四种罗非鱼挥发性成份的GC-MS分析

为了研究四种罗非鱼挥发性成份的化学成分,采用水蒸气蒸馏法提取罗非鱼挥发性成份,用气相色谱-质谱联用仪对其进行分离测定,结合计算机检索对分离的化合物进行结构鉴定,应用色谱峰面积归一化法测定各成分的相对百分含量。结果共鉴定出45种物质:奥利亚和奥尼各26种,尼罗24种,吉富18种。其中,有7种化合物为4种罗非鱼的挥发性成份所共有。2,4-二叔丁基苯酚在挥发性组份中的含量最高(奥利亚38.44%;尼罗37.34%;吉富35.21%;奥尼除外,占14.10%)。在挥发性成份中酯类、醇类、烯烃和有机酸类居多,分别有10种、6种、5种和4种,其中大部分为有特殊香味的挥发性物质,且该类物质在奥利亚、尼罗和奥尼三种罗非鱼中含量较多,在吉富中含量较少。奥尼罗非鱼中还检测出大量的特殊的挥发性物质L-抗坏血酸棕榈酸酯,其含量高达33.64%。     

日本蟳幼体发育的研究

日本蟳Charybdis(charybdis)Japonica(A.Milne-Edwards)是我国大型海产食用蟹类之一。它遍布我国、日本、朝鲜和马来西亚沿岸,红海等亦有分布。关于日本蟳幼体发育的研究,Aikawa(1937)曾观察了第1期溞状幼体,Kurata和Nishina(1975)观察到第4期溞状幼体;八塚刚(1952、1957、1962)和寺田正之(1979)也曾对日本蟳的溞状幼体进行过描述,而我国沿海日本蟳发育,迄今未见研究报告。笔者自1984年7月,开始了日本蟳的室内人工繁殖和幼体培育,并培养出第1期幼蟹,85年又对各期幼体的发育形态进行了系统的观察和研究。现将结果整理如下。     

Effect of transketolase-like protein 1 on proliferation of human nasopharyngeal carcinoma cells

AIM: To investigate the effect of transketolase-like protein 1 (TKTL1) on proliferation of human nasopharyngeal carcinoma cells in vitro. METHODS: The siRNA against TKTL1 mRNA was constructed and transfected into human nasopharyngeal carcinoma cells (CNE cell line). The activity of transketolase was detected before and after RNA interference.Real-time PCR was used to determine the mRNA expression of transketolase (TKT) gene family in the CNE cells.Flow cytometry and MTT test were used to detect the effect of anti-TKTL1 siRNA on cell proliferation and cell cycle in the CNE cells. RESULTS: The total transketolase activity was significantly decreased in the CNE cells transfected with siRNA TKTL1 construct compared with the cells transfected with control vector or untransfected CNE cells. No significant difference in the expression level of TKT and TKTL2 gene between the CNE cells transfected with siRNA TKTL1 construct and the cells transfected with control vector or untransfected CNE cells was observed (P>0.05). However, the expression level of TKTL1 gene was significantly downregulated in the CNE cells transfected with siRNA TKTL1 construct compared with the cells transfected with control vector.Cancer cells were arrested in G0/G1 phase, and cancer cell proliferation was significantly inhibited in the CNE cells transfected with siRNA TKTL1 construct. CONCLUSION: TKTL1 plays an important role in the total transketolase activity and cell proliferation of human nasopharyngeal carcinoma. TKTL1 may be considered as a potential target for novel anti-cancer therapy.     

Polyamines enhance chilling tolerance of cucumber (Cucumis sativus L.) through modulating antioxidative system

Cucumber chilling-resistant cultivar Changchun mici and -sensitive cultivar Beijing jietou were used in this study to investigate the effects of exogenous PAs on protection against chilling injury as well as on changes of physiological features, and the fluctuation of free PAs content in the leaves under chilling stress. Upon chilling treatment, free spermidine (Spd), spermine (Spm) and putrescine (Put) were remarkably induced in the leaves of cv. Changchun mici 1 day after treatment. The induction of Put declined thereafter, whereas Spd and Spm levels increased steadily. In the leaves of cv. Beijing jietou, Put content was increased only at 1 day after chilling while Spd content decreased significantly upon chilling treatment. Chilling reduced soluble protein content, and decreased the activities of antioxidant enzymes, including superoxidase dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) only in Beijing jietou. However, these changes could be renovated by exogenous application of Put and Spd. It was also found that pretreatment with Put and Spd diminished the increased electrolyte leakage and malondialdehyde (MDA) content caused by chilling in the leaves of both cultivars. Pretreatment of methyglyoxal-bis-(guanylhydrazone) (MGBG), the PAs biosynthetic inhibitor cancelled the effects of PAs in most of the treatments. Moreover, histochemical staining and quantitative measurements showed that exogenous application of Put and Spd eliminated but MGBG exaggerated the hydrogen peroxide (H₂O₂) accumulation caused by chilling stress, especially in leaves of Beijing jietou. Interestingly, Changchun mici was found to contain higher endogenous free PAs contents compared to Beijing jietou. While no significant difference of SOD, POD and CAT activities was found between non-chilling Changchun mici and Beijing jietou seedlings, the former exhibited higher APX activity than the latter. These results suggest that PAs play important roles in the tolerance of cucumber against chilling stress, which is most likely achieved by acting as oxidative machinery against chilling injury.     

