A framework for a regional integrated food security early warning system: a case study of the Dongting Lake area in China     

Xiaoxing Qi  Laiyuan Zhong  Liming Liu 《Agriculture and Human Values》2015,32(2):315-329

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通过使用窄带通滤波器和小波分析用以检测共轭耦合点谐波电压的跳变来实现孤岛检测     

王中  吴赛 《林业科技情报》2015,47(1):57-63

此文表述了基于编码的使用窄带通滤波器和小波滤波器用以在Simulink中实现孤岛检测的功能。分布式电网的拓扑结结构由并网逆变器和LCL滤波器构成。比例谐振控制器用以来控制逆变器。窄带通滤波器用来提取所有信号中的基波分量。开关断开用以来模拟孤岛现象,并采用两种方法来检测孤岛的发生。第一种采用窄带通滤波器来检测特定的共轭耦合点上的谐波电压在孤岛前和孤岛后的变化,第二种采用小波滤波器来检测谐波电压的跳变。  相似文献   

稳定性肥料发展与展望   总被引：13，自引：5，他引：8  

武志杰  石元亮  李东坡  卢宗云  魏占波  张丽莉  宫平  王玲莉  房娜娜  李杰  李忠  薛妍  宋玉超 《植物营养与肥料学报》2017,23(6):1614-1621

稳定性肥料的核心是脲酶抑制剂和硝化抑制剂，是指在肥料的生产过程中添加脲酶抑制剂或硝化抑制剂，或者同时添加两种抑制剂的肥料。其良好的农学效应和环境效益为实现农业节本增效提供重要途径。近年来稳定性肥料在基础科研和生产应用领域均发展较快，本文对国内外相关研究进行系统总结，并指出未来的发展方向。首先，回顾了抑制剂的研发、作用机理等方面的进展；其次，概述了稳定性肥料的品种、生产工艺、产能及推广应用情况；最后，对稳定性肥料应用后的作物产量和环境效应进行了阐述。为了促进稳定性肥料产业的健康持续发展，未来需要进一步加强环境友好型抑制剂品种的研发；重视抑制剂保护技术的研究，以解决抑制剂作用效果持久性和稳定性的问题；加强不同抑制剂配伍协同，抑制剂与增效剂复合作用机理与技术的研究；研究开发针对不同区域、不同作物的稳定性专用肥料。  相似文献   

自制中药颗粒剂对腹泻仔猪小肠黏膜病理结构及养分消化率的影响     

赵娟  陈剑波  王志俊  刘一飞  吴苏君  杨忠  夏艳婷  赵敏 《养猪》2015,(4)

为了研究自制中药复方颗粒剂对腹泻仔猪小肠黏膜组织结构和营养消化率的影响,试验选用人工感染大肠埃希菌引起腹泻的28日龄断奶的杜长大仔猪36头,随机均分为2组,每组3个重复,每个重复6头。抗生素治疗组在饮水中添加盐酸林可霉素2.0 m L/头饮水,2次/d,连续5 d;中药复方颗粒剂治疗组在饮水中添加2.0 g/头饮水,2次/d,连续5 d。分别于用药后14 d时,每组每个重复随机抽取1头屠宰,无菌采集小肠黏膜,通过石蜡切片和HE染色观测小肠黏膜病理组织学变化。其余仔猪继续饲养14 d,采用内源指示剂法进行消化试验。结果显示,小肠黏膜组织结构:中药复方颗粒剂治疗组小肠黏膜除有少量出血外,未发现明显病理变化。抗生素治疗组小肠黏膜脱落,有广泛充血、出血;黏膜上皮细胞变性坏死;嗜酸性粒细胞浸润,有大量以淋巴细胞杯状细胞为主的炎性细胞浸润;微绒毛排列紊乱、脱落;细胞受损严重,线粒体等细胞器结构异常。养分消化率:对于有机物质、磷的消化率,各组之间无显著差异,中药复方颗粒剂治疗组对钙的消化率为57.10%,显著高于抗生素治疗组(56.10%),并与健康仔猪组(57.40%)差异不显著。中药复方颗粒剂治疗组对粗蛋白质的消化率为79.30%,显著高于抗生素治疗组(78.50%),并与健康仔猪组(79.20%)差异不显著。中药复方颗粒剂治疗组对粗纤维的消化率为48.30%,极显著高于抗生素治疗组(46.10%),并与健康仔猪组(48.20%)差异不显著。中药复方颗粒剂治疗组对粗脂肪的消化率为63.40%,极显著高于抗生素治疗组(62.10%),并与健康仔猪组(63.60%)差异不显著。结论:抗生素治疗仔猪腹泻造成小肠黏膜明显的病理变化和功能障碍,而中药治疗有利于仔猪小肠黏膜组织结构的修复,并能显著提高小肠的养分消化率。为防治仔猪腹泻、提高仔猪的生长性能提供依据。  相似文献   

Whistle signal variations among three Indo-Pacific humpback dolphin populations in the South China Sea: a combined effect of the Qiongzhou Strait's geographical barrier function and local ambient noise?     

