Peng Yin Wyss Institute for Biologically Inspired Engineering Harvard University Biography Publications Institution JoVE Articles Peng Yin has not added a biography. If you are Peng Yin and would like to personalize this page please email our Author Liaison for assistance. Publications Determining the Functions of HIV-1 Tat and a Second Magnesium Ion in the CDK9/Cyclin T1 Complex: A Molecular Dynamics Simulation Study PloS One. 2015 | Pubmed ID: 25909811 Infected Nonunion of Tibia and Femur Treated by Bone Transport Journal of Orthopaedic Surgery and Research. 2015 | Pubmed ID: 25889513 Tau-dependent Kv4.2 Depletion and Dendritic Hyperexcitability in a Mouse Model of Alzheimer's Disease The Journal of Neuroscience : the Official Journal of the Society for Neuroscience. Apr, 2015 | Pubmed ID: 25878292 [Hoarse Voice As the First Symptom of the Thyroglossal Cyst: a Case Report] Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi = Chinese Journal of Otorhinolaryngology Head and Neck Surgery. Jan, 2015 | Pubmed ID: 25764934 An ESIPT-based Fluorescent Probe for Highly Selective and Ratiometric Detection of Mercury(ii) in Solution and in Cells The Analyst. Apr, 2015 | Pubmed ID: 25715950 Usage of FMRI for Pre-surgical Planning in Brain Tumor and Vascular Lesion Patients: Task and Statistical Threshold Effects on Language Lateralization NeuroImage. Clinical. 2015 | Pubmed ID: 25685705 The Associations Between Ambient Air Pollution and Adult Respiratory Mortality in 32 Major Chinese Cities, 2006-2010 Environmental Research. Feb, 2015 | Pubmed ID: 25601729 Quantitative Proteomic Analysis Reveals Heat Stress-induced Injury in Rat Small Intestine Via Activation of the MAPK and NF-κB Signaling Pathways Molecular BioSystems. Mar, 2015 | Pubmed ID: 25537883 A "turn-on" Fluorescent Sensor for Ultrasensitive Detection of Melamine Based on a New Fluorescence Probe and AuNPs The Analyst. Feb, 2015 | Pubmed ID: 25512948 Aged Monkey Brains Reveal the Role of Ubiquitin-conjugating Enzyme UBE2N in the Synaptosomal Accumulation of Mutant Huntingtin Human Molecular Genetics. Mar, 2015 | Pubmed ID: 25343992 Monitoring and Risk Assessment of 74 Pesticide Residues in Pu-erh Tea Produced in Yunnan, China Food Additives & Contaminants. Part B, Surveillance. 2015 | Pubmed ID: 25308103 Detection of Inherited Mutations for Hereditary Cancer Using Target Enrichment and Next Generation Sequencing Familial Cancer. Mar, 2015 | Pubmed ID: 25151137 Transport Stress Induces Apoptosis in Rat Myocardial Tissue Via Activation of the Mitogen-activated Protein Kinase Signaling Pathways Heart and Vessels. Dec, 2014 | Pubmed ID: 25448624 Paper-based Synthetic Gene Networks Cell. Nov, 2014 | Pubmed ID: 25417167 Toehold Switches: De-novo-designed Regulators of Gene Expression Cell. Nov, 2014 | Pubmed ID: 25417166 α(2A) Adrenergic Receptor Promotes Amyloidogenesis Through Disrupting APP-SorLA Interaction Proceedings of the National Academy of Sciences of the United States of America. Dec, 2014 | Pubmed ID: 25404298 DNA Brick Crystals with Prescribed Depths Nature Chemistry. Nov, 2014 | Pubmed ID: 25343605 Casting Inorganic Structures with DNA Molds Science (New York, N.Y.). Nov, 2014 | Pubmed ID: 25301973 Wnt/β-catenin Signaling Induces the Transcription of Cystathionine-γ-lyase, a Stimulator of Tumor in Colon Cancer Cellular Signalling. Dec, 2014 | Pubmed ID: 25193114 Bone Transport for the Treatment of Infected Forearm Nonunion Injury. Dec, 2014 | Pubmed ID: 25172529 A Prospective Randomized