China latest patents query

The latest invention patents collect the data information of China invention patents from 2000 to 2024, typesetting according to the date of patent publication, including patent number, application date, invention Bibliographic data, abstracts, and specification data of people are convenient for scientific researchers to quickly browse and search for patents.

Portable multifunctional oral cleaner

ActiveCN106580499BIncrease the lengthEasy to cleanSurgeryDental flossTongue scrapersEngineering

Owner:曾迪

A waste gas purification device

ActiveCN111249845BImprove cleanlinessProtect physical and mental healthCombination devicesElectric machineExhaust fumes

Owner:上海和达化工石油工程技术有限公司

Timepiece escapement and method of operation of the same

ActiveCN108700845BVisual indicationEscapementsClassical mechanicsEngineering

Owner:DETRA

A kind of metal-edta complex solution and its preparation method and application

ActiveCN105835182BNo precipitationGood storage stabilityBiocidePlant growth regulatorsEthylene diamine tetra aceticEthylene diamine

Owner:INNER MONGOLIA AGRICULTURAL UNIVERSITY

A damage identification method for beam structures based on support reaction force and inclination slope

ActiveCN110487580BVerification Damage IdentificationElasticity measurementClassical mechanicsMechanics

Owner:XIANGTAN UNIV

A trend analysis method and system based on UAV autonomous flight situation awareness trend

ActiveCN113568435BReliable for autonomous flightImprove universalityPosition/course control in three dimensionsSimulationUncrewed vehicle

Owner:深圳火眼智能有限公司

Display device and shared control method thereof

ActiveCN104053045BEasy to controlImprove convenienceCathode-ray tube indicatorsSelective content distributionComputer hardwareDisplay device

Owner:HISENSE VISUAL TECH CO LTD

Multi-index analysis chip with pre-reaction function and its application method

ActiveCN108490197BGood for adjusting flow resistanceAvoid connectivity crosstalkLaboratory glasswaresMaterial analysisImmune profilingPhysical chemistry

Owner:TSINGHUA UNIV

Deep water seal rubber sleeve cable and manufacturing process thereof

ActiveCN104143390AGuaranteed reliabilityExcellent longitudinal watertightnessSubmarine cablesInsulated conductorsCable transmissionElectric power transmission

Owner:安徽宏源特种电缆集团有限公司

Powder material compression molding safety equipment assisted by ultrasonic vibration

ActiveCN105643975BReduce internal frictionReduce external frictionShaping pressTransducerUltrasonic vibration

Owner:INST OF CHEM MATERIAL CHINA ACADEMY OF ENG PHYSICS

Handle belt transfer installation troweling device of handle installation machine and its use method

ActiveCN112060682BSolve the problem of slow installation and instabilityPaper-makingBox making operationsLeveling mechanismStructural engineering

Owner:名创启博温职技术转移转化(温州)有限公司

An inorganic magnesium-based adhesive for bonding and grouting fractured stone cultural relics and its preparation method

ActiveCN113563806BLight textureGood weather resistanceNon-macromolecular adhesive additivesInorganic adhesivesAdhesiveSalicylic acid

Owner:ZHEJIANG UNIV

Acellular ligament stent and seed cell compound culture method

ActiveCN101829359BPromote growthVertebrate cellsArtificial cell constructsPorosityLigament structure

Owner:SECOND MILITARY MEDICAL UNIV OF THE PEOPLES LIBERATION ARMY

Test system for routing equipment

ActiveCN108737220BUnderstand intuitiveObserve carefullyData switching networksTester deviceComputer science

Owner:广东九博科技股份有限公司

Method of making a back-illuminated radiation sensor and a back-illuminated radiation sensor

ActiveCN104797981BSolid-state devicesDiodeRadiation sensorP type doping

Owner:ASML NETHERLANDS BV

A virtualized dpdk network performance improvement method, system, terminal and storage medium

ActiveCN112003797BPerformance impactRealize rational utilizationTransmissionVirtualizationComputer architecture

Owner:INSPUR SUZHOU INTELLIGENT TECH CO LTD

Device for Improving Temperature Resolution of Long-Distance BODR Systems Using Distributed Raman Amplification and EDFA Techniques

ActiveCN104776870BReduced temperature resolutionReduce noise powerConverting sensor output opticallySpecial purpose recording/indication apparatusTemporal resolutionImage resolution