Jing YUAN  Zhitao WANG  Pengxiang DUAN  Yousheng XIAO  Hongke ZHANG  Zhixiong HUANG  Ruichun ZHOU  Hua WEN  Kexiong WANG  Ding WANG 《Integrative zoology》2021,16(4):499-511

Geographic variations in the dolphin whistles could be useful in assessing association and isolation among populations. Whistle of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis) among the Pearl River Estuary (PRE), Leizhou Bei (LZB) and Sanniang Bay (SNB) populations were investigated. A total of 2850 whistles with legible fundamental contour were extracted and 15 acoustic parameters were measured. Contrary to SNB, PRE and LZB had the same relative proportion of tonal type compositions with flat and sine representing the most frequent types. The generalized linear model analysis showed significant acoustic difference among populations and tonal types. All frequency parameters in SNB were significantly higher than those in PRE and LZB, where no significant variation was observed in most of the parameters either at the population level or within each tonal type. Canonical discriminant functions analysis showed a smaller difference between PRE and LZB than between PRE and SNB and between LZB and SNB. Compared with previous recordings, recent recordings demonstrated a consistent pattern of becoming higher in whistle frequency parameters in both LZB and SNB populations, suggesting that noise pollution in LZB and SNB increasing with time according to the acoustic niche hypothesis. Dolphin whistle's geographic variations could be shaped by the combined function of the geographical barrier function of the Qiongzhou strait and local ambient noise. Considering the isolated condition and the relatively smaller population size of the humpback dolphin in the SNB, more effective and proactive conservation actions should be taken to prevent the extinction of small populations.  相似文献   

3PZ-6000型智能苹果植保机设计          下载免费PDF全文

尚忠  于建波  张金超  张雪芹  姜秀美 《农业工程》2018,8(10):95-97

为减小果树的病虫害影响，设计一种3PZ-6000型智能苹果植保机。该机结构紧凑，具有可升降轴流风送式喷雾装置、液力驱动无级变速履带式行走机构。并配备无线射频控制平台，可实现对机器启停、速度和药量调整等智能控制，极大提高苹果植保环节的作业效率，经济、生态和社会效益明显，是促进苹果生产全程机械化的一种重要机型。   相似文献   

Atmospheric humidity and genotype are key determinants of the diurnal stomatal conductance pattern     

Xinying Zhang  Yajing Wang  Guirong Huang  Fu Feng  Xiaoying Liu  Rui Guo  Fengxue Gu  Xin Hu  Ziguang Yang  Xiuli Zhong  Xurong Mei 《Journal of Agronomy and Crop Science》2020,206(2):161-168

Great understanding of the genotypic difference in diurnal stomatal conductance (g_s) pattern and the key determinants of the pattern is important for saving water by adopting cultivars appropriately. Fifteen wheat genotypes were studied under different soil conditions and various meteorological conditions with pot cultivation in rain shelter for two years. Genotype and air humidity were found to be key determinants of diurnal g_s pattern. All genotypes under low relative humidity (LRH) and most genotypes under high relative humidity (HRH) displayed a gradual decline pattern from morning through the afternoon. Under moderate relative humidity (MRH), all genotypes present a single-peak curve pattern, but they differed in peak time, which may lead to unreliable g_s comparison between genotypes and get ostensible contrasting materials. The stomatal conductance was significantly different among genotypes under LRH and the increased g_s magnitude is also significantly different when it was compared between LRH and HRH. The present results provide new thinking for selecting and adopting appropriate cultivars with specific stomata traits for the area with various meteorological conditions.  相似文献   

上海市规模化奶牛场布鲁氏菌病和牛结核病风险评估分级体系研究     

卢军  夏炉明  吴秀娟  王建  黄忠  沈素芳  杨显超  杨德全  赵洪进 《中国动物检疫》2020,37(2):3-9

为尽快实现上海崇明奶牛布鲁氏菌病和牛结核病(以下简称"两病")区域净化示范区净化目标,通过建立奶牛场"两病"输入性风险评估和内部风险评估模型,结合奶牛场"两病"流行史,构建了上海市规模化奶牛场"两病"风险评估分级体系;应用该体系将奶牛场划分为高、中、低风险场,为实施分类管理策略奠定基础。运用该体系,对上海市崇明区奶牛场每年开展1次"两病"风险评估分级。经过连续3年的风险分级与管理,崇明区奶牛场的"两病"净化效率得到极大提高,并使崇明奶牛"两病"区域净化示范区顺利通过国家验收,表明该体系符合上海市奶牛"两病"净化工作实际。  相似文献   

Association of pituitary adenylate cyclase-activating polypeptide and myogenic factor 6 genes with growth traits in Nile tilapia (Oreochromis niloticus)     

Guiwei Zou  Yuanyuan Zhu  Hongwei Liang  Zhong Li 《Aquaculture International》2015,23(5):1217-1225

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Germ cell-specific expression of dead end (dnd) in rare minnow (Gobiocypris rarus)     

Jundan Duan  Gongqing Feng  Pei Chang  Xueyan Zhang  Qingchun Zhou  Xueping Zhong  Chao Qi  Songguang Xie  Haobin Zhao 《Fish physiology and biochemistry》2015,41(2):561-571

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