Trial of Selective Versus Nonselective Esophagogastric Devascularization for Portal Hypertension Journal of Huazhong University of Science and Technology. Medical Sciences = Hua Zhong Ke Ji Da Xue Xue Bao. Yi Xue Ying De Wen Ban = Huazhong Keji Daxue Xuebao. Yixue Yingdewen Ban. Aug, 2014 | Pubmed ID: 25135728 Sensitive Detection of Acetylcholine Based on a Novel Boronate Intramolecular Charge Transfer Fluorescence Probe Analytical Biochemistry. Nov, 2014 | Pubmed ID: 25132563 Determination of 16 Phthalate Esters in Tea Samples Using a Modified QuEChERS Sample Preparation Method Combined with GC-MS/MS Food Additives & Contaminants. Part A, Chemistry, Analysis, Control, Exposure & Risk Assessment. 2014 | Pubmed ID: 24983158 Altered β1,6-GlcNAc Branched N-glycans Impair TGF-β-mediated Epithelial-to-mesenchymal Transition Through Smad Signalling Pathway in Human Lung Cancer Journal of Cellular and Molecular Medicine. Oct, 2014 | Pubmed ID: 24913443 Nanolithography Based on Metalized DNA Templates for Graphene Patterning Current Protocols in Chemical Biology. 2014 | Pubmed ID: 24903883 Complex Reconfiguration of DNA Nanostructures Angewandte Chemie (International Ed. in English). Jul, 2014 | Pubmed ID: 24899518 β1,6 GlcNAc Branches-modified PTPRT Attenuates Its Activity and Promotes Cell Migration by STAT3 Pathway PloS One. 2014 | Pubmed ID: 24846175 Critical Roles of MiRNA-mediated Regulation of TGFβ Signalling During Mouse Cardiogenesis Cardiovascular Research. Jul, 2014 | Pubmed ID: 24835278 The Bifunctional Liposomes Constructed by Poly(2-ethyl-oxazoline)-cholesteryl Methyl Carbonate: an Effectual Approach to Enhance Liposomal Circulation Time, PH-sensitivity and Endosomal Escape Pharmaceutical Research. Nov, 2014 | Pubmed ID: 24805279 Developmental Self-assembly of a DNA Tetrahedron ACS Nano. Apr, 2014 | Pubmed ID: 24720462 Comparison of Lateral and Posterior Surgical Approach in Management of Extra-articular Distal Humeral Shaft Fractures Injury. Jul, 2014 | Pubmed ID: 24685053 Polyhedra Self-assembled from DNA Tripods and Characterized with 3D DNA-PAINT Science (New York, N.Y.). Apr, 2014 | Pubmed ID: 24625926 The Protective Effect of Caffeic Acid Against Inflammation Injury of Primary Bovine Mammary Epithelial Cells Induced by Lipopolysaccharide Journal of Dairy Science. May, 2014 | Pubmed ID: 24612802 Ultraspecific and Highly Sensitive Nucleic Acid Detection by Integrating a DNA Catalytic Network with a Label-free Microcavity Small (Weinheim an Der Bergstrasse, Germany). May, 2014 | Pubmed ID: 24585636 Effect of Simulated Transport Stress on the Rat Small Intestine: A Morphological and Gene Expression Study Research in Veterinary Science. Apr, 2014 | Pubmed ID: 24560020 Multiplexed 3D Cellular Super-resolution Imaging with DNA-PAINT and Exchange-PAINT Nature Methods. Mar, 2014 | Pubmed ID: 24487583 Punicalagin Inhibits Inflammation in LPS-induced RAW264.7 Macrophages Via the Suppression of TLR4-mediated MAPKs and NF-κB Activation Inflammation. Jun, 2014 | Pubmed ID: 24473904 The Prevalence of Mild Cognitive Impairment and Its Etiological Subtypes in Elderly Chinese Alzheimer's & Dementia : the Journal of the Alzheimer's Association. Jul, 2014 | Pubmed ID: 24418053 CHD7 Interacts with BMP R-SMADs to Epigenetically Regulate Cardiogenesis in Mice Human Molecular Genetics. Apr, 2014 | Pubmed ID: 24293546 Simultaneous Determination of Thiophanate-methyl and Its Metabolite Carbendazim in Tea Using Isotope Dilution Ultra Performance Liquid