半群OPP IE*（X）的秩

设X为有限全序集,E为X上的凸等价关系.令OPP IE*（X）为所有E类方向保序变换所构成的半群,得到了OPP IE*（X）的秩

XGPON上行突发接收机的关键技术

阐述了应用于万兆无源光网络（XGPON）光线路终端（OLT）收发模块的2.5Gbit/s突发接收机的基本原理,为了提高接收机性能,采用自动调节电路频域特性的方法,设计了一种接收电路,该电路能够在很短的时间间隙内建立接收信号,同时还具有极高的灵敏度

The Moderating Effect of Delay Discounting between Sensation Seeking and Risky Driving Behavior

摘要：前人发现感觉寻求是影响违规等风险驾驶行为的稳定预测因素。延迟折扣指随着获得奖励时间的延长，人们感知到的奖励价值也会随之下降的现象。延迟折扣率可反应个体追求即时金钱奖励还是延时更多金钱奖励的倾向。考虑到风险驾驶行为的出现可能涉及到即时感觉寻求满足与未来安全收益间的权衡，因此有必要讨论感觉寻求和延迟折扣率共同对风险驾驶的影响。本研究旨在探究人们对虚拟奖励的延迟折扣率与自我报告的风险驾驶行为间的关系，及其在感觉寻求与风险驾驶间可能存在的调节作用。研究采用网络问卷的形式收集数据，329名中国驾驶者完成了感觉寻求量表（SSS）、金钱选择问卷（MCQ）及驾驶行为问卷（DBQ）。研究结果表明：（1）大延迟金额（80元）下的延迟折扣率可负向预测一般性违规、错误及风险驾驶总分；（2）大延迟金额（80元）下的延迟折扣率在感觉寻求对风险驾驶的影响中起调节作用，即只有在延迟折扣率较高（追求即时奖励）时，高感觉寻求者风险驾驶行为更多，而在延迟折扣率较低（追求延时更多金钱奖励）时，高低感觉寻求者风险驾驶行为差异不大。本研究初次探讨感觉寻求和延迟折扣率共同对风险驾驶的影响，并发现只有当个体倾向于放弃较大延迟金额追求即时奖励时，其感觉寻求程度才可预测风险驾驶频率；而对于选择较大延迟金额的个体来说，可能由于其可以更好地考虑到未来的安全收益，并放弃追求即时感觉满足，因此感觉寻求程度无法预测风险驾驶频率。研究具备一定的理论价值，并可为选拔和培训驾驶员以提升道路安全性等实际应用提供一定的指导。</p

不同植被带生态恢复过程土壤团聚体及其稳定性-以黄土高原为例

为分析黄土高原不同植被带植被恢复对土壤团聚体分布特征及其稳定性的影响,以黄土高原从北到南不同纬度梯度分布的3 个典型植被类型区域(草原带、森林草原带和森林带)为研究对象,对不同植被类型和恢复年限下的土壤团聚体分布及其稳定性进行了研究.结果表明:不同植被对土壤团聚体分布及其稳定性影响显著,大于0.25mm 团聚体含量(WR 0.25 )、稳性团聚体平均重量直径(E WMD )、水稳性团聚体几何平均直径(E GMD )和有机质含量(SOM)整体上均表现为:森林带&gt;森林草原带&gt;草原带.不同植被带下不同恢复类型对土壤团聚体及其稳定性影响不一,森林草原带表现为灌木&gt;草地&gt;乔木,森林带则表现为乔木&gt;草地.随植被恢复年限增大,各种恢复类型WR 0.25 、E GMD 、SOM 整体呈逐渐增加趋势,团聚体结构破坏率(PAD)和可蚀性因子(K)呈现相反的变化趋势;分形维数(D)无显著差异.冗余分析表明,植被带对土壤团聚体及其稳定性的影响最大,其次是恢复年限,恢复类型与植被带和恢复年限具有较强的交互作用.本研究有利于加强对区域生态恢复过程机理的认识</p

The application of computer simulation of spinal osteotomy in making surgical plan for correction of kyphosis in ankylosing spondylitis

