203 research outputs found

    物流业的产业影响效应及其政策启示——基于全国35个大中城市面板数据的实证研究

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    基于全国35个大中城市面板数据,可构建跨城市面板数据模型从价值层面与实物层面同时探析物流业对三大产业的影响效应,在对估计结果进行稳健性与内生性检验基础上,深入分析该影响效应的地区异质性表现。研究结果发现,两个层面衡量的物流业对三大产业均有显著的促进效应,且该估计结果通过了稳健性检验;经过内生性检验后物流业对三大产业的正向影响效应仍显著存在,且消除内生性问题影响后,该效应均得到了显著加强;物流业对东部、中部、西部地区产业的影响效应存在地区异质性,对东部地区第一产业的正向影响效应不显著,但对中部地区第二产业的促进效应最为明显,而对东部地区第二、第三产业的促进效应不及中部和西部地区,表明物流业对东部发达地区产业的促进效应相对最弱;劳动力成本、购买力水平、教育投入、基础设施建设水平等均对三大产业有促进效应,地方政府规模却对三大产业均有负向影响效应。基于此,我国应解除制约物流业发展的体制机制障碍,打破物流业整体布局的区域壁垒;提高物流业与各产业的融合度与动态匹配度,建立现代产业体系;提高物流业驱动下的产业发展与地区经济发展战略的有效契合度,促进地区经济快速发展。国家自然科学基金项目“区域果蔬外贸冷链物流模式及其机制创新研究”(71562033

    信息港建设与信息服务的辩证关系

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    信息港建设与信息服务是相互影响、相互促进的辩证关系。丰富的网上信息、四通八达的网络、直观快速的检索、传递和反馈机制、功能改进的有线电视网和方便快捷的电子商务功能为信息服务发展拓新提供了有利条件 ;另一方面 ,信息服务也对信息港建设起推动、促进或制约作

    翔安文教园文献资源共建共享初探

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    厦门翔安文教园分布着厦门大学翔安校区和厦门海洋学院等多座高校,园内各院校图书馆各自为政,缺乏协调与合作。文章提出翔安文教园开展文献资源共建共享的构想,探讨翔安文教园各院校图书馆提高文献利用率和文献保障能力的策略

    The Atmospheric Mercury Pollution Survey During Autumn and Winter Seasons in Xiamen

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    文章采用两次金汞齐-冷原子荧光光谱法对厦门地区秋冬季节大气汞的污染状况作了初步调查分析,结果表明厦门地区大气中汞的浓度平均为11.037 ng/M3,其含量高于北半球大气气态总汞含量的背景值(1.5--2.0 ng/M3),表明该地区已受到一定程度的大气汞污染;在一定的采样区域,大气汞浓度与温度、太阳辐射量、大气压、空气湿度成正相关,与风速成负相关;气态汞的含量在80%左右,这与该地区的人为活动多有关,与其他地区报道的类似区域情况的汞污染状况相符;工业区,学校实验室周边区域,生产过程中以汞为原料的工厂等附近区域,大气中汞的含量较高,开阔区域的海边含量较低,交通繁忙区域最低(所选采样点与交通要道有一定的距离),这种浓度分布说明了大气中汞的存在具有区域性特征。In this paper,the atmospheric mercury pollution during autumn and winter seasons in Xiamen was analyzed with the method of two-stage gold amalgamation-cold vapor atomic fluorescence spectroscopy.The results show that the average concentration of atmospheric mercury in Xiamen is 11.037ng/m3,which is higher than the background value(1.5ng/m3--2.0ng/m3) of the atmospheric mercury in the northern hemisphere.It indicates that there is a certain degree of mercury pollution in Xiamen.there is a positive relationship between mercury concentration and temperature、solar radiation、atmospheric pressure and humidity,while there is a negative relationship between mercury concentration and wind speed.The content of gaseous mercury in Xiamen is about 80%,which shows analogous level compared to the mercury concentration in other areas.The high content of gaseous mercury in Xiamen maybe related to the human activities.The mercury concentration is high in some regions such as industrial zone,areas around school laboratories,factories which use mercury as raw materials,while the mercury concentration is a little lower in the open area of the seaside,and the mercury concentration is the lowest in traffic busy areas(there is some distance between sampling locations and traffic busy in this study).The distribution of mercury concentration indicates that there is a regional character of atmospheric mercury in Xiamen

    乙醛酸电合成研究进展

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    较为全面地总结了乙醛酸制备的技术路线,综合评价其工艺的优缺点;详述了电合成乙醛酸工艺开发方面的情况,总结其最佳工艺条件,提出了存在的问题和今后发展的方向

