刚果12号桉W5无性系与尾叶桉U6无性系胶合板材立木     

莫介羽  梁景生 《广东林业科技》2007,23(1):53-55

利用雷州林业局刚果12号桉W5无性系林分中胸径8～18 cm径阶，树高11～23 m的样木1 207株和尾叶桉U6无性系林分中胸径8～18 cm径阶，树高10～21 m的样木784株，按材种规格标准造材实测材积，且分别建立刚果12号桉W5无性系和尾叶桉U6无性系胶合板材立木出材量二元回归方程，经检验精度可靠，可供参考使用。  相似文献   

Prediction of bending properties for structural glulam using optimized distributions of knot characteristics and laminar MOE     

Jun Jae Lee  Joo Saeng Park  Kwang Mo Kim  Jung Kwon Oh 《Journal of Wood Science》2005,51(6):640-647

This study established a prediction model for bending properties of glued-laminated timber (glulam) using optimized knot and modulus of elasticity (MOE) distributions of lumber laminate as the main input variables. For this purpose, knot and MOE data were investigated for all pieces of lumber that were prepared for glulam manufacturing, and statistical distributions of knot size, knot number in one lumber, and MOE of each laminate were optimized as distribution functions. These knot and MOE data were used as input variables in the prediction model for bending properties, and were also used in generating virtual glulam using the inverse transform method. Prediction of bending properties for glulam was carried out using the transformed section method, which is partially provided in ASTM D 3737 (Annex A4). Predicted values were compared with those from full-scale four-point bending tests for 60 six-layered glulams with 10 different laminar combinations. Finally, the allowable bending properties of glulam for each specific laminate combination were determined by calculating the fifth percentile of the modulus of rupture and the average modulus of elasticity from virtual test results of more than 1000 virtual glulams. From the results of this study, predicted bending properties for glulam and their distributions could be used for structural design in both allowable stress design and limit state design.  相似文献   

海南美兰机场动物卫生监督检查机制     

尹亚娇  陈斌玺  莫凡  蒲姝旸  李忠值 《中国动物检疫》2015,32(1):41-42

介绍了美兰机场省际动物卫生监督检查站的机构设置、人员配备、监管依据、工作程序、联防联控等监督检查机制。  相似文献   

应用荧光定量RT-PCR检测J亚群禽白血病病毒     

屈素洁  邹联斌  陈芳芳  张步娴  胡杰  莫胜兰  施开创  李军  尹彦文 《中国动物检疫》2015,32(6):56-59

针对J亚群禽白血病病毒（ALV-J）基因序列保守区域设计一对特异性引物和一条特异性探针,通过构建重组阳性标准质粒作为阳性标准品,建立了检测ALV-J核酸的荧光定量PCR方法。优化反应体系和条件后进行特异性、敏感性、重复性试验。结果显示,该检测方法特异性强,与其它禽源病毒如A亚群禽白血病病毒（ALV-A）、B亚群禽白血病病毒（ALV-B）、新城疫病毒（ NDV）、禽流感病毒（AIV）、鸡传染性贫血病毒（CIAV）和马立克病病毒（MDV）均不发生交叉反应;该方法可检测到3.2×102拷贝/μL的病毒核酸,与常规RT-PCR相比,敏感性高100倍;重复性试验的变异系数小于2%。研究结果表明,建立的Real-time RT-PCR 检测方法特异性强、灵敏度高、可重复性好,可用于ALV-J的定量检测。  相似文献   

Qualitative Analyses of Protein Phosphorylation in Bovine Pluripotent Stem Cells Generated from Embryonic Fibroblasts          下载免费PDF全文

W Nong  TS Xie  LY Li  AG Lu  J Mo  YF Gou  G Lan  H Jiang  J Len  MM Li  QY Jiang  B Huang 《Reproduction in domestic animals》2015,50(6):989-998

