70 research outputs found
浅析互联网保险中的风险、逆向选择问题及其对策
随着互联网技术的不断发展,依靠互联网这一媒介和云计算的大数据发展起来的互联网保险成为保险业蓬勃发展的新动力。它突破时间和地域的限制,使保险销售的模式发生了根本性变革。在带来便利的同时,互联网保险也面临着更大更复杂的风险。本文拟从互联网保险的风险尤其是道德风险角度分析目前其面临的挑战,并提出监管建议
饲喂不同浓度黄曲霉毒素B_1饲料对异育银鲫成鱼的生长和毒素积累的影响
以含不同浓度黄曲霉毒素B1(AFB1)的配合饲料饲喂异育银鲫(Carassius auratus gibelio)成鱼56d,研究异育银鲫成鱼[(122.3±0.7)g]生长、生理反应、肝脏组织学变化、卵巢发育以及鱼体各组织中的AFB1的毒素积累状况。实验分为5个实验组,不同实验组饲料中AFB1含量分别为0、5、20、50、500μg/kg饲料(实测值分别为2.59、4.12、12.39、46.23、454.07μg/kg饲料),每个处理3个平行。在整个实验过程中各实验组均未表现出外部形态和行为异常,各组存活率均达到100%。各实验组异育银鲫成鱼终末体重、摄食率(FR)、特定生长率(SGR)和饲料效率(FE)均无显著差异。饲料AFB1水平对异育银鲫血清总胆固醇(TC)含量、血清谷丙转氨酶(GPT)、谷草转氨酶(GOT)和碱性磷酸酶(AKP)活性均无显著影响。各毒素组血清超氧化物岐化酶(SOD)活性与对照无显著差异。各毒素组肝脏和卵巢均未见明显的组织学病理变化。肌肉和性腺中的AFB1积累量低于FDA食品安全限定标准(5μg/kg)。肝胰脏中的AFB1积累和饲料中的AFB1水平呈对数关系。饲喂AFB1≥50μg/kg饲料使异育银鲫成鱼肝脏AFB1积累超过安全限量标准。结果表明,异育银鲫成鱼至少可耐受AFB1含量达500μg/kg饲料(实测值:454.07μg/kg饲料)56d
Automatic Dressing and Compensation Method of Diamond Wheel in CNC Grinding Machine
金刚石砂轮在使用过程中会磨损、钝化,影响磨削性能,需要定期修整。本文介绍砂轮修整原理,并给出一种砂轮修整的全自动控制方法和补偿方法。通过长时间连续自动运行,验证了该方法的实际应用效果。After a period of using,the diamond grinding wheel will be worn and blunted,which can seriously affect the grinding performance.So,the diamond grinding wheel requires dressing regularly.The article introduces the principle and methods of dressing and gives an automatic control and compensation method.Through a long continuous running,the result of practical application of this method has been verified.国家“高档数控机床与基础制造装备”科技重大专项(2010ZX04001-162
急性心肌梗死冠状动脉侧支血流分数与左室功能关系的探讨
【目的】测定压力源性的冠状动脉侧支血流分数,评价其与传统的Rentrop分级间的相关性;并探讨该冠状动脉侧支血流分数与急性心肌梗死直接经皮冠状动脉介入治疗成功后左室功能变化之间的关系。【方法】29例急性心肌梗死患者行直接经皮冠脉介入术,术中用冠状动脉内压力导丝根据“病变远端楔嵌压/主动脉平均压”计算冠脉侧支血流分数,以0.24为截值将29例分为两组:A组(19例)冠状动脉侧支血流分数>0.24,B组(10例)侧支血流分数≤0.24。术后根据冠状动脉造影行Rentrop分级。采用Simpson’s测左室射血分数、左室收缩及舒张末期容积,计算相关的容积指数。【结果】Rentrop分级与压力源性的冠状动脉侧支血流分数呈正相关性,该冠状动脉侧支血流分数同30d后左室射血分数呈正相关性。【结论】冠状动脉内压力源性的侧支血流分数可预测临床成功的直接经皮冠脉介入术后左室功能的恢复,并可对急性心肌梗死时侧支循环血流作出定量评价
Study on removal boron from solargrade silicon with hydrometallurgy
湿法提纯作为冶金法制备太阳能级硅的前处理工序,可以去除大部分金属和硼杂质。研究了以氢氟酸-硫酸混合酸为浸出剂,有机溶剂甲醇作为后处理剂,去除硅粉中硼杂质的方法。采用电感耦合等离子体发射光谱仪(ICP)等对产品进行表征。酸浸过程优化工艺条件:硫酸质量分数为55%,氢氟酸质量分数为7%,酸浸温度为70℃、酸浸时间为4 H、液固质量比为8∶1。酸浸后可使硅粉中的硼杂质质量分数由6.893x10-6降至3.867x10-6,去除率为41.9%。在酸浸基础上采用有机溶剂甲醇作为后处理剂,杂质硼质量分数降至3.84x10-6,去除率为44.29%。从硼酸浸后形成的产物入手探索提高硼去除率的方法,实验验证了该方法的可行性,为研究湿法冶金预处理太阳能级硅提供了新的参考。As a pretreatment unit for preparing solargrade silicon(SG-Si) by metallurgic method,wet purification could remove most metallic impurities and nonmetallic impurities,such as boron.Experiment researched a new method to remove boron from SG-Si with mixed hydrofluoric acid-sulfuric acid as leaching agent and with organic solvent methanol as posttreatment agent.Samples were characterized by ICP and other analysis methods.When SG-Si powder had been leached at optimized conditions as