冻胀反力系数在渠道衬砌冻胀弹性地基梁模型中的应用     

李宗利  姚希望  李云波  吴正桥  肖帅鹏  刘士达 《农业工程学报》2021,37(17):97-106

为了探究渠道基土在冻胀过程中的非线性变形特性对渠道衬砌冻胀的影响,基于冻土三轴试验结果,建立考虑围压和温度的邓肯-张本构模型,参考室内三轴试验测定基床系数方法,应用数值模拟法建立冻胀反力系数随被约束冻胀量变化的计算式,并基于有限差分法离散弹性地基梁平衡微分方程。模型考虑衬砌不同点因被约束冻胀量不同引起冻胀反力系数不同的取值问题,克服以往模型中冻胀反力系数取常量的不足。应用解析解验证模型的合理性,探究冻胀反力系数分别为变量与常量时在梯形渠道衬砌冻胀力学响应计算结果上的差异。结果表明,对于边坡和渠底衬砌板,常量冻胀反力系数计算出的最大冻胀反力是变量的1.43倍,计算出的弯矩最大值平均是变量的1.12倍。因此在采用弹性地基梁理论分析渠道衬砌冻胀问题时,若冻胀反力系数采用常量,不考虑冻土的非线性变形,会使得计算结果偏大。研究结果可为大型梯形渠道衬砌抗冻胀设计提供参考。  相似文献   

农业机器人研究现状及发展趋势   总被引：2，自引：0，他引：2  

朱凤武  于丰华  邹丽娜  岳仕达 《农业工程》2013,3(6):10-13

对国内外最新农业机器人研究成果进行了综合研究。介绍了农业机器人的国内外发展现状,对当前农业机器人进行分类阐述,分析了当前农业机器人的工作原理和关键技术,最后对我国农业机器人的发展趋势进行了预测。   相似文献   

Expression of mRNA of chemokine receptor CXCR4 in feline mammary adenocarcinoma   总被引：5，自引：0，他引：5  

Tanabe S  Nakadai T  Furuoka H  Oomachi T  Kobayashi Y  Omata Y  Koyama T  Hondo E  Uzuka Y  Sarashina T  Ducusin RJ  Shida T  Dorf ME 《The Veterinary record》2002,151(24):729-733

The expression of mRNA of the chemokine receptor CXCR4 in 65 surgically resected mammary adenocarcinomas from cats was investigated by in situ hybridisation. No expression of the receptor's mRNA was detectable in the mammary tissue of healthy cats, but it was expressed in areas adjacent to necrosis, surrounding blood vessels and cells infiltrating the lymphatics of 47 (72.3 per cent) of the 65 samples. There was a significant relationship between lymphatic infiltration by neoplastic cells and the expression of the receptor's mRNA (P < 0.005), but there was no significant relationship between its expression and the one-year survival of the cats.  相似文献   

Effects of heat treatment on brittleness of <Emphasis Type="Italic">Styrax tonkinensis</Emphasis> wood     

Le Xuan Phuong  Satoshi Shida  Yukie Saito 《Journal of Wood Science》2007,53(3):181-186

A new approach is proposed for the evaluation of the brittleness of heat-treated Styrax tonkinensis wood. Heat treatment made wood more brittle when wood was heated at a higher temperature or for a longer time. The brittleness increased to four times that of the control when wood was heated at 200°C for 12 h. For treatment at 160°C, the increase in brittleness without any change in weight is thought to be possibly caused by the relocation of lignin molecules. At higher temperatures, loss of amorphous polysaccharides due to degradation is thought to become the main factor affecting brittleness. The crystallites that were newly formed after 2 h of treatment showed brittleness that was different from that of the inherent crystallites remaining after 12 h of heat treatment. This inherent crystalline cellulose possibly plays a role in brittleness. There is also the possibility of using color to predict the brittleness of heat-treated wood.  相似文献   

