Evidence of synergy with ‘stacked’ intrarow cultivation tools          下载免费PDF全文

B Brown  E R Gallandt 《Weed Research》2018,58(4):284-291

Intrarow cultivation efficacy is often low and highly variable. As the mechanisms affecting weed mortality likely vary by tool, several companies have developed cultivators with the ability to use several different intrarow tools at once. We evaluated the potential for such ‘stacking’ of cultivation tools to increase efficacy. We used different sequences of torsion weeders, finger weeders and row harrows in a test crop of maize with surrogate weeds, Sinapis alba and Panicum miliaceum. Most tool combinations resulted in an additive increase in efficacy compared with the individual tools, but the combination of torsion–finger–row harrow demonstrated a synergistic increase in efficacy. In separate experiments, forward speed, soil moisture and weed size were negatively correlated with efficacy, but the torsion–finger–row harrow combination continued to demonstrate a synergistic increase in efficacy compared with the individual tools in 7 of 11 cases. The drawback was high crop mortality (16.0 ± 1.16%); further mechanistic research is needed to reduce crop mortality while maintaining high mean efficacy, through tool design, adjustment and cultural factors.  相似文献   

房屋建筑中的钢筋焊接网的优质建设思考          下载免费PDF全文

孙熙辰 《现代农业研究》2018,(12):123-124

我国钢筋焊接网在房屋建筑中的应用还处于起步阶段,没有形成规范性的应用规模, 与国外相差甚远。本文总结了当前最为实用的计算方法和应用表征,介绍焊接钢筋网产品质量 特性,从提高房屋建筑施工整体质量的角度,探讨如何为施工单位创造优良的经济效益。  相似文献   

不同水深条件对普通野生稻及其转基因水稻杂种F_1的影响     

张若依云  何美丹  李栋  袁睿智  李润  袁潜华  裴新梧 《热带生物学报》2016,(3):325-331

通过研究不同水深条件下海南普通野生稻(Oryza rufipogon Griff)及其转bar基因水稻杂种F1(简称"Bar野杂种F1")的农艺性状等指标的变化情况,分析水深条件对Bar野杂交后代适应性的影响。结果表明,Bar野杂种F1种子活力总体高于普通野生稻;在生物量方面,水深为10 cm时,野生稻总体生长优势明显,且随水深升高,野生稻和Bar野杂种F1生物量均有不同程度的下降;野生稻在各水深条件下株高普遍高于Bar野杂种F1,而水深对各品种的剑叶面积无显著影响。对比本实验与模拟野生稻原生境中的杂草生长情况,结果表明,深水对杂草生长的抑制作用明显。  相似文献   

Torsion behavior of Steel encased Concrete Composite Beams     

ZHAO Jing  CAI Jian lin 《保鲜与加工》2009,(5):16-23

In order to study torsion behavior of steel encased concrete composite beams, experiments were carried out with eight specimens. The destruction shape, working mechanism and the crack development and distribution were analyzed under pure torsion and combine torsion conditions. And also the relationships were investigated between torque and torsion ratio, load and strain, bending moment and deflection and load crack. On the basis of elasticity plastic theory, the formulas of cracking torsion were presented for pure torsion and combined torsion of combined beam. And with spatial truss model of variable angle, formulas for ultimate torsion strength of pure torsion and combined torsion were put forward. The predicted results were in good agreement with measured ones. The proposed formulas provided basis for evaluating safety and stability of the structural.  相似文献   

Evidence-Based Advances in Rabbit Medicine     

《Veterinary Clinics of North America: Exotic Animal Practice》2017,20(3):749-771

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河流心滩形成模式与构建技术研究   总被引：2，自引：0，他引：2  

