43results about How to "Overcoming the problem of low yield" patented technology

The invention belongs to the field of chemical engineering, and particularly discloses a synthetic method of ethyl salicylate with high purity and conforming to drug use. The method comprises the steps of using sulfuric acid for catalytic synthesis of the ethyl salicylate, washing a product and purifying the product; a mixture of ethanol and water is collected while ethanol with high concentration is added to a reaction system in the synthesis process, forward esterification reaction can be effectively promoted, and the improvement of the reaction yield is facilitated; the obtained ethyl salicylate product is high in purity, no unknown impurities are introduced, the requirements of the drug use are met, the quality is guaranteed from raw materials, and the unknown risk of the product during clinical use is reduced.

The invention relates to a catalyzed synthesis method for drug intermediate diaryl-class compounds. According to the method, arylhydrazine and arylboronic acid are taken as raw materials, and under the catalysis of Pd(acac)<2> / triphenylphosphine / acetic acid, the diaryl-class compounds are successfully prepared. Due to adding of auxiliaries, catalysis is effectively concerted, and smooth conducting of the reaction is promoted. The optimum solvent type adapting to a catalytic system is studied, and the method has the advantages of being high in yield coefficient, and moderate in reaction, and has the quite wide large-scale application value and market potentials.

The invention discloses a preparation method of an isotropic graphite material, specifically: after doping mesophase carbon microspheres with different particle sizes and chopped carbon fibers, undergoing liquid phase oxidation treatment, and then passing through secondary cold isostatic pressing Compression molding process, followed by carbonization and graphitization. The invention effectively overcomes the problem of low yield caused by product cracking in the existing ink preparation technology using mesocarbon microspheres as raw materials, and also improves the bending strength of graphite materials, improves compactness, reduces resistivity and Open porosity, thereby improving the performance of graphite materials.

The invention relates to a method for separating and purifying mussel mucin by using a mixed adsorption chromatography. Mussel mucin contains a group of L-3,4- -Dihydroxyphenylalanine (L-DOPA), a phenohydroxyl group thereof can act as the supplier for hydrogen bond, the benzene ring thereof can generate a hydrophobic effect, and the lysine thereof with strong positive charges is capable of forming a static bond. On the basis of the properties of mussel mucin, a mixed adsorption chromatography (i.e. the adsorption chromatography based on three principles of adsorption with hydrogen bond, adsorption with hydrophobic effect, and static adsorption) is adopted to overcome the problem of low yielding rate of mussel mucin in the prior art for separating and purifying mussel mucin. An strong acidextraction is adopted to eliminate small-molecular compounds from a desalting column, an argar medium with high concentration and high cross-linking degree to separate and purify mussel mucin, and anacetic acid-urea- polyacrylamide gel electrophoresis is used to differentiate mussel mucin through specific chromogenesis with nitro blue tetrazolium. Three principles adopted with one separation medium to separate mussel mucin achieve high selectivity, simplify the purification technology, and decrease production cost.

The invention belongs to the field of genetic engineering of molecular biology, and relates to the nucleotide sequence and encoded amino acid sequence of macrobrachium rosenbergii thymosin β4 gene, as well as the codon-optimized nucleotide sequence, in particular to macrobrachium rosenbergii thymosin Preparation method for recombinant expression of β4 protein. The recombinant expression of MrThyβ4 protein can overcome the problem of low yield in the purification and separation process, further study the function of the protein, and lay the foundation for the wide application of the protein in the research fields of biology, medicine and agriculture.

The invention discloses a method for cultivating green tea, comprising the following steps: selecting a yellow soil area with convenient irrigation and flat terrain as an organic green tea planting site, plowing the planting site and treating it step by step, and opening a planting ditch with equal depth and width; Apply the planting base fertilizer to the planting ditch in late September; transplant the green tea saplings in late October, transplant the green tea saplings together with the soil around the roots into the planting ditch after applying the planting base fertilizer, then apply soil amendments, and water regularly. Roots, followed by stamping until the soil is compacted after covering the soil completely, and fully watering; the tea seedlings are regularly trimmed, and the trunk height is kept at 40-45cm; fertilization ditch is excavated on both sides of the planting ditch, and planting base fertilizer is applied to the fertilization ditch Excavating a soil improvement ditch along the vertical direction of the planting ditch, applying a soil conditioner to the soil improvement ditch; picking mature tea trees in spring, and daily strengthening the prevention and control of diseases and insect pests.