Chromatography-tandem Mass Spectrometry Journal of Chromatographic Science. Nov-Dec, 2014 | Pubmed ID: 24256946 The Prevalence of Dementia in Urban and Rural Areas of China Alzheimer's & Dementia : the Journal of the Alzheimer's Association. Jan, 2014 | Pubmed ID: 23871765 [Effectiveness Comparison Between Locking Compression Plate Fixation and Locked Intramedullary Nail Fixation for Humeral Shaft Fracture of Types B and C] Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi = Zhongguo Xiufu Chongjian Waike Zazhi = Chinese Journal of Reparative and Reconstructive Surgery. Dec, 2013 | Pubmed ID: 24640365 Inhibition of Heat-induced Apoptosis in Rat Small Intestine and IEC-6 Cells Through the AKT Signaling Pathway BMC Veterinary Research. 2013 | Pubmed ID: 24295139 Design Space for Complex DNA Structures Journal of the American Chemical Society. Dec, 2013 | Pubmed ID: 24256506 Conditional Dicer Substrate Formation Via Shape and Sequence Transduction with Small Conditional RNAs Journal of the American Chemical Society. Nov, 2013 | Pubmed ID: 24219616 Sertad1 Encodes a Novel Transcriptional Co-activator of SMAD1 in Mouse Embryonic Hearts Biochemical and Biophysical Research Communications. Nov, 2013 | Pubmed ID: 24211589 Comments on Mahaluxmivala Et Al. "Ilizarov External Fixator: Acute Shortening and Lengthening Versus Bone Transport in the Management of Tibial Non-unions" Injury. Dec, 2013 | Pubmed ID: 24094555 [Effect of the Near Infrared Spectrum Resolution on the Nitrogen Content Model in Green Tea] Guang Pu Xue Yu Guang Pu Fen Xi = Guang Pu. Jul, 2013 | Pubmed ID: 24059175 DNA-directed Self-assembly of Shape-controlled Hydrogels Nature Communications. 2013 | Pubmed ID: 24013352 Isothermal Self-assembly of Complex DNA Structures Under Diverse and Biocompatible Conditions Nano Letters. Sep, 2013 | Pubmed ID: 23978049 Molecular Computing: in Situ Computation of Cell Identity Nature Nanotechnology. Aug, 2013 | Pubmed ID: 23912106 BMI, WC, WHtR, VFI and BFI: Which Indictor is the Most Efficient Screening Index on Type 2 Diabetes in Chinese Community Population Biomedical and Environmental Sciences : BES. Jun, 2013 | Pubmed ID: 23816582 Comparative Study of Perpendicular Versus Parallel Double Plating Methods for Type C Distal Humeral Fractures Chinese Medical Journal. Jun, 2013 | Pubmed ID: 23786950 MAGI2 Enhances the Sensitivity of BEL-7404 Human Hepatocellular Carcinoma Cells to Staurosporine-induced Apoptosis by Increasing PTEN Stability International Journal of Molecular Medicine. Jun, 2013 | Pubmed ID: 23754155 Facile Preparation of Magnetic Graphene Double-sided Mesoporous Composites for the Selective Enrichment and Analysis of Endogenous Peptides Proteomics. Aug, 2013 | Pubmed ID: 23716354 A New Turn-on Fluorescent Probe for Selective Detection of Glutathione and Cysteine in Living Cells Chemical Communications (Cambridge, England). Apr, 2013 | Pubmed ID: 23579416 Metallized DNA Nanolithography for Encoding and Transferring Spatial Information for Graphene Patterning Nature Communications. Apr, 2013 | Pubmed ID: 23575667 Nanoscale Growth and Patterning of Inorganic Oxides Using DNA Nanostructure Templates Journal of the American Chemical Society. Apr, 2013 | Pubmed ID: 23574340 Degradation Pattern of Gibberellic Acid During the Whole Process of Tea Production Food Chemistry. Jun, 2013 | Pubmed ID: 23411203 Down-regulation of DNA Methyltransferase 3B in Staurosporine-induced Apoptosis and Its Mechanism in Human Hepatocarcinoma Cell Lines