刺激割胶制度对橡胶树死皮病发生的生理效应

当刺激或割胶所造成的生理伤害超过橡胶树能忍受的限度，便引起产胶与排胶生理平衡失调，表现在：干胶含量、总固形物含量、硫醇含量、排胶初速和堵塞指数明显下降，而长流胶比例和反映创伤生活方式的过氧化物酶同工酶活性明显增加。生理平衡持续失调会导致乳管细胞自毁，丧失产胶功能，导致死皮病的发生。结果表明，产胶与排胶的动态平衡是可以通过刺激强度、割胶强度或割胶模式加以调控的，因而死皮病的发生亦是可控的。     

间作橡胶林地土壤肥力和土壤酶活性特征研究

对2种割龄A割龄(开割年限1~10 a,胶乳初产期)和B割龄(开割年限11~20 a,胶乳旺产期)的间作与纯作胶园土壤肥力和土壤酶活性特征进行了研究。结果表明:土壤肥力和土壤酶活性均以间作胶园高于纯作胶园。在间作胶园中,有机质和全N、水解N含量以旺产期高于初产期,而速效K和速效P含量则相反;过氧化氢酶、脲酶、磷酸酶以旺产期高于初产期,而转化酶和多酚氧化酶则相反;在A割龄间作胶园中,磷酸酶与有机质、全N、水解N、速效P,脲酶与速效P之间的相关性达显著水平,可以用磷酸酶和脲酶活性来表征土壤肥力状况;在B割龄间作胶园中,过氧化氢酶和有机质、水解N,转化酶和速效P之间的相关性达显著水平,可以用过氧化氢酶和转化酶活性来表征土壤肥力状况。     

荒漠环境中电池板表面灰尘颗粒力学模型建立

高海拔荒漠地区电池板表面积灰严重制约着光伏发电效率和光伏组件寿命。该文在分析表面能的基础上,假设接触不变形条件下,依据宏观分子间作用理论分析提出了电池板表面灰尘颗粒粘附受力模型。结合青海共和地区电池板表面灰尘主要成分和粒径组成,给出了灰尘受力参数;计算了灰尘颗粒所受的范德华力、静电力及重力,给出由参数改变引起的灰尘受力的变化规律。结果表明：当灰尘颗粒半径较小时,颗粒与电池板间的主要粘附力为范德华力,当灰尘颗粒半径较大时,重力分量则成为主导粘附力,粘附合力取值范围为10-10～10-8 N;Lifshitz常数和分子间平均间距主要影响的是范德华力;灰尘颗粒总的静电力随灰尘颗粒半径的增大而增大,静电力的取值小于范德华力和重力分量。对灰尘粘附受力大小及其规律的研究,为高海拔荒漠地区光伏除尘提供理论依据。     

环京津贫困区耕地资源与农民收入的关系——基于保定市7个贫困县的面板数据分析

为研究环京津贫困区耕地面积变化对农民收入的影响,采用保定市7个贫困县的1997—2011年统计资料对两者关系进行了实证研究。首先采用聚类分析法对7县进行区域划分,然后通过构建面板数据模型分析了耕地面积与农民收入的关系及区域差异。结果表明,3个区域(山区、环京和近京区域)均显示耕地面积与农民人均纯收入之间存在长期的均衡关系;山区区域农民人均纯收入与耕地面积呈正相关关系,而环京和近京区域两者关系均呈负相关关系;两者的关系在区域内部各县之间存在差异;区域间农民人均纯收入增长幅度也存在差异。耕地数量与农民收入的正负向关系及差异原因与农民的收入来源及收入结构关系密切,并与其资源禀赋、区位条件和社会经济条件等有关。     

基于TVDI的沁水煤田地表土壤水分时空演变分析

温度植被干旱指数（Temperature Vegetation Dryness Index,TVDI）是表征地表干旱的有效指标,其时空格局分析是地表干旱与全球环境变化相互影响下的地表覆被变化的研究内容。以山西沁水煤田为研究区,结合2000—2010年MODND1M和MODLT1M数据,构建了NDVI-Ts特征空间并对干湿边拟合分析。结果表明:近11年来,沁水煤田年平均TDVI均大于0.4,且总体呈显著增加趋势,地表土壤湿度很低,部分区域处于中度和重度干旱之间。年度内,月平均TVDI处于0.5~0.7之间,且7月份TDVI存在明显波动。在空间上,研究区地表土壤湿度分布与地表植被分布基本一致。煤田南部和东部以干旱和极干旱为主,西北山区地带以正常或湿润为主,矿区密集区土壤湿度含量明显低于其他地区,矿井分布附近较其他区域地表干旱现象突出。     

