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乙烯制取实验发生“爆沸”的原因及预防
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作者 杨鸿德 《化学教学》 CAS 北大核心 1999年第8期40-41,共2页
“乙烯的制取及性质”实验,看似简单,但在实际操作中,却偶发“爆沸”现象,为解除这一隐患,我针对这个实验发生“爆沸”的原因,进行了深入细致的研究,现公诸于众.一.可能发生“爆沸”的几种情况1配制“制气液”时,操作不当... “乙烯的制取及性质”实验,看似简单,但在实际操作中,却偶发“爆沸”现象,为解除这一隐患,我针对这个实验发生“爆沸”的原因,进行了深入细致的研究,现公诸于众.一.可能发生“爆沸”的几种情况1配制“制气液”时,操作不当而“爆沸”由于浓硫酸与乙醇的混合过... 展开更多
关键词 实验发生 乙烯过程 反应器 导气管 乙醇 醇回流 反应容器 温度过高 混合过程 预防措施
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实验室发生纳米气溶胶吸湿性表征 被引量:10
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作者 王轩 陈建华 +4 位作者 陈建民 叶兴南 刘红杰 王玮 邓建国 《环境科学研究》 EI CAS CSCD 北大核心 2011年第6期621-631,共11页
气溶胶吸湿特性对于灰霾的形成、气溶胶对气候变化的影响及人体健康效应具有重要意义.采用加湿迁移差分分析(HTDMA)法,对实验室发生的8种纳米级无机和有机气溶胶进行吸湿特性定量表征,从而判定影响气溶胶吸湿特性的主要因素.结果表明,N... 气溶胶吸湿特性对于灰霾的形成、气溶胶对气候变化的影响及人体健康效应具有重要意义.采用加湿迁移差分分析(HTDMA)法,对实验室发生的8种纳米级无机和有机气溶胶进行吸湿特性定量表征,从而判定影响气溶胶吸湿特性的主要因素.结果表明,NaCl和(NH4)2SO4气溶胶的潮解点为相对湿度(RH)75%±2%,与理论计算结果相接近,说明测试系统具有一定的可靠性.对以往研究较少的NaNO3,CaCl2,CaSO4,合成海盐,乙二酸和己二酸气溶胶的测试表明,NaNO3,CaCl2以及合成海盐气溶胶随RH的升高粒径逐渐增大;合成海盐气溶胶在RH为86%时吸湿性生长因子(Gf)达到1.80;CaSO4,乙二酸和己二酸气溶胶随着RH增大未见明显吸湿增长.通过扫描电镜分析了8种化合物气溶液在不同RH下的形态特征,为掌握各种化学组分对气溶胶吸湿特性的影响提供了微观形态分析的依据. 展开更多
关键词 实验发生气溶胶 吸湿性 HTDMA系统
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蒸汽发生器实验回路倒流特性仿真分析 被引量:1
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作者 胡高杰 于雷 +1 位作者 郝建立 储玺 《原子能科学技术》 EI CAS CSCD 北大核心 2017年第1期67-72,共6页
针对立式倒U型管蒸汽发生器传热管内出现的倒流现象,基于RELAP5/MOD3.3程序,采用新的控制体划分方案对蒸汽发生器实验段进行建模,模拟实验回路中发生的倒流现象。通过与实验数据进行对比分析,验证建模方案的正确性。在此基础上,分析倒... 针对立式倒U型管蒸汽发生器传热管内出现的倒流现象,基于RELAP5/MOD3.3程序,采用新的控制体划分方案对蒸汽发生器实验段进行建模,模拟实验回路中发生的倒流现象。通过与实验数据进行对比分析,验证建模方案的正确性。在此基础上,分析倒流现象对蒸汽发生器实验段流动传热的影响。结果表明:倒流现象发生在较短管内,对于单个U型管,倒流管的流量高于正流管。倒流发生后,系统进入相对稳定状态,但蒸汽发生器实验段的换热功率和进出口腔室负压降绝对值显著降低。 展开更多
关键词 蒸汽发生实验 倒流 数值模拟
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中国的华生——郭任远实验的发生心理学解析 被引量:1
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作者 张翠白 吕英军 《科教文汇》 2011年第28期178-180,共3页
郭任远是中国近代具有国际影响力的少数心理学家之一,在国际心理学界最先提出否认本能、取消遗传的观点。作为一位激进的行为主义者,郭任远认为心理学是一门建立在实验基础上的精确的自然科学,坚决主张抛弃心理学中一切主观性的名词术... 郭任远是中国近代具有国际影响力的少数心理学家之一,在国际心理学界最先提出否认本能、取消遗传的观点。作为一位激进的行为主义者,郭任远认为心理学是一门建立在实验基础上的精确的自然科学,坚决主张抛弃心理学中一切主观性的名词术语。他明确提出,心理学应该以人类或动物的行为或动作作为研究对象,其根本目的就是要在客观的和行为的基础上建立一种新的心理学解释,即实验的发生心理学。 展开更多
关键词 郭任远 本能 实验发生心理学 反动单位
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从信息到创新:课堂教学的价值追求——以“实验室制取二氧化碳的研究”教学为例 被引量:1
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作者 唐云波 《化学教育》 CAS 北大核心 2015年第13期40-43,共4页
以“实验室制取CO2的研究”为例,通过探究实验室制取气体的反应原理以及选择、改进发生装置为手段,促使学生的学习沿着“信息”—“知识”—“智力”—“创新”的路线转化,这是课堂教学的价值追求.
关键词 探究实验 实验发生装置 反应原理 价值追求 二氧化碳
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氨水溶液解吸-压缩制冷循环的理论研究与实验 被引量:3
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作者 梅宁 丁爽 刘小军 《中国海洋大学学报(自然科学版)》 CAS CSCD 北大核心 2009年第5期1131-1136,共6页
氨水溶液解吸-压缩制冷循环(简称ADAR循环)是1种以氨水溶液解吸-吸收过程取代蒸发和冷凝过程的制冷循环。对该循环进行理论分析和热力计算,并对循环的关键步骤低压发生过程进行实验。结果表明:在相同高低温下ADAR循环的理论制冷系数随... 氨水溶液解吸-压缩制冷循环(简称ADAR循环)是1种以氨水溶液解吸-吸收过程取代蒸发和冷凝过程的制冷循环。对该循环进行理论分析和热力计算,并对循环的关键步骤低压发生过程进行实验。结果表明:在相同高低温下ADAR循环的理论制冷系数随低压发生过程压降幅度的减小而升高;在其他条件不变的情况下,增大冷却水进口温度,循环COP下降;增大低温热媒进口温度,循环COP升高;低压发生器的变压解吸过程可以实现。 展开更多
关键词 氨水 解吸-压缩 制冷循环 低压发生实验
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氨水低压低温的传热传质研究
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作者 刘小军 梅宁 丁爽 《山西建筑》 2009年第36期174-175,共2页
对氨水溶液解析—压缩制冷循环的氨水低压发生部分进行实验研究,并对该发生过程的多次实验过程进行了对比和分析,结果表明:饱和氨水在低压环境中能够在套丝网管中形成升膜解析出氨气并能释放出比氨气潜热大得多的冷量,通过实验发现通过... 对氨水溶液解析—压缩制冷循环的氨水低压发生部分进行实验研究,并对该发生过程的多次实验过程进行了对比和分析,结果表明:饱和氨水在低压环境中能够在套丝网管中形成升膜解析出氨气并能释放出比氨气潜热大得多的冷量,通过实验发现通过节流阀单级节流作用和大温差换热的等温降压发生会得到与理论上相近的制冷效果。 展开更多
关键词 氨水 单级节流降压 低压发生实验
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Conversion of Methane by Steam Reforming Using Dielectric-barrier Discharg 被引量:9
