62 research outputs found

    Insecticidal Activity for Benzaldehyde L-Cysteine Schiff Base Combined with Xylosma Wood Vinegar

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    木醋碱杀虫剂是一种基于木炭副产物木醋液的绿色杀虫剂,是将精馏木醋液、苯甲醛L-半胱氨酸席夫碱、水杨酸按照一定比例配制而成的.以酪氨酸酶筛选模型研究了苯甲醛L-半胱氨酸席夫碱、精馏木醋液、木醋碱杀虫剂对酪氨酸酶的抑制作用,其导致酪氨酸酶活性的半抑制质量浓度(IC50)分别为15,2.53,0.53 mg/m L.探讨了木醋碱杀虫剂对小菜蛾(Plutella xylostella)、棉铃虫(Helicoverpa armigera)、玉米螟(Pyrausta nubilalis)幼虫的杀虫活性,结果表明木醋碱杀虫剂中苯甲醛L-半胱氨酸席夫碱质量浓度达到15 mg/m L时即可对小菜蛾、棉铃虫、玉米螟二龄幼虫达到很好的杀灭效果.急性毒理实验表明木醋碱杀虫剂实际无毒.慢性毒理研究按照3 g/kg给药量连续灌胃3个月,昆明小鼠的肝脏和肾脏并不存在毒理性变化,表明木醋碱杀虫剂没有慢性毒性.综上所述,木醋碱杀虫剂不仅对酪氨酸酶有很好的抑制作用,还对小菜蛾、棉铃虫、玉米螟等常见农业害虫具有较强的毒杀活性,且实际无毒,具有良好的农业应用前景.The wood vinegar was based on by-product in the process of firing Xylosma charcoal.The wood vinegar base insecticide was a new green type insecticide.We mixed the rectificated wood vinegar,benzaldehyde L-cysteine Schiff base and salicylic acid to make the wood vinegar base insecticide proportionally.The inhibition on tyrosinase in screening model of benzaldehyde L-cysteine Schiff base,rectificated wood vinegar and the wood vinegar base insecticide were determined. The half maximal inhibitory concentration( IC50) were 15,2. 53,0. 53 mg/m L,respectively.Additionally,the insecticidal effects on Plutella xylostella,Pyrausta nubilalis and Helicoverpa armigera of wood vinegar base insecticide were investigated.The results showed that the wood vinegar base insecticide could effectively kill the second-stage juveniles of P.xylostella,P. nubilalis and H. armigera. The results showed that the wood vinegar base insecticide had insecticidal effect.The acute toxicological results showed that the wood vinegar base insecticide had no toxicity.In the chronic toxicological experiment,the group was given a gavage of 3 g / kg with the wood vinegar base insecticide in 3 months.We took the liver and kidney in paraffin section and HE staining after executing the Kunming mouse with cervical dislocation method.The results showed that the wood vinegar base insecticide had no chronic toxicity.In conclusion,the wood vinegar base insecticide could not only inhibit the tyrosinase acitivity,but also show good insecticidal effects on P. xylostella,P. nubilalis and H. armigera with low toxicity.The wood vinegar base insecticide had shown good application prospects in agricultural areas.国家自然科学基金(31371857

    Tunable narrow linewidth fiber laser with two FBG-FPs

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    基于游标原理,利用一对自由谱宽(fSr)略有不同的光纤布喇格光栅法布里-珀罗腔(fbg-fP)作为模式选择器件,设计了一种新颖的环形腔光纤激光器。从理论和实验上研究了该激光器的特性。通过对可调谐fbg-fP应力调谐,在1552.240~1552.912 nM范围内,以96 PM为平均间距,获得了8个由固定fbg-fP的透射谱所确定的窄线宽稳定激光输出。8个输出波长的平均功率为-17.66 dbM,波动在0.7 db范围内。当泵浦光的功率为95 MW的时候,输出信号的信噪比均大于50 db。实验上每隔1 MIn用光谱分析仪(OSA)对输出光波长自动扫描,记录的输出光波长漂移在数皮米范围内,且功率的波动小于0.1 db。这种可调谐的窄线宽光纤激光器在光纤通信和光纤传感方面有潜在的应用价值。Using a pair of Fiber Bragg grating Fabry-Pérots(FBG-FP)with a little different FSR as its wavelength-selective components,a novel ring laser based on the vernier effect is proposed.We have studied the characteristics of this kind of tunable fiber laser both theoretically and experimentally,and obtained 8 discretely tunable laser wavelengths ranging from 1552.240 nm to 1552.912 nm with an average 96 pm span by pulling the tunable FBG-FP.The output spectrum peak is uniform among different wavelength at-17.66 dBm with a fluctuation of 0.7 dB.When the pump power is 95 mW,the signal-to-noise ratio is better than 50 dB.The output spectrum of the laser is recorded automatically by an optical spectrum analyzer(OSA)once a minute.It is found that the output wavelength drift within a few pico-meter and the fluctuation of the output power is less than 0.1 dB.This kind of fiber ring laser may have potential applications in optical communications and sensors.国家自然科学基金项目(No.61077031/F050208); 福建省教育厅B类科技研究项目(No.JB11097)资

