121 research outputs found

    Asymmetric Transfer Hydrogenation of Ketones Catalyzed by Chiral Multidentate Aminophosphine Ligands/Iron Cluster

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    从廉价易得、绿色环保的铁簇合物Fe_3(CO)_(12)出发,开展了其与手性多齿胺膦配体(R,R,R,R)-PN_4H_6原位生成的催化体系在酮; 的不对称转移氢化中的应用研究.通过考察温度、添加剂等影响因素,探索最优的反应条件,并将其进一步应用于多种芳香酮的不对称转移氢化反应,得到高达96; % ee的对映选择性.As one of the most abundant metals on earth, iron is cheap and low toxicity. Herein we reported the asymmetric transfer hydrogenation of (ATH) ketones catalyzed by the system generated in situ from chiral multidentate aminophosphine ligand (R, R, R, R)-PN4H6 and Fe-3(CO)(12). The effects of temperature and additive on the ATH of propiophenone were examined. After optimizing the reaction conditions, we applied the catalytic system to the ATH of various aromatic ketones, obtaining the corresponding optical active alcohols with high enantioselectivities (up to 96% ee).National Natural Science Foundation of China [21173176, 21673190];; Fundamental Research Funds for the Central Universities [20720150040

    分层架构下智能电动汽车纵向运动自适应模糊滑模控制

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    针对智能电动汽车(intelligent electric vehicles,IEV)的纵向控制在不确定性干扰下存在非线性、强时变特征,提出一种分层控制架构下的智能电动汽车纵向跟车运动自适应模糊滑模控制方法.根据经典理..

    Preparation of potassium diformate by methyl formate and potassium hydroxide

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    联系人:李清彪. 第一作者:詹国武(1986—),男,学士.[中文文摘]本研究采用甲酸甲酯、氢氧化钾、甲酸为原料,一步反应制备二甲酸钾。系统地考察了影响产品收率的主要因素,优化了工艺条件,结果表明,当n(MF)/n(KOH)=1.20,n(HCOOH)/n(KOH)=1.44,反应时间为30min,反应温度为55℃时,二甲酸钾产品收率可达 98.8%。产品经红外光谱分析及成分测定,符合质量标准。[英文文摘]In this study, methyl formate, potassium hydroxide and formic acid were used as raw materials for one-step synthesis of potassium diformate. The main factors affecting the quality and yield of product were investigated. The optimal conditions for reaction were: molar ratio of MF to KOH 1.20:1, molar ratio of HCOOH to KOH 1.44:1, reaction time 30 min and reaction temperature 55℃. The product met the quality standard of potassium diformate after infrared spectrum analysis and composition determination.厦门大学创新性实验计划资助项

    Study on dissolution behaviors of chalcopyrite in acid solution

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    为了探索黄铜矿低温常压湿法氧化(O2)浸出的可行性,研究了黄铜矿在酸性介质中的溶解行为,考察了温度、酸浓度及溶浸时间等对黄铜矿酸浸行为的影响,计算了酸浸过程中铜的浸出率,分析了元素硫的变化行为及残渣微观结构。结果表明,黄铜矿常压湿法氧化(O2)浸出过程的酸浸阶段会产生硫化氢;黄铜矿的溶解能力随温度变化先快后慢,后段接近线性增长,溶解主要发生在前2小时;低温有利于溶解,而最适酸浸pH约-0.4。pH对溶解的影响小于温度的影响。The dissolvability behaviors of chalcopyrite in acid solvent,including the influences of temperature,pH value and the acidic leaching time on the dissolvability behaviors of chalcopyrite,are studied to probe the feasibility of hydro-oxidation leaching at normal pressure and low-temperature.The changing behaviors of elemental sulfur and the microstructure of the residue are also analyzed.The results show that:①sulfureted hydrogen can be produced in the acidic leaching of chalcopyrite's wet oxidation at ordinary pressure and low-temperature;②the dissolvable capacity of chalcopyrite change with time fleetly at first then slowly,which is linear increase at the later part,the dissolution occurs mostly at 2 hours afore;③low temperature is beneficial to the dissolution and the optimum pH value is-0.4.And the influence of temperature is stronger than that of pH

    ~(18)O isotopic study of photo-induced formation of peroxide species on cubic Nd_2O_3

