晶须增强金属基复合材料疲劳短裂纹扩展速率

利用等效夹杂理论及能量释放率导出了金属基复合材料短裂纹疲劳扩展速率，公式中考虑了晶须及裂纹前端塑性区对裂纹的影响，并给出了等效裂纹长度公式。将理论结果同实验结果进行了比较，吻合得较好；分析了短裂纹扩展规律，指出晶须对裂纹扩展的作用及在裂纹越过晶须一段距离后，可以认为晶须已经失去增强作用，此时相当于无晶须的情形。     

Scaling up: Bringing public institutions and food service corporations into the project for a local,sustainable food system in Ontario

This paper reports on a relationship between the University of Toronto and a non-profit, non-governmental (“third party”) certifying organization called Local Flavour Plus (LFP). The University as of August 2006 requires its corporate caterers to use local and sustainable farm products for a small but increasing portion of meals for most of its 60,000 students. LFP is the certifying body, whose officers and consultants have strong relations of trust with sustainable farmers. It redefines standards and verification to create ladders for farmers, Aramark and Chartwells (the corporations that won the bid), and the University, to continuously raise standards of sustainability. After years of frustrated efforts, other Ontario institutions are expressing interest, opening the possibility that a virtuous circle could lead to rapid growth in local, sustainable supply chains. The paper examines the specificities of the LFP approach and of the Toronto and Canadian context. Individuals in LFP acquired crucial skills, insights, experience, resources, and relationships of trust over 20 years within the Toronto “community of food practice,” located in a supportive municipal, NGO and social movement context. Harriet Friedman PhD, is Professor of Sociology at the University of Toronto Mississauga and at the Centre for International Studies University of Toronto. Her research is in international and local politics of food and agriculture, focusing on contested transitions between food regimes. Her current research is on politics of standards and certification. Thanks to Lori Stahlbrand, Mike Schreiner, and Rod MacRae of LFP and Debbie Field and Zahra Parvinian of FoodShare for sharing time and insights at length, and to Wayne Roberts of TFPC, David Clandfield of New College, Josee Johnston, and Amber McNair for helpful conversations about our “community of practice.” Thanks to Yossi Cadam for the ladder metaphor.     

红皮云杉人工林生长节律

红皮云杉人工林，≥０℃时芽展开，≥５℃时高生长开始树高年生长量４４．９６ｃｍ，生长最速期在６月中旬。日平均高生长量１．７８ｃｍ，红皮云杉高生长天数为６１ｄ，属短速型树种。树高生长与积温，降水，日照相关紧密。直径生长６月中旬开始。７月上旬进入速生期，直径平均日生长量为０．０１ｃｍ，８月中旬直径停止生长。直径生长天数为５６ｄ，胸高直径年生长量为０．５２６ｃｍ。     

奶牛与肉牛不同生长发育阶段肝脏转录组比较分析

为探究奶牛与肉牛肝脏组织在不同生长发育阶段中的差异,利用RNA-seq技术和生物信息学的研究方法,分别对海福特肉牛与荷斯坦奶牛6、9和12月龄3个不同生长发育阶段的肝脏组织进行基因差异表达及表达趋势分析。结果表明：1）海福特肉牛与荷斯坦奶牛之间在6、9和12月龄分别获得的差异表达基因为699、486和769个;2）对海福特肉牛与荷斯坦奶牛之间的差异表达基因进行功能注释,发现细胞色素P450信号通路和PPAR信号通路中差异表达基因的表达量在肉牛与奶牛之间存在差异,并且在不同生长阶段表达也不同。其中与脂肪细胞增殖和脂质代谢有关的功能基因：ACOX1、APOA1和ACADM,与天然免疫相关的通路中BoLA-DQB、BLA-DQB和BoLA-DQA这3个基因在海福特肉牛中的表达均高于荷斯坦奶牛;3)STEM分析结果显示荷斯坦奶牛与海福特肉牛肝脏组织在生长发育阶段中具有相同表达趋势中,奶牛与肉牛的时序性表达基因与代谢途径相关信号通路上存在差异。综上,本研究表明与脂质代谢和脂肪生成等代谢过程有关的途径可能在协同调控奶牛与肉牛生长发育阶段中发挥的作用及表达模式存在差异,这为深入研究奶牛与肉牛在生长发...     

海北高寒湿地地气长、短波辐射的季节变化特征

利用2004年微气象观测资料,分析了海北高寒湿地长、短波辐射以及地表反射率(A)和光合有效辐射(PAR)占太阳总辐射(DR)比例(η)的变化特征。结果表明,海北高寒湿地长、短波辐射均具有明显的季节变化。DR在12月最低,4月最高。PAR在12月最低,7月最高。受下垫面性质影响,反射辐射(UR)和A在1~2月明显大于其他季节,7~10月小,A在植物生长季节的5~9月平均值为0.172,年平均值为0.299。地面长波辐射(DLR)、大气逆辐射(ULR)和净辐射(Rn)的最低值均出现在1月,最大值出现时期则不同,DLR与Rn均出现在6月,而ULR出现在8月。地面有效辐射(ELR)无明显的季节变化。η的季节变化比较弱,7月最高值为0.434,1月最低值为0.316,年平均值为0.40。     

水稻密播短秧龄机插秧试验

水稻密播短秧龄机插对于水稻节本增效具有重要意义,探索合适的技术参数对于水稻生产至关重要。本试验探索通过育秧时增加每盘播种量,同时适当缩短秧龄,从而减少每亩用秧盘量、降低育秧成本的可行性。试验研究四种播量处理对水稻秧苗素质、群体动态、产量构成及产量和经济效益的影响,为该技术的推广应用提供可用的技术参数支持。试验结果表明：播量130克/盘和150克/盘可有效节约成本,进而实现节本增效目标,这一创新技术可在陕西地区推广。