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1.
A series of 3,6-disubstituted s-triazolo[3,4-b]-1,3,4-thiadiazoles have been synthesized,whosestructures were determined by elemental and spectral analyses;all the new compounds showed significantantibacterial activity.  相似文献   

2.
Two symmetrical (10a, 10b) and three unsymmetrical carbodiimides (10c, 10d, 10e) were synthesiz-ed from tris(β-methoxymethyl)ethylamine (1), bis(methoxymethyl)methylamine (2), and tris(methox-ymethyl)methylamine (3). They are neutral and readily soluble in many organic solvents including pe-troleum ether and possess sufficient solubilities in water except 10a which is less soluble. Their relativeabilities as condensing agent in the formation of peptide bonds were tested preliminarily by couplingphthalyl glycine and glycine ethyl ester in chloroform as well as in water and can be related to the stericeffects exerted by methoxymethyl-substituted alkyl residues with the order: tertiary>primary>secondary.1,3-Bis[bis(methoxymethyl)methyl] carbodiimide (10b) is promising as an all-soluble condensing agentfor the formation of peptide linkage and by its ready availability.  相似文献   

3.
Several chiral mixed-ligand complexes have been synthesized and theirefficiency as catalysts for the asymmetric synthesis of chrysanthemic acid tested.  相似文献   

4.
A new frog skin peptide, ranamargarin depicted as H-Asp-Asp-Ala-Ser-Asp-Arg-Ala-Lys-Lys-Phe-Tyr-Gly-Leu-Met-NH_(2′), was synthesized by the conventionalmethod. Comparisons of chemical and biological properties of both the synthetic and natural ranamargarins indicated that they were identical, so the chemical structure of ranamargarin was confirmed. Preliminary pharmacological study showed that ranamargarin was highly selective towards the SP-P subtype receptor.  相似文献   

5.
Seven polystyrene-type adsorbents (Ⅰ—Ⅶ) were synthesized by the modification of styrene-divinylbenzene copolymer respectively with hydroxymethyl, aminomethyl, methoxymethyl, phenoxymethyl, (4-hydroxy phenoxy)methyl, (4-acetylphenoxy)methyl, and acetyl groups. Their structures were characterized with chemical methods and physical techniques. The adsorption capacities of the adsorbents to stevioside and gypenosides were determined via batch test in which the HPLC method was used for the analysis of Saponin concentration of solution. The results showed that all the adsorbents could adsorb these saponins to a certain extent, but Ⅵ and Ⅶ had large capacities owing to their moderate polarities.  相似文献   

6.
A series of imidazolate-bridged heteropolynuclear complexes containing Cu2+ or Zn2+ were synthesized and characterized by reflectance spectroscopy, NMR and X-ray diffraction analysis. The bonding nature and the stability of imidazolate bridges in the complexes were studied by ESR spectroscopy, and the catalytic activity of the complexes in dismutation of O-2 was determined by NBT method. Results obtained indicate that the central Cu with N4 and N2O2 square planar or N4O square pyramidal coordination in which there is a weak bond H2O or ClO-4 on axial position, has a comparatively higher activity, but that with N5 square pyramidal having a strong bond axial ligand has almost no activity. Thus the results imply a possible formation of Cu-O-2 intermediate adduct in the catalytic process by Cu, Zn-SOD.  相似文献   

7.
INTRODUCTIONAnionic polymerization of MMA could be carried out with alkyllithium or Grignard reagent etc. in a non-polarsolvent. However, this polymerization system often involves multiple active species and side reactions dependingon initiator, countercation, solvent and polymerization temperature etc. Therefore, the molecular weightdistribution and stereomicrostructure of PMMA obtained would be very different[1-4]. These differences wouldbe mainly caused by the nucleophilic attack of…  相似文献   

8.
In this paper various non-dispersion solutions of nonlinear waves in the atmosphere are discussed. We turn the nonlinear partial differential equations into the nonlinear ordinary differential equations after the phase angle function has been introduced. The nature around the equilibrium points and singular points of these ordinary differential equations is discussed and various analytic expressions of the nondispersion solutions are obtained. In part (Ⅰ), two problems are dealt with mainly. (ⅰ) The relation between pseudo-energy and the pseudo-energy influence function and nonlinear waves is discussed. Through the discussion of the pseudo-energy influence function, we can determine the existential condition of the periodic solution, the solitary wave solution, the discontinuous periodic solution and the discontinuous solitary wave solution. We also indicate that if there exists an external source, which occasions infinitely small changes in the pseudo-energy influence function, the nonlinear solitary  相似文献   

