[目的]探讨骨密度水平对老年脊柱骨折患者骨痛和手术预后的影响.[方法]收集2017年7~12月在本院骨科接受手术治疗的老年(>60岁)脊柱骨折患者,采用双能X线测定骨密度,根据骨密度水平分为低水平骨密度组(T值<1.0)和高水平骨密度组(T...[目的]探讨骨密度水平对老年脊柱骨折患者骨痛和手术预后的影响.[方法]收集2017年7~12月在本院骨科接受手术治疗的老年(>60岁)脊柱骨折患者,采用双能X线测定骨密度,根据骨密度水平分为低水平骨密度组(T值<1.0)和高水平骨密度组(T值≥-1.0).两组均采用模拟疼痛评估量表(VAS)评估疼痛程度,随访记录患者的术后相关指标评估其预后状况.[结果]低水平骨密度组在术后12 h、24 h VAS量表评分均显著高于高水平骨密度组(P<0.05),而术后48 h两组VAS量表评分比较差异无统计学意义(P>0.05);两组术后至出院的天数、总住院天数、术后并发感染及低钾血症构成比比较差异有统计学意义(P<0.05);术后12 h VAS评分与患者骨密度水平呈显著负相关(P<0.05),而术后24 h、48 h VAS评分与患者骨密度水平无显著相关性(P>0.05).骨密度水平减低是术后骨痛程度增加的危险因素(P<0.05);此外,术后并发感染、骨折段数和椎体压缩程度也均为骨痛程度增高的危险因素(P<0.05).[结论]低骨密度水平可能是影响老年脊柱骨折患者骨痛水平的一个危险因素,同时低骨密度水平也可影响患者术后的预后状况.展开更多
In this article, we prove the local existence and uniqueness of the classical solution to the Cauchy problem of the 3-D compressible Navier-Stokes equations with large initial data and vacuum, if the shear viscosity ...In this article, we prove the local existence and uniqueness of the classical solution to the Cauchy problem of the 3-D compressible Navier-Stokes equations with large initial data and vacuum, if the shear viscosity μ is a positive constant and the bulk viscosity λ（ρ） = ρ^β with β≥0. Note that the initial data can be arbitrarily large to contain vacuum states.展开更多
Propellant ionization in the Hall thruster discharge channel is a significant process and has strong influence on the thruster＇s efficiency. In this work, the functional relation has been established between the ioni...Propellant ionization in the Hall thruster discharge channel is a significant process and has strong influence on the thruster＇s efficiency. In this work, the functional relation has been established between the ionization density distribution and the function of the ion energy distribution through the basic equations governing the ion flow in the Hall thruster channel and the method achieved for reconstructing the ionization density distribution inside the channel by ordinary plasma diagnosis of the potential distribution and ion energy spectrum of the plasma jet. The ionization density distributions of single and double charged ions in an ATON-thruster channel have been reconstructed according to the experimental data of the potential distribution along the axis of the channel and the ion energy spectrum of the plasma jet. The agreement between the calculation and experimental results of the percentage of double charged ions proves the validity of our method achieved in this work.展开更多
A novel 3-dimensional potassium supermolecular compound [K（HDNR）（H2DNR）（H20）], （H2DNR 2,4-dinitro resorcinol） was synthesized and characterized by elemental analysis and FT-IR spectroscopy. The crystal structu...A novel 3-dimensional potassium supermolecular compound [K（HDNR）（H2DNR）（H20）], （H2DNR 2,4-dinitro resorcinol） was synthesized and characterized by elemental analysis and FT-IR spectroscopy. The crystal structure investigated by X-ray single crystal diffraction shows that [K（HDNR）（HzDNR）（H20）],, crystallizes with a monoclinic unit cell in the space group P2（1）/c with unit cell dimensions of a= 17.648（5） A, b= 12.527（3） A, c= 7.735（2） A, β=94.33（2）°, V= 1705.00（73） A3, Z=4. The structure was refined to the final R=0.0670 and wR= 0.0722 for 2022 observed reflections with 1〉2σ（/）. In the compound, potassium cation is assembled into one-dimensional chains along c-axis through oxygen atoms from water molecules, and the chains were connected by the bridged HDNR- anions to form a two-dimensional net structure. The two-dimensional nets constructed a three-dimensional supramolecular architecture via intermolecular hydrogen bonds and N--O…π interaction. Density functional theory （DFT） B3LYP was employed to optimize the structure and calculate energies for three tautomers of HDNR univalent anion. Three stable tautomers were located. It was found that the structure （I） with O（1） losing hydrogen atom is more stable than the structure （II） also with O（1） losing hydrogen atom and the structure （III） with O（4） losing hydrogen atom.展开更多