Molecular and Cellular Biochemistry. Apr, 2013 | Pubmed ID: 23397112 Direct Proteomic Mapping of Streptomyces Avermitilis Wild and Industrial Strain and Insights into Avermectin Production Journal of Proteomics. Feb, 2013 | Pubmed ID: 23201115 Myocardial Mycn is Essential for Mouse Ventricular Wall Morphogenesis Developmental Biology. Jan, 2013 | Pubmed ID: 23063798 [Anti-motion Sickness Efficacy of the Extracted Mixture of Chinese Medical Herbs and Its Influence on the Blood Level of Hormones] Zhongguo Ying Yong Sheng Li Xue Za Zhi = Zhongguo Yingyong Shenglixue Zazhi = Chinese Journal of Applied Physiology. Sep, 2012 | Pubmed ID: 23252288 Three-dimensional Structures Self-assembled from DNA Bricks Science (New York, N.Y.). Nov, 2012 | Pubmed ID: 23197527 [Survey of Dietary Intake of Chinese Adults in 2010] Zhonghua Yu Fang Yi Xue Za Zhi [Chinese Journal of Preventive Medicine]. Aug, 2012 | Pubmed ID: 23157861 Quantitative Analysis of Neurochemical Panel in Rat Brain and Plasma by Liquid Chromatography-tandem Mass Spectrometry Analytical Chemistry. Nov, 2012 | Pubmed ID: 23098234 Submicrometre Geometrically Encoded Fluorescent Barcodes Self-assembled from DNA Nature Chemistry. Oct, 2012 | Pubmed ID: 23000997 Application of Next-generation Sequencing in Clinical Oncology to Advance Personalized Treatment of Cancer Chinese Journal of Cancer. Oct, 2012 | Pubmed ID: 22980418 High Efficiency Enrichment of Low-abundance Peptides by Novel Dual-platform Graphene@SiO2@PMMA Nanoscale. Nov, 2012 | Pubmed ID: 22964978 [Influence of CO2 Pneumoperitoneum Pressures on the Expression of Adhesion Molecules of Gastric Cancer Cells] Zhonghua Wei Chang Wai Ke Za Zhi = Chinese Journal of Gastrointestinal Surgery. Aug, 2012 | Pubmed ID: 22941688 [Comparison of Three Different Bone Grafts for Spinal Fusion of Degenerative Lumbar Disease] Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi = Zhongguo Xiufu Chongjian Waike Zazhi = Chinese Journal of Reparative and Reconstructive Surgery. Jul, 2012 | Pubmed ID: 22905609 Preparation of Sandwich-structured Graphene/mesoporous Silica Composites with C8-modified Pore Wall for Highly Efficient Selective Enrichment of Endogenous Peptides for Mass Spectrometry Analysis Proteomics. Sep, 2012 | Pubmed ID: 22837154 Past Dust and GAS/FUME Exposure and COPD in Chinese: the Guangzhou Biobank Cohort Study Respiratory Medicine. Jul, 2012 | Pubmed ID: 22795505 Complex Shapes Self-assembled from Single-stranded DNA Tiles Nature. May, 2012 | Pubmed ID: 22660323 Involvement of Oxidative Stress and Mitogen-activated Protein Kinase Signaling Pathways in Heat Stress-induced Injury in the Rat Small Intestine Stress (Amsterdam, Netherlands). Mar, 2012 | Pubmed ID: 22452662 Sp1 is Involved in Regulation of Cystathionine γ-lyase Gene Expression and Biological Function by PI3K/Akt Pathway in Human Hepatocellular Carcinoma Cell Lines Cellular Signalling. Jun, 2012 | Pubmed ID: 22360859 Optimizing the Specificity of Nucleic Acid Hybridization Nature Chemistry. Mar, 2012 | Pubmed ID: 22354435 [Association Between Frequency of Fruit and Vegetable Intake and Chronic Obstructive Pulmonary Disease] Zhonghua Yu Fang Yi Xue Za Zhi [Chinese Journal of Preventive Medicine]. Aug, 2011 | Pubmed ID: 22169691 High Throughput Identification of Components from Traditional Chinese Medicine Herbs by Utilizing Graphene or Graphene Oxide As MALDI-TOF-MS Matrix Journal of Mass Spectrometry : JMS. Aug, 2011 | Pubmed ID: 21834019 Prevalence of COPD and Its Association with Socioeconomic Status in China: Findings from China Chronic Disease Risk Factor Surveillance 2007 BMC Public Health. 