上盘矿柱诱导冒落回收力学分析

针对缓倾斜、中厚矿体高效开采方法研究中,上盘岩体含水、破碎,回采爆破易造成该岩体损伤、破坏而导致贫化过早,涌水量增大,矿石结块,放矿困难等问题,提出预留上盘矿柱,减缓爆破震动对上盘围岩损伤;同时在下分段布置诱导炮孔,破坏残留区域根基,诱导预留矿柱冒落,达到回收矿柱的目的.采用Flac3d对回采过程中预留矿柱的应力、位移、塑性区等扩展、发育过程中力学机制进行模拟分析,反演了回采过程中预留矿柱对减缓上盘岩层破坏力学过程,得出在分段上盘预留2 m厚的三角保护矿柱,可有效地控制塑性区的发展,有利于维持上盘的稳定性,且在下分段拉槽时,进行诱导崩落,可以将该矿柱完全回收.     

太子矶航道水下钻孔爆破地震波测试与分析

以长江太子矶航道疏浚爆破工程为例,通过对其爆破地震波的测试与分析,得出爆破振动速度的衰减经验公式,提出爆破振动速度安全判据及不同状态下的最大允许药量,并依据实测数据评估了水下钻孔爆破对长江大堤的影响。     

最大公共子图的约束符号求解方法

【目的】探索求解两个图最大公共子图的方法。【方法】建立最大公共导出子图的软约束满足问题(Soft CSP)模型,提出代数决策图(ADD)的符号求解算法。首先,分别对两个图中的变量和值域进行编码,完成两个图的ADD表示;其次,基于深度优先分支定界算法的思想,利用符号ADD的相关操作,实现对最大公共导出子图的求解。【结果】算例结果表明,该方法准确可行。【结论】该方法能有效缩减搜索空间,从而提高问题的求解效率。     

Induced pluripotent stem cell (iPS) technology: promises and challenges

In 2006, an article published in Cell by Shinya Yamanaka took by surprise the stem cell research community. By performing systematic retroviral transduction of factors enriched in embryonic stem (ES) cells, the authors demonstrated the reprogramming of mouse fibroblasts into an ES cell-like state. These cells, baptized iPS (induced pluripotent stem) cells, were immediately recognized as a ground-breaking discovery. Subsequently, the same authors and other groups reported a similar achievement with human fibroblasts. Two years later, the number of top quality papers on iPS is astonishing, and interest in the scientific community has risen to a fever pitch. But although iPS has the potential to revolutionize Regenerative Medicine, important questions still remain unanswered. Work from multiple laboratories worldwide including ours is focused on deciphering the molecular mechanisms of iPS, and trying to improve the technique to make it suitable for the clinic. In this review article we briefly discuss the past, present and future of iPS, with emphasis on urgent issues to be solved. Supported by the National Nature Science Foundation of China (Grant Nos. 30725012, 30630039 and 90813033), Knowledge Innovation Project of Chinese Academy of Sciences (Grant No. KSCX2-YW-R-48), National Key Basic Research and Development Program of China (Grant Nos. 2006CB701504, 2006CB943600, 2007CB948002, 2007CB947804. 2007CB947900) and Guangzhou Science and Technology Development Funds (Grant No. 2008A1-E4011)     

面向拥堵问题的枢纽航线网络优化模型

为解决枢纽机场客流拥堵问题,提高机场运行效率,减少运营成本,提出了一种面向拥堵问题的枢纽航线网络优化模型。该模型基于非严格枢纽航线网络结构,以不同运输方式的费用和流量为约束条件,以枢纽航线网络成本最低为目标,设计了能够减少求解运算的复杂变量表示方法,以及减少陷入局部最优解概率的模拟退火粒子群优化(simulated annealing particle swarm optimization, SAPSO)算法。实验结果表明,相较于严格的枢纽航线网络,所提优化模型能够显著地缓解枢纽机场的拥堵,均衡枢纽机场间客流量,减少网络成本;同时,所提算法具有较快的收敛速度和良好的稳定性。     

EMS对枇杷花药胚状体细胞有丝分裂的影响

采用不同浓度的EMS对枇杷花药胚状体进行离体诱变,并以未诱变的材料作对照,对其引起的细胞学效应进行了研究．结果表明：在EMS诱变过的材料中均观察到一定数量的染色体畸变;球胚细胞中随着EMS浓度的升高有丝分裂指数降低,而染色体畸变率升高．胚性细胞与球胚细胞中有相同的变化趋势,但各自的分裂指数和染色体畸变率并不相同．     

基于水量讯号装置的某型制冷机安全控制装置

介绍了制冷机冷却水系统的作用及完成安全控制的水量讯号装置,讨论了水量讯号装置与制冷机电路系统配合工作来完成的制冷机安全控制。     

沙参麦冬汤对运动性免疫抑制干预作用的研究

目的观察沙参麦冬汤对游泳小鼠免疫指标和运动能力的影响,为改善运动性免疫抑制寻找有效的干预措施。方法建立运动性免疫抑制的模型,观察沙参麦冬汤对小鼠免疫器官、外周血T淋巴细胞亚群及运动能力的影响。结果与运动组比较,运动＋沙参麦冬汤组小鼠的脾指数、胸腺指数、CD4^＋T淋巴细胞百分比、CD4^＋／CD8^＋比值均显著提高（P〈0．05）,并明显延长了小鼠力竭性游泳时间（P〈0．05）。结论沙参麦冬汤能改善大强度运动训练引起的小鼠免疫功能低下,提高小鼠的运动能力。     

In-situ observation on the deformation behaviors of Fe-Mn-C TWIP steel

The microstructure and crack behaviour of twinning induced plasticity (TWIP) steel during tensile deformation was investigated with in-situ scanning electron microscopy (SEM). The results show that there are two modes of plastic deformation during tensile test in the Fe-Mn-C TWIP steel: dislocation gliding and deformation twins. During the process of tensile deformation, secondary deformed twins are found. Inclusions have played a role in the course of ductile fracture, and microcracks initiate from inclusions and twin-twin intersections.     

土地使用权流转对农业技术创新的动力作用研究

近年我国农民收入中农林牧渔业所占比重呈下降趋势,导致这一现象的主要原因是土地产权制度存在缺陷、农民务农积极性下降、农业技术创新动力不足。随着土地使用权流转的逐渐放开,农地向农业从业人员转移,土地规模经营效益增加,农民素质得到提高,农业技术创新有效需求增加,刺激上游科研单位技术有效供给,下游加工销售部门创新,最后认为土地使用权流转将成为农业技术创新的动力源,并为土地合理有效有序流转提出一些有价值的建议。