ABSTRACT
Objective@#To analyze the policies that are aimed at the prevention and control of myopia in children and adolescents, and to provide a reference for the adjustment and optimization of follow up policies.@*Methods@#Based on policy tool theory, content analysis was performed to construct a two dimensional framework of "policy tools-policy objects" and a quantitative analysis of 43 national level policy texts related to the prevention and control of myopia in children and adolescents.@*Results@#From the perspective of policy tools, environment oriented policy tools were the most widely applied (48.36%), followed by supply oriented tools (26.39%) and demand oriented tools (25.25%) which were used closely in frequency. From the perspective of policy objects, the texts put forward requirements in schools (26.15%) were the most and in society the least (6.18%).@*Conclusion@#The policies for the prevention and control of myopia in children and adolescents should aim to improve the efficacy of supply based policy tools and increase the frequency with which demand based policy tools are adopted, while scientific research should be applied to optimize the quality of environment based policy tools.
ABSTRACT
According to the registered product standards specification of medical devices, combined with the standard reviewing work, the common problems of standards during medical devices registration were analyzed and corresponding suggestions were proposed to standardize the standard of the registered product, accelerate the standardization and promote the industry standardized.
Subject(s)
Device Approval , Equipment and Supplies , Reference StandardsABSTRACT
For the existing measurement methods of residual voltage which can't turn the power off at peak voltage exactly and simultaneously display waveforms, a new residual voltage detection method is put forward in this paper. First, the zero point of the power supply is detected with zero cross detection circuit and is inputted to a single-chip microcomputer in the form of pulse signal. Secend, when the zero point delays to the peak voltage, the single-chip microcomputer sends control signal to power off the relay. At last, the waveform of the residual voltage is displayed on a principal computer or oscilloscope. The experimental results show that the device designed in this paper can turn the power off at peak voltage and is able to accurately display the voltage waveform immediately after power off and the standard deviation of the residual voltage is less than 0.2 V at exactly one second and later.
Subject(s)
Electric Power Supplies , Equipment Design , Microcomputers , Signal Processing, Computer-AssistedABSTRACT
Designed a contrast pinhole detect testing including water leak method, electrical method and improved electrical method, and concluded that the water leak method is most suitable as the arbitration method, and recommended the national standard add the requirement on electrolytic liquid filling volume of electrical test in order to improve detection accuracy.
Subject(s)
Condoms , Latex , Materials Testing , Methods , RubberABSTRACT
OBJECTIVE: To investigate the protective effect of berberine on CCl4-induced acute liver injury in mice.METHODS: Kunming mice were included and equally divided into 6 groups: normal group,model group,berberine groups(40,20,10 mg?kg-1).After intragastric administration of corresponding drugs for 5 consecutive days,the mice were intraperitoneally injected with CCl4(10 mL?kg-1) to establish liver injury mice model.Alanine transaminase(ALT) and aspartate transaminase(AST) in serum,activities of superoxidase(SOD) and malondialdehyde(MDA) content in liver homogenate were measured.RESULTS: In Berberine-treated groups compared the model group,serum ALT level and AST activity decreased significantly(P
ABSTRACT
Objective:To construct the retroviral vector containing HBx gene so as to investigate the effects of HBx gene in the pathogenesis of HBV-dependent hepatic cell carcinoma(HCC)and further construct animal models of hepatic cell carcinoma.Methods:HBx gene was amplified from the HBx adenovirus Plasmid by polymerase chain reaction(PCR)technique whose primer was designed according to the announced sequences of HBx gene in gene bank,then cut by two endonucleases and directionally cloned into the pseb-hus vector and analyzed by gene sequencing analyzer,the correct constructed vectors were transfected into L02 cell line.At last,HBx protein was detected by Western Blotting.Results:Through PCR,endonuclease cutting and gene sequencing,the target gene was verified into be correctly cloned to retroviral plasmid pSEB-HUS and the high expression of green fluorescence protein(GFP)in L02 cell line was observed under fluorescent microscope.The expression of HBx protein was also observed by Western Blotting.Conclusion:Recombinant retroviral vector expressing HBx protein was successfully constructed.