207 research outputs found

    针对读者需求的图书馆营销策略

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    认为针对用户需求开展营销活动是提高图书馆服务质量的最佳途径。结合国内外一些图书馆的典型案例和部分经济学原理,从如何充分挖掘读者需求、与读者建立密切关系、加强读者合作管理、整合图书馆营销体系等4个方面探讨图书馆的营销策略

    我国未成年人附条件不起诉制度探究

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    未成年人附条件不起诉制度是起诉便宜主义的体现,它能够节约司法资源、促进未成年犯罪嫌疑人的改造、实现特殊预防。在我国司法实践中,该制度得到了众多基层检察机关的认同,并进行了有益尝试。鉴于未成年人身份的特殊性和附条件不起诉制度本身的价值,从保护未成年人、合理配置司法资源的角度出发,结合司法实践中的经验以及出现的一些问题,2012年3月14日修订的《刑事诉讼法》对该制度进行了规定。然而,这些规定有其不合理之处,需要进一步探讨和完善

    Design and Analysis of Protograph-based LDPC Codes in Shallow Water Acoustic Channels

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    原模图低密度奇偶校验码相较于传统LDPC码,具有结构简单、迭代译码门限低、易于扩展及线性编译码复杂度等优点。针对强多途、长时延、窄带宽的浅海水声信道,该文研究了PG-LDPC码的设计及性能特征,提出一种码型设计方案,并采用基于原模图度分布的外部信息转移图算法,对所设计PG-LDPC码的纠错性能进行分析及预测。仿真与实验结果表明,与(3,6)随机规则LDPC码相比,所提的PG-LDPC码在低、高信噪比区域均有良好的纠错性能。Proto Graph-based Low Density Parity Check(PG-LDPC) codes have many advantages over the conventional LDPC codes, such as simple structure, low iterative decoding threshold, easy extension and linear encoding/decoding complexity. After investigating the characteristics of PG-LDPC codes over the Shallow Water Acoustic(SWA) channels, which have the features of strong multipath interference, long delay spreading and limited bandwidth, a new design scheme to search for good codes is proposed. Furthermore, protographdegree-distribution-based EXtrinsic Information Transfer(EXIT) chart algorithm is used to predict and analyze the error performances of protograph-based LDPC codes. The simulation and experiment results show that the proposed code outperforms the(3, 6) randomly regular LDPC code in both low and high SNR region, over the SWA channels.国家自然科学基金(41176032;41376040;41476026);; 教育部高等学校博士学科点专项科研基金(20130121120033);; 中央高校基本科研业务费专项资金/厦门大学基础创新科研基金(20720140506)~

    概率盒框架下多响应模型确认度量方法研究

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    在随机和认知混合不确定性表征的概率盒框架下,提出一种多响应模型确认度量方法.概率盒框架下的模型确认度量主要采用面积方法量化仿真与试验结果的一致程度,但传统面积度量方法并不适用于多个相关响应量的多输出确认度量问题.不确定性条件下多响应量模型确认度量问题,实质上就是量化计算模型的多个响应量的联合概率分布与试验观测数据所服从的联合概率分布之间的差异程度.首先引入马氏距离的概念对多响应量模型确认度量问题进行降维,以马氏距离作为转换的统计量,将多响应量的多指标确认度量问题转化为马氏距离的综合指标度量问题.数值仿真算例验证了方法的正确性和稳定性,并将该方法应用于“2014年圣地亚验证与确认挑战问题”的研究.研究表明,基于概率盒和马氏距离的确认度量方法可以有效解决多相关响应量多输出模型确认度量问题

    Si-Cu合金化渣剂精炼去除冶金级硅中金属杂质

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    采用Si-Cu合金精炼与CaO-SiO2-CaCl2造渣精炼相结合的方法对冶金级硅进行精炼,通过多种分析方法考察了合金造渣过程、渣剂添加剂和合金成分对金属杂质铁(Fe)、铝(Al)和钙(Ca)去除效果的影响。结果表明,提高Si-Cu合金中的Cu含量可以有效增加Cu3Si相在Si中的含量,合金造渣过程会产生多而弥散的合金相,造渣后的金属杂质Fe、Ca聚集在Si-Cu合金的Cu3Si相中。在渣剂中添加CaCl2助溶剂可有效提高金属杂质Fe、Al和Ca的去除率。此外,随着Si-Cu合金中Cu含量的增加,Cu在合金中的析出现象明显,Fe的去除率上升,Al的去除率不变,Ca的去除率下降。当Si-30%Cu合金与45%CaO-45%SiO2-10%CaCl2渣剂进行精炼后,Fe的去除率为68%,Al的去除率为94%,Ca的去除率为86%

