Mr. Yan’s practice focuses on patent reexamination and invalidation, patent infringement analysis, patent litigation, patent consultation and patent search in organic and high polymer chemistry, chemical engineering, photoelectric material, semiconductor material, environmental protection, medical device, analysis and detection device, oil field mining equipment and related fields; and he has studied US Patent Law, European Patent Law and examination practice study in US and Germany for a long time; besides, he has successfully handled many patent filings covering various technical fields.