    49味中药及其复方与抗生素对溶藻弧菌的体外抑菌作用

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    【目的】筛选对溶藻弧菌(Vibrio alginolyticus)有抑菌作用的中草药及其复方以及抗生素。【方法】采用改良的牛津杯法对诃子、白芍、甘草等49种单味中药进行溶藻弧菌体外抑菌试验,以体外抗菌活性较好的22种药物,按中药配伍规则组成二联、三联复方,采用生药质量浓度分别为60、240 mg/mL的中药进行中药复方体外抑菌试验。用抗生素对溶藻弧菌进行药敏试验。【结果】当单种中药体外抑菌药物质量浓度为240 mg/mL时,诃子、乌梅、醋五味子等对溶藻弧菌抑菌作用明显,为极敏感。在二联中药体外抑菌试验中,当中药质量浓度为60mg/m L时,诃子、乌梅组成复方中药等8种复方对溶藻弧菌协同抑菌作用明显,为极敏感,药物质量浓度在240mg/m L时,诃子与白芍等14种双联中药的协同抑菌作用明显,为极敏感。在三联中药体外抑菌试验中,在药物质量浓度60 mg/mL时,诃子、乌梅、蒲公英等组成24种复方中药按质量比1∶1∶1的抑菌效果极为敏感,药物质量浓度在240mg/m L时,黄芩、诃子、黄芪等22复方中药按质量比1∶1∶1对的抑菌作用明显,为极敏感。溶藻弧菌对恩诺沙星、盐酸多西环素、土霉素及甲氧苄啶/磺胺甲噁唑4种药物高度敏感。【结论】18种单味中药对溶藻弧菌有抑制作用,黄芩、诃子、黄芪等24个三联复方中药药效较强,多个抑菌作用效果良好的三联复方中药可用于鱼病防治研究。国家自然科学基金(31702384、31502194)福建省科技重大专项(2016NZ0001-3)2018年开放课题基金项目(LYC2018RS04,闽海鸥[2018]31号)福建省自然基金项目(2018J01455)2017年集美大学研究生教育教学改革研究项目(集大研No.[2017]18号)教育部鳗鱼工程研究中心开放基金项目(RE201704

    Study on threshold value of Irrigation with SalineWater and Response function of Cotton Yield to Salt with drip irrigation under mulch

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    本研究以中国科学院阿克苏绿洲农田生态系统国家野外研究站为依托,采用盆栽、测坑试验,研究咸水灌溉条件下膜下滴灌棉田土壤水盐动态规律、灌溉水矿化度对土壤理化性质与棉花生物量及水分利用效率的影响,探求膜下滴灌棉花灌溉水矿化度指标;建立棉花盐分生产函数,推求膜下滴灌棉花耐盐度指标,为棉田水盐综合调控和灌溉管理提供基本技术参数。主要结论如下:(1)咸水灌溉条件下生育末土壤储水量随着矿化度的增加而增大;随着灌溉水矿化度的增加,且盐分在表层积盐越明显。(2)咸水灌溉对土壤容重、田间持水量、饱和导水率影响不大;对土壤化学性质的影响主要表现为增加了Cl-,K+,Na+的含量。(3)咸水灌溉条件下,膜下滴灌棉花90%的根系分布在0-60 cm 深度;咸水灌溉对根系长度、根系面积和根系干物重都具有抑制作用,尤其在吐絮期,随着灌溉水矿化度的增大抑制作用更强;咸水灌溉对株高、果枝数、蕾铃数、叶面积指数、产量、单株铃数有显著性影响,对脱落数、单铃重、衣分无影响;咸水灌溉降低了棉花水分利用效率。(4)在播前灌采用淡水灌溉的条件下,当灌溉水矿化度大于1.37 g/L 且小于3.02g/L 时,棉花产量对灌溉水矿化度的反映敏感,减产剧烈;(5)膜下滴灌棉花生育期耐盐顺序为:苗蕾期< 种子萌芽期<花铃期<吐絮期,具体指标为:萌发期耐盐临界值为0.71%,极限值为3.21%苗蕾期耐盐临界值为0.69%,极限值为2.34%;花铃期耐盐临界值为0.82%,极限值为2.79%;吐絮期耐盐临界值为0.92%,极限值为2.78%

    A Hybrid Tree Structured Neural Network for Implicit Discourse Relation Recognition