    Novel Antifouling Technology Research: Progress and Prospects

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    海洋生物污损问题给海洋事业的发展带来了许多危害,传统防污技术已日渐不能满足要求,研发新型环境友好型防污剂迫在眉睫.用仿生学原理和化学生态学的方法发展新型无毒仿生防污材料和技术是解决海洋污损问题的新思路.本文综述了污损生物防除技术的发展,并重点介绍了基于化学生态学发现的仿生抗生物附着先导化合物和防污材料,展望了仿生防污技术的发展趋势

    Extraction of insecticidal toosendanin from meliaceae by supercritical CO_2

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    王宏涛(1968-),男,博士,副教授,主要研究方向为天然产物的提取分离等, E-mail: [email protected]。[中文文摘]苦楝素是楝科植物中制备植物源农药的主要杀虫成分。针对不同种源楝树的皮、叶及果实,采用溶剂浸提法提取筛选苦楝素含量较高的种源作为实验原料,采用乙醇提取,考察液固质量比、提取时间和提取次数等参数对苦楝素提取率的影响。当液固质量比为25∶1、提取时间为4 h、提取次数为3次时,苦楝素的提取率达18%。进一步采用超临界CO2萃取考察压力、温度、萃取时间、原料粒径和夹带剂等参数对苦楝素萃取率的影响,当温度为40℃、压力为20 MPa、时间为2.0 h、原料粒径为40目、夹带剂乙醇质量为CO2质量的12.5%时,苦楝素的萃取率达43.5%。在对萃取液结晶纯化中成功分离得到质量分数达98%的苦楝素。[英文文摘]Toosendanin is the main insecticidal component of meliaceae plants for producing botanical insecticides.The extraction of toosendanin from the parks,leaves and fruits of the various meliaceae plants was studied by using ethanol,and the part of the meliaceae plants with the maximal mass fraction of toosendanin was selected as experimental materials.The effects of the mass ratio of liquid to solid,extraction time,and extraction times on the yield of toosendan were investigated by using ethanol extraction method. The yield of toosendanin is up to 18% at them ass ratio of liquid to so lid of 25:1, extraction time of 4h and extract ing 3 times. The effects of pressure, temperature, extraction time, and the partic le size of materials and the dosage of mod if iers on the yield of toosendanin w ere investigated bym eans of supercritical CO2 extraction. The yield of toosendan in is up to 43.5% when ethanol is used as mod ifier with its mass 12.5% of CO2 mass at temperature 40,pressure 20 MPa,extraction time 2h and material particle size 40 mesh. The toosendanin crystal with mass fraction 98% was separated from the extracts by using crystalliza tionm ethod.福建省新世纪人才支持计划项

    Composite microparticles of ibuprofen/lipid generated by supercritical fluids from their melts