Owner:HUNAN HAIDUN OPTICAL FIBER SENSING TECH ENG LAB

Data processing method, device, electronic device, and computer-readable storage medium

ActiveCN111459635BImprove task processing efficiencyProgram initiation/switchingComputer hardwareProcessing

Owner:RAJAX NETWORK &TECHNOLOGY (SHANGHAI) CO LTD

Electromagnetic Induction Inertial Power Engine

InactiveCN101890905BNo pollution in the processNo fuel consumptionPropulsion partsControl devicesReduction driveFlywheel

Owner:黄德固

Chime bell and chime playing device

ActiveCN112863462BShort aftertasteAchieve the effect of "one bell and two tones"Percussion musical instrumentsMechanical engineeringReverberation

Owner:郝学志

A kind of composite calcium sulfonate lubricating grease and preparation method thereof

ActiveCN108949328BImprove high temperature performanceImprove extreme pressure performanceAdditivesHydroxystearic AcidStearic acid

Owner:SOUTHWEST JIAOTONG UNIV

A method of interfering with giant salamander reproduction

ActiveCN104381217BAvoid economic harmNot harmful to healthAnimal husbandryArtificial rearingGiant salamander

Owner:MABIAN XUEHE ANDRIAS BREEDING PROFESSION COOP

Method for controlling electronic expansion valve of air conditioner

ActiveCN106152399BEasy to adjustRegulation stabilityMechanical apparatusSpace heating and ventilation safety systemsControl engineeringControl theory

Owner:QINGDAO HAIER AIR CONDITIONER GENERAL CORP LTD

An energy-saving heating device for lithium battery pack

ActiveCN106099253BSave crafting materialsReduce lossesSecondary cellsEngineeringHeating effect

Owner:ZHEJIANG HUAYUAN ELECTRIC HEAT

Production method of nanocrystalline TiO2 solar battery prototype device

InactiveCN101295586BImprove production efficiencyStrong process controllabilityLight-sensitive devicesFinal product manufactureChemical fractionElectrical battery

Owner:SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI

Method for operating a current converter and current converter operating according to said method

ActiveCN109715432ACutting costsHigh resolutionSpeed controllerAc-dc conversionControl signalElectric machine

Owner:VALEO EAUTOMOTIVE GERMANY GMBH

Method for constructing block encryption algorithm based on random function

ActiveCN102571330BImprove securityHeavy calculationKey distribution for secure communicationPlaintextPassword

Owner:桂林碧琪信息科技有限公司

Control apparatus for continuously-variable transmission of vehicle

ActiveCN1959159BWith high-speed action requirementsPrevent slippingGearingGearing controlHigh speed controlAutomatic transmission

Owner:JATCO LTD +1

A kind of core-shell sustained-release nanosphere and its preparation method

InactiveCN105709232BSolve the problem of unsatisfactory sustained release effectGrowth inhibitionOrganic active ingredientsPharmaceutical non-active ingredientsCholic acidMedicine

Owner:HUBEI UNIV

Rail surface wave wear and damage detection device and method

ActiveCN108828068BAnalysing solids using sonic/ultrasonic/infrasonic wavesTrackwayAngular velocity

Owner:WUHAN HANNING TECH +1

A kind of high-density waterproof fabric and its processing method

ActiveCN107815881BIncrease contact areaIncrease contact frictionFilament/thread formingPolyurea/polyurethane coatingsGlass fiberPolyester

Owner:ZHEJIANG CADY IND

A low-noise construction site pile driver

ActiveCN106522225BIsolation from noise pollutionReduce the impact of noiseBulkheads/pilesLow noiseArchitectural engineering

Owner:江苏铭源物流有限公司

Flow control valve

InactiveCN101410769ATuning Control CharacteristicsControl characteristic adjustmentOperating means/releasing devices for valvesFlow control without auxillary powerControl valvesHydraulic fluid

Owner:SCHAEFFLER TECH AG & CO KG

Disparity map and quality evaluation method and device for 3D video

InactiveCN103686161BAvoid subjective biasImprove the quality of reviewsTelevision systemsSteroscopic systemsParallaxImage conversion