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    隐式篇章关系识别的主要挑战是如何表示两个文本单元的语义信息.由于句子的语义信息往往由语法树中的信息焦点(谓词部分)所决定,所以关注信息焦点可以提; 升篇章关系识别的效果.为了增强信息焦点的作用,引入树状长短时记忆(tree-structured long short-term; memory,Tree-LSTM)网络,使用其遗忘门的特性区别对待不同孩子节点的信息.最后利用神经张量网络(neural tensor; network,NTN)来计算两个句子语义向量之间的关系.基于PDTB2.0(Penn Discourse; Treebank)语料数据进行实验,实验结果表明混合树结构神经网络比传统的RNN模型在大部分关系中的Fscore上提高了3.0%左右.The most critural challenge of implicit discourse relation recognition; lies in how to represent the semantic information of each discourse; argument.However,the semantic value of the sentence is mainly decided by; its specific information focus in linguistics. Therefore,the discourse; relation may mostly depend on links between information; focuses.Intuitively,we cannot give equal treatment to every phrase; branches during composition up the syntactic parse tree.To resolve the; problem,we introduce the tree-structured long short-term; memory(Tree-LSTM)network to selectively incorporate information from; each child to compute the distributed semantic representation of two; arguments.Consequently,it can emphasize those informative predicative; branches that indicate the"focus" of a sentence.Then the neural tensor; network(NTN)is used to predict the semantic correlation between these; two discourse arguments across multiple dimensions.Experimental results; on PDTB corpus show that our model has achieved some improvement on the; task of discourse relation recognition.国家自然科学基金; 福建省自然科学基金; 教育部海外留学回国人员科研启动基

    激波风洞实验测力技术研究

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    由于激波风洞运行冲击载荷大、有效测量时间短,模型和天平支撑机构在风洞运行过程中所受到冲击响应会对天平力信号带来很大的干扰,因此激波风洞的测力技术是高超声速实验的一个难点。本文利用加速度传感器采集应变和压电结合的天平测力元件的加速度信号,运用谱减法对应变元件测量所得的力信号进行数值补偿,并对球头钝锥体和某高超声速布局标模进行了实验验证。实验结果表明,本文所采用的技术可以对原本受强干扰的力信号进行合理补偿,轴向力、法向力以及压心的实验结果能与理论解或数值计算结果很好的吻合

    膜下滴灌条件下不同矿化度水对土壤水盐动态及棉花产量的影响

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    塔里木盆地分布着相当大面积矿化度在3~5 g/L之间的浅层地下咸水,有很大的开发利用潜力。通过微区测坑试验,采用膜下滴灌技术,用不同矿化度的咸水灌溉棉花,探求其对土壤水盐动态和棉花产量的影响。研究表明:(1)土壤盐分和水分二者的动态变化是紧密相关的,其中,土壤盐分动态变化主要受大气和灌溉水的影响,土壤水分的动态变化主要受棉花生长阶段和灌溉水的影响;(2)咸水膜下滴灌与淡水膜下滴灌同样具有淋洗和压盐效果;(3)通过棉花产量分析发现:与采用淡水灌溉相比,咸水灌溉对产量,单株铃数和单铃重具有一定的影响,对衣分没有影响;(4)当灌溉水矿化度大于3.24 g/L时,不利于塔里木盆地进行农业生产

    基于压电效应的高超声速摩阻直接测量技术

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    表面摩阻是影响高超声速飞行器性能的重要因素,在高超声速飞行时摩阻可达总阻力的30~50%。本文针对高超声速激波风洞摩阻测量开展了新技术方案以及可行性相关研究。利用压电材料仅对单向力敏感的特性,提出了适用于脉冲风洞的摩阻直接测量传感器方案,通过晶体叠加技术提高了传感器灵敏度。研制了适用于激波风洞的压电摩阻测量系统并进行了标定,实验表明测量系统具有良好的性能。在激波风洞中开展了模型实验。结合数值补偿方法,获得了摩阻实验数据,与CFD 计算结果的对比,验证了该测量方案和原理的可行性

    电子束辐照对InP(100)表面硫钝化的增强作用

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    采用含有过量硫的(NH_4)_2S_x对InP(100)表面进行化学钝化和辉光放电电子束辐照处理,液氮下光致发光强度比未辐射的光致发光强度提高了1.5倍,比未钝化的提高了5倍.利用X射线光电子谱研究了电子辐照对InP表面硫钝化的影响.结果表明,硫钝化InP表面经电子束辐照可以促使S与InP更好的化合

    Effect of atmospheric NH_3 and hydroponic solution nitrogen levels on chlorophyll fluorescence of corn genotypes with different nitrogen use efficiencies

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    采用开顶式气室(Open Top Chambers)进行水培试验,以两种氮效率玉米(ZeamaysL.)基因型为供试作物,通过不同大气NH3浓度处理,测定苗期各叶绿素荧光动力学参数。结果表明,供氮介质和大气NH3浓度升高对两种氮效率玉米基因型的初始荧光值(Fo)不存在显著影响。高供氮介质下,在NH3浓度升高时,氮高效5号基因型的最大荧光产量(Fm)和可变荧光(Fv)均显著减小(p<0.05),而氮低效基因型四单19的Fm、Fv值显著增加;低供氮介质下,大气NH3浓度升高对2种基因型Fm、Fv值的影响结果与高供氮介质时相反。说明大气NH3浓度升高对生长在高供氮介质下的氮高效5号基因型有一定的抑制作用,而对氮低效基因型四单19有一定程度的促进作用。在不同供氮介质下,大气NH3浓度升高时,两种氮效率玉米基因型的qN、qP值减小,说明大气NH3浓度升高时,作物对光合机构的保护能力比大气背景NH3浓度时弱
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