  相似文献   

云冷杉天然次生林种子雨时空分布特征     

程福山  刘志宇  吴蒙嘉  周末  关乃千  王玉文  姜润华  夏富才  娄明华 《东北林业大学学报》2021,49(6):16-18,52

以东北云冷杉天然次生林为对象,在吉林省汪清林业局,设立面积为1 hm2(100 m×100 m)的样地12块,在每个样地安装面积为0.64 m2(0.8 m×0.8 m)的种子收集器5个.自2018年7月末开始收集种子,每月收集1次,至11月末结束.在实验室将收集的种子分成完整种子、干瘪或霉烂种子、被取食种子3类,分析种子雨时空分布特征.结果表明:整个种子雨阶段,共收集177561粒种子,平均种子雨密度为1257.42粒·m-2.完整种子占种子雨总量的比例较高(99.43％),其中水曲柳种子完整率为98.20％,高于其他树种;冷杉种子完整率为89.79％;未收集到鱼鳞云杉种子.研究区大部分树种种子在10月份达到成熟高峰,整个群落及各树种种子雨在不同时间均表现出显著差异(P<0.05).种子空间变异系数为1.35,水曲柳变异系数最大(7.02).该地区种子雨产量丰富、种子完整度高、天然更新潜力大、种子空间变异程度大、种子分布不均匀.  相似文献   

锦鲤暴发性出血症病原的研究   总被引：6，自引：0，他引：6  

莫介化  李春枝  张邦杰  黄永强  李本旺 《水产科技情报》2002,29(6):280-283

从患暴发性出症的锦鲤体内分离出2株细菌－052202和052203，应用细菌分离鉴定方法和法国Biomerieux FRC公司的API全自动微生物鉴定系统进行鉴定，结果显示：052202株为嗜麦芽窄食单胞菌（Stenotrophomonas maltophilia),052203株为温和气单胞（菌（Aeromonas sobria)。生物毒性试验的结果表明，温和气单胞菌可使健康锦鲤死亡，引起体表出血，肝，肾，脾，胆囊发生病变，有致病性；而嗜麦芽窄食单胞菌不引起健康锦鲤死亡，无致病性，28例药物的药敏试验结果表明，温和气单胞菌对新霉素，卡那霉素，庆大霉素，头孢噻吩，头孢曲松的头孢他啶的敏感性强或较强。  相似文献   

具有排气功能的毛管末端自动冲洗阀设计与结构优化     

莫彦  赵新凯  王建东  张彦群  龚时宏  夏辉  李巧灵  王烨 《农业工程学报》2022,38(6):72-79

该研究创制一种具备自动排气功能（Auto-Exhaust function, AE）的毛管末端自动冲洗阀,以提高冲洗时长和冲洗水量。选取延时流道齿长和齿宽、上腔体容积和冲洗阀进口压力共4个因素,采用L18（37）正交试验设计18种规格的AE冲洗阀,并设置4种无排气装置（Non-Exhaust function, NE）的冲洗阀为对照,探究排气装置提升冲洗阀水力性能的作用机理和AE冲洗阀性能参数对试验因素的响应规律。结果表明,当进口压力为0.06～0.14 MPa时,AE冲洗阀的冲洗时长、冲洗水量和冲洗流速分别为18.2～67.7 s、3 904～12 367 mL和0.88～1.40 m/s。冲洗时长和水量与流道齿长、齿宽和上腔体容积均为正相关关系,与进口压力为负相关关系,冲洗流速只与进口压力有关,为正相关关系。流道齿长、齿宽和上腔体容积对冲洗时长和水量影响显著,进口压力对冲洗时长和流速影响显著（P<0.05）。AE冲洗阀能自动排出上腔体中的空气,增加蓄水容积,使其冲洗时长和水量分别比NE冲洗阀提高83.5%与75.4%以上。综合考虑延时流道抗堵塞性能、冲洗时长和水量等因素,推荐AE冲洗阀流道齿长、齿宽、上腔体容积和进口压力分别为1.2 mm、2.2 mm、19.1 mL和0.06 MPa,其冲洗时长和水量分别是NE冲洗阀的2.8和2.7倍,是进口冲洗阀的7.4和7.0倍,为67.7 s、12 194 mL。研究结果可为具有排气功能的毛管末端自动冲洗阀的研发提供依据。  相似文献   