Owner:PEKING UNIV +2

Focusing optical system based on a single objective lens

InactiveCN103424879BReduce the difficulty of adjustmentIncrease flexibilityOptical elementsLight spotOptical axis

Owner:UNIV OF SHANGHAI FOR SCI & TECH

Programmable integrated circuits with redundant circuits

ActiveCN103812502BSpecial data processing applicationsLogic circuits using elementary logic circuit componentsRedundant codeMultiplexer

Owner:ALTERA CORP

A circuit power failure and leakage protection device

ActiveCN104201646BCut off in timeAvoid Electric Shock AccidentsEmergency protective arrangements for automatic disconnectionElectricityEngineering

Owner:STATE GRID CORP OF CHINA +2

Recording monophone primary and sap or primary stereo

InactiveCN1875625ATelevision system detailsPulse modulation television signal transmissionMonauralEngineering

Owner:THOMSON LICENSING SA

Sterilization method and sterilization device

ActiveCN108686241ALavatory sanitoryChemicalsVaporizationBiomedical engineering

Owner:SHINVA MEDICAL INSTR CO LTD

microwave steamer

ActiveCN105698147BReduce pollutionImprove efficiencySteam generation using hot heat carriersFood scienceMicrowaveEngineering

Owner:湛江市华升机械设备有限公司

Optical module set and optical recording/reproducing device using same

InactiveCN1925032AHigh light transmittanceMake full use of light energyRecord information storageOptical beam guiding meansOptical ModuleEllipse

Owner:HONG FU JIN PRECISION IND (SHENZHEN) CO LTD +1

Control method and electronic device for infrared light source assembly

InactiveCN107480588BAcquiring/recognising eyesEngineeringIris recognition

Owner:GUANGDONG OPPO MOBILE TELECOMM CORP LTD

A Method of Scheduling and Allocation of Measurement and Control Resources Based on Multi-agent and DNN

ActiveCN107798388BCalculation method is simpleImprove search abilityForecastingNeural architecturesEngineeringNeural network nn

Owner:SPACE STAR TECH CO LTD

Display device and display method thereof

ActiveCN108806637BNo flickeringCathode-ray tube indicatorsComputer hardwareControl signal

Owner:SHENXUN COMP KUNSHAN +1

A carbon-supported sodium vanadium fluorophosphate and its preparation and application

ActiveCN111293307BSmall particlesUniform particlesCell electrodesSecondary cellsCarbon coatingElectrolytic agent

Owner:DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI

A cement road automatic paving equipment

ActiveCN106868992BStir wellAutomate placementRoads maintainenceHydraulic cylinderArchitectural engineering

Owner:兴物城建集团有限公司

Traditional Chinese medicine composition for treating bronchial asthma in remission stage

ActiveCN103191331BSigns improvedImprove the quality of lifePowder deliveryUnknown materialsSide effectMagnolia officinalis

Owner:如东县东广物流有限公司

Loading machine and loading method

InactiveCN104648997BSimple structureEasy to operateControl devices for conveyorsDisplay deviceEngineering

Owner:GUANGZHOU FASTPRINT CIRCUIT TECH +2

Decolorization method for recycling vinyl benzene with abstraction distillation

ActiveCN101429091BImprove solubilityStrong redoxDistillation purification/separationChemical modification purification/separationDistillationSolvent

Owner:CHINA PETROLEUM & CHEM CORP +1

A composite wing UAV

ActiveCN106394856BGuaranteed to pass throughTo achieve a fixed connectionAll-wing aircraftFuselagesPropellerFixed wing

Owner:北京尖翼科技有限公司

Exciting method of flexible electric braking exciting loop of self-exciting hydraulic generator

ActiveCN102340276BEnsure safetyReliable bootGenerator control by field variationRotor (electric)Electric generator

Owner:NARI TECH CO LTD +1

Single Image Rain Noise Removal Method and Device Based on Double Fidelity Term Regular Model Based on Wavelet Transform

ActiveCN109636738BGood removal effectAchieve separationImage enhancementImage analysisImage resolutionNoise removal

Owner:WENZHOU MEDICAL UNIV

A nanoscale extraction system of plant components

ActiveCN104083901BRealize the extraction of all ingredientsNo waste of raw materialsEnergy based chemical/physical/physico-chemical processesSolid solvent extractionWave pressureTemperature control