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作者 张旭 王保伟 +1 位作者 刘永卫 许根慧 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2009年第4期625-629,共5页
Conversion of methane by steam reforming was carried out by means of dielectric-barrier discharge.A systemic procedure was employed to determine the suitable experimental conditions.It was found that one of the plasma... Conversion of methane by steam reforming was carried out by means of dielectric-barrier discharge.A systemic procedure was employed to determine the suitable experimental conditions.It was found that one of the plasma generators can match the system best.A higher power input can always bring a higher conversion,but the selectivity to C2H6 decreased from 52.48% to 39.43% as the power increased from 20W to 49W.When discharge distance was 4mm,selectivities to almost all main products reached the max.The inner electrode made of stainless steel and the outer electrode with aluminum foil were one of the best options which can obviously enhance the conversion of methane.A larger flow rate always resulted in a lower conversion of methane.In the most time,19.93% steam promoted conversion of methane. 展开更多
关键词 METHANE STEAM dielectric-barrier discharge PLASMA
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Otolith development in larval and juvenile Schizothorax davidi: ontogeny and growth increment characteristics 被引量:1
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作者 严太明 胡佳祥 +4 位作者 蔡跃平 熊森 杨世勇 王雄延 何智 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2017年第5期1197-1204,共8页
Laboratory-reared Schizothorax davidi larvae and juveniles were examined to assess the formation and characteristics of David’s schizothoracin otoliths.Otolith development was observed and their formation period was ... Laboratory-reared Schizothorax davidi larvae and juveniles were examined to assess the formation and characteristics of David’s schizothoracin otoliths.Otolith development was observed and their formation period was verifi ed by monitoring larvae and juveniles of knownage.The results revealed that lapilli and sagittae developed before hatching,and the first otolith increment was identified at 2 days post hatching in both.The shape of lapilli was relatively stable during development compared with that of sagittae;however,growth of four sagittae and lapilli areas was consistent,but the posterior area grew faster than the anterior area and the ventral surface grew faster than the dorsal surface.Similarly,the sum length of the radius of the anterior and posterior areas on sagittae and lapilli were linearly and binomially related to total fish length,respectively.Moreover,daily deposition rates were validated by monitoring knownage larvae and juveniles.The increase in lapilli width was 1.88±0.080 0μm at the ninth increment,which reached a maximum and the decreased gradually toward the otolith edge,whereas that of sagittae increased more slowly.These results illustrate the developmental biology of S.davidi,which will aid in population conservation and fish stock management. 展开更多
关键词 OTOLITH DEVELOPMENT otolith microstructure GROWTH Schizothorax davidi
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Experimental study on angiogenesis in rabbit VX_2 brain tumor using perfusion CT
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作者 Liqing Kang Yunting Zhang Shimei Sun 《The Chinese-German Journal of Clinical Oncology》 CAS 2006年第6期431-435,共5页
