《说文》“多形多声”说研究

“多形多声”说是近两千年文字学中悬而未决的疑案。本文吸收古今文字学研究成果,逐一考察了大徐本载列的全部多形多声字共82个。除“”字构形不明外,无一多形多声字。由此指出许氏“多形多声”说理论上的偏颇就在于不能用辩证的观点和方法来分析形声字内部形符和声符的矛盾运动规律及其运动轨迹。

Review of research on sonar imaging technology in China

Over the past 20 years,sonar imaging technology particularly for the high-technology sector has been a focus of research,in which many developed countries,especially those with coast lines,have been competing with each other.It has seen a rapid development with increasing widespread applications that has played an important and irreplaceable role in underwater exploration with great prospects for social,economic,scientific,and military benefits.The fundamental techniques underlying sonar imaging,including multi-beamforming,synthetic-aperture and inverse synthetic-aperture sonar,acoustic lensing,and acoustical holography,are described in this paper.This is followed by a comprehensive and systematic review on the advantages and disadvantages of these imaging techniques,applicability conditions,development trends,new ideas,new methods,and improvements in old methods over recent years with an emphasis on the situation in China,along with a bold and constructive prediction to some development characteristics of sonar imaging technology in the near future in China.The perspectives presented in this paper are offered with the idea of providing some degree of guidance and promotion of research on sonar imaging technology.

Spatial acoustic emission evolution of red sandstone during multi-stage triaxial deformation

Multi-stage triaxial compression tests for cylindrical red sandstone specimens(diameter of 50 mm,height of 100 mm) were carried out with a rock mechanics testing system and spatial acoustic emission(AE) locations were obtained by adopting an AE monitoring system.Based on spatial AE distribution evolution of red sandstone during multi-stage triaxial deformation,the relation between spatial AE events and triaxial deformation of red sandstone was analyzed.The results show that before peak strength,the spatial AE events are not active and distribute stochastically in the specimen,while after peak strength,the spatial AE events are very active and focus on a local region beyond final microscopic failure plane.During multi-stage triaxial deformation with five different confining pressures,the spatial AE distribution evolution in the red sandstone was obtained.The obtained spatial AE locations of red sandstone at the final confining pressure agree very well with the ultimate failure experimental mode.Finally,the influence of confining pressure on the spatial AE evolution characteristics of red sandstone during triaxial deformation was discussed.The AE behavior of red sandstone during multi-stage triaxial deformation is interpreted in the light of the Kaiser effect,which has a significant meaning for predicting the unstable failure of engineering rock mass.

Clinical, brain electric earth map, endothelin and transcranial ultrasonic Doppler findings after hyperbaric oxygen treatment for severe brain injury

目的 探讨高压氧治疗重型颅脑损伤的疗效及机制。方法 重型颅脑损伤患者 35例为治疗组 ,2 0例为对照组 ,观察高压氧治疗前后临床 (GCS)、脑电地形图 (BEAM)、血内皮素 (ET)、经颅多普勒超声 (TCD)及预后 (GOS)的变化。结果 治疗组患者经高压氧治疗后临床 (GCS)、脑电地形图及预后均明显改善 ,与对照组相比有统计学意义。高压氧治疗 1个疗程后 ,治疗组血内皮素由 91 2 4± 12 18ng/L下降到 6 8 88± 14 37ng/L(P <0 0 1) ;经颅多普勒超声示大脑中动脉Vm也由 6 4 2± 4 8cm/s下降到 51 6± 4 2cm/s(P <0 0 1) ;同时 ,大脑中动脉VsPI也明显下降。统计学有显著性意义 (P <0 0 1)。结论 高压氧治疗能够明显改善重型颅脑损伤患者的临床、脑电地形图及预后 ,并且通过降低急性期血内皮素、改善大脑中动脉血流速度及血管阻力来改善重型颅脑损伤后脑血管痉挛及脑缺血缺氧。同时 ,降低颅内压是高压氧治疗重度颅脑损伤的重要机制之一。

GLOBAL UNIQUENESS IN THE INVERSE ACOUSTIC SCATTERING PROBLEM WITHIN POLYGONAL OBSTACLES

The authors prove the uniqueness in the inverse acoustic scattering problem within convex polygonal domains by a single incident direction in the sound-soft case and the sound-hard case, and by two incident directions in the case of the impedance boundary condition. The proof is based on analytic continuation on a straight line.