Owner:上海少亨生物科技有限公司

A kind of andrographolide nanosuspension

ActiveCN109568266BReduce dosageFix stability issuesAntibacterial agentsOrganic active ingredientsEngineeringMicroparticle

Owner:SHINEWAY PHARMA GRP LTD +1

Visual indication of target tracking

ActiveCN104349874BProgramme controlProgramme-controlled manipulatorLighting systemHuman–computer interaction

Owner:RETHINK ROBOTICS

Special screw thread joint of high air-tight seal oil sleeve

ActiveCN102011557BSolving Stress Corrosion ProblemsReduce contact stressDrilling rodsDrilling casingsEngineeringSingle level

Owner:BC P INC CHINA NAT PETROLEUM CORP +1

Drill pipe handling device

InactiveCN102459804BDrilling rodsDrilling casingsPosition sensorRotation sensor

Owner:LONGYEAR TM

Compound admixture for high performance concrete

InactiveCN101805139BGive full play to the gelling propertySuperimposed effectSolid waste managementEcological environmentMineral Sources

Owner:BEIJING QING MAI HUA QING HLDG GRP CO LTD

Directional gear transmission, sprocket transmission and bicycle

ActiveCN105083462BWheel based transmissionGear driveGear wheel

Owner:武君

A convenient method for detecting aluminum ions based on carbon quantum dots synthesized by flavonoid glycosides and their derivatives

ActiveCN111208101BQuick checkEasy to operateFluorescence/phosphorescenceAluminum IonPhoto irradiation

Owner:HUNAN AGRICULTURAL UNIV

Tri-measuring range potential difference meter adapting transposition branch

InactiveCN100412551CAc/dc potentiometric measuring arrangementsElectrical resistance and conductancePotential difference

Owner:骆乃光

A welding head material for ultrasonic welding of plastics and its preparation method

ActiveCN106011669BTissue distributionReduce mechanical wear and tearTemperingUltrasonic welding

Owner:德召尼克(常州)焊接科技有限公司

A high-speed motor winding

ActiveCN109672290BIncrease loading capacityIncrease speedWindings conductor shape/form/constructionElectric machineControl theory

Owner:SHENZHEN HENGDRIVER MOTOR CO LTD

Power safety and quality on-site monitoring master station - wireless data terminal management system

ActiveCN104318739BEffective supervisionImprove the accuracy of safety and quality supervisionData processing applicationsTransmission systemsTask analysisWireless data

Owner:ANSHAN POWER SUPPLY COMPANY OF STATE GRID LIAONING ELECTRIC POWER COMPANY +2

An intelligent clothes drying device

ActiveCN110004677BWith shakingAvoid getting wetOther drying apparatusTextiles and paperEngineeringMechanical engineering

Owner:义乌市倩飞科技有限公司

Navigation menu display method and device based on human-computer interaction

InactiveCN105183304BImprove experienceEasy to operateInput/output processes for data processingDisplay deviceHuman system interaction

Owner:崔毅

Device and method for estimating discomfort in watching 3D images by bioelectricity

ActiveCN102133099BImprove reliabilityDiagnostic recording/measuringSensorsBiological body3d image

Owner:INST OF BIOMEDICAL ENG CHINESE ACAD OF MEDICAL SCI

Nitrogen-oxygen separation device

InactiveCN104803358ABurn fullyReduce pollutionOxygen preparationHigh concentrationCombustion

Owner:SHENZHEN Z AIDE TECH DEV

Photovoltaic panel monitoring and cleaning aerial robot system and photovoltaic panel cleaning method

ActiveCN105799910BMonitor Surface CleanlinessRealize real-time wireless monitoringCleaning using toolsCleaning using gasesTransceiverAir monitoring

Owner:辽宁宏成电力股份有限公司

A Quick Test Method of Digital Circuit Based on Tcl Language

ActiveCN111123084BAvoid modificationImprove test efficiencyDigital circuit testingTest efficiencyBatch processing

Owner:NO 20 RES INST OF CHINA ELECTRONICS TECH GRP

Saw-blade saw bit with bionic sawteeth for cutting maize straws

InactiveCN103069971BImprove wear resistanceImprove work efficiencyHarvestersCuttersTriangular functionWear resistance

