最新刊期
期 4 ， 2000
- 摘要：Poly(Tetramethyl-p-Silphenylene-Diphenylsiloxane) (PTMPS-DPS) copolymer was synthesized by two different catalysts. The effect of 60Co γ irradiation on morphological structure and mechanical properties of PTMPS-DPS copolymer was investigated by using of GPC, WAXD, DSC, et al. The result showed that molecular weight, crystallinity, tensile strength and elongation at break were not changed very much by irradiation with dose of 8.5×105Gy. The copolymer by means of the nonequilibrium catalysis system has a better irradiation stability.关键词：Organosiloxane polymer;60Co γ ray irradiation;Morphological structure;Mechanical properties
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发布时间：2023-04-13 - 摘要：The properties of EB curing coating films, which were determined by the structure of oxidative-polymerized linseed oil, were as following: good gloss, low hardness, better flexibility and impact resistance, low glass transition temperature and bad adhesion on tinplate. Oxidative-polymerized linseed oil could be used with other compositions not only as oligomer, but also as functional monomer to improve the properties of coating films of composite systems. Both absorbed doses and Cobaltous naphthenate had little influence on the properties of these coating films.关键词：Linseed oil;Oxidative-polymerization;EB curing;Absorbed dose;Property of coating
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发布时间：2023-04-13 - 摘要：Electron beam curing of various blends of epoxy resin was studied in this paper. Radiation effect of epoxy resin systems of 828, 648 and 207, and their blends was compared. The effect of resin compounding ratio and radiation dose on blends of epoxy resin 828 and 648 systems was analyzed. The performance of the blend with different ratio of epoxy resin 207 and 648 was also studied. The results of study show that radiation effect of epoxy resin is associated with its chemical constitution, steric effect, and crystallinity. The mixing of various epoxy resin can improve radiation curing effect of system, reduce required radiation dose, and enhance performance of radiation product.关键词：Epoxy resin;Electron beam;Radiation curing;Radiation effect;Molecular constitution
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发布时间：2023-04-13 - 摘要：The halogen-free flame-retarding material with good property satisfying the aims of "jiuwu" project "the study and product development of radiation-crosslinking cable and wire materials" was manufactured by choosing the basic resin, changing the addition amount of flame-ratarding agents, anti-oxygen agents, coupling agents, crosslinking sensitizer and radiation dose. Its rheological property is studied at the same time. OI is 40; tensile strength is 11.5MPa; and elongation at break is 370%.关键词：Radiation crosslinking;Halogen-free flame-retarding material;Mechanical property;Aging property;Rheological property
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发布时间：2023-04-13 -
GRAFTING OF STARCH-ACRYLAMIDE BY 60Co γ RAY PRE-IRRADIATION-EFFECT OF VARIOUS CONDITIONS ON GRAFTING
摘要：In present paper, the grafting reaction of starch-acrylamide by 60Co γ pre-irradiation was carried out. The grafted copolymer was prepared and identified by IR spectrophotometer. The grafting yield was measured with element analysis. Various influence factors such as absorbed dose, reaction temperature, reaction duration, post-irradiation effect etc. on grafting yield were studied. The grafting yield higher than 80% could be obtained when the grafting reaction was proceeded at 25~30℃ within 10minutes after 10kGy irradiation.关键词：Pre-irradiation;Starch-acrylamide;Grafting- 2
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发布时间：2023-04-13 - 摘要：Using time-resolved technique of 248nm laser flash photolysis, electron transfer from 2'-deoxyguanosine-5'-monophosphate (dGMP) to oxidized riboflavin (VB2) radical was observed for the first time due to the buildup of the oxidized dGMP radical matching the decay of oxidized riboflavin radical at different pH values in aqueous solution. The reaction rate constants were derived to be 5.6×108, 5.8×108 and 6.2×108dm3•mol-1•s-1 at pH 3, 5 and 7.5, respectively. The direct observation of oxidized guanine radical has provided unambiguously direct initial proof for photosensitization process of dGMP by oxidized riboflavin radical.关键词：Riboflavin;dGMP;Oxidized radical;Electron transfer;Laser flash photolysis
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发布时间：2023-04-13 - 摘要：The dose distribution in two kinds of polyethylene materials were determined by use of electron beam from 1.0~3.0 MeV electron accelerator. The effects of four different metal base-plate such as Al、Fe、Cu and Pb for dose depth distribution in materials were compared. And the boundary effects of absorbed dose were also observed. The expand uncertainty of absorbed dose measurement was 7.8%. This work is a useful experimental method for optimizing technology of radiation processing and realizing quality control of irradiation products.关键词：Electron beam;Radiation processing;Dose distribution;Optimizing technology;Experimental method
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发布时间：2023-04-13 - 摘要：Changes in time-course and dose-effect relationship of the DNA-binding activity of NF-κB in thymocytes and splenocytes after whole-body irradiation (WBI) were observed using the method of electrophoresis mobility shift assay (EMSA). Results showed that there existed two types of dimers binding specifically to the κB site in the nuclear extracts of the thymus and spleen. The radiation-induced changes in time-course and dose-effect relationship of these two types of dimers were significantly different. The DNA-binding activity of p50/p65 in thymocytes only slightly increased after WBI with 2Gy, but that of p50/p50 started to increase at 1h after irradiation and reached its peak at 4h, and keeped at high levels until 12h. At 12h after irradiation, the changes in the binding activity of p50/p65 in thymocytes were not obvious for all doses, while the binding activity of p50/p50 showed a increase with the dose increase at the dose above 1Gy, suggesting that maybe the later complex with transcription repression activity could be chiefly induced by medium or high doses. Lower doses of radiation caused slightly the expression of p50/p65 and higher doses resulted in its depression in the spleen, and there was hardly any influence on the activity of the p50/p50 dimer in this organ. The results suggest that there may exist differences in compositions of NF-κB complexes in different immune organs and differences in their reaction to ionizing radiation.关键词：Whole-body irradiation;Thymocytes;Splenocytes;Transcription factor;NF-κB subunits
