摘要：目的探讨心血管外科手术后脑卒中的危险因素,并为其预防提供依据。方法采用1∶2匹配设计的病例对照研究。以2010年1月1日至2017年12月31日期间在广东省人民医院进行心血管外科手术,手术后30 d内出现脑卒中的患者168例为病例组。选取同期在该院进行心血管外科手术,手术后30 d内未发生脑卒中的患者336例为对照组。调查内容包括患者基本情况和既往病史、手术前临床评估结果、手术前实验室检查结果、手术前超声心动图检查结果、手术相关因素等。运用Logistic回归分析寻找该并发症的危险因素。结果本研究期间,心血管外科手术后脑卒中发生率为0.78%(168/21 493)。其独立危险因素包括脑血管病史(OR=2.485)、既往心脏手术史(OR=8.335)、感染性心内膜炎(OR=3.855)、脉压差>40 mmHg(1 mmHg=0.133 kPa)(OR=2.438)、术前血糖>6.1 mmol/L(OR=2.409)、血浆纤维蛋白原>4 g/L(OR=2.718)、胸部大血管手术(OR=2.502)、急诊手术(OR=3.061)。结论心血管外科手术后脑卒中是多因素综合作用的结果。针对手术后卒中预期风险较高的患者,采取综合干预措施,有可能减少该并发症的发生。

摘要：目的:建立自体心包外支架包裹静脉移植物减轻内膜增生的动物模型,探讨自体心包外支架预防静脉移植物再狭窄的可行性。方法:以“no-touch”方法取犬一侧颈外静脉,对半剪成两段后分别吻合在双侧股动脉上,其中一侧静脉移植物外包裹自体心包(实验组),另一侧为单纯的静脉移植(对照组)。术后2周、4周分别切取移植静脉,行HE和WEIGERT染色,图像分析系统测量和计算内膜厚度、内膜面积。免疫组化法检测静脉移植物平滑肌细胞增殖细胞核抗原(PCNA)的表达水平。结果:除1条犬死亡外,余12条成活,所有动静脉吻合口无狭窄。实验组静脉移植物术后2周、4周内膜厚度、内膜截面积和PCNA指数均明显低于对照组(P<0.01)。结论:该动物模型设计合理,自体心包可作为静脉外支架的材料,能明显减轻内膜的增生,减少平滑肌细胞的增生。

摘要：采用完全随机设计,解析不同牧草种类(老芒麦、扁穗冰草、垂穗披碱草和紫花苜蓿)、补播量(0、12.54、16.72和20.90 kg/hm^(2))和施肥量(0、53.73、107.46和161.49 kg/hm^(2)干牛粪)对退化草地牧草营养品质和产量的影响,旨在明确退化草地牧草高产优产的最适管理方式。结果表明:不同管理方式显著改变了牧草干物质、粗蛋白、中性洗涤纤维、酸性洗涤纤维、有机物、粗脂肪和总能(P<0.05)。退化草地补播豆科植物紫花苜蓿的牧草干草产量及各营养物质产量均显著高于补播禾本科牧草(P<0.05)。随着补播量和施肥量的增加,牧草的干草产量以及各营养物质产量均有显著提高(P<0.05)。退化草地补播紫花苜蓿(补播量20.90 kg/hm^(2)),且施53.73 kg/hm^(2)干牛粪时,地上混合牧草的综合营养价值最高。

摘要：A helium cryogenic system is designed by the Institute of Modern Physics,Chinese Academy of Sciences,to supply different cooling powers to the cryomodules of ion-Linac(iLinac)accelerator,which serves as the injector of the High Intensity Heavy-Ion Accelerator Facility *** iLinac is a superconducting heavy-ion accelerator approximately 100 m long and contains 13 cryomodules cooled by superfluid *** article describes the cryogenic system design of the iLinac *** requirements of the cryogenic system,such as cooling mode,refrigeration temperature,operating pressure and pressure stability,are introduced and described in *** addition,heat loads from different sources are analyzed and calculated *** equivalent cooling capacity of 10 kW at 4.5 K was determined for the cryogenic system according to the total heat ***,a system process design was conducted and analyzed in ***,the system layout and the main equipment are presented.