follows:mass fraction of sulfuric acid was 55%,mass fraction of hydrofluoric acid was 7%,reaction temperature was 70 ℃,reaction time was 4 h,and liquid-solid mass ratio 8∶1,it was found that mass fraction of impurity boron in SG-Si was reduced to 3.867×10-6 from 6.893×10-6 and the removal rate was 41.9% after acid leaching;on the basis of the former procedure,mass fraction of impurity boron was reduced to 3.84×10-6 and the removal rate was 44.29% when treated with organic solvent.Experiment proved the feasibility of the method and provided a new reference for researching on the pretreatment of SG-Si by hydrometallurgy
Effect of Flue-gas Cleaning Devices on Mercury Emission From Coal-fired Boiler
为研究燃煤锅炉烟气净化设施对汞排放特性的影响,采用Ontario-Hydro方法,对设有催化脱硝、静电除尘、海水脱硫的300MW燃煤锅炉排放烟气中汞的含量与形态进行分析,同时测定锅炉的煤、底渣、飞灰等固体样品以及脱硫塔前后、曝气之后海水样品中的汞含量。实验结果为:烟气中的气态汞占总汞的79.1%以上,脱硝催化剂对汞的价态具有强烈的转化作用,烟气中83.4%的气态Hg0被氧化成气态Hg2+;静电除尘对颗粒态汞的去除率几乎达到100%;在脱硫塔中,海水对烟气中汞的洗脱率高达73.6%,曝气后排放前的海水中含汞量是新鲜海水的5.5倍。研究表明锅炉烟气净化设施对汞的排放特性有着重要的影响。In order to study the effect of flue-gas cleaning devices on mercury emission from coal-fired boiler, Ontario-Hydro method had been applied to determine the mercury concentration and speciation in the flue-gas emitted from a 300MW coal-fired boiler, which was equipped with various pollution control devices, including selective catalyst reduction (SCR) De-NOx system, electrostatic precipitator (ESP), and flue-gas seawater De-SO2 system (FGD). Mercury concentration in raw coal, bottom ash and fly ash of the boiler, seawater at the inlet and outlet of SO2 absorption reactor and the drainage of aeration sink, were also analyzed. The results indicate that the percentage of gaseous mercury in total mercury discharged is more than 79.1%. De-NOx catalyst strongly affects the mercury speciation transformation, showing a conversion rate of 83.4% for Hg0 to Hg2+. The removal efficiency of particulate mercury by ESP is close to 100%. With seawater FGD, the removal efficiency of mercury is as high as 73.6%. The mercury concentration in the seawater of drainage from aeration sink is 5.5 times higher than that in fresh seawater. The study shows that the flue-gas cleaning devices in coal-fired power plant play an important role on mercury emission characterization
一种催化剂及其制备和应用
本发明涉及一种用于航天推进级高浓度一氧化二氮分解的六铝酸盐催化剂及制备方法。应用该方法制备的催化剂能够使一氧化二氮在450℃~600℃温度条件下即可实现自发分解,并且能够耐受一氧化二氮分解产生的高温(1000℃~1400℃)富氧燃气,对一氧化二氮的催化分解具有较高活性、高热稳定性。带填
Researches on Atypical Lateralization of Autisms′ Language Development
自闭症谱系障碍(autismspectrumdisorders,ASD)是一种广泛发展障碍,以社会交往障碍、言语和非言语交流缺陷、兴趣狭窄和行为刻板等为主要临床特征.本文简述了自闭症的核心症状——语言障碍,回顾了自1986年以来,对自闭症语言障碍神经机制的研究,从其大脑结构、功能不对称性及相关利手因素的影响三个方面,综述了自闭症语言功能的异常偏侧化领域的研究成果和进展,期望为自闭症语言障碍的鉴别与治疗提供帮助,并促进汉语背景下自闭症患者的语言功能偏侧化研究
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