粮农能对价格做出正确响应吗?——基于参照点效应的视角

研究粮农对价格信号的种植行为响应,对于解决粮食安全问题具有重要的现实意义。在前景理论框架下,分析了粮农对市场价格的种植决策响应机制。利用面板门限模型和2002年至2015年全国各省区粮食生产数据资料,检验了粮食价格的心理参照点效应对粮农种植行为的影响。研究发现,粮农种植行为具有参照点依赖的特征,即粮农对亏损和盈利的判断是相对于价格参照点而言的。参数估计结果显示,当粮农将市场状态编辑为盈利前景时,粮农对价格信号反应不足,且是风险厌恶的;当粮农将市场状态编辑为亏损前景时,粮农对价格信号反应过度,对风险和成本的反应不足。相较于市场的盈利前景,粮农对市场亏损前景下的谷物和油料价格更敏感。研究启示在于,政策制定者应重视粮农市场预期及其种植行为的心理决策机制,结合粮农的价格参照点设计更灵活的粮食政策。     

The Flint Animal Cancer Center (FACC) Canine Tumour Cell Line Panel: a resource for veterinary drug discovery,comparative oncology and translational medicine

Mammalian cell tissue culture has been a critical tool leading to our current understanding of cancer including many aspects of cellular transformation, growth and response to therapies. The current use of large panels of cell lines with associated phenotypic and genotypic information now allows for informatics approaches and in silico screens to rapidly test hypotheses based on simple as well as complex relationships. Current cell line panels with large amounts of associated drug sensitivity and genomics data are comprised of human cancer cell lines (i.e. NCI60 and GDSC). There is increased recognition of the contribution of canine cancer to comparative cancer research as a spontaneous large animal model with application in basic and translational studies. We have assembled a panel of canine cancer cell lines to facilitate studies in canine cancer and report here phenotypic and genotypic data associated with these cells.     

近43年岱海湖区气候变化特征分析

利用岱海湖区的气象观测资料,对岱海湖区的气候变化特征进行了初步分析。结果表明:近43年来,岱海湖区气温呈现出明显的升高趋势,其中20世纪90年代上升幅度为最大,高出多年平均水平0.63℃;而湖区的降水量和蒸发量则呈现出减少趋势,其变化倾向率分别为-9.64mm/10 a和-12.98 mm/10 a;结合大气干旱指数的计算结果,对岱海湖区的气候变化特征进行了阶段性划分,其中20世纪60年代和70年代为相对冷湿期,80年代是冷湿向暖干发展的过渡期,而90年代以后湖区则呈现出明显的暖干化趋势。     

A design and application of compound multi-functional sensor in wood-based panel processing

Introduction Multi-functional sensor, a new developmental direction of sensor field, can integrate several sense organs to measure several parameters at one time (Liu 1999). This sensor not only has small size but also has strong functions. Moreover, the …     

Gender status effect on carcass and meat quality traits of feedlot Angus × Nellore cattle

The study evaluated the effect of gender status on carcass and meat quality of feedlot Angus × Nellore cattle. A total of 176 cattle, 20 months old, were confined for 190‐days and assigned to four treatments: bulls, immunocastrated, steers, and heifers. Bulls had greater rib eye area and HCW (p = 0.0001). Heifers had increased fat thickness (p = 0.0001). Steers and heifers had higher marbling scores (p = 0.0001). There was interaction between gender and aging time for Warner‐Bratzler Shear Force (p = 0.0002), L* (p = 0.0118), and b* (p = 0.0113) values of beef. The sensory panel results showed that beef from bulls had the lowest consumer overall acceptance (p = 0.0278). Especially, regardless tenderness, steers and immunocastrated beef were considered tender, independent of aging time. Beef produced by heifers, steers, and immunocastrated is considered to be of higher quality than bulls. Thus, it is may be an interesting alternative to produce high‐quality beef than bulls, to attend the consumer demand for high‐quality products. Additionally, the low fatty acids n6 levels and low n6:n3 ratio, high levels of CLA, MUFAs, and oleic acid suggests that the heifer meat is favorable for human health.