216 results about "Bifunctional" patented technology

The invention discloses an acid recovery process based on nanofiltration-reverse osmosis, and belongs to the technical field of wastewater treatment, the acid recovery process comprises the following steps: step 1, adsorbing aluminum ions in chemical polishing waste liquid through extraction resin, evaporating and concentrating effluent, and using the effluent as recycled chemical polishing tank acid liquid; step 2, desorbing the adsorbed extraction resin by using distilled water, separating aluminum ions from the obtained desorption liquid through diffusion dialysis, and separating the recovered acid liquid through nanofiltration; step 3, concentrating the nanofiltration thin liquid through reverse osmosis to obtain concentrated acid liquid which is used as recycled sulfuric acid desorption liquid; and 4, adding alkali into the diffusion dialysis residual liquid, the nanofiltration concentrated liquid and the reverse osmosis thin liquid for neutralization to prepare the aluminum-containing flocculating agent. According to the method, adsorption, diffusion dialysis, nanofiltration and reverse osmosis processes are combined, and an amino-containing imidazolium salt modified polyamide nanofiltration membrane and a phosphonic acid-sulfonic acid bifunctional group-containing reverse osmosis membrane are adopted, so that efficient separation and recovery of acid and aluminum ions in the chemical waste liquid are realized, and economic benefits are increased while the cost is reduced.

The invention provides a bifunctional nano-enzyme SERS (Surface Enhanced Raman Scattering) detection platform for ultrasensitively detecting mi RNA (Ribonucleic Acid) related to cerebral infarction and a preparation method, and relates to the technical field of biomedical engineering. The preparation method comprises the following steps: synthesizing gold nanorods (AuNRs) by using a seed growth method, and growing Pt on the surface of a product to prepare gold platinum nanorods (Au (at) Pt NRs); the preparation method comprises the following steps: synthesizing gold nano hexagonal plates (AuNHs) by using a seed growth method, and preparing an AuNHs array through oil-water interface self-assembly; and modifying an aptamer complementary chain (H1) on the Au (at) Pt NRs obtained in the step (1) through an Au-S bond. And combining the assembled AuNHs array with a nucleic acid aptamer (cDNA) corresponding to mi R-106a-5p to functionalize the assembled AuNHs array in the step (2), so as to construct an SERS (Surface Enhanced Raman Scattering) detection platform. The target mi R-106a-5p can be specifically combined with cDNA, so that Au (at) Pt NRs carrying H1 are separated from the surface of an AuNHs array, TMB oxidation is reduced, and SERS signals are remarkably reduced. And according to SERS signal intensity, substituting the SERS signal intensity into a linear regression equation to realize quantitative detection of mi RNA.

Described herein are heterobifunctional small molecules, methods of making, pharmaceutical compositions and medicaments comprising such heterobifunctional small molecules, and methods of using such heterobifunctional small molecules are described herein, in the treatment of diseases and conditions, such as cancer, autoimmune diseases, and inflammatory diseases.

This invention relates to a method for synthesizing iron-cobalt alloy-doped carbon nanofibers for electrocatalysis using zinc oxide etching, belonging to the technical field of electrode materials and catalysts. The preparation method includes the following steps: 1) mixing DMF (dimethylformamide), PMDA (pyromellitic dianhydride), and ODA (4,4-diaminodiphenyl ether) in a certain proportion to prepare a PAA (polyamic acid) spinning solution; 2) preparing PAA nanofibers from the PAA spinning solution using an electrostatic melt-blowing device; 3) imidizing the PAA nanofibers using a programmed temperature rise method to obtain PI nanofibers; 4) impregnating the PI nanofibers in a salt solution; 5) carbonizing the impregnated PI nanofibers with a large number of metal ions on their surface in an inert atmosphere using a certain temperature rise program to obtain iron-cobalt alloy-doped carbon nanofibers. The iron-cobalt alloy-doped carbon nanofibers prepared by this method exhibit excellent performance as an ORR / OER bifunctional electrocatalyst and have wide applications.

The invention relates to the fields of food, cosmetics and biological medicines, in particular to a chitosan derivative containing bifunctional groups (triazole and coumarin) and a preparation method and application thereof. The structure of the derivative is shown as a formula (1). According to the method, mild reaction conditions are adopted, raw materials which are easy to obtain and low in cost are used, the prepared chitosan derivative has good water solubility and meanwhile has remarkable antioxidant activity and antifungal activity, and the application range of chitosan in all industries is effectively widened. The chitosan derivative containing bifunctional groups (triazole and coumarin) has wide application potential in the fields of cosmetics, foods, biological medicines and the like, and is convenient for industrial popularization. # imgabs0 # formula (1).