刍议HACCP体系在水产养殖中的应用   总被引：3，自引：0，他引：3  

袁久尧  罗海忠  邵仕达 《水产科技情报》2002,29(5):231-233

一、ＨＡＣＣＰ体系简介1 .体系的概念ＨＡＣＣＰ(危害分析和关键控制点 )体系是国际上公认的食品安全卫生保证体系。它通过对影响食品安全的显著危害加以识别、评估和控制 ,保证食品在整个生产过程中免受可能发生的生物、化学、物理因素的危害。该体系强调对危害的预防 ,而不是主要依赖于最终产品的检验 ,可以应用于从初级生产到最终消费的整个食品产业链中。ＨＡＣＣＰ概念于二十世纪 60年代由美国的Ｈ .Ｂａｕｍａｎ博士最早提出。当时Ｈ .Ｂａｕｍａｎ博士所在的Ｐｉｌｌｓｂｕｒｙ公司正为美国太空计划生产并提供宇航食品。他认为公司…  相似文献   

Determination of phenol in honey by liquid chromatography with amperometric detection     

K Takeba  M Matsumoto  Y Shida  H Nakazawa 《Journal of the Association of Official Analytical Chemists》1990,73(4):602-604

A sensitive, selective analytical method has been developed for determination of phenol in honey by liquid chromotography (LC) with amperometric detection (AMD). Phenol is extracted with benzene from the distillate of honey. The benzene extract is washed with 1% sodium bicarbonate solution and then reextracted with 0.1N sodium hydroxide followed by cleanup on a C18 cartridge. Phenol is determined by reverse-phase LC with amperometric detection. An Inertsil ODS column (150 X 4.6 mm, 5 microns) is used in the determination. The mobile phase is a mixture (20 + 80 v/v) of acetonitrile and 0.01M sodium dihydrogen phosphate containing 2mM ethylenediaminetetraacetic acid, disodium salt (EDTA) with the pH adjusted to 5.0. The flow rate is 1 mL/min under ambient conditions. The applied potential of the AMD using a glassy carbon electrode is 0.7 V vs an Ag/AgCl reference electrode. Average recoveries of phenol added to honey were 79.8% at 0.01 ppm spiking level, 90.4% at 0.1 ppm, and 91.0% at 1.0 ppm. Repeatabilities were 3.4, 1.3, and 1.8%, respectively. The detection limit of phenol in honey was 0.002 ppm. For analysis of 112 commercial honey samples, the range and average values of 32 detected samples were 0.05-5.88 ppm and 0.71 ppm, respectively.  相似文献   

Extended glucuronidation is another major path of cyanidin 3-O-beta-D-glucopyranoside metabolism in rats     

Ichiyanagi T  Shida Y  Rahman MM  Hatano Y  Konishi T 《Journal of agricultural and food chemistry》2005,53(18):7312-7319

We previously determined that five rather hydrophobic metabolites appeared in blood plasma after oral administration of cyanidin 3-O-beta-D-glucopyranoside, but a group of hydrophilic metabolites still remained unidentified. In the present study, 12 hydrophilic metabolites found were collected from urine and plasma samples by high-performance liquid chromatography (HPLC) and then analyzed by tandem MS spectrometry. From the MS spectra, four metabolites out of 12 were assigned as glucuronides of cyanidin 3-O-beta-D-glucopyranoside and six out of 12 were glucuronides of the primary metabolites of cyanidin 3-O-beta-D-glucopyranoside (O-methyl cyanidin 3-O-beta-D-glucopyranoside). Extended glucuronides of cyanidin 3-O-beta-D-glucopyranoside and O-methyl cyanidin 3-O-beta-D-glucopyranoside showed their maximum plasma concentrations at 15 and 60 min (or 30 min) after oral administration, respectively. Their maximum plasma concentrations ranged from 15 to 70 nM. From the profile of urinary-excreted anthocyanins after intravenous administration, it was deduced that extended glucuronides of cyanidin 3-O-beta-D-glucopyranoside and O-methyl cyanidin 3-O-beta-D-glucopyranoside were mainly produced in the liver rather than by intestinal flora. The area under the plasma concentration curve was 0.25 micromol min/L for extended glucuronides of cyanidin 3-O-beta-D-glucopyranoside and 0.14 micromol min/L for O-methyl cyanidin 3-O-beta-D-glucopyranoside, respectively, when evaluated as cyanidin 3-O-beta-D-glucopyranoside equivalent, indicating that extended glucuronidation is a critical pathway in cyanidin 3-O-beta-D-glucopyranoside metabolism in rats.  相似文献   