Owner:JILIN UNIV

A drive circuit for a display

ActiveCN111477164BIncrease charging timeAverage data bandwidth requirementsStatic indicating devicesDriver circuitDriving current

Owner:SHENZHEN CHINA STAR OPTOELECTRONICS SEMICON DISPLAY TECH CO LTD

Electrode plate material preparation process of graphene nickel-zinc battery and graphene nickel-zinc battery

ActiveCN106898761BEfficient coatingCoated evenlyCell electrodesNickel accumulatorsMixed materialsDischarge rate

Owner:卢国骥 +2

Silica gel chromatographic filler and its preparation method and application

ActiveCN111250069BImprove stabilitySimple processIon-exchange process apparatusOther chemical processesEthoxidinePolymer science

Owner:浙江月旭材料科技有限公司

A (ba _x ca _1‑x )(ti _y m _1‑y )o ₃ Preparation method of system piezoelectric ceramic material

ActiveCN104761260BUniform grain sizeClear grain boundariesMaterials scienceSolid phases

Owner:南通双辉医疗器械科技有限公司

Frequency domain echo canceller

InactiveCN100459448CReduce computational complexityLine-transmissionTime domainModem device

Owner:TELEFON AB LM ERICSSON (PUBL)

Wet cleaning equipment

ActiveCN109411402BReduce the gas flow rateReduce defect densitySemiconductor/solid-state device manufacturingRotary stageWafer

Owner:NINGBO SEMICON INT CORP

Technique method of producing high-quality coke by residual oil or medium and low temperature coal tar

ActiveCN103305270BMeet with heatQuality improvementTreatment with hydrotreatment processesPtru catalystHydrogenation reaction

Owner:SINOPEC NANJING ENG & CONSTR +1

Rapid Analysis Method of Concrete Chloride Ion Diffusion Coefficient Based on Double Control Lines

ActiveCN105717000BSurface/boundary effectPhysical chemistryChloride

Owner:GUANGXI UNIV

A kind of ice tea melon seeds and preparation method thereof

ActiveCN104172312BUneven appearanceParticles with uneven appearanceFood scienceMonosodium glutamateMint Flavor

Owner:WUHAN XUDONG FOOD

Water dispenser photocatalytic gas phase sterilizer

InactiveCN103170241BEasy to recycleImprove cleanlinessDispersed particle filtrationDeodrantsGas sterilizerPhotocatalytic reaction

Owner:SHANGHAI NORMAL UNIVERSITY

Plane otter board stuffing type cross flow type hypergravity swinging bed and uses thereof

InactiveCN100586525CLow gas resistanceEnhanced mass transferUsing liquid separation agentFractional distillationDust controlElectric machinery

Owner:SOUTH CHINA UNIV OF TECH

Wafer pre-aligner and method of pre-aligning wafer

PendingCN112466802APhase-affecting property measurementsSemiconductor/solid-state device manufacturingWaferingEngineering

Owner:YASKAWA DENKI KK +1

Production method of water-proof heat-insulating coiled material

InactiveCN1261299CSolve the problem of waterproof and heat insulation materialsNo pollution in the processSynthetic resin layered productsLaminationEmulsionNonwoven fabric

Owner:孙凤勤

System and method for measuring corona loss of high-voltage AC transmission line

ActiveCN106226603BGuaranteed synchronization accuracyImprove accuracyDielectric property measurementsNon-electrical signal transmission systemsData acquisitionComputational physics

Owner:CHINA ELECTRIC POWER RES INST +2

A wastewater treatment device for electrolytic copper foil production and method of using the same

ActiveCN112028142BAchieve effectPoor degradation efficiencyWaste water treatment from metallurgical processWater/sewage treatmentElectrolysisCopper foil

Owner:淮安同方盐化工业污水处理有限公司

Closed cold-temperature precision forging die for straight-tooth bevel gear

ActiveCN103056264BEasy to take outImprove stress conditionForging/hammering/pressing machinesGear wheelEngineering

Owner:周卫星

A transmission demonstration teaching aid for equipment machinery

ActiveCN112447090BEasy to locate and installEasy to replaceEducational modelsMechanical engineeringIndustrial engineering

Owner:ARMY ENG UNIV OF PLA

A kind of data transmission method and device based on udp

ActiveCN105791154BImprove reliabilityData switching networksPacket lossData transmission