The invention discloses a propolis extract-loaded sprayable bifunctional gel as well as a preparation method and application thereof. The preparation method comprises the following steps: synthesizing acetylated carboxymethyl chitosan by taking carboxymethyl chitosan and acetic anhydride as raw materials; the preparation method comprises the following steps: reacting acetylated carboxymethyl chitosan and aminophenylboronic acid serving as raw materials to synthesize a boric acid modified acetylated carboxymethyl chitosan gel precursor; the preparation method comprises the following steps: blending a boric acid modified acetylated carboxymethyl chitosan gel precursor with water, and self-assembling into A-CC-PBA hydrogel under the action of a hydrogen bond and a pi-pi bond; and adding the propolis extract into the A-CC-PBA hydrogel, so as to obtain the A-CC-PBA hydrogel. The gel prepared by the invention has good adhesion performance, can stably retain in the local part of the oral ulcer and can realize efficient targeted recognition and slow release of drugs to realize efficient sterilization and long-acting anti-inflammatory effects, the curative effect on the oral ulcer is obviously improved, and a new preparation type is provided for oral mucosa administration.

The invention discloses a lactoferrin and antibacterial peptide bifunctional hydrogel dressing as well as a preparation method and application thereof. The hydrogel dressing is prepared by mixing lactoferrin, antibacterial peptide NZ2114, a magnesium lithium silicate gel matrix and water. The hydrogel dressing provided by the invention has the following advantages: 1) the hydrogel dressing is simple to prepare, low in cost and suitable for batch production; 2) the gel is convenient to apply, has a moisturizing effect, is long in residence time, good in biocompatibility, small in irritation, safe and reliable, or is accurately injected to the wound, moisturizes, slowly releases and efficiently improves the compliance of the body, and 3) the gel is good in antibacterial and anti-inflammatory effects, good in biocompatibility, free of irritation and capable of promoting wound healing, and only needs to be smeared on the surface of the wound.

The invention belongs to the field of medicinal chemistry, and particularly relates to a compound shown in a formula (I), pharmaceutically acceptable salt, deuterated substance, stereoisomer, tautomer or a mixture thereof, which can be used as a protein degradation agent for degrading an androgen receptor or a spliceosome thereof. The compound can be used for preparing medicines for treating and / or preventing diseases related to androgen receptors or spliceosomes thereof. # imgabs0 #

The invention belongs to the technical field of chemical pharmacy, and particularly relates to a preparation method and application of an impurity of a beta2 adrenal receptor stimulant and M receptor antagonist bifunctional active compound. According to the impurity preparation method of the beta2 adrenal receptor stimulant and M receptor antagonist bifunctional active compound, acetylation of amino is successfully realized by using acetylation reagents such as acetyl chloride and alkali accelerators such as N, N-diisopropylethylamine, then debenzylation is performed through hydrogenation reaction, and the compound shown in the formula I is successfully prepared. Then, through liquid chromatography purification, a high-purity compound as shown in the formula I is obtained, and the raw material medicine as shown in JKN2304 can meet the requirements of reference substances in the research and development process; the technical problem that in the prior art, an impurity synthesis process of a beta 2 adrenal gland receptor agonist and M receptor antagonist bifunctional active compound is lacked is solved.

The present invention relates to compounds of formula (I) wherein the variables m, R1, R2, R3, R4, R5 and R6 are as defined in the description. The invention also relates to a preparation method of the compound shown in the formula (I), a photocurable composition containing the compound shown in the formula (I), a photocurable material prepared from the photocurable composition and application of the compound shown in the formula (I) in the field of photocurable materials. The invention has the following beneficial effects: (1) the compound of formula (I) has good photopolymerization activity, and can be rapidly cured under the action of ultraviolet light; and (2) the surface hydrophobicity, heat resistance and tensile property of the cured film can be improved by adding the compound in the formula (I). # imgabs0 #

The invention belongs to the technical field of novel functional nano materials, immunoassay and biosensing, and provides preparation of a dual-mode immunosensor based on PdSn dual-function nano enzyme, which is used for sensitively detecting cardiac troponin I (cTnI). A palladium-tin alloy / molybdenum carbide composite material (PdSn / Mo2C-C) serving as a second antibody beacon and a gold nanoparticle / hydrogen bond organic framework composite material (Au NPs / HOFs) serving as a substrate material are prepared respectively, a sandwich type sensor is constructed based on the materials, and the cTnI antigen concentration in an actual serum sample is quantitatively detected by using dual modes (an electrochemical method and a colorimetric method). Visually explainable and ultra-sensitive bimodal analysis is realized, the advantages of high sensitivity, low detection limit and the like are shown, and a new thought is provided for cTnI detection.