    单、双胎早产的高危因素及早产儿结局比较研究

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    目的探讨双胎早产与单胎早产高危因素的特点以及单、双胎早产儿的结局。方法回顾性分析广州医科大学附属第三医院2009年1月至2015年12月的单、双胎孕产妇与新生儿临床数据资料。结果研究期间在该院分娩的36 931例新生儿,双胎2080例,单胎34 851例,其中早产5877例,双胎早产1395例(双胎早产组),早产率为67.07%;单胎早产4482例(单胎早产组),单胎早产率为12.86%,总计早产发生率为15.91%,双胎早产率明显高于单胎,差异有统计学意义(P22~26岁组、>26~30岁组、>30~34岁组、>34~39岁组和>39岁组中,双胎早产率均明显高于单胎(单胎早产率对双胎早产率分别为:19.65%vs.64.86%、11.45%vs.70.85%、10.49%vs.68.16%、12.88%vs.65.41%、19.67%vs.64.51%、22.83%vs.68.42%,P均<0.05);单、双胎孕产妇不同孕周出生率比较,双胎在孕20~37周之间的出生率均高于单胎出生率;对早产的高危因素进行对比分析,双胎早产组中人工授精、体外受精-胚胎移植、羊水过多、胎膜早破、妊娠期糖尿病、妊娠期肝内胆汁淤积症的比例均明显高于单胎早产组,差异有统计学意义(1.79%vs.0.16%、1.79%vs.0.16%、2.79%vs.1.38%、32.48%vs.29.65%、19.50%vs.15.84%、2.22%vs.1.41%,P均<0.05);对新生儿的结局进行比较,单胎早产组中死胎、出生缺陷、新生儿呼吸窘迫综合征发生率均明显高于双胎早产组(8.68%vs.2.22%、11.20%vs.8.52%、15.35%vs.12.90%,P均<0.05),1 min、5 min、10 min Apgar评分双胎早产组明显高于单胎早产组,差异有统计学意义[(9.43±0.023)min vs.(9.06±0.026)min、(9.85±0.013)min vs.(9.69±0.016)min、(9.92±0.011)min vs.(9.81±0.014)min,P均<0.05]。结论双胎发生早产的风险显著高于单胎,与单胎早产相比,人工授精、体外受精-胚胎移植、羊水过多、胎膜早破、妊娠期糖尿病、妊娠期肝内胆汁淤积症等高危因素与双胎早产的关系更加密切,早产儿结局优于单胎早产组。国家重点研发计划(2016YFC1000405/2016YFC1000303);;国家自然科学基金(81571518

    Function of a methyl-accepting chemotaxis protein Tlp1 in Azorhizobium caulinodans ORS571

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    【目的】考察茎瘤固氮根瘤菌中趋化基因簇上游的受体蛋白Tlp1编码基因的突变表型,初步探究其功能机理。【方法】利用同源重组和三亲本接合转移的方法构建突变株,在TY培养基中测定生长情况,半固体平板法观察趋化圈,刚果红固体培养基观察胞外多糖和次生代谢产物的分泌,乙炔还原法测定菌株的固氮酶活性。【结果】与野生型菌株相比,tlp1突变株的生长速率没有影响。在以甘油为碳源的L3半固体平板上突变株的趋化圈变小,其回补菌株能部分回补趋化能力。突变株的胞外多糖分泌与野生型没有区别,但其次生代谢产物黑色素出现的时间比野生型稍早。在固氮酶活性测定中,发现突变株酶活性明显比野生型降低,回补菌株能够部分回补。【结论】茎..

    Electrosynthesis of glyoxylic acid in a static bed reactor with cooled cathode

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    以过饱和草酸水溶液为阴极液,盐酸溶液为阳极液,在阴极冷却固定床电化学反应器内草酸电解合成乙醛酸。考察了电流密度、电极和电解液温度、阴极材料对合成乙醛酸时空产率和电流效率的影响。结果表明,阴极冷却固定床反应器是一种较理想的反应器,用石墨板作阳极,铅作阴极,电流密度为400.5A/m2,阴极空速u0=0.505m/s,电解温度为20℃左右时,电解1.5h,在阴极可得到质量分数为5.45%的乙醛酸溶液,平均时空产率可达0.12kg/dm3·h以上。Glyoxylic acid was produced by electroreduction of oxalic acid in the static bed reactor with cooled cathode. The cathodic and anodic electrolytes were super-saturated oxalic acid and hydrochloric acid aqueous solutions. The current efficiency and time-space yield of glyoxylic acid were studied under different current densities, temperatures of cathode and electrolyte,materials of cathode. The results indicated that the cooled cathode static bed reactor is an excellent reactor. The average space-time yield of glyoxylic acid is over 0.12 kg/dm~3·h and the concentration of glyoxylic acid can reach 5.45% after 1.5 h electrolysis with cathode of lead and anode of graphite board under conditions of temperature 20℃,superficial flow rate of 0.505 m/s and current density of 400.5 A/m~2 in the cooled cathode static bed reactor.福建省自然科学基金资助项目(F99029

    The effect of nurse initiated patient/family education strategy on people with schizophrenia in Beijing

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    2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

    Synthesis and Bioactivity of 5-Ivermectin B_(1a) Esters

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    依维菌素B1a与羧酸在DMAP/DCC体系中直接酯化 ,得到 10个 5 IVB1a酯衍生物 ,产率 6 6 %~ 82 %;它们的化学结构得到IR ,1HNMR ,13 CNMR和MS谱的确证 .它们具有良好的杀虫、杀螨活性 .Ten 5-Ivermectin B 1a ester derivatives were prepared from Ivermectin B 1a and carboxylic acids in the systems of DCC/DMAP. Their chemical structures were determined by IR, 1H NMR, 13C NMR and MS spectra. The preliminary results of bioassay showed that L-1~L-10 have good insecticidal activities.国家自然科学基金(No .2 9832 0 5 0 )资助项
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