目的:探讨计算机辅助设计在强直性脊柱炎后凸畸形矫形术手术方案制定中的应用价值。方法:将5例强直性脊柱炎后凸畸形患者在手术前后进行胸腰椎CT扫描,获得的数据导入Mimics10.01软件进行三维重建。手术前在重建模型上模拟经椎弓根椎体截骨术进行虚拟截骨、预测矫形效果,并测算截骨椎体所需截骨角度及相应在椎板及椎体后缘的截骨宽度。手术后在预测模型及术后重建模型上分别测量全脊柱后凸角,颈7椎体中心点与骶骨后上角的水平距离,截骨节段相邻上下椎体棘突间及双侧横突间距离等指标,并进行比较。结果:5例手术前后均顺利完成三维建模。术前模拟截骨测算出截骨椎体所需截骨角度、椎板截骨宽度和椎体后缘截骨宽度的值分别为(26.34±3.16)°(23.30～30.11°)、(27.71±1.22)mm(26.53～29.15mm)和(14.45±1.62)mm(12.17～16.62mm),在虚拟截骨模型上及术后重建模型上测得的比较指标相近。结论:应用计算机对强直性脊柱炎后凸畸形截骨矫正手术进行仿真模拟设计的方法具有可行性,能比较直观、精确反映矫形效果,可为制定手术方案提供较科学的依据。Objective: To discuss the application of computer simulation of spinal osteotomy in making surgical plans for patients with kyphosis deformity due to ankylosing spondylitis. Methods: 4 patients underwent CT scan before and after the operation and the collected data were put into the Mimics 10.01 to reconstruct 3D images. Virtual vertebrectomies were carried out on the models to guide actual operations. The corrected angle, the width of the lamina, the width of resected lumbar posterior marginal bone was predicted. In the model of virtual vertebrectomies and the postoperative reconstructed, the total spinal kyphosis angle, the distance between the cervical line on the center of C7 and the postero-superior part of S1, the distance of the spinous process and the distance of both sides of transverse process were measured and compared. Results: The models were successfully reconstructed and virtual vertebrectomies were well completed in every case. The mean predictive value of the corrected angle, the width of the lamina, the width of resected lumbar posterior marginal bone were (26.34 ±3.16)° (23.30~30.11° ), (27.71 ±1.22) mm (26.53~29.15 mm), and (14.45 ±1.62) mm (12.17~16.62 mm) respectively. The mean predictive value was close to the mean real values. Conclusions: Computer simulation of vertebrectomy can directly and accurately reflect the correction effects before surgery, which is convenient for defining the best surgical plan as well as improving the safety and accuracy of the operation

低阈值基横模脊形波导GaAs/AlGaAs单量子阱激光器

报道了脊形波导结构GaAs/AlGaAs量子阱激光器的研究成果,采用湿法化学腐蚀方法,通过对器件结构参数的优化,制备了性能优越的脊形波导GaAs/AlGaAs量子阱激光器,器件的阈值电流低于10mA,最低值为7.3mA.而且实现了基横模工作,这是国内报道的该结构激光器的最好水平

酶解低温提取灵芝水提取物过程研究

通过试验选出了以木瓜蛋白酶、纤维素酶、果胶酶为组合的复合酶的最佳灵芝水提取物(粗多糖)初步提取条件,以硫酸苯酚法检测其多糖产出率,结果表明:最佳酶解条件为pH4.5,反应温度45℃,料液比1∶30,复合酶用量0.8%(对底物),反应时间3 h,酶解次数2次。复合酶最佳酶配比为木瓜蛋白酶∶纤维素酶∶果胶酶=1∶2∶2。酶解低温提取所获得的灵芝水提物中的灵芝多糖含量较传统的水提醇沉法中的热水浸提提升了20%以上,为今后酶解低温提取在工业上的应用提供了重要依据。</p

The Preparation Method and Methanol Electrocatalytic Activity of Ternary PtRhSn/GN

本研究通过多元醇还原法制备了石墨烯(grAPHEnE,gn)负载的PT及PT基多元催化剂:PT/gn、PTrH/gn、PTSn/gn、PTrHSn/gn.X射线粉末衍射(Xrd)和透射电镜(TEM)结果表明,所制备的催化剂分布均匀,PT/gn和PTrH/gn具有立方体形状,PTSn/gn呈现三维网络形貌,PTrHSn/gn则为立方体延伸的三维网络.循环伏安研究表明,rH的加入提升了甲醇电催化氧化的活性,而Sn的加入明显降低了甲醇在PT上的起始氧化电位,负移达到106MV.电化学原位红外光谱研究进一步证明,rH和Sn的加入使得PT基催化剂对甲醇氧化的起始氧化电位负移;rH的加入使得CO谱峰强度增大,而Sn的加入明显降低了CO谱峰强度.三元催化剂PTrHSn/gn很好地综合了rH和Sn的电子效应及协同效应特点,相比于PT/gn催化剂,起始氧化电位负移60MV,且催化活性达到其1.57倍,表明该三元催化剂在直接甲醇燃料电池中将会有较好的应用前景.Pt/GN,PtRh/GN,PtSn/GN and PtRhSn/GN catalysts were synthesized through a polyol method.The results of transmission electron microscopy(TEM)and X-ray diffraction(XRD)indicated that the as-synthesized catalysts were uniformly dispersed on the graphene(GN)surface.Both Pt/GN and PtRh/GN were composed of homogeneous cubics,while PtSn/GN showed threedimensional network morphology(TDNM)and PtRhSn/GN presented a cubic extended TDNM.Electrochemical cyclic voltammetric(CV)result revealed that the additive element Rh was able to promote the activity,while Sn lowered the onset potential as much as106 mV compared with Pt/GN catalyst for methanol electro-oxidation.In-situ electrochemical Fourier transform infrared spectroscopy(FT-IR)results showed that Rh and Sn could lower the onset potential,and Sn declined the CO peak intensity while Rh increased it.The electronic effect and synergistic effect between the additive element Rh,Sn and Pt make ternary PtRhSn/GN a promising lowPt catalyst for direct methanol fuel cells,which shows a peak current of 1.57 times as much and the onset potential shifting negatively by 60 mV compared with Pt/GN.国家自然科学基金(21273180;21361140374;21321062