Polymerizable, radiation-curable compositions are provided and comprise (i) monomers and (ii) at least one further component, wherein the (i) monomers comprise (a) at least one urethane (meth)acrylate that is at least difunctional, (b) at least one monofunctional acrylate having an alicyclic group and / or at least one monofunctional methacrylate having an alicyclic group, and (ii) the at least one further component comprises (c) at least one photoinitiator for the UV and / or visible range or a photoinitiator system for the UV and / or visible range. The compositions are usable for producing, via a rapid prototyping, manufacturing, or tooling process, dental prosthetic parts, orthopaedic instruments, or dental pre-forms that have a flexural strength of greater than or equal to 75 MPa, a modulus of elasticity of greater than or equal to 2600 MPa, and / or a water absorption of less than 45 [μg / mm3].

The invention relates to the technical field of coatings, in particular to a high-efficiency photocuring monomer based on bio-based star-shaped polyester polyol and a preparation method of the high-efficiency photocuring monomer based on bio-based star-shaped polyester polyol. Castor oil derived trimethylolpropane is used as a core, adipic acid and epoxidized soybean oleic acid are introduced through a condensation polymerization reaction to form star-shaped structure polyol; an acrylate group is introduced into a polyol molecule through a glycidyl methacrylate ring-opening reaction, and an epoxy group in the epoxidized soybean oleic acid is retained; through unique molecular structure design, reasonable component selection and innovative process optimization, multiple technical breakthroughs are realized. The bio-based branching design has remarkable effects in the aspects of cost reduction and environmental protection; the reaction activity and the curing performance of the material are greatly improved through the synergistic effect of bifunctional groups; and the problem of environmental pollution in the traditional process is solved by green process integration. The invention provides a high-performance and environment-friendly novel photocuring monomer for the field of photocuring materials.

The invention discloses a transition metal doped base bifunctional CO2 adsorbent, a preparation method and application thereof. The transition metal doped base bifunctional CO2 adsorbent comprises a base bifunctional material and transition metal. The preparation method comprises the following steps: weighing transition metal, Ni, Na and Zr sources, mixing and dissolving in deionized water, stirring to form a uniform solution, weighing a precipitant, dissolving in deionized water, adding into the mixed system after complete dissolution, and stirring to form a uniform solution; stirring and precipitating the mixed system in a constant-temperature water bath kettle, drying the precipitate, calcining the obtained solid powder, and grinding into powder to obtain the transition metal doped base bifunctional CO2 adsorbent. The preparation method of the transition metal doped basic group difunctional CO2 adsorbent material is simple, a coprecipitation method preparation process is adopted, transition metal is doped into Ni-Na2ZrO3, formation of in-situ holes and pore channels is promoted, and the exposed area of active sites of the adsorbent is increased; meanwhile, the formation of lattice defects in unit cells is promoted, the surface energy of the crystal face of the material is changed from the physical dimension of a solid, and the adsorption capacity and cycling stability of CO2 are improved.

The invention belongs to the field of feed additive preparation, and particularly relates to an acidophilic difunctional NSP enzyme and application thereof in improving the digestibility of monogastric animals to grains and / or byproducts thereof, and the amino acid sequence of the acidophilic difunctional NSP enzyme is shown as SEQ ID NO: 1. The NSP enzyme is extremely acid-resistant bifunctional beta-glucanase / xylanase, and can effectively hydrolyze barley and degrade beta-glucan and xylan, so that the viscosity caused by the NSP is reduced, the digestibility of the barley is improved, and the digestibility can be improved by about 8% compared with that of a control group (no enzyme is added).