文摘[目的]探讨骨密度水平对老年脊柱骨折患者骨痛和手术预后的影响.[方法]收集2017年7~12月在本院骨科接受手术治疗的老年(>60岁)脊柱骨折患者,采用双能X线测定骨密度,根据骨密度水平分为低水平骨密度组(T值<1.0)和高水平骨密度组(T值≥-1.0).两组均采用模拟疼痛评估量表(VAS)评估疼痛程度,随访记录患者的术后相关指标评估其预后状况.[结果]低水平骨密度组在术后12 h、24 h VAS量表评分均显著高于高水平骨密度组(P<0.05),而术后48 h两组VAS量表评分比较差异无统计学意义(P>0.05);两组术后至出院的天数、总住院天数、术后并发感染及低钾血症构成比比较差异有统计学意义(P<0.05);术后12 h VAS评分与患者骨密度水平呈显著负相关(P<0.05),而术后24 h、48 h VAS评分与患者骨密度水平无显著相关性(P>0.05).骨密度水平减低是术后骨痛程度增加的危险因素(P<0.05);此外,术后并发感染、骨折段数和椎体压缩程度也均为骨痛程度增高的危险因素(P<0.05).[结论]低骨密度水平可能是影响老年脊柱骨折患者骨痛水平的一个危险因素,同时低骨密度水平也可影响患者术后的预后状况.
基金supported by China Postdoctoral Science Foundation(2012M520205)supported by National Natural SciencesFoundation of China(11171229,11231006)Project of Beijing Chang Cheng Xue Zhe
文摘In this article, we prove the local existence and uniqueness of the classical solution to the Cauchy problem of the 3-D compressible Navier-Stokes equations with large initial data and vacuum, if the shear viscosity μ is a positive constant and the bulk viscosity λ（ρ） = ρ^β with β≥0. Note that the initial data can be arbitrarily large to contain vacuum states.
文摘Propellant ionization in the Hall thruster discharge channel is a significant process and has strong influence on the thruster＇s efficiency. In this work, the functional relation has been established between the ionization density distribution and the function of the ion energy distribution through the basic equations governing the ion flow in the Hall thruster channel and the method achieved for reconstructing the ionization density distribution inside the channel by ordinary plasma diagnosis of the potential distribution and ion energy spectrum of the plasma jet. The ionization density distributions of single and double charged ions in an ATON-thruster channel have been reconstructed according to the experimental data of the potential distribution along the axis of the channel and the ion energy spectrum of the plasma jet. The agreement between the calculation and experimental results of the percentage of double charged ions proves the validity of our method achieved in this work.
基金Supported by National Science and Technology Support Program of China "Large-scale Breeding and Healthy Farming Techniques of Special Species in the Middle and Lower Reaches of the Yangtze River"(2012BAD25B06)~~
基金Project supported by the National Natural Science Foundation of China （No. 20471008）, the Project of State Key Laboratory of Science and Technology （No. YBKT10-03） and the Program for New Century Excellent Talents in University （No. NCET-09-0051）.
文摘A novel 3-dimensional potassium supermolecular compound [K（HDNR）（H2DNR）（H20）], （H2DNR 2,4-dinitro resorcinol） was synthesized and characterized by elemental analysis and FT-IR spectroscopy. The crystal structure investigated by X-ray single crystal diffraction shows that [K（HDNR）（HzDNR）（H20）],, crystallizes with a monoclinic unit cell in the space group P2（1）/c with unit cell dimensions of a= 17.648（5） A, b= 12.527（3） A, c= 7.735（2） A, β=94.33（2）°, V= 1705.00（73） A3, Z=4. The structure was refined to the final R=0.0670 and wR= 0.0722 for 2022 observed reflections with 1〉2σ（/）. In the compound, potassium cation is assembled into one-dimensional chains along c-axis through oxygen atoms from water molecules, and the chains were connected by the bridged HDNR- anions to form a two-dimensional net structure. The two-dimensional nets constructed a three-dimensional supramolecular architecture via intermolecular hydrogen bonds and N--O…π interaction. Density functional theory （DFT） B3LYP was employed to optimize the structure and calculate energies for three tautomers of HDNR univalent anion. Three stable tautomers were located. It was found that the structure （I） with O（1） losing hydrogen atom is more stable than the structure （II） also with O（1） losing hydrogen atom and the structure （III） with O（4） losing hydrogen atom.