9.
Complexes of Cu~Ⅱ, Ni~Ⅱ, Co~Ⅱ, Zn~Ⅱ, Fe~Ⅲ, Cr~Ⅲ, Cd~Ⅱ and Mn~Ⅱ with the natural product 5-hydroxy-7,4′-dimethoxyflavone(1) have been prepared and their probable structures were proposed on the basis of elemental analyses, thermal analyses and IR and UV spectral data. The ligand and all the complexes were tested in vitro for their antibacterial activity.  相似文献   

10.
Methods for the synthesis of five types of acidic phosphates, phosphonates as well asohosphinates have been deseribed. The mechanism of extrastion of rare earth of these com-pounds is examined. A free energy relationship existed in plotting equilibrium constantsagainst either pKa or ∑σ values of the acidic organophosphorus compounds under investiga-tion. Steric effects play an important role in these extrastion systems as expected. Thereactivity-selectivity principles in solvent extraction proposed by our laboratory are well de-monstrated in extraction of rare earth by acidic phosphorus--based ligands.  相似文献   

11.
In search of a suitable adsorbent used for the enrichment and separation of natural saponins from an aqueous solution, a series of porous cross-linked poly (vinylacetophenone) resins Ⅰ-Ⅸ were synthesized via the. Friedel-Crafts acylation of styrene-divinyl-benzene copolymer beads. Their carbonyl contents were characterized by infrared spectra and elemental analysis. Their physical properties such as bulk densities, skeleton densities, and specific surface areas were also determined. The tests for the resins adsorption of gypenosides showed that only those resins with high carbonyl contents and large specific surface areas could favorably adsorb gypenosides from an aqueous solution with much higher capacities.  相似文献   

12.
The development of nonfullerene small molecular acceptors (NF-SMAs) has dominated the improvement of efficiencies for organic solar cells and the near-infrared (NIR) absorption is the primary feature of NF-SMAs compared with fullerene derivatives. In this article, a series of acceptor-donor-acceptor-structured NF-SMAs (named CPICs ) containing 4H-cyclopenta[1,2-b : 5,4-b′]dithiophene (CPDT) electron donor and F-substituted 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (2FIC) as electron acceptor were designed and synthesized. With the increase of CPDT units, the elongated conjugations broadened the absorption range of the acceptors and tuned their energy levels sequentially. Therefore, their charge-transporting polarities switched from electron-only type to bipolar mode in organic field-effect transistors. Moreover, these changes also influenced the voltages, current densities, and eventual PCEs of their corresponding cells. When blending with PBDB-T, a champion efficiency of 10.01% was achieved in CPIC-2 based cells. This work demonstrated the importance of absorptions, suitable energy levels and charge transports in improving the efficiencies of organic solar cells.  相似文献   

13.
The compositions and the carbon isotope characteristics of methanes of the coal-bed gases from 14 coal mines and 3 deep to medium boreholes are studied in this paper.It is found that the coal-bed gases from the coal mines are characterized by the drying or lightening phenomena, which are absent in coal-bed gases from the boreholes.The drying and lightening features were not observed in the coalbed gases derived from both the primary zones and the lignite pyrolysis simulation experiments.Therefore, it is considered that the drying and lightening of coal-bed gases in the coal mines result from the secondary destructive processes.The origins of dried or lightened coal-bed gases may be due to (ⅰ) desorption-diffusion, (ⅱ) the exchange equilibrium of carbon isotopes between CH_4 and CO_2, and (ⅲ) mixing of primary coal-bed gases with syncoalification or postcoalification of biogenetic gases, among which the desorption-diffusion origin is of primary importance.  相似文献   

14.
Based on a statistical treatment of the quantitative relation between the extents of mod-ification of protein functional groups and the decrease of their biological activity, a meth-od was proposed (Tsou, Sci. Sin., 1962, 11:1535) and widely used for the determination ofthe number of residues essential for the biological activity ot the protein modified. How-ever, the original method depends on a trial and error approach and manual calculation tofind the best fit for the data obtained. A computer program is described in this paper forthe treatment of experimental data to produce the number of essential and non-essentialgroups modified and the ratio of rates for their modification which best fit the data ob-tained. Applications of this method show that in some cases wrong conclusions were reachedin literature and in other cases quantitative conclusions can sometimes be drawn when orig-inally either no quantitative data treatment was presented or attempts at manual curve fit-ting were unsuccessful.  相似文献   