The invention relates to a difunctional chimera heterocyclic compound for targeted degradation of an androgen receptor and application of the difunctional chimera heterocyclic compound, and particularly provides a compound shown in a formula (I), or an isotope compound of the compound, or an optical isomer of the compound, or a tautomer of the compound, or a pharmaceutically acceptable salt of the compound, or a prodrug of the compound, or a solvate of the compound, aRB is an androgen receptor recognition / combination part, L is a linking part, and U is a ubiquitin protease recognition / combination part; the three parts are connected through chemical bonds. The compound provided by the invention can degrade androgen receptors in prostate cancer cells in a targeted manner and inhibit proliferation of the prostate cancer cells, and also shows good metabolic stability and pharmacokinetic properties. The compound provided by the invention has a good application prospect in preparation of a protein degradation targeting chimera of an androgen receptor and in preparation of drugs for treating related diseases (including prostatic cancer, breast cancer and Kenildie disease) regulated and controlled by the androgen receptor. # imgabs0 #

The application discloses a bifunctional HMGR mutant, which is obtained by replacing aspartic acid at the 154th amino acid of the amino acid sequence of natural HMGR with other amino acids. The application also discloses a nucleotide sequence and an amino acid sequence. The application further discloses a preparation method and application of the bifunctional HMGR mutant. The HMGR mutant of the application has high activity to both NADP(H) and NAD(H) substrates, and has significantly improved catalytic activity in a certain pH range.

The invention provides a novel bifunctional material and a preparation method and application thereof, and relates to the technical field of catalyst preparation, the bifunctional material has the following general formula: A-M / CaO-S, wherein A is an active component, M is an auxiliary agent metal, and S is a bifunctional material carrier; a is selected from at least one of Rh, Ru and Ni; m is selected from at least one of La, Ce, K and Na. According to the invention, the problems of tedious steps, low carbon efficiency, low energy efficiency and poor technical economy due to mutual independence of carbon dioxide trapping and chemical utilization processes are solved, and the technical effects of efficiently trapping carbon dioxide, catalyzing the reaction of carbon dioxide and methane in situ and successfully generating synthesis gas (H2 and CO) are achieved; and a solid scientific support is provided for economical efficiency and resource utilization of carbon dioxide.

The invention discloses a Cu-Al-Ca bifunctional material with a core-shell structure as well as a preparation method and application of the Cu-Al-Ca bifunctional material. A core of the Cu-Al-Ca bifunctional material is an Al-Ca adsorbent composed of Al2O3 and CaO, and a shell of the Cu-Al-Ca bifunctional material is metal Cu; wherein based on the total mass of the Cu-Al-Ca bifunctional material, the mass fraction of the metal Cu in the bifunctional material is 0.5-3.0 wt%, and based on the total mole number of the metal elements of the Cu-Al-Ca bifunctional material, the mole ratio of the Al element to all the metal elements is 1-10%. The Cu-Al-Ca bifunctional material has a stable structure, is not easy to sinter and inactivate, can be used for CO2 capture and in-situ reverse water gas shift preparation of CO, still has excellent CO2 absorption capacity, CO2 conversion rate and CO product selectivity after multiple times of cyclic utilization, and has high cycle stability.

The invention discloses a monomolecular bifunctional organic catalyst for ring-opening copolymerization of epoxide and cyclic anhydride. The structural formula of the monomolecular bifunctional organic catalyst is shown as a formula (I). In the formula (I), the structural formula of X is shown as the following formula (II-1) or (II-2), and in the formula, B is a boron atom; r1 is selected from alkyl; # imgabs0 # represents a connecting bond; the structural formula of Y is as shown in the following formula (III), wherein O is an oxygen atom; r2 is selected from one or more of Li, Na, K, Cs, quaternary ammonium cations and bis (triphenylphosphine) ammonium cations; l is selected from the group consisting of unsubstituted C4-C11 alkyl groups; the monomolecular bifunctional organic catalyst disclosed by the invention is specially used for the ring-opening copolymerization reaction of epoxide and cyclic anhydride, the TOF of the monomolecular bifunctional organic catalyst can be up to 13500h, and the prepared polymer has high molecular weight and low molecular weight distribution and also shows excellent air stability and thermal stability. # imgabs1 # (I); # imgabs2 # (II-1); 3 # imgabs3 # (II-2); and 4 # imgabs4 # (III).