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    采用原位显微rAMAn光谱和18O同位素示踪技术,以325 nM激光为激发光源,对立方nd2O3上过氧物种的光诱导生成过程进行了详细表征,进一步证实过氧源于分子氧对晶格氧的氧化反应.结果还表明,325 nM激光在室温下即可诱导过氧的生成,在实验条件下,生成的过氧物种可与nd2O3的晶格氧发生快速的氧交换反应,位于nd2O3体相的晶格氧也可迁移至样品表层进而参与过氧的生成.325 nM激光照射有助于促进晶格氧的迁移以及晶格氧与分子氧之间的氧交换反应.Photo‐induced formation of peroxide species on cubic Nd2O3 was studied by in situ microprobe Raman spectroscopy using 18O as a tracer and a 325‐nm laser as an excitation source.The results confirmed that the peroxide ions were formed through photooxidation of the lattice oxygen species in neodymium sesquioxide by molecular oxygen species.Under UV excitation(λ = 325 nm), the reaction between O2 and O2- could take place at room temperature.A fast oxygen exchange between the peroxide ions and the lattice oxygen species in Nd2O3 took place under the experimental condi‐tions studied.Also, bulk lattice oxygen species in Nd2O3 could migrate to the surface layer and par‐ticipate in the formation of peroxide ions.The migration of lattice oxygen species and the oxygen exchange between lattice oxygen and peroxide ions were promoted by UV laser irradiation.supportedbytheNationalBasicResearchProgramofChina(973Program;2010CB732303); theNationalNaturalScienceFoundationofChina(21173173;21033006;21373169); theProgramforChangjiangScholarsandInnovativeResearchTeaminUniversity(IRT1036)~

    Uptake and Metabolism Kinetics of TBT in Whelk(Thais clavigera)Exposed to Dietary

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    将牡蛎消化腺分别暴露在1000ng.l-1和100ng.l-1TbT水溶液中4周,然后将染毒的牡蛎消化腺分别投喂疣荔枝螺(THAIS ClAVIgErA)。经过45d的暴露和30d的净化,我们发现雌雄疣荔枝螺的消化和生殖系统能较快地吸收TbT(吸收速率ku=0.004-0.022.d-1),并且其代谢(生物代谢系数bdI=5.59-23.30)和排出速率(净化速率kE=0.024-0.053.d-1)也相对较快,各器官中TbT的代谢产物MbT占了相对较高的比例,因此TbT在食物链传递过程中没有出现生物放大的现象。此外,TbT有逐渐从雌螺消化系统向生殖系统转移的趋势,并且雌螺生殖系统对TbT的吸收和富集能力(ku=0.006-0.022.d-1,生物放大系数bMf=0.181-0.664)要显著强于雄螺(ku=0.004-0.014.d-1,生物放大系数bMf=0.142-0.376),但其代谢和净化速率(bdI=5.59-10.50,kE=0.024-0.025.d-1)却显著低于雄螺(bdI=11.5-12.4,kE=0.031-0.050.d-1),雌螺的生殖系统被认为是TbT转移和富集的潜在靶器官,这对我们今后开展TbT污染的环境监测和评价具有重要的参考价值。Oysters were respectively exposed to 1000 ng·L-1 and 100 ng·L-1 tributyltin(TBT) aqueous for 4 weeks,which was as dietary to feed the female and male Thais clavigera whelks for 45 days.Then these Thais clavigera were depurated for 30 days.The results show that TBT rapidly accumulated in their digestive and reproductive organs(ku=0.004-0.022 d-1).Moreover,elimination and biotransformation of TBT were also rapid(BDI=5.6-23.30,ke=0.024-0.053 d-1).MBT was the dominant metabolite in each tissue.Therefore,bio-magnification of TBT did not occur during the trophic transfer process.Additionally,to females,the mobilization of TBT from digestive to reproductive organs and bioaccumulation of TBT(ku=0.006-0.022 d-1,BMF=0.181-0.664) were more obvious than that of the males.However,lower metabolism and elimination of TBT(BDI=5.6-10.5,ke=0.024-0.025 d-1) in female reproductive organs,which indicated that the reproductive organs of females were the main targets of TBT accumulation.The results are important to the risk assessment of TBT contamination in coastal environments.国家“863”项目No.2007AA09Z126;国家自然科学基金项目No.40476048;20777060;海洋公益性行业科研专项经费;No.20080509

    Abundance and production of bacteria and their correlations with environmental factor

