US Sheep Industry and the Public Grazing Fee

Since the mid-1940s US sheep inventory has experienced dramatic declines, which has weakened the sheep industry significantly, making it increasingly important to analyze potential policy implications that could affect US sheep inventories in the future. Public grazing lands are often used in sheep production, especially within the western United States. The public grazing fee is, therefore, a cost within the production of sheep. A US sheep model applying capital stock inventory accounting methodology is developed to model both the supply and demand within the joint sheep and wool industries. The model is used to create a baseline projection for the next several years. Various public grazing fee policies are created to demonstrate the effects of the policies on the levels of sheep inventory and sheep and wool production within the country. Results indicate removing the public grazing fee (set at $0/animal unit month) may slow the rate of decline but would not be effective at reversing the declining trend. This suggests reducing the public grazing fee is not a viable policy option to help bring stability to the sheep and wool industries. However, projections indicate raising the grazing fee would have a substantial adverse effect on the industries. Consideration should be given to these results as grazing fee policy is adjusted moving forward.     

弧形挑膜齿残膜清理滚筒主要部件的强度分析

介绍了一种弧形挑膜齿残膜清理滚筒的结构、工作原理和主要工作部件,运用有限元分析软件对残膜清理滚筒的主要部件进行了强度分析,并对整机进行了实地试验测试,证明该机构设计合理,残膜回收率可达85%以上。     

章古台沙地樟子松人工林土壤有效氮的研究

该文对科尔沁沙地章古台地区围栏和未围栏的樟子松人工林土壤NH+4-N、NO-3-N、矿质N和微生物体N进行了一个生长季的观测.结果表明,无论围栏还是未围栏林地,土壤NH+4-N、NO-3-N和矿质N含量均很低.围栏林地中土壤NH+4-N和矿质N比未围栏林地高（P0.001）,土壤NO-3-N的结果则相反（P0.001）,而土壤微生物体N差异不明显（P0.05）.方差分析表明,土壤NH+4-N、NO-3-N、矿质N和微生物体N均存在明显的月份之间差异（P0.001）;土壤NH+4-N、NO-3-N和矿质N表现为明显的季节性的单峰变化;土壤微生物体N并不是完全随季节波动,而与土壤含水量存在极强的相关性（P0.001）.林分和月份对土壤NH+4-N和矿质N的交互作用十分明显（P0.001）,对土壤微生物体N作用明显（P0.05）,而对土壤NO-3-N作用不明显（P0.05）.可见,与未围栏相比,围栏对提高樟子松林N养分有效性、林分生产力和稳定性以及保护环境都是有利的.为此,建议对章古台地区的樟子松人工林实行禁牧和禁止凋落物收集等管理措施.      

菜花采后生理变化研究

以新鲜白菜花为试验原料,通过对其失重率、呼吸强度、VC、褐变度、还原糖、过氧化物酶活性的测定,研究其采后贮藏过程中的生理变化。结果表明：菜花采后贮藏过程中,失重率、褐变度均呈上升趋势,呼吸强度和VC含量均呈下降趋势,还原糖含量呈先上升后下降趋势,过氧化物酶活性呈先下降后上升趋势。     

贮穗温度对水稻开颖及花粉生活力的影响

把离体稻穗分别放置于0℃、10℃、20℃、30℃等温度中,存放不同时间后取出,在室温下观察CO_2诱导颖花的开颖率,测定颖花的生理活性及花粉生活力。结果表明:随着贮穗温度的升高或存放时间的延长,颖花的呼吸强度、ATP含量、开颖率、花粉生活力均表现为下降趋势。放在10℃左右温度中贮藏的稻穗,能较好地保持开颖能力、花药的开裂能力及花粉的生活力。此项技术可应用于水稻杂交。     

石林县2010～2013年降水情况分析

利用石林气象观测站2010～2013年以及多年降水观测资料,采用数理统计的方法分析了2010 ～2013年石林县降水量变化特征.结果表明,2010年以来石林地区降水异常偏少,尤其是2011年偏少最多;季节和月度降雨量分布不均,总体趋势均为春夏季降雨量偏少;4年的总体降雨强度偏小,但单点暴雨频发.     

冷型小麦及其育种意义

通过多年对小麦不同品种群体温度的连续观测，结果发现：自然界存在冷型小麦，其冷域发达，叶片功能期较长，蒸腾旺盛，净光合率较高，十分利于籽粒充实。由于冠层温度和小麦的一系列重要性状紧密相关，因而，这为利用红外技术选择优良株系、品系、品种提供了可能。     

牡丹对不同强度和频度去叶的补偿性生长响应(英文)

[Objective] It aimed to find an optimum condition for compensatory growth of peony.[Method] The different defoliation intensies and frequencies of penoy were implemented to observe accumulated aboveground biomass, regenerated bud number,stem-leaf ratio and the chlorophyll concentration change in residual leaves.[Result] When the defoliation frequency was conducted every 20 d once and defoliaton intensity was from 40%-60%,the accumulated biomass was biggest, when the defoliation frequency was conducted every 10 d once and defoliation intensity was from 60%-80% the regenerated bud number was maximum.The stem-leaf ratio of mild and moderate defoliation intensities(20%-60%) was significantly lower than that of control group.When the defoliation frequency was conducted every 20 d once and defoliation intensity was from 40%-60%,the chlorophyll concentration in residual leaves was obviously higher than that of control group.[Conclusion] The proper defoliation intensity(60%) and lower defoliation frequency(defoliation was conducted every 20 d once) were most favorable to the growth and regenerated of peony which was the compensatory growth.     

基于城市流强度的山东半岛城市群城市经济联系分析

[目的]了解山东半岛城市群城市经济联系.[方法]以山东半岛城市群为研究区域,利用城市流强度的方法,对济南、青岛等8个地级市之间的经济联系进行计算.[结果]在研究区域各个行业中制造业的外向性最为明显,而服务业有待于进一步发展;各城市城市流强度差距较大,根据计算结果将8个地级市分为高城市流强度、中城市流强度和低城市流强度三个等级;青岛城市流强度明显高于其他城市,居于核心地位,与周围城市经济联系较为紧密,济南与其他城市经济联系较为松散.[结论]各城市城市流强度在波动中上升,经济联系日益紧密.     

拦河大坝对河流有色溶解有机质赋存特征的影响初探

运用紫外-可见吸收光谱和三维荧光光谱技术,分析了长江三峡大坝上下游河水中有色溶解有机质(CDOM)的含量水平和荧光组分构成及其空间变化。结果表明,自三峡水库支流香溪河河口(回水区)向下游至三峡水库主库区,CDOM的紫外吸收系数(a355从1.30 m-1增至5.21 m-1)和类酪氨酸组分荧光强度及其在荧光组分中所占比例(从25%升至62%)均呈上升趋势,至三峡大坝附近达到全段峰值,而类腐殖质荧光强度及其在荧光组分中所占比例逐步下降;过坝后,CDOM吸收系数在黄陵庙处急剧降至全干流检测段最低(a355=0.95 m-1),但类腐殖质在荧光组分中所占比例达到全段最高(76%);再往下游至葛洲坝库区南津关处,CDOM吸收系数(a355=6.83 m-1)又回升至全段最高,其中类酪氨酸为绝对优势组分。水体类酪氨酸组分的增加主要源自水库浮游生物新生产活动以及微生物转化作用的增强;而CDOM的减少是因为颗粒物的吸附作用。拦河大坝形成的湖泊效应和下泄流过程将对河流有色溶解有机质的赋存特征有显著影响。