The invention discloses a catalyst for photocatalytic coupling of CO2 reduction and HMF oxidation as well as a preparation method and application of the catalyst. The preparation method comprises the following steps: dissolving a noble metal precursor in a titanium dioxide dispersion liquid, and then adding a reducing agent for reaction; the catalyst for photocatalytic coupling of CO2 reduction and HMF oxidation is obtained. The Au-coated TiO2 Schottky heterojunction bifunctional photocatalyst prepared by the invention has the effects of simultaneously reducing CO2 and oxidizing HMF, electrons and holes are fully utilized, the CO precipitation efficiency can reach 17.6 [mu] mol g <-1 > h <-1 >, the yield of HMFCA reaches 34.6%, and the selectivity exceeds 95.0%. Visible light is used as energy to drive reaction, and energy consumption and environmental pollution are reduced. In addition, energy fuel and high-added-value chemicals can be synchronously produced, good environmental and economic benefits are achieved, harmful by-products are not generated in the whole photocatalysis process, and the principle of green chemistry is met.

Embodiments of the disclosure relate to methods of selectively depositing a metal after use of a flowable polymer to protect a substrate surface within a feature. A first metal layer is deposited by physical vapor deposition (PVD). The semiconductor substrate surface is exposed to one or more monomers to form a flowable and flexible polymer film on the first metal layer within the at least one feature. The flowable polymer film forms on the first metal layer on the bottom. The one or more monomers are selected from one or more of amines with bi-functional groups, aldehydes with bi-functional groups, cyanates with bi-functional groups, ketones with bi-functional groups, and alcohols with bi-functional groups. At least a portion of the first metal layer is selectively removed from the top surface and the at least one sidewall. The flowable polymer film is removed.

This invention provides a thiourea-tertiary amine bifunctional chitosan microsphere and its preparation method, belonging to the field of adsorption material technology. Through a stepwise functionalization and sequential crosslinking method, thiourea groups are first introduced onto the chitosan microspheres, followed by the introduction of tertiary amine groups and secondary crosslinking, successfully preparing chitosan microspheres possessing both thiourea and tertiary amine bifunctional groups. The thiourea and tertiary amine groups in the microspheres of this invention exhibit a synergistic adsorption effect on noble metal chloride anions, significantly improving the selective adsorption capacity and adsorption rate for noble metals such as palladium, platinum, and rhodium. Simultaneously, the dense three-dimensional network structure constructed through stepwise crosslinking greatly enhances the chemical stability and mechanical strength of the microspheres under strongly acidic environments, extending their service life. This preparation method is simple, mild, and environmentally friendly. The prepared adsorbent is particularly suitable for the efficient and selective recovery of noble metals from complex acidic wastewater or electronic waste leachates.

The invention relates to the field of chemical amplification gel, and discloses a bifunctional molecular group and a preparation method and application thereof.The bifunctional molecular group comprises PAG, PQD1 and PQD2, the PQD1 and the PQD2 are the same or different, and the synthesis method of the bifunctional molecular group comprises the steps that under the alkaline condition, acetone glyceryl reacts with PAG to generate 1-PGA-acetone glyceryl ether, the product is hydrolyzed under the acidic condition to obtain 1-PGA-glyceryl ether, and the 1-PGA-glyceryl ether is hydrolyzed under the acidic condition to obtain the 1-PGA-glyceryl ether. The product reacts with PQD1 and PQD2 in the presence of a catalyst under the heating reflux condition to obtain a target bifunctional molecular group, and when the bifunctional molecular group is applied to chemical amplification glue, the contrast ratio of the chemical amplification glue can be effectively improved, and the resolution ratio is increased.

The invention discloses an oxygen-doped carbon nanofiber bifunctional electrocatalytic oxidation film and a preparation method and application thereof. The atomic ratio of nitrogen atoms to oxygen atoms in the oxygen-doped carbon nanofiber bifunctional electrocatalytic oxidation film is 11: (6-15). The catalytic performance of the electrocatalytic oxidation film can be improved by controlling the atomic ratio of nitrogen atoms to oxygen atoms in the oxygen-doped carbon nanofiber bifunctional electrocatalytic oxidation film, and then the catalytic efficiency of the electrocatalytic oxidation film is improved.