15.
Six kinds of polymer ligands, supported on SiO_2, containing coordinating atoms P, S and N respectively, have been synthesized. The Ru(Ⅲ)-Co(Ⅱ) bimetallic complexes of these polymer ligands have been obtained and examined as catalysts for the hydroformylation of cyclohexene. The effects of reaction temperature, pressure and Co/Ru ratio etc. on the activities of catalysts were investigated in detail. The catalysts are all polymer-noncarbonyl-metal complexes, easily to be prepared, active and stable. From the experimental results it can be suggested that under reaction conditions such polymer-noncarbonyl-metal complexes convert "in situ" to polymer-carbonyl-metal complexes, thus become active catalysts. The course of this conversion is supposed as a preliminary approach.  相似文献   

16.
The chemistry of the thiacrowns,especially,of the polymer-supported thiacrowns,has not been developed to the extend of the crowns or azacrowns.Very few functionalized thiacrown compunds have been prepared.No paper concerning the polymer-supported thiacrowns platinum complexes and their catalytic behavior has been published yet.In this paper,the synthesis of fumed silica-supported polyundecyloxymethyl-1,4-dithia-7,10,13-trioxa cyclopentadecane siloxane and silica-supported poly-undecyloxymethyl-1,4-dithia-7,10,13,16-tetraoxacyclooctadecane siloxane,as well as their platinum complexes,and the catalytic activity of the complexes for the hydrosilylation of olefins with triethoxysilane are reported.  相似文献   

17.
In search of a suitable adsorbent used for the enrichment and separation of natural saponins from an aqueous solution,a series of porous cross-linked poly (vinylaceto-phenone) resins I-Ⅸ were synthesized via the Friedel-Crafts acylation of styrene-divinyl-benzene copolymer beads.Their carbonyl contents were characterized by infrared spectra and elemental analysis.Their physical properties such as bulk densities,skeleton densities,and specific surface areas were also determined.The tests for the resins adsorption of gypenosides showed that only those resins with high carbonyl contents and large specific surface areas could favorably adsorb gypenosides from an aqueous solution with much higher capacities.  相似文献   

18.
Analogues of yeast alanyl tRNA with I_(34) replaced by A_(34) or G_(34) were synthesized. Synthetic analoguesof yeast alanyl tRNT occupy the same position as the natural yeast alanyl tRNA on polyacrylamide gelelectrophoresis, and their purity is about 95% after electrophoresis on a 10% or 20% polyacrylamide gel.The two terminal and nearest neighbour nucleotides of the analogues are all correct. The accepting acti-vity of the synthetic analogues is similar to that of the reconstituted natural yeast alanyl tRNA. The in-corporation activity of alanine into proteins of the synthetic analogues is about 30% of that of the naturalof reconstituted natural yeast alanyl tRNA when I_(34) is replaced by A, and is 90% when I_(34) is replaced byG.The reason of the variation in biological function of the analogues of yeast alanyl tRNA after I_(34) re-placed by A or G was discussed.  相似文献   

19.
The comparison of Raman spectra of the chondrites (C, H, L, LL) has confirmed thatthere exist two types of meteorite carbon: one is the primary carbon present in carbonaceouschondrites (c) and the other is the secondary carbon contained in ordinary chondrites (H, L,LL). The parameter of order (I_G/I_D intensity ratio, similarly hereinafter) of primary car-bon tends to decrease with increasing petrologic type and it can reflect the temperature ofdust carrier at the time plasma gases in the early nebula were condensed to form primarycarbonaceous material and the hydrogen content in primary carbonaceous material. This kindof primary carbonaceous material maybe has not experienced late stage thermometamorphismwithin the parent body of chondrites, indicating that the carbonaceous chondrites wereformed and retained in the low temperature region of the solar system. The parameter oforder of the secondary carbon tends to increase with increasing petrologic type and it can re-flect the degree of graphitization o  相似文献   

20.
A thirty-nine nucleotide fragment (nucleotides 38—76) of yeast alanyl tRNA was prepared by using calf spleen phosphodiesterase to delete C_(36)m~1I_(37) from the 3′-half molecule of this tRNA under controlled conditions. Analogs of yeast alanyl tRNA with A, G or C instead of m~1I_(37) were synthesized and their biological activities determined. The results indicated that the aminoacylation activity of these analogs was not affected in the rat liver aminoacyl-tRNA synthetase system, compared with natural yeast alanyl tRNA. However, the incorporation activity (i. e. the activity of transferring alanine into proteins) of these analogs was significantly reduced to 20—30% of that of natural yeast alanyl tRNA in the rabbit reticulocyte lysate cell-free protein synthesizing system.  相似文献   

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