王兵  顾岚  王翠峰  高甲荣 《北京林业大学学报》2013,35(5):79-83

选取北京市白河人为扰动较少的24 个样点河段内的12 处心滩进行实地调查,并依靠调查数据对心滩的形 成、分布特征及在增加物种多样性方面作了相关的分析与研究。结果表明,河流心滩有增加河道断面形式和生物 多样性等多种作用。考虑到城市河流生态系统较为脆弱的现状,认为可通过在城市河道修建人工心滩的方式来对 城市河道进行生态改造。在此基础上提出了心滩的构建原则,以及“直道滩冶“弯道滩冶“群滩冶3 种构建方式,旨在 为城市河道生态治理和恢复提供参考。   相似文献   

棒料高速变节距柔性交接装置设计与优化     

刘子建  潘松君  魏翔翔 《湖南农业大学学报(自然科学版)》2013,40(11):51-57

针对目前棒料高速柔性交接装置工作可靠性不高,上下游机节距不能根据需要调整,从而限制了下游机速度提高等问题,提出了一种棒料变节距柔性交接装置的工作原理,对棒料交接过程及运动干涉情况进行了分析.为提高棒料柔性交接的可靠性,对装置结构参数进行了多目标优化,改善了棒料轴向制动过程,减小了交接相对速度差和凸轮最大压力角,并通过仿真分析验证了优化设计的合理性.该装置交接定位准确、稳定,轴向制动平缓,变节距技术和装置为设计速度更高的下游机创造了有利条件,具有较高的实用价值.  相似文献   

Unilateral uterine torsion secondary to an inflammatory endometrial polyp in the bitch     

Chambers B  Laksito M  Long F  Yates G 《Australian veterinary journal》2011,89(10):380-384

A 9-year-old bitch was presented because of lethargy and abdominal distension. Abdominal ultrasound revealed an enlarged, fluid-filled uterus and associated mass. Subsequent exploratory laparotomy revealed unilateral uterine torsion involving the mass. Recovery following ovariohysterectomy was uneventful and the histopathological diagnosis was of a benign endometrial inflammatory polyp. Reports of uterine torsion in the English-language literature are reviewed to identify factors associated with the incidence of uterine torsion. The aetiology of the cystic endometrial hyperplasia/pyometra complex and its possible role in the development of inflammatory polypoid lesions in the bitch is also discussed.  相似文献   

犬胃扩张-肠扭转的风险因子和预防     

寻欣国 《畜牧兽医杂志》2011,30(1):33-36

胃扩张-肠扭转(Gastric Dilatation-Volvulus--GDV)又称为"臌"、"胃扭转"。GDV是一个极其严重,并应视为严重威胁犬生命的紧急事件,是仅次于癌症导致犬死亡的第二大杀手。24%的犬臌是由胃膨胀引起的。但是大多数的情况(75%)是由于胃扭转,弯曲和切断胃内容物的流入和流出。由于胃部膨胀,可旋转90°至360°,固定附着在食道和十二指肠之间缠绕。膨胀的胃妨碍腹部静脉、减少血液返回到心脏,丧失血液供应,导致低血压、胃缺血、休克、脏器损害,要在育种,饲养和管理上加强监管,有效的降低形成和促发GDV风险因子的条件,加强对GDV风险因子的预警和识别,以及发生后的及时发现和立即处理治疗。  相似文献   

转bar基因水稻恢复系的生理性状和农艺性状   总被引：5，自引：1，他引：5  

段发平  范树国  段俊  黎垣庆  梁承邺 《杂交水稻》2003,18(2):58-61

通过杂交将转bar基因水稻亲本（Gulfmont、Bengal Hu-10和Cypress PB-6）中的bar基因转发转移到恢复系测64、明恢63和特青中，培育出6个抗除草剂（Liberty）的同型恢复系测64－B（G）、测64－B(C)、特青－B（C）、明恢63－B（G）和明恢63－B（C）。抗除草剂同型恢复系的大部分生理性状和主要农艺性状与原恢复系接近。将同型恢复系与不育系杂交，选配出8个抗除草剂三系杂交组合和2个抗除草剂两系杂交组合，抗除草剂组合能保持或略高于原组合的产量水平，利用这项技术有望解决杂交稻制种过程中出现的纯度问题。  相似文献