Objective: To study the perfusion CT features of rabbit VX2 brain tumor with correlation to MVD and VEGF, and to validate perfusion CT for reflection of tumor angiogenesis. Methods: Rabbit VX2 brain tumor model was ... Objective: To study the perfusion CT features of rabbit VX2 brain tumor with correlation to MVD and VEGF, and to validate perfusion CT for reflection of tumor angiogenesis. Methods: Rabbit VX2 brain tumor model was established by injection of 100 μL viable tumor cells (10qmL) through a 2 mm-hole 5 mm to the right of the sagittal suture and 5 mm posterior to the coronal suture bored by dental drill. MRI was performed every 2 days after seven days of implantation to evaluate the growth of the tumor. Twenty New Zealand White rabbits with tumor size over 3 mm in diameter were randomly divided into 2 groups according to the tumor growth time with those less than 3 weeks as group 1 and those more than 3 weeks as group 2, and perfusion CT were performed accordingly. CT measurements of BV, BF and PS from tumor, peritumor and contralateral normal tissue regions were obtained. After that the animals were sacrificed and 2% Evans blue (2 mL/kg) was given intravenously in 16 of these animals 1 h prior to sacrifice to detect breakdown of the blood brain barrier. VEGF and MVD were evaluated in immunohistochemical examination of the specimens. Results: Tumor had significantly higher BV, BF and PS (P=0.000) than peritumor and normal tissue region. Tumor BV, BF and MVD in group 2 were significantly higher than that in group 1 (P〈0.01). Significant linear correlation was found between MVD and BV (t=-0.915, P=-0.000), MVD and BF (t=0.901, P=-0.000), and MVD and PS (t=-0.459, P=0.042). We also found a rank correlation between PS and blue stain of tumor (rs=0.861, P=0.000). Conclusion: Perfusion CT can distinguish tumor from peritumor and normal tissue clearly, reflect tumor angiogenesis accurately, and provide useful information for the evaluation of brain tumor. 展开更多
关键词 brain neoplasms angiogenesis factor PERFUSION tomography X-ray computed
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Experimental study on MyoD gene induced differentiation of bone marrow mesen-chymal stem cells into myoblasts in vitro
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作者 张勇 邹仲敏 +5 位作者 郭朝华 周进明 王劲 范文辉 罗成基 程天民 《Journal of Medical Colleges of PLA(China)》 CAS 2003年第1期27-31,共5页
Objective: To explore the possibility of the transfection of MyoD gene induced bone marrow mesenchymal stem cells ( MSCs) to differentiate into myoblasts in vitro. Methods: The eukaryotic expression plasmid vector pIR... Objective: To explore the possibility of the transfection of MyoD gene induced bone marrow mesenchymal stem cells ( MSCs) to differentiate into myoblasts in vitro. Methods: The eukaryotic expression plasmid vector pIRES2-EGFP-MyoD was transfected into MSCs with lipotransfection method, and the positive cells were selected by G418; The expression of MyoD was detected in the transfected MSCs with RT-PCR and the amplified, purified product was identified by sequencing; The reporter gene enhanced green fluorescence protein ( EFGP) was observed in the transfected cells under a fluorescent and a laser confocal microscopes; Immunohistochemical methods was used to examine the expressions of MyoD, myogenin, myosin, myoglobin and desmin in the differentiated cells. The ultrastructure changes of the cells before and after transfection were observed with electron microscopy. Results: The expression of MyoD was detected in the transfected MSCs with RT-PCR and the amplified, purified product was as same in sequence as that from Genbank; Green fluorescence was observed in the transfected cells under a fluorescent and a laser confocal microscopes; Immunohistochemical methods indicated that MyoD, myogenin, myosin, myoglobin and desmin were expressed in the transfected cells; The transfected cells showed the morphological characteristics of mature cells with filaments in their cytoplasm. Conclusion: MyoD gene can induce cultured MSCs to successfully differentiate into myoblasts , probably providing an experimental foundation for trauma repair. 展开更多