Computed tomography and radiographic lymphography of the thoracic duct by subcutaneous or submucosal injection     

Ando K  Kamijyou K  Hatinoda K  Shibata S  Shida T  Asari M 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2012,74(1):135-140

A simple method of lymphography of the thoracic duct was investigated. Using three female beagles, contrast media were administered rectally, vaginally and into the perianal tissue. The administration sites were gently massaged, and imaging was carried out at constant intervals using computed tomography and radiograph. Moreover, Indian ink was administered into the rectum mucous membrane in dogs for proof of this method of lymphography, and the lymph drainage routes were observed. The investigation showed that clear computed tomography and radiographic contrast images of the thoracic duct were obtained by subcutaneous and submucosa injection of angiography contrast medium and 3D processing of these images revealed the three-dimensional positions and course of the thoracic duct and cisterna chyli.  相似文献   

Salsolinol is present in the bovine posterior pituitary gland and stimulates the release of prolactin both in vivo and in vitro in ruminants     

Hashizume T  Shida R  Suzuki S  Nonaka S  Yonezawa C  Yamashita T  Kasuya E  Sutoh M  Oláh M  Székács D  Nagy GM 《Domestic animal endocrinology》2008,34(2):146-152

The aims of the present study were to determine whether salsolinol (SAL), a dopamine-related compound, is present in the bovine posterior pituitary (PP) gland, and to clarify the effect of SAL on the secretion of prolactin (PRL) in ruminants. SAL was detected in extract of bovine PP gland using high-pressure liquid chromatography with electrochemical detection (HPLC-EC). A single intravenous (i.v.) injection of SAL (5 and 10mg/kg body weight) significantly and dose-dependently stimulated the release of PRL in goats (P<0.05). Plasma PRL levels reached a peak 10min after the injection, then gradually returned to basal values in 60-80min. The PRL-releasing pattern was similar to that in response to sulpiride (a dopamine receptor antagonist). The intracerebroventricular (i.c.v.) injection of 1mg of SAL had no significant effect on the release of PRL in calves, however, 5mg significantly stimulated the release (P<0.05) with peak values reached 30-40min after the injection. Moreover, SAL significantly stimulated the release of PRL from cultured bovine anterior pituitary cells at doses of 10(-6) and 10(-5)M, compared to control cells (P<0.05). Taken together, our data clearly show that SAL is present in extract of the PP gland of ruminants, and has PRL-releasing activity both in vivo and in vitro. Therefore, this endogenous compound is a strong candidate for the factor having PRL-releasing activity that has been previously detected in extract of the bovine PP gland.  相似文献   

基于温差电池的温室地埋供热金属管道阴极保护改进   总被引：2，自引：2，他引：0  

王立舒  李欣然  苏继恒  张旭  孙士达 《农业工程学报》2018,34(19):195-201

北方温室为种植反季节植物以及南方植物,普遍采用地埋供热金属管道供热。阴极保护技术可以有效控制土壤对管道的电化学腐蚀,但常规的外接电流阴极保护方式成本高、占地大,牺牲阳极方式的保护寿命过短。为了给温室地埋供热金属管道提供可靠的阴极保护,该文利用地埋供热金属管道表面余热,基于温差电池,对地埋供热金属管道提供外接电流方式的阴极保护。通过现场试验发现,该装置温差电池正常工作时冷热两端温差为33.2℃,当该装置提供的保护电位为–1 100 m V时,管道保护度达到了92.79%。该研究为温室地埋供热金属管道的保护提供了一种较为可行的方案,同时也对外接电流方式的短距离管道保护技术进行了初步探索。  相似文献