2011 | Pubmed ID: 21781320 Genetic Variations of α(2)-adrenergic Receptors Illuminate the Diversity of Receptor Functions Current Topics in Membranes. 2011 | Pubmed ID: 21771490 Drinking Behaviour Among Men and Women in China: the 2007 China Chronic Disease and Risk Factor Surveillance Addiction (Abingdon, England). Nov, 2011 | Pubmed ID: 21771141 Profilin1 Facilitates Staurosporine-triggered Apoptosis by Stabilizing the Integrin β1-actin Complex in Breast Cancer Cells Journal of Cellular and Molecular Medicine. Jun, 2011 | Pubmed ID: 21692986 [Latent Membrane Protein-1 of EB Virus and the Phenotype of Epithelial-mesenchymal Transition and Cervical Lymph Node Metastasis in Nasopharyngeal Carcinoma] Lin Chuang Er Bi Yan Hou Tou Jing Wai Ke Za Zhi = Journal of Clinical Otorhinolaryngology, Head, and Neck Surgery. Mar, 2011 | Pubmed ID: 21650062 The PI3K-Akt Pathway Regulates Calpain 6 Expression, Proliferation, and Apoptosis Cellular Signalling. May, 2011 | Pubmed ID: 21255642 Integrating MiRNA and MRNA Expression Profiles in Response to Heat Stress-induced Injury in Rat Small Intestine Functional & Integrative Genomics. Jun, 2011 | Pubmed ID: 21057845 Involvement of ERK1/2 Signalling and Growth-related Molecules' Expression in Response to Heat Stress-induced Damage in Rat Jejunum and IEC-6 Cells International Journal of Hyperthermia : the Official Journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group. 2010 | Pubmed ID: 20707649 Development of Mesoporous TiO(2) Microspheres with High Specific Surface Area for Selective Enrichment of Phosphopeptides by Mass Spectrometric Analysis Journal of Chromatography. A. Apr, 2010 | Pubmed ID: 20219200 Concanavalin A-immobilized Magnetic Nanoparticles for Selective Enrichment of Glycoproteins and Application to Glycoproteomics in Hepatocelluar Carcinoma Cell Line Proteomics. May, 2010 | Pubmed ID: 20217867 Effect of Heat Stress on the Porcine Small Intestine: a Morphological and Gene Expression Study Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology. May, 2010 | Pubmed ID: 20096800 Selective Data Pruning-based Compression Using High-order Edge-directed Interpolation IEEE Transactions on Image Processing : a Publication of the IEEE Signal Processing Society. Feb, 2010 | Pubmed ID: 19887318 Resistin Up-regulates COX-2 Expression Via TAK1-IKK-NF-kappaB Signaling Pathway Inflammation. Feb, 2010 | Pubmed ID: 19774455 Lipid Accumulation Mediated by Adiponectin in C2C12 Myogenesis BMB Reports. Oct, 2009 | Pubmed ID: 19874712 Arachidonic Acid Induces Acetyl-CoA Carboxylase 1 Expression Via Activation of CREB1 Endocrine. Dec, 2009 | Pubmed ID: 19842072 Intermolecular Hydroamination Between Nonactivated Alkenes and Aniline Catalyzed by Lanthanide Salts in Ionic Solvents Organic Letters. Sep, 2009 | Pubmed ID: 19708694 Smoking, Smoking Cessation and Aortic Arch Calcification in Older Chinese: the Guangzhou Biobank Cohort Study Atherosclerosis. Feb, 2009 | Pubmed ID: 18436226 Programming DNA Tube Circumferences Science (New York, N.Y.). Aug, 2008 | Pubmed ID: 18687961 An Assessment of the Quality of Randomised Controlled Trials Conducted in China Trials. 