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    以2014年8月南海北部海水样品为研究对象,利用平板计数法和流式细胞仪计数法对南海北部表层和垂直海域可培养细菌和细菌总数分布状况进行研究,对细菌; 生产力进行测定,并结合环境因子进行相关性分析。结果表明:珠江口到南海北部海域,水平方向可培养细菌总数变化范围是3.70*10~2 ~; 1.42*10~3 CFU/mL,细菌总数变化范围是5.12 * 10~5 ~1.61 * 10~6; cells/mL,细菌生产力的变化范围是0.03 ~0.40 mg/m~3/h;垂直方向上可培养细菌变化范围是1.08 *10~3 ~9.00; *10~3 CFU/mL,细菌生产力变化范围是0.01 ~0.08; mg/m~3/h,其中表层海水中的细菌生产力明显高于底层。与环境因子相关性分析表明,水平方向上,影响南海北部表层海水细菌总数和细菌生产力的主要因; 素是温度、盐度、硝酸盐(NO_3-N)、硅酸盐(SiO_3-Si)、亚硝酸盐(NO_2-N)和磷酸盐(PO_4-P)(P<0.05);垂直方向上; ,影响南海北部可培养细菌总数的主要因素是NO_2-N(P<0.05),影响细菌生产力的主要影响因素是温度和盐度(P; <0.05)。可见,南海北部表层海水中细菌总数高于可培养细菌总数2; ~3个数量级,表明该海域表层海水存在大量不可培养细菌;细菌的生命活动在海水表层相较底层更为活跃。Distribution of abundance and production of bacteria and their; correlations with environmental factor were investigated, using plate; count method and flow cytometry, in the surface and vertical waters of; the northern south China sea in August 2014. The cultivable bacterial; abundance ranged from 3.70 * 10~2 CFU/mL to 1.42 * 10~3 CFU/ mL, the; total bacterial abundance ranged from 5.12 * 10~5 cells/mL to 1.61 *; 10~6 cells/mL and the bacterial productions varied from 0.03 mg/m~3/h to; 0.40 mg/m~3/h in horizontal distribution. In vertical distribution, the; cultivable bacterial abundance ranged from 1.08 * 10~3 CFU/mL to 9.00 *; 10~3 CFU/mL and the bacterial productions varied from 0.01 mg/m~3/h to; 0.08 mg/m~3/h, respectively. The correlation analysis results showed; that the environmental factors affecting the abundance of total bacteria; and bacterial productivity included temperature, salinity,; nitrate(NO_3-N),silicate (SiO_3-Si), nitrite (NO_2-N),and phosphate; (PO_4-P) (P<0.05). NO_2-N was the main influencing factor to cultivable; bacteria abundance (P < 0.05), while bacterial productivity was highly; correlated with temperature and salinity in vertical distribution of; northern south China sea (P < 0.05). The total bacterial abundance was 2; ~ 3 orders of magnitude higher than cultivable bacteria, suggesting that; there were many uncultured bacterium in surface water of northern south; China sea and bacterial activities in the surface maybe more active than; in the bottom.全球变化与海气交互作用; 国家重点研发计划全球变化及应对专项; 海洋公益性行业科研专

    Mirk/Dyrk1b在上皮性卵巢癌组织中的表达及意义

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    目的:探讨Mirk/Dryk1b(Minibrain-related kinase/Dual specificity tyrosine-phosphorylation-regulated kinase1B)在卵巢组织中的表达及其临床意义。方法:利用免疫组化检测Mirk/Dyrk1b在30例上皮性卵巢癌、20例上皮性卵巢囊腺瘤、10例正常卵巢组织中的表达。结果:Dyrk1b在上皮性卵巢癌中的表达明显高于上皮性卵巢囊腺瘤及正常卵巢组织(P0.05)。结论:Dyrk1b在上皮性卵巢癌中高表达,提示其可能参与了肿瘤的发生和发展,并有望成为临床早期诊断的肿瘤标志物和新的卵巢癌治疗的靶基因

    低龄DDH患儿初次开放复位术中股骨截骨必要性的前瞻性随机对照试验研究方案

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    回顾性研究发现,股骨截骨术并非低龄DDH患儿手术治疗所必须的,而应根据患儿具体情况合理选择;本研究通过多中心前瞻性研究进一步探讨对于18个月至3岁DDH患儿是否要行股骨截骨术。FSODDH项目为一项多中心前瞻性随机对照临床试验研究。研究设计拟招募200名单侧低龄DDH患儿,随机分成股骨截骨组(n=100)和股骨不截骨组(n=100)。股骨截骨组患儿全部采取髋关节开放复位术、骨盆截骨术及股骨截骨术治疗;股骨不截骨组患儿全部采取髋关节开放复位术及骨盆截骨术治疗;术后定期随访至少2年。收集术前、术后1周、术后1个月、术后3个月、术后6个月、术后1年及术后2年的髋关节正位X线影像资料,比较两组患儿的髋臼指数、股骨头坏死率、再脱位率、术中出血量、手术时间和住院天数等临床指标。这一多中心前瞻性研究将能为低龄DDH患儿是否需行股骨截骨术提供循证医学证据
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