关键词 mesenchymal stem cells MYOGENESIS MYOD
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Heparanase antisense oligodeoxynucleotide inhibits angiogenesis and metastasis of human mammary carcinoma cell xenografts in nude mice
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作者 张友磊 傅志仁 +3 位作者 丁国善 张军 沈茜 王义 《Journal of Medical Colleges of PLA(China)》 CAS 2007年第3期143-148,共6页
Objective: To evaluate the inhibitory effect of heparanase antisense oligodeoxynucleotide (AS-ODN) on the angiogenesis and metastasis of human mammary carcinoma cell xenografts in nude mice. Methods: The AS-ODN co... Objective: To evaluate the inhibitory effect of heparanase antisense oligodeoxynucleotide (AS-ODN) on the angiogenesis and metastasis of human mammary carcinoma cell xenografts in nude mice. Methods: The AS-ODN complementary to the start codon region of heparanase mRNA and its control, scrambled nonsense oligodeoxynucleotide (NS-ODN) were designed and synthesized. A subcutaneous growth model and an acute hematogenous metastasis model of human mammary carcinoma were established in nude mice and were treated with ODNs. The heparanase expression in tumor was evaluated by RT-PCR and Western blot. The microvessel density (MVD) was measured by immunohistochemistry for factor VS. The tumor volume was calculated and lung metastatic nodules were counted. Results : The heparanase expression, MVD, tumor volume and lung metastatic nodules in AS-ODN treated group were significantly decreased compared with that in NS-ODN treated group and that in PBS group (P〈0.01). Conclusion : Heparanase AS-ODN has significant inhibitory effect on the angiogenesis and metastasis of human mammary carcinoma cell xenografts in nude mice. 展开更多
关键词 HEPARANASE antisense oligodeoxynucleotide mammary carcinoma ANGIOGENESIS METASTASIS
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A New Generator for Tsunami Wave Generation
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作者 Tetsuya Hiraishi Ryokei Azuma +2 位作者 Nobuhito Mori Toshihiro Yasuda Hajime Mase 《Journal of Energy and Power Engineering》 2016年第3期166-172,共7页
A middle size experiental wave generator has been implemented is the Ujikawa Open Laboratory, Disaster Prevention Research Institute, Kyoto University. The generator is composed of a pistontype wave maker, a head stra... A middle size experiental wave generator has been implemented is the Ujikawa Open Laboratory, Disaster Prevention Research Institute, Kyoto University. The generator is composed of a pistontype wave maker, a head strage water tank and a current generator to mainly reproduce long waves like tsunami and storm surge. The paper desribes several experimental series to predict the applicability of the generator to model tests. The three operating sysemes are capable to be controlled in one operating sysytem and start time is contorolled separately according with the target tsunami and storm surge profiles. A sharp tsunami profile is reproduced in adjusting the start timing of piston type wave maker and opening gates of head storage tunk. Any type of tsunami waves are reproduced in the generator and it becomes a storong tool to predict the effective of"resiliency" of hardwares. 展开更多
关键词 TSUNAMI storm surge experimental generator tool wave maker.
