腹腔镜下全直肠系膜切除术后尿管拔除时机和方法探讨

目的:探讨腹腔镜下全直肠系膜切除术后尿管拔除的时机和方法。方法:将102例腹腔镜下全直肠系膜切除术后直肠癌患者随机分为实验组和对照组,每组各51例。实验组术后第4天夹闭尿管,膀胱充盈时拔除尿管,患者自行排尿。对照组术后第4天开始训练膀胱功能,夹闭尿管3~4 h放尿1次,第7~10天患者有尿意感后拔除尿管,患者自行排尿。结果:两组相比较,实验组尿路感染率明显降低,差异具有统计学意义(P=0.014),及早拔除尿管可以减轻下尿路不适症状(P=0.005),而两组患者急性尿潴留需要再次插尿管发生率和住院天数无明显差异(P>0.05)。结论:腹腔镜下全直肠系膜切除术后及早拔除尿管可减轻下尿路不适症状,降低患者尿路感染发生率,拔管前不需要训练膀胱功能,直接拔除尿管,不增加尿潴留和再次插管率。

An Exploratory Analysis of Vegetation Strategies to Reduce Shallow Landslide Activity on Loess Hillslopes, Northeast Qinghai-Tibet Plateau, China

Heavy summer rainfall induces significant soil erosion and shallow landslide activity on the loess hillslopes of the Xining Basin at the northeast margin of the Qinghai-Tibet Plateau. This study examines the mechanical effects of five native shrubs that can be used to reduce shallow landslide activity. We measured single root tensile resistance and shear resistance, root anatomical structure and direct shear and triaxial shear for soil without roots and five root- soil composite systems. Results show that Atriplex canescens （Pursh） Nutt. possessed the strongest roots, followed by Caragana korshinskii Kom., Zygophyllum xanthoxylon （Bunge） Maxim., Nitraria tangutorum Bobr. and Lycium chinense Mill. Single root strength and shear resistance relationships with root diameter are characterized by power or exponential relations, consistent with the Mohr- Coulomb law. Root mechanical strength reflects their anatomical structure, especially the percentage of phloem and xylem cells, and the degree and speed of periderm lignifications. The cohesion force of root- soil composite systems is notably higher than that of soil without roots, with increasing amplitudes of cohesion force for A. canescens, C. korshinskii, Z. xanthoxylon, N. tangutorurn and L. chinense of 75.9%, 75.1%, 36.2%, 24.6% and 17.0 % respectively. When subjected to shear forces, the soil without root samples show much greater lateral deformation thanthe root-soil composite systems, reflecting the restraining effects of roots. Findings from this paper indicate that efforts to reduce shallow landslides in this region by enhancing root reinforcement will be achieved most effectively using A. canescens and C. korshinskii.

一种毫米波宽锁定范围的注入锁定倍频器设计

为提高毫米波段倍频器在低功耗下的工作带宽,采用IHP130 nm SiGe BiCMOS工艺,设计了一种采用双端注入(DEI)技术的毫米波宽锁定范围注入锁定倍频器。该注入锁定倍频器主要由谐波发生器和带有尾电流源的振荡器构成,由巴伦产生差分信号双端注入振荡器的形式提高三次谐波注入强度,使其在E、W等波段输出宽锁定范围和良好相位噪声性能的三倍频信号。仿真结果表明,注入锁定倍频器在工作电压为1.2 V,输入信号功率为0 dBm时,其锁定范围在57~105 GHz内。在相同工作电压和输入信号功率下,输入频率为32 GHz时,一次、二次和四次谐波抑制大于20 dBc,功耗为9.1 mW。