农业车辆视觉实际导航环境识别与分

分析了对路径识别影响较大的变光照环境、杂草环境和阴影环境对农业车辆导航路径的影响,提出一种实际环境中的农业车辆视觉导航研究方法,即先采用神经网络算法对农田环境进行自动分类,然后再相应的选择不同的路径识别方法进行处理.环境识别与分类试验结果证明,该方法能够提高农业车辆视觉导航系统的实用性和可靠性,导航环境的分类准确率为95%,单幅图像平均耗时23 ms.     

制动器耗散功率原理在ABS标定匹配中的应用

为解决ABS逻辑门限值方法匹配成本高、周期长的问题,将制动器耗散功率原理应用于匹配中.结合逻辑门限值与制动器耗散功率的各自优点,将制动器耗散功率原理能自适应识别各种路面状况的特点应用于匹配中;根据制动器耗散功率极大值对应的滑移率略小于临界滑移率且相差不大的原理,采用制动器耗散功率极大值对应的滑移率代替峰值附着系数对应的滑移率对ABS进行控制;滑移率与制动器耗散功率曲线获得较为简单,因此可以大大提高匹配效率.经过实车匹配验证,本方法提高了匹配效率和控制质量,节约了匹配成本.     

电激励信号频率对红点病苹果采后电学特性影响

研究了红点病富士苹果采后果实电特性的变化规律,为从电特性角度揭示红点病病害发病的内在机制提供理论参考。运用LCR电子测量仪测定了20℃恒温条件下贮藏70 d的红点病果实在100 Hz、1 kHz、10 kHz、100 kHz和1 MHz频率下复阻抗等电学参数。结果表明,在同一贮藏时间下,随着频率的增加,不论是病果还是正常果其果实的介电常数ε′、复阻抗Z、电抗X和电感L_p值均在减小;果实的Z、X和L_p间存在着显著相关;对100 Hz下以及1、10、100 kHz和1MHz的病果和正常果的Z、X和L_p进行方差分析结果显示,两者差异均不显著(P>0.05),但两者在ε′和损耗因子tanδ上有明显差异(P<0.05)。tanδ和ε′基本可以反映水果的实际品质。     

一种采用无线数据传输方式的储粮仓群测温系统

基于无线收发芯片和1-Wire总线数字温度传感器,实现了可进行无线数据传输的大型储粮仓群温度监测系统。该系统包括主机和信号采集分机,主机负责管理每个粮仓的温度信号采集分机,定时或根据操作者指令向分机发出数据传输指令,各个粮仓分机根据收到的指令进行温度数据的传输。该系统在继承了全数字粮仓测温系统硬件结构简单、安装及维修方便等优点的基础上,实现了测温数据的无线传输,适于在大型分散式储粮仓群以及不便于布线的粮库中应用。     

物料悬浮速度测试方法研究

悬浮速度是物料空气动力学的一个重要参数,一直是从事物料特性研究者关心的问题。但是国内外对物料悬浮速度测试的研究一直很少,主要以简单的机械机构控制和理论计算测试为主,存在着操作繁琐、计算复杂、数据误差大等缺点。为此,重点对比分析了几种物料悬浮速度测试方法的测试原理与特点,旨在为相关研究提供参考。     

传感器在农业采摘机器人中的应用

作为智能机器人的一种,农业采摘机器人是机器人技术应用的典范.与工业机器人相比较,农业采摘机器人工作环境的特殊性、非结构性,对农业采摘机器人的智能程度提出了更高的要求.为此,针对农业采摘机器人工作特性,叙述了传感器在农业采摘机器人中所起的作用,分析了农业采摘机器人传感器选取的方法,介绍了多传感器信息融合技术在采摘机器人中的应用,为农业采摘机器人智能传感器的选取与研究提供了依据.