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A policy analysis based on policy network theory in yunnan province
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作者 ZHANG Chi GUO Kai FAN Yuting 《International English Education Research》 2018年第2期77-79,共3页
"Mass entrepreneurship and innovation" as become the new engine of China's economic development. In this paper, based on the policy network theory, to conduct the thorough research to the college students' innovat... "Mass entrepreneurship and innovation" as become the new engine of China's economic development. In this paper, based on the policy network theory, to conduct the thorough research to the college students' innovative undertaking policy in yunnan province, and connecting with the present situation of college students' innovative undertaking in yunnan, through to explain the framework For the college students' innovative undertaking policy change for empirical analysis. In order to further promote the innovation and entrepreneurship of yuunan university students, it also needs to solve the problems of policy overlap, reintroduction, light execution, and long management. 展开更多
关键词 innovation and entrepreneurship policy Policy networkpolicy implementation innovation drive
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Effect of temperature and photoperiod on maturation of Cephalothrix hongkongiensis(Nemertea: Palaeonemertea)
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作者 李应东 宋肖跃 +2 位作者 张珊珊 朱林 孙世春 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2014年第4期764-772,共9页
The limited knowledge about the relationships between environmental factors and the maturation and reproductive seasonality of nemerteans is mostly obtained from field studies, and in many cases is conjectural. Few sp... The limited knowledge about the relationships between environmental factors and the maturation and reproductive seasonality of nemerteans is mostly obtained from field studies, and in many cases is conjectural. Few species have been studied under well-controlled laboratory conditions. In this work, the effects of temperature and photoperiod on gonad development and spawning of Cephalothrix hongkongiensis were observed by rearing worms under different temperatures and photoperiods. Worms reared at 4~C and 6~C showed no growth or gonadal development, and all died within 109 days. At 8~C and 12~C, gonads could be seen from 90 days to the termination of the 360-day experiment, but no spawning was observed. Worms maintained at 16, 24, and 28~C showed both gonadal development and spawning, and matured faster at higher temperatures. Under a fixed temperature (16℃), photoperiod did not have any significant impact on maturation and spawning. It is likely that temperature plays a major role in regulating the maturation and reproductive cycle of C. hongkongiensis. 展开更多
关键词 TEMPERATURE PHOTOPERIOD gonad development REPRODUCTION Cephalothrix hongkongiensis NEMERTEA
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An Empirical Study on Regional Differences of Higher Education Financial Aid in China
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作者 ZHAN Hong-yi 《Journalism and Mass Communication》 2017年第9期516-528,共13页
This paper uses empirical data to examine the issue of fairness of higher education student financial aid in China, noting different levels of regional economic development as the reason to explain the wide differ... This paper uses empirical data to examine the issue of fairness of higher education student financial aid in China, noting different levels of regional economic development as the reason to explain the wide differences in available financial resources for student aid. Government efforts aimed at reducing the gap in recent years is discussed. 展开更多
关键词 regional differences higher education financial aid China
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Experimental Design as a Tool for the Development of Citric Acid Production by Yarrowia lipolytica Using Glycerol as a Feedstock
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作者 Luana V. da Silva Camila B. Tavares Roberta dos R. Ribeiro Fernando L. P. Pessoa Maria Alice Z. Coelho Priscilla F. F. Amaral 《Journal of Food Science and Engineering》 2013年第8期435-446,共12页