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    采用CO2及N2辅助的气体饱和溶液微粒形成技术制备布洛芬/肉豆蔻酸、布洛芬/三棕榈酸甘油酯复合微粒,考察它们的形态、颗粒分布以及复合微粒中药物的溶出情况。N2辅助过程制得的布洛芬(质量分数5%)/肉豆蔻酸复合微粒与用该过程得到的纯肉豆蔻酸大小及粒径分布大致相同,而CO2辅助过程制得的布洛芬/肉豆蔻酸复合微粒却要比该过程得到的纯肉豆蔻酸的粒径要大,分布也较宽;CO2及N2辅助形成的布洛芬/肉豆蔻酸复合微粒无缓释效果。用N2辅助制备得到的含20%布洛芬(质量分数)的复合微粒保持了三棕榈酸甘油酯微粒化后的颗粒形貌,粒径更大;用CO2辅助制备得到的含20%布洛芬的复合微粒其粒径比三棕榈酸甘油酯微粒化后的颗粒粒径要小,粒径分布更窄;布洛芬/三棕榈酸甘油酯复合微粒具有缓释效果,而且用N2辅助制备的布洛芬含量为5%的复合微粒比布洛芬含量为20%的复合微粒溶出慢。Using the CO2-assisted and N2-assisted atomization processes,ibuprofen/lipid composite microparticles can be produced;the lipid includes myristic acid(MA) and tripalmitin(TP).The ibuprofen(5% in mass ratie)/MA composite microparticles show similar particle sizes to that of pure MA from the N2-assisted process,while the composite microparticles have a large particle size and particle size distribution,compared to that of pure MA from the CO2-assisted process.The dissolution reveals no controlled release of ibuprofen for the ibuprofen/MA composite microparticles either from the N2-assisted process or from the CO2-assisted process.For the ibuprofen/TP system,the obtained composite microparticles containing 20%(in mass) ibuprofen show similar particle morphology,while has a larger particle size(PS) than that of the pure myristic acid particles in the case of N2-assisted process.Nevertheless,the microparticles from the CO2-assisted process has a small PS and narrow PSD,compared to that of the pure myristic acid particles.The obtained ibuprofen/TP composite microparticles containing 5% or 20% ibuprofen show an evidently controlled drug release.For example,the drug release is only 20% in 500 min for the ibuprofen/TP microparticles containing 20% ibuprofen,prepared by the CO2-assisted process.国家自然科学基金资助项目(20406015);; 福建省新世纪优秀人才支持计划;; 福建省自然科学基金资助项目(2007J0167

    Separation of terpenes and oxygenated compounds from citrus oil by supercritical CO_2 extraction

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    以冷榨柑橘精油为原料,采用gC/MS对柑橘精油原料进行定性及定量分析,确定了柑橘精油中的7种萜烯类化合物成分作为分离考察对象。实验探讨了超临界萃取压力、萃取温度、萃取时间和CO2流量等因素对含氧化合物分离效果的影响。实验结果表明,萃取相中萜烯类化合物的回收率总体上随着萃取压力、温度、时间和CO2流量的增大而增大。当萃取压力为12MPA,萃取温度为45℃,萃取时间为4H以及CO2流量为1.0l/MIn时,分离效果最佳,其萃取相中萜烯类化合物的回收率高达90.03%。Supercritical CO2 extraction was employed to separate terpenes and oxygenated compounds from citrus oil.The raw oil,the extract,and the raffinate were qualitatively and quantitatively analyzed by GC/MS,respectively,with the terpenes being represented by seven typical compounds.The influences of several experimental factors including extration pressure,extraction temperature,extraction time and CO2 flow rate on the separation of the oxygenated compounds were studied.The results indicate that the recovery rate of terpenes in the extract generally increases with the increasing of extraction pressure,temperature,time and CO2 flow rate.The optimum conditions for extracting terpenes are as follows: pressure 12 MPa,temperature 45 ℃,extraction time 4 h,and CO2 flow rate 1.0 L/min.Under these optimum conditions,the recovery rate of terpenes in the extract is 90.03%.福建省新世纪人才支持项目(0000-X04157

    脉冲电源电解处理含氰含银电镀废水

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    利用脉冲电源从含氰含银电镀废水中回收银和去除氰,对比了脉冲电源与直流电源对含氰镀银废水的处理效果,系统研究了脉冲电源的电解电压、占空比和脉冲频率等参数对电能消耗、银回收率和除氰率的影响。结果表明,脉冲电源较直流电源能更加有效降低阳极的超电位,减少电极的极化,从而降低槽电压,进而有效地降低电能消耗。脉冲电源的优化参数是:脉冲电压2.0V,脉冲频率1200Hz,占空比50%。在循环流速100ml.min-1,pH值10~11,曝气速率1.0L·min-1的实验条件下,通入电解电压2.0V、脉冲频率1200Hz以及占空比50%的脉冲电源,电解2.0h后,银回收率高达99%,除氰率达到86%
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