Owner:ZHEJIANG DAHUA TECH CO LTD

Method for training action planning model and target search method

ActiveCN110059646BImage analysisCharacter and pattern recognitionAlgorithmAction plan

Owner:暗物智能科技(广州)有限公司

A distributed security management method based on dynamic intelligent analysis of big data weights

ActiveCN105069336BAvoid major lossesReduce the possibility of trust errorsDigital data authenticationData profilingDistributed security

Owner:ZHONGSHAN YIYUN CLOUD COMPUTING

Otoprint recognition remote image body diagnosis system

ActiveCN104799828BEarly identification of the possibility of diseaseImprove efficiencyDiagnostic recording/measuringSensorsWhole bodyChain code

Owner:戚如嬅耳纹科技(深圳)有限公司

A Compensation Method for Orientation Error of Voltage-Current Hybrid Flux-Linkage Observer of Asynchronous Motor

ActiveCN114389497BHigh precisionImprove reliabilityElectronic commutation motor controlAC motor controlOvervoltageControl vector

Owner:希望森兰科技股份有限公司

Strong inhibition type anti-collapse foam liquid for drilling

InactiveCN101798499BIncreased water carrying capacityPrevent immersionDrilling compositionFoaming agentCarrying capacity

Owner:CNPC SICHUAN GASOLINEEUM GEOPHYSICAL PROSPECTING ENG TECH RES INST

A Method for Channel Estimation in Multi-user MIMO-ofdm System

ActiveCN106506415BGood estimateCommon sparse support setRadio transmissionChannel estimationChannel state informationEstimation methods

Owner:CHONGQING UNIV OF POSTS & TELECOMM

Method and device for operating and controlling mobile phone contacts

ActiveCN106713584BImprove operational flexibilitySubstation equipmentInput/output processes for data processingComputer scienceMobile phone

Owner:成都车音智能科技有限公司

A method and device for measuring the communication effect of social channels

ActiveCN104253737BFully determinedAccurately determineHardware monitoringData switching networksNetwork communicationApplication software

Owner:TENCENT TECH (SHENZHEN) CO LTD

A carding machine cover opening device

ActiveCN103741274BSimple structureReasonable designCarding machinesHydraulic cylinderAgricultural engineering

Owner:安徽宏业纺机有限公司

A control method of cloud central control system

ActiveCN108901101BMeet diverse needsElectrical apparatusElectroluminescent light sourcesData packControl system

Owner:河南云拓智能科技有限公司

Lead-containing assistant of frit used for preparation of ceramics

InactiveCN102731157BImprove smoothnessGood enamelFritAcetophenone

Owner:CARLOBBIA GLAZE KUNSHAN

Method and system supporting movement of mobile network

InactiveCN101212773BImplement Mobility ManagementReduce complexityData switching networksNetwork data managementMobility managementComputer science

Owner:HUAWEI TECH CO LTD

A power distribution cabinet with heat dissipation and dust removal and its cutting device

ActiveCN113629515BEasy to install and disassembleEasy to fixSubstation/switching arrangement cooling/ventilationSubstation/switching arrangement casingsDust controlStructural engineering

Owner:JIAXING HENGTONG ELECTRIC CONTROL EQUIP

Air purification method through dehumidifying and dedusting with phosphoric acid adsorption

InactiveCN102294158BIncrease profitAvoid corrosionUsing liquid separation agentPhosphoric acidChemical industrySorbent

Owner:GUANGXI MINGLI CHEM

Gear oil composition for non-road transportation dump truck

InactiveCN102134524BGood extreme pressure and anti-wear propertiesGood thermo-oxidative stabilityLubricant compositionAntioxidantSuccinic acid

Owner:CHANGAN UNIV

Medicament for treating encephalitis b and preparation method thereof

ActiveCN101352571BQuality improvementHigh yieldPowder deliverySerum immunoglobulinsWhole blood productIntravenous gammaglobulin

Owner:SICHUAN YUANDASHUYANG PHARM CO LTD +1

A preparation method of a composite material, a nickel-iron battery electrode comprising the composite material, and a nickel-iron battery

ActiveCN108511738BRealize localizationInhibit shuttleCell electrodesNickel accumulatorsOrganic solventElectrical battery

Owner:广东省大汽联科技有限公司