Due to the scarcity of fossil fuels in the world, there is increasing interest in the commercial production of biodiesel, which leads to obtaining large amounts of glycerol as a byproduct. If not disposed of properly,... Due to the scarcity of fossil fuels in the world, there is increasing interest in the commercial production of biodiesel, which leads to obtaining large amounts of glycerol as a byproduct. If not disposed of properly, glycerol can generate environmental impact. One of the promises, the application of the crude glycerol is the production of citric acid by microbial fermentation. Citric acid is industrially produced by a submerged fermentation process with Aspergillus niger, using sucrose as carbon source, but due to increased demand for citric acid, alternative processes using renewable sources or waste materials as substrates and the cultivation of yeast strains are being studied. The aim of the study was to determine the best culture condition for maximum citric acid synthesis and lower isocitric acid production from crude glycerol through experimental design tool. For this purpose, the yeast strain Yarrowia lipolytica IMUFRJ-50682 was cultivated in nitrogen-limited glycerol-based media. Therefore, glycerol and yeast extract concentrations and agitation speed were evaluated as independent variables. With pure glycerol, the highest citric acid production achieved was 16.5 g/L with an isocitric acid production of 7.7% (in relation to citric acid). With crude glycerol, citric acid production reduced to 6.7 g/L because of higher biomass yield. Therefore, an increase in the initial carbon to nitrogen molar ratio from 714 to 1,561 was necessary to increase citric acid production to 9.2 g/L, reducing isocitric acid production and to achieve a yield of 0.41 g of citric acid per glycerol consumed. In this condition, less nitrogen source was used, reducing production costs. 展开更多
关键词 Yarrowia lipolytica crude glycerol media composition optimization citric acid experimental design.
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Focus on Creating Teaching in Classroom, Cultivate Innovation Ability
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作者 Xiaoping Hu Hong Xie 《Sociology Study》 2015年第9期685-688,共4页
Generative resources are mainly derived from the students (sometimes from the teachers), which is dynamically generated in the students' practice, self-inquiry, and cooperative communication. Gifted children refer ... Generative resources are mainly derived from the students (sometimes from the teachers), which is dynamically generated in the students' practice, self-inquiry, and cooperative communication. Gifted children refer to a group of children who have such characteristics as high IQ (intelligence quotient), strong creativity, and good personality. Their intelligence and capability have great potential for further development. As cognitive ability is one of the prominent characteristics of supernormal children, the lecturers can not only pay attention to teaching knowledge (facts teaching), but also need provide proper opportunities for them to develop their aggressiveness, creativities, and challenges when teaching these children. Because students are active in thinking, in the classroom, students often have some unexpected ideas, that is, the generation of the classroom, in the face of this situation, teachers should be how to do? A joke between students in the class, sparked the interest of a classmate, and then under the teachers' guidance, they invented a chemistry experiment instrument Ω type pipe, illustrated the importance of the teachers focus on creating teaching. 展开更多
关键词 Creating teaching gifted children Ω tube
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自制仪器探究二氧化碳的性质 被引量:1
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作者 张君 杨学刚 《中小学实验与装备》 2018年第1期52-53,共2页
1实验器材 自制二氧化碳发生器,自制套管装置,自制二氧化碳挡板火盒,自制喷泉演示器,饮料瓶,导管,橡胶塞等。2实验用品盐酸、大理石、被石蕊试液染成紫色的纸条、澄清石灰水、氢氧化钠等。
关键词 二氧化碳发生 仪器 实验用品 澄清石灰水 橡胶塞 饮料瓶 大理石 实验器材 试液 挡板
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一种李萨如图形的作法
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作者 闵安东 《大学物理实验》 1996年第1期10-11,共2页
本文介绍了使李萨如图形稳定、准确的一种作法,即频率比与相位差的控制。
关键词 李萨如图形 频率比 相位李萨如图形演示实验是采用两台正弦信号发生 由于无法准确控制两正弦信号的频率比及初始相位差而造成图形不稳定.现就DWS—1多功能物理综合实验仪作该实验的原则作简要介绍.1方案选择满足李萨如图形的信号的基本条件是:x=Asln(.zt+9 )y=B
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