The invention discloses a preparation method and application of a high-selectivity chemical warfare agent fluorescent probe based on free radicals, and belongs to the field of fluorescent probe materials. The invention aims to solve the problem that the existing fluorescent probe is seriously interfered by protonic acid. The method comprises the following steps: 1, preparing CZ-DTE-C1; and 2, preparing a filter paper strip membrane by using CZ-DTE-Cl doped polyoxyethylene. The high-selectivity chemical warfare agent fluorescent probe based on the free radicals is used for detecting mustard gas, phosgene or sarin and has high selectivity. Compared with the traditional fluorescent probes, such as an organic metal compound probe, a nitrogen-oxygen bifunctional nucleophilic reagent probe, a nitrogen-based nucleophilic reagent probe and an oxygen-based nucleophilic reagent probe, the fluorescent probe provided by the invention is a novel free radical-based sensing reaction, and can simultaneously realize visual-fluorescent dual-mode detection of mustard gas, phosgene and sarin simulants; the selectivity is high.

The invention belongs to the field of new energy materials and technologies, and particularly relates to a non-noble metal difunctional electrolyzed water catalyst and a preparation method and application thereof. According to the non-noble metal bifunctional electrolyzed water catalyst, foam metal serves as a matrix, molybdenum carbide, iron-cobalt layered double hydroxides or derivatives of the iron-cobalt layered double hydroxides are evenly loaded on the matrix, and the molybdenum carbide and the iron-cobalt layered double hydroxides or the derivatives of the iron-cobalt layered double hydroxides are in contact doping to generate FeCoMo nano-particle heterojunctions in irregular shapes. The preparation process of the non-noble metal bifunctional water electrolysis catalyst is simple, the production cost is reduced, the production efficiency is improved, the performance of the catalyst is improved, and a more efficient, economical and environment-friendly catalyst solution is provided for hydrogen production through water electrolysis.

The invention provides a preparation method of a novel chiral thiourea / phosphine bifunctional organic catalyst with a cis-cyclic 1, 2-phosphinamine skeleton and application of the novel chiral thiourea / phosphine bifunctional organic catalyst in an asymmetric catalytic reaction. The chiral organic catalyst is prepared by taking cis chiral 2-(diphenylphosphine)-1, 2, 3, 4-tetrahydro-1-naphthylamine and an isothiocyanate compound as raw materials through a one-step reaction under a mild condition. The chiral thiourea / phosphine bifunctional organic catalyst is simple to prepare and stable in property, and shows excellent catalytic activity and stereoselectivity in an asymmetric hydrosilylation reaction of o-amido benzophenone.

The invention relates to the technical field of industrial wastewater denitrification, in particular to an industrial wastewater deep denitrification method based on a graphene adsorption material, which comprises the following steps: introducing industrial wastewater containing total nitrogen into an adsorption reaction unit; ammonia nitrogen and nitrate nitrogen in the wastewater are removed by adjusting the empty bed contact time; when the adsorption material is saturated, the particles are regenerated, and regenerated liquid is collected for nitrogen resource utilization. According to the core-shell type dual-functional graphene adsorption particle, rich amino functional groups on a PEI chain of the core of the core-shell type dual-functional graphene adsorption particle can efficiently and specifically adsorb and remove ammonia nitrogen through the ion exchange effect, the shell of the core-shell type dual-functional graphene adsorption particle is composed of magnesium-aluminum hydrotalcite growing in situ, exchangeable anions between hydrotalcite laminates can be subjected to ion exchange with nitrate nitrogen, and therefore the ammonia nitrogen can be removed through the core-shell type dual-functional graphene adsorption particle. Selective adsorption of nitrate nitrogen is realized; the synchronous deep removal of ammonia nitrogen and nitrate nitrogen in industrial wastewater is realized, the treatment efficiency is greatly improved, and the process flow is simplified.

The invention discloses a double-function (p) ppGpp synthetase or hydrolase mutant, a biological material and application of the double-function (p) ppGpp synthetase or hydrolase mutant to preparation of L-threonine, and belongs to the technical field of gene engineering. The technical problem to be solved by the invention is how to improve the yield of L-threonine. Relative to a wild type, the bifunctional (p) ppGpp synthetase or hydrolase mutant comprises one or more of the following mutations: K1) mutation of 174th amino acid of SEQ ID NO: 2 into cysteine, K2) mutation of 529th amino acid of SEQ ID NO: 2 into phenylalanine, and K3) insertion of histidine and aspartic acid between 84th amino acid and 85th amino acid of SEQ ID NO: 2. The bifunctional (p) ppGpp synthetase or hydrolase mutant provided by the invention can be used for improving the yield of L-threonine of Escherichia coli.