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SADHU DP 《Nature》1956,177(4522):1236-1237
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The radioprotective effects of 6 Gui-Pi-Wan extracts were investigated by examining cell viability and 30-d survival of mice after total-body 60Co irradiation. Pretreatment with Gui-Pi-Wan precipitate by water extraction and alcohol precipitation (PWA) prior to irradiation resulted in significantly higher cell survival and lower apoptosis rates at 24 h after 5 Gy radiation, and increased 30-d survival in mice after exposure to a potentially lethal dose of 8 Gy. These results collectively indicate that PWA of Gui-Pi-Wan extracts is an effective radioprotective agent.  相似文献   

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Thalidomide as a possible biological acylating agent   总被引:1,自引:0,他引:1  
S Fabro  R L Smith  R T Williams 《Nature》1965,208(5016):1208-1209
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研制了一种改性脲醛树脂堵剂 .以聚丙烯酰胺为改性剂加入尿素、甲醛的反应体系中 ,经加成、缩合及缩聚反应生成具有一定弹性的脲醛树脂 .该树酯的制备反应受组分质量分数、反应温度、反应体系 p H值等的影响 ,在 2 5~ 80℃的条件下 ,反应时间为 1 .5~ 1 3.0 h,生成的改性脲醛树脂不溶于水 ,在盐水溶液中具有良好的稳定性 ,在碱性水溶液中易于解溶 .反应配制液黏度低 ,可注入油水井不均质储层的大孔道及高渗透带 ,在储层温度下生成树脂而起到调剖或封堵作用  相似文献   

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环保型阻垢剂聚天冬氨酸的研制   总被引:3,自引:0,他引:3  
以天门冬氨酸为单体 ,采用加热缩聚法 ,合成了聚天冬氨酸 ,研究了温度、时间对收率的关系。测定了不同浓度下的聚天冬氨酸的阻垢性能 ,实验结果表明 ,聚天冬氨酸具有较好的阻垢分散性能 ,是一种优良的环保型水质稳定剂。  相似文献   

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Interleukin-1 (IL-1) describes two inflammatory proteins, IL-1 alpha and IL-1 beta, produced by activated macrophages and other cell types and encoded by two genes. Their amino acid sequences have only 26% similarity, but their biological activities are comparable, with a few exceptions; indeed, both molecules appear to act at the same receptor. As IL-1 release prostaglandins which sensitize nociceptors in man and in experimental animals, we tested IL-1 alpha and IL-1 beta in rats for hyperalgesic (nociceptive) activity. Our results show that IL-1 beta given systemically is an extremely potent hyperalgesic agent with a probable peripheral site of action; IL-1 alpha is approximately 3,000 times less active than IL-1 beta. We have delineated the region of IL-1 beta mediating the hyperalgesic effect and developed an analgesic tripeptide analogue of IL-1 beta which antagonizes hyperalgesia evoked by IL-1 beta and by the inflammatory agent carrageenan.  相似文献   

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The convenient preparation of organometallic precursor fac-[99mTc(CO)3 (H2O)3] opens a new route to design new radiopharmaceuticals. Based on this precursor, a new cocaine analogue, Tropyn, is designed and synthesized,and “2 1” mixed-ligands approach is used to prepare a neutral complex [^99mTc(CO)3(Tropyn)I]. Biodistribution in mice and rats proves that it has sufficient brain uptake. Rat regional brain biodistribntion indicates that the complex is highly concentrated in the striatum (ST) with rapid clearance in the cortex (CT) and hippocampus (HP), which make it valuable for further investigation as the potential Second-Generation DAT imaging agent.  相似文献   

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利用溶液聚合法制备了水溶性淀粉接枝丙烯酸(AA)/醋酸乙烯酯(VAc)固沙剂乳液,考察了单体质量比、AA中和度、引发剂用量、聚合温度对乳液性能的影响,采用FT-IR、TG对乳液进行了表征,并初步研究了固沙剂的表面固化效果、抗压强度等固沙性能。结果表明单体质量比(mAA∶mVAc)为2∶1、AA中和度为25%、引发剂质量为单体质量的0.8%、聚合温度为80℃时,固沙剂乳液外观、黏度及放置稳定性等均较优;固沙剂在200℃下热稳定性良好,固化作用及抗压强度能够满足实际固沙应用中的要求。  相似文献   

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为了改善水凝胶的强度,通过端丙烯酸酯基阴离子型聚氨酯(PU)与甲基丙烯酰氧乙基苄基二甲基氯化铵(MAEBDAC)的共聚交联,合成了系列两性水凝胶(简称L1—L5)。采用差式扫描量热法(DSC)分析了阴阳离子摩尔比为0.3/1(样品L1)、1/1(样品L3)和1.3/1(样品L5)的干凝胶,结果表明,两组分间相容性良好。处于等电点的样品L3中没有微孔结构,且其可冻结水含量仅为总溶胀水量的11.7%,而在样品L1和L5中均具有微孔结构且可冻结水含量增至50%。研究pH响应性表明,水凝胶的响应行为取决于凝胶中过量电荷的性质,外加电介质对样品L3的吸水能力影响较小。凝胶强度随聚氨酯链段的引入而提高。  相似文献   