2008 | Pubmed ID: 18435861 Isolation of Soluble Proteins from an Industrial Strain Streptomyces Avermitilis in Complex Culture Medium for Two-dimensional Gel Electrophoresis Journal of Microbiological Methods. May, 2008 | Pubmed ID: 18378344 Identification and Purification of the Main Components of Cellulases from a Mutant Strain of Trichoderma Viride T 100-14 Bioresource Technology. Oct, 2008 | Pubmed ID: 18331790 Molecular Characterization, Chromosomal and Expression Patterns of Three Aquaglyceroporins (AQP3, 7, 9) from Pig Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology. Mar, 2008 | Pubmed ID: 18249020 Programming Biomolecular Self-assembly Pathways Nature. Jan, 2008 | Pubmed ID: 18202654 [The Prevalence and Characteristics of Aortic Arch Calcification Among Middle and Elderly Population in Guangzhou] Zhonghua Liu Xing Bing Xue Za Zhi = Zhonghua Liuxingbingxue Zazhi. Feb, 2007 | Pubmed ID: 17649691 Gene Organization, Alternate Splicing and Expression Pattern of Porcine Visfatin Gene Domestic Animal Endocrinology. Apr, 2007 | Pubmed ID: 16857338 Polymer-controlled Crystallization of Zinc Oxide Hexagonal Nanorings and Disks The Journal of Physical Chemistry. B. Feb, 2006 | Pubmed ID: 16494299 Transcriptional Regulation of the Resistin Gene Domestic Animal Endocrinology. Feb, 2006 | Pubmed ID: 16076545 A DNAzyme That Walks Processively and Autonomously Along a One-dimensional Track Angewandte Chemie (International Ed. in English). Jul, 2005 | Pubmed ID: 15945114 Programmable DNA Self-assemblies for Nanoscale Organization of Ligands and Proteins Nano Letters. Apr, 2005 | Pubmed ID: 15826117 On Assembling Polychlorinated Aromatic Hydrocarbons from Carbon Tetrachloride Via Dichlorocarbene Intermediary by a Solvothermal Reaction: a Reaction Pattern from Carbene-ylide Interconversion The Journal of Organic Chemistry. Feb, 2005 | Pubmed ID: 15704976 Theoretical and Practical Advances in Genome Halving Bioinformatics (Oxford, England). Apr, 2005 | Pubmed ID: 15513986 Comparisons of the M1 Genome Segments and Encoded Mu2 Proteins of Different Reovirus Isolates Virology Journal. 2004 | Pubmed ID: 15507160 A Unidirectional DNA Walker That Moves Autonomously Along a Track Angewandte Chemie (International Ed. in English). Sep, 2004 | Pubmed ID: 15372637 Yin Yang 1 is a Negative Regulator of P53 Cell. Jun, 2004 | Pubmed ID: 15210108 Structures and Stability of N13+ and N13- Clusters Journal of Molecular Modeling. Feb, 2004 | Pubmed ID: 14677050 Characterization of Polychlorinated Aromatic Hydrocarbons by Reversed-phase Liquid Chromatography with Ultraviolet Absorbance and Mass Spectrometric Detection Journal of Chromatography. A. Oct, 2003 | Pubmed ID: 14601828 [Analysis on Quality Control of Blood in Blood Banks in a Five-year Program in Hunan Province] Zhonghua Liu Xing Bing Xue Za Zhi = Zhonghua Liuxingbingxue Zazhi. Jul, 2003 | Pubmed ID: 12975011 Inhibition of NF-kappaB Activity by Plasmid Expressed AlphaMSH Peptide Journal of Neuroimmunology. Apr, 2002 | Pubmed ID: 11960637 Self-assembly of Complex Two-dimensional Shapes from Single-stranded DNA Tiles Bryan Wei1, Michelle K. Vhudzijena2, Joanna Robaszewski2, Peng Yin2,3 1Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, 2Wyss Institute for Biologically Inspired Engineering, Harvard University, 3Department of Systems Biology, Harvard Medical School JoVE 52486 Química
Self-assembly of Complex Two-dimensional Shapes from Single-stranded DNA Tiles Bryan Wei1, Michelle K. Vhudzijena2, Joanna Robaszewski2, Peng Yin2,3 1Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, 2Wyss Institute for Biologically Inspired Engineering, Harvard University, 3Department of Systems Biology, Harvard Medical School JoVE 52486 Química