摘要：本文设计合成了一系列杜仲活性成分香豆素类与苯丁酸氮芥衍生物(B-1~B-4),所有化合物均通过1HNMR、13C-NMR、HRMS进行结构确认。通过CCK-8法筛选出新型衍生物B-2对A-253细胞具有较高的抗增殖作用,IC_(50)值为18.490±1.398μM,且对人正常细胞的毒性最低,IC_(50)值为80.9±10.432μM。采用流式细胞术、蛋白免疫印迹技术、吖啶橙AO染色等方法,研究了B-2对A-253细胞细胞凋亡、细胞周期及线粒体膜电位的影响。研究发现,随着B-2浓度的升高,A-253细胞处于G2/M期的比例升高,凋亡细胞逐渐增多,线粒体功能受损逐渐加重。B-2以浓度依赖的方式下调了细胞周期相关蛋白CDK2和Cyclin A2的表达,使A-253细胞周期停滞;上调细胞凋亡关键蛋白Cleaved caspase-3和Cleaved PARP而诱导A-253细胞发生凋亡;激活自噬相关标记物Beclin 1和LC3的表达,诱导A-253细胞发生自噬,进一步抑制细胞生长。

摘要：目的:在实际工程服役过程中,纤维增强塑料(FRP)约束混凝土柱在遭遇极限荷载前往往已经经历了长时间的轴压荷载作用。因此,相比其短期力学性能,本文旨在研究FPR约束混凝土柱在长期荷载作用后的力学性能。创新点:1.考虑长期轴压荷载作用,提出一种轴压作用下圆形截面FRP约束混凝土柱的长期变形分析模型;2.提出了长期轴压作用后的FRP约束混凝土本构模型,从本构关系的角度描述两个方面的影响机理。方法:运用混凝土和FRP徐变的长期变形分析迭代计算方法(图3)。结论:1.提出的长期变形分析模型实现了对FRP约束混凝土柱任意目标时刻的应力和应变状态的高效、准确预测;2.将提出的本构模型嵌入有限元软件中,有效地实现对长期轴压作用的考虑;3.基于Open Sees有限元软件,验证了长期变形分析模型和本构模型的有效性和准确性。

摘要：This article reports the design and construction of a multiple-epitope foot and mouth disease virus （FMDV） antigen, designated as OAAT. This recombinant antigen consists of the structural protein VP1 genes from serotypes A and O FMDV, five major VP1 immunodominant epitopes from two genotypes of Asial serotype, and three Th2 epitopes originating from the nonstructural protein, three ABC gene and structural protein VP4 gene. Expressions of target gene from these plasmids in HeLa cells were verified by Western-blot. BALB/c mice were immunized intramuscularly with the DNA vaccines thrice every two weeks. We found that pA could induce simultaneously specific antibodies against serotypes A, Asial, and O FMDV. Compared to those of the controls, the spots of FMDV-specific IFN-7 and cytotoxic activity from mice immunized with pA were significantly increased, pA provided full protection in 2/4 guinea pigs from challenge with FMDV O/NY00 and Asial/YNBS/58, respectively. The results show that although pA did not give full protection in 100% immunized guinea pigs from challenge with type O and Asial FMDV, respectively, OAAT may be potential immunogen against FMDV and pA may be potential DNA vaccines against FMDV.

摘要：随着计算机技术的飞速发展 ,并行计算机用户环境的设计日益成为一个至关重要的问题 ,它是并行计算机用户的工作平台 .并行计算机用户环境的优劣将直接影响到高性能计算机的发展和应用 .文中分析了并行计算机用户环境设计中存在着的诸多问题 ,从理论模型、实现方法深入探讨了如何解决这些问题 ;以此设计和实现了曙光 2 0 0 0 的用户环境 ;同时进一步讨论了用户环境体系结构的可扩展性 .

摘要：Topological phase is an important development and unexplored degree of freedom of traditional band theory[1].Generally,it manifests in physics through the boundary states revealed by the bulkedge *** bulk topology implies various low-dimensional states at the boundary,giving extraordinary approaches to manipulate *** structure that encodes the band topology is the system associated with space–time evolution,such as Floquet topological insulator[2,3].Its quasistatic limit involves time-dependent dynamic adiabatic evolution[4,5].However,dynamic evolution is challenging as it requires fast modulation to overcome the dissipation of state before it is pumped from one edge to another[6].An alternative approach is to use an additional degree of freedom to replace the role of time,and an illuminating system is the weakly coupled waveguides,whose governing equation can be directly mapped to Schrodinger equation with time modulation replaced by wave propagation along the ***,such strategy has been largely explored to realize the pumping of topological boundary states in optics[7,8]and elastic wave[9,10].However,the strategy for acoustics is subtly different as the coupling of the acoustic waveguides is not weak for the fundamental waveguide *** exploring the possibility to realize two-dimensional(2D)topological acoustic pumping in a continuous regime remains an open question.

摘要：为准确评估高压压气机畸变特性而进行了一系列相关试验,重点阐述了高压压气机进气压力畸变试验方法,提出了对综合畸变指数、动态和稳态畸变成分、门槛值、畸变图谱等特征参数的指标要求,以及测试方案和试验数据处理方法,并据此完成某型高压压气机进气压力畸变试验,获得总压畸变对该高压压气机性能的影响,以及相关稳定性评定数据.试验结果表明:该高压压气机非设计转速压力畸变敏感系数明显高于风扇部件,抗畸变能力弱于风扇部件;设计转速压力畸变敏感系数与风扇部件相当,表现出较强的抗畸变能力和良好的气动稳定性.