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为探究土凝岩新型固化剂稳定路基粉质黏土的干缩性能,对粉质粘土添加土凝岩新型固化剂和传统固化剂水泥后的干缩进行对比试验探究,并利用IBM SPSS Statistics与MATLAB数据处理软件对两种固化土进行无重复双因素回归曲线估计分析,结果表明:水泥掺量6%与土凝岩固化剂掺量8%固化土的干缩应变较小,两种固化土在失水率达到最优含水率左右出现干缩应变最大值,同时前15天所产生的干缩应变在整个稳定应变的80%之上,固化剂的干缩应变与失水量(相应的含水量)关系较密切且掺量对干缩应变的影响大于时间因素,土凝岩新型固化剂的前期保水性较优可延缓与减小收缩,利用时间与干缩应变倒数回归曲线方程式反映实际固化土干缩应变。整体这种新型固化剂不仅充分利用了工业废料并在干缩性能上还略优于水泥,说明这种经济环保土凝岩新型固化剂在稳定粉质黏土的干缩性能上可代替水泥使用。  相似文献   

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采用水热法制备了纳米ZnFOH结构阵列,包括纳米柱阵列和纳米带阵列.研究了ZnFOH在不同条件下的沉积方式.在低酸碱度pH=6.0时,在ZnO晶种基底上形成菱形纳米柱阵列,这源于正交晶体固有的结晶习性.在较高的酸碱度pH=8.0时,由于Zn2+优先吸附在原子核的(010)表面上,在Zn2+基底上形成ZnFOH 纳米带阵列.NH4F作为控制剂调节ZnF+的过饱和,这有助于基底上的非均相成核.  相似文献   

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陶瓷解凝剂聚丙烯酸纳的研究与应用   总被引:2,自引:0,他引:2  
采用溶液聚合法合成了陶瓷用聚丙烯酸钠解凝剂,研究了聚合物分子量、解凝剂添加量对陶瓷解凝效果的影响,并对解凝机理进行探讨。与常规解凝剂如碳酸钠、硅酸钠等比较,结果表明添加量相同时.聚丙烯酸钠(30%水溶液)使陶瓷流动性大大增加。  相似文献   

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The increasing consumption of plastics inevitably results in increasing amounts of waste plastics. Because of their long degradation periods, these wastes negatively affect the natural environment. Numerous studies have been conducted to recycle and eliminate waste plastics. The potential for recycling waste plastics in the iron and steel industry has been underestimated; the high C and H contents of plastics may make them suitable as alternative reductants in the reduction process of iron ore. This study aims to substitute plastic wastes for coal in reduction melting process and to investigate their performance during reduction at high temperature. We used a common type of waste plastic, polyethylene terephthalate (PET), because of its high carbon and hydrogen contents. Composite pellets containing PET wastes, coke, and magnetite iron ore were reduced at selected temperatures of 1400 and 1450°C for reduction time from 2 to 10 min to investigate the reduction melting behavior of these pellets. The results showed that an increased temperature and reduction time increased the reduction ratio of the pellets. The optimum experimental conditions for obtaining metallic iron (iron nuggets) were reduction at 1450°C for 10 min using composite pellets containing 60% PET and 40% coke.  相似文献   

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Corma A  Rey F  Rius J  Sabater MJ  Valencia S 《Nature》2004,431(7006):287-290
Solid materials with uniform micropores, such as zeolites, can act as selective catalysts and adsorbents for molecular mixtures by separating those molecules small enough to enter their pores while leaving the larger molecules behind. Zeolite A is a microporous material with a high void volume. Despite its widespread industrial use in, for example, molecular separations and in detergency, its capability as a petroleum-refining material is limited owing to its poor acid-catalytic activity and hydrothermal stability, and its low hydrophobicity. These characteristics are ultimately a consequence of the low framework Si/Al ratio (normally around one) and the resulting high cationic fraction within the pores and cavities. Researchers have modified the properties of type-A zeolites by increasing the Si/Al compositions up to a ratio of three. Here we describe the synthesis of zeolite A structures exhibiting high Si/Al ratios up to infinity (pure silica). We synthesize these materials, named ITQ-29, using a supramolecular organic structure-directing agent obtained by the self-assembly, through pi-pi type interactions, of two identical organic cationic moieties. The highly hydrophobic pure-silica zeolite A can be used for hydrocarbon separations that avoid oligomerization reactions, whereas materials with high Si/Al ratios give excellent shape-selective cracking additives for increasing propylene yield in fluid catalytic cracking operations. We have also extended the use of our supramolecular structure-directing agents to the synthesis of a range of other zeolites.  相似文献   

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