018 nm closely coplanar with the topmost copper layer, and the four Cu-N bond lengths are 0.182 nm and the fifth Cu-N distance is 0.199 nm. For Cu(111) system, the existence of aberrant Cu(100) reconstructed structure is approved at higher coverage, and at low coverage the structure is almost an ideal Cu(111) surface structure. With respect to Cu(110) system, the N atoms are adsorbed at LB and H3 sites, not at SB site. The diffusion passage and diffusion barrier of adsorbed N atoms were also studied.  相似文献   

16.
IntroductionIt is well known that ZnO, a wide band-gap semi-conductor, is a promising material because of its wideband gap of 3.37 eV at room temperature(RT) and itslarge excitonic binding energy of about60 meV; it canbe used to prepare high-efficiency ul…  相似文献   

17.
A new method is described for the electroless deposition of copper onto glass.Commercially available glass slide was modified with γ-aminopropyltrimethoxysilane to form self-assembled monolayer (SAM) on it .Then it was dipped directly into PdCl2 solution instead of the conventional SnCl2 sensitization followed by PdCl2 activation.Experimental results showed that the Pd^2 ions from PdCl2 solution were coordinated to the amino groups on the glass surface resulting in the formation of N-Pd complex.In an electroless copper bath containin a formaldehyde reducing agent,the N-Pd complexes were reduced to Pd^0 atoms,which then acted as catalysts and initiated the deposition of copper metal.Although the copper deposition rate on SAM-modified glass was slow at the beginning,it reached to that of conventional method in about 5min.  相似文献   

18.
pH dependence of the adsorption of Na, Sc, Ga, As, Se, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, and Pd on -Fe2O3 from a 0.1 mol dm–3 NaCl solution was studied by using a multitracer technique. Desorption of the metal ions from the -Fe2O3 with the adsorbed metal ions at pH 11 was also studied by lowering the pH of the suspensions. The desorption curve of each element was in good agreement with the adsorption curve except for Ru and Rh under conditions studied. Adsorption kinetics showed that the adsorption of most metal ions increases with shaking time before an adsorption equilibrium is attained. An increase in the adsorption was also observed with an elevation in temperature for the elements, suggesting that the adsorption is involved in chemisorption.  相似文献   

19.
Metal-matrix composites are made of materials with different physical and chemical properties. It is possible to change the mechanical, thermal and electrical properties by variation of the mass ratio of the components; therefore, metal-matrix composites have great value for industrial and technological applications. Copper–carbon composites have a good chance to be used as heat sinks for electronic components, which can be explained by their high thermal conductivity, low density and an adjustable coefficient of thermal expansion. On the other hand, the mechanical adhesion of copper and carbon is extremely weak because of their immiscibility and weak chemical interactions. In order to compensate for the low wettability of carbon by copper, a thin molybdenum intermediate layer is used as an adhesion promoter. In this work a time of flight secondary ion mass spectrometry technique was primarily used to detect the carbide formation in the molybdenum and copper layers, depending on different temperature conditions during sputter deposition and annealing afterwards. The CuMo layers were deposited by magnetron sputtering. The adhesion of the samples was determined by a destructive pull-off test. We found that heat treatment mainly modifies the carbide formation in the molybdenum and copper layers.  相似文献   

20.
Theoretical Studies on the Coordin...  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号