辽宁省生长季气候变化及其对春玉米产量的影响     

王蔚丹  孙丽  裴志远  陈媛媛  孙娟英  董沫 《水土保持研究》2022,29(2):281-286

为了明确气候变化对辽宁省春玉米产量的影响,基于1968—2017年气象站点数据,结合标准化降水蒸散指数(Standardized Precipitation Evapotranspiration Index,SPEI),运用M-K趋势分析、相关分析及回归分析等数理统计方法研究了辽宁省春玉米生长季各气候要素、干湿变化特征及其与春玉米产量的关系。结果表明:降水量除丹东呈增加趋势外,其它地区呈现减少趋势; 大部分地区温度呈现升高趋势,风速呈显著减弱趋势,相对湿度变化趋势不显著; 日照时数除辽阳、本溪呈不显著增加外,其他地区呈减少趋势。降水、最高温和平均温是影响辽宁省春玉米产量的重要因子,尤其是朝阳、葫芦岛、锦州、阜新和大连地区,春玉米对这些要素更敏感,与降水量正相关,与最高温、平均温负相关,未来降水量减少、温度升高将不利于这些地区春玉米生长。随着位置东移降水量逐渐以负效应为主,温度逐渐表现为正效应。除阜新、抚顺、本溪等部分地区呈现干旱化外,其他地区表现为不显著的湿润化趋势。朝阳、葫芦岛、阜新等地区春玉米产量对6月、7月的干湿变化较敏感,易受旱减产; 干旱化将使阜新春玉米生产形势变得严峻,朝阳、锦州、大连地区湿润化对春玉米生长有利; 沈阳、鞍山、辽阳和营口地区5—9月的干湿状况均对春玉米产量有影响,抚顺、本溪、铁岭等地区则易受6—8月的干湿状况影响,这些地区当前较适宜春玉米生长; 丹东地区易受涝减产,且湿润化趋势将会对该地区玉米生产造成不利影响。辽宁省不同气候要素及干湿变化对不同地区春玉米产量的影响效应有正有负,程度也各不相同,各地应因地制宜采取合理措施促进玉米丰产。  相似文献   

Soil water affects transpiration response to rainfall and vapor pressure deficit in poplar plantation   总被引：2，自引：0，他引：2  

Lixin Chen  Zhiqiang Zhang  Tonggang Zha  Kangle Mo  Yan Zhang  Xianrui Fang 《New Forests》2014,45(2):235-250

Influences of environmental factors on transpiration are interactive. Sensitivities of transpiration responses to both evaporative demand and rainfall under contrasting soil water conditions constitute the physiological basis of the drought tolerance of trees. Such knowledge is practically significant for plantation management, especially for irrigation management. We therefore conducted a 6-year study on the transpiration of a poplar plantation in temperate China to elucidate the existence and pattern of the influence of the soil water over stand transpiration responses to (1) vapor pressure deficit (VPD), the major indicator of air dryness and (2) the rainfall, in terms of total amount and event size. The results showed that the response of plantation transpiration (E _c ) to VPD was conditioned by soil moisture. There was a significant difference in the frequency distribution of maximum sap flux under contrasting soil relative extractable water. E _c after rainfall of different sizes varied under similar VPD. The increasing occurrences of only large rainfall events led to enhanced total E _c during the growing season, but prolonged rainless intervals did not lead to a continuous decrease of E _c , suggesting appreciable supplements from the soil water were present to sustain transpiration. In addition, the balance of soil water between replenishment and extraction also conditioned the influence of rainfall over subsequent E _c during the respective rainless intervals. Based on the E _c responses to VPD and rainfall under different soil moisture levels, irrigation that directly replenishes the deep soil layers in order to alleviate water stress on transpiration during the small-rain event-dominated growing season is an effective and water-saving approach to guarantee trees survival during drought period.  相似文献