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发布时间：2023-04-13 - 摘要：To study whether the frequencies of chromosome aberrations observed in 4# and 7# are in agreement with their DNA content or physical length and how is the distribution of translocations among the cells. The chromosome aberrations in humam peripheral lymphocytes are detected by fluorescence in situ hybridization using 4# and 7# conbination of composite whole chromosome-specific DNA probes and Giemsa stain. The frequencies of chromosome aberrations observed in 4# and 7# are in quite good agreement with their DNA content or physical length. The distribution of translocations among the cells is close to Poisson except dose points 0.25Gy. More of incomplete translocations were observed than complete translocations after 52h culture. The number of t(Ab) observed is > that of t(Ba). The observed and expected frequencies of chromosome aberrations in 4# and 7# are in quite good agreement, and are propotional to the DNA content or DNA physical length of the two chromosomes.关键词：60Co γ radiation;Fluorescence in situ hybridization;Chromosome aberration
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发布时间：2023-04-13 - 摘要：The kinetic energy released in Chinese hamster splenctic cells for incident ultrasoft X rays with the energies from 0.9 to 1.55keV, which were from a laser-plasma X ray source, was calcualted by resorting to the energy spectrum integration method and the equivalent energy approach, respectively. In the calculations, the X ray transmission, attenuation, and energy transfer in the biological material were considered. A difference between the two calculations was found to be about 15%. The distribution of the kinetic energy relased in material (kerm) in the cells was also estimated using the chemical composition of the cells.关键词：Ultrasoft X ray;Kerma calculating
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发布时间：2023-04-13 - 摘要：The purpose of the present study was to observe the changes of expression of Fos protein using immunohistochemistry and image analysis as well as flow cytometry. The result showed that the expression of Fos protein incresed rapidly in mouse thymocytes after whole body irradiation (WBI) with 75mGy X rays. It reached the peak value at 24 h, and then gradually returned to the basic level. These findings were in accordance with our previous observation of the effect of low dose radiation on transcription level of c-fos mRNA in mouse thymocytes. The results indicate that low dose radiation could enhance the function of immune cells.关键词：Low dose radiation;Fos protein;Oncogene
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发布时间：2023-04-13 - 摘要：This study investigated the role of the JAK/STAT signaling pathway regulating cell cycle progression in the irradiated KG-1 cells. By permanent transfecting the cells with DN-STAT5 cDNA to block the JAK/STAT signaling pathway and then transient transfecting with cyclin D1 or cyclin B1 cDNA, the effects of cyclin D1 protein and cyclin B1 protein on the cell cycle progression were examined. Results showed that after irradiation with 8Gy 60Co γ rays, the irradiated KG-1 cells transfected with only DN-STAT5 cDNA can not recover form the G1 arrest, even though GM-CSF was added. Meanwhile, the cells transfected with both the DN-STAT5 cDNA and cyclin D1 cDNA or cyclin B1 cDNA can recover from the G1 arrest or the G2 arrest to a great extent. Thus, it was proved indirectly that the JAK/STAT signaling pathway activated by GM-CSF regulated the cell cycle progression through cyclin D1 and cyclin B1 protein.关键词：Irradiation;Cell cycle;Cyclin D1;Cyclin B1
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发布时间：2023-04-13 - 摘要：The effects of DP and AMP on the immune function in X-ray irradiated mice with different doses were studied in this dissertation.Mice(BALB/C) were irradiated with different doses(0, 1, 2, 4Gy) of X-rays.The spontanous proliferation of thymocytes and ConA-induced proliferation reaction of splenocytes in mice pretreated with DP(2mg) and AMP(5mg) were detected. The results were as follows:the spontanous proliferation of the thymocytes and the ConA-induced proliferation reaction of splenocytes in mice injected with DP and AMP decreased markdely, but increased significantly in mice treated with DP and AMP prior to irradiation by 1Gy and 2Gy X-rays.关键词：DP;AMP;Ionizing radiation;Immune function
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发布时间：2023-04-13 - 摘要：To explore the effect of ionizing radiation on the expression of metallothionein (MT) in immune organs, the 109Cd-hamoglobulin affinity assay was employed to measure the content of MT in tissues. The dose effect relationship of the MT expression in mouse thymus and spleen was investigated 16h after exposure to 0.5, 1, 2, 4 and 6Gy whole body irradiation(WBI). And the time course changes in MT expression in mouse thymus and spleen were also determined at different time intervals after 4Gy WBI. The results showed that the MT content in mouse thymus was significantly increased 16h after 4Gy and 6Gy irradiation compared with that in sham-irradiated mice (p <0.05, respectively). And it was found that the MT content in mouse thymus was also increased significantly from 8h to 48h after 4Gy irradiation compared with that in sham-irradiated mice (p < 0.05 ~p <0.001). However, there were no markedly changes for the MT expression in the mouse spleen after exposure to X rays. These results mentioned above suggest that the MT expression in immune organs could be induced by X rays, which may be tissue-specific.关键词：Ionizing radiation;Metallothionein;Thymus;Spleen
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发布时间：2023-04-13 - 摘要：Characteristics of an electron linear accelerator, which has 6~12MeV energy, 4.2kW average beam power is introduced. Results show that it has advantages on improving the characteristic of semiconductor devices such as diodes, triodes, SCR, preventing garlic from sprout, preservation of food, and so on.关键词：Electron linear accelerator;Electron irradiation;Semiconductor devices;Garlic;Food
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发布时间：2023-04-13
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