Subjects: Medicine, Pharmacy >> Preclinical Medicine submitted time 2017-12-07 Cooperative journals: 《南方医科大学学报》
Abstract： Objective To assess the relationship between visit-to-visit blood pressure (BP) variability (BPV) and vascular endothelial function in a cohort of elderly hypertensive patients. Methods A total of 174 elderly patients with essential hypertension were included in the study. The participants had their office BP measured during the 12-month follow-up. Right brachial artery diameter was assessed at rest, during reactive hyperemia (flow-mediated dilation, FMD), and after nitroglycerin administration (nitroglycerin-mediated dilation, NMD). The participants were divided into two groups according to FMD% or FMD/NMD ratio. The correlations between BPV and endothelial function were analyzed by univariate analysis and multiple linear regression analysis． Results The participants classified as having a decreased endothelial function according to FMD/NMD ratio had significantly lower FMD% and higher BPV and NMD% (P<0.05). The percentage of CCBs use in normal endothelial function group was significantly higher than that in decreased endothelial function group (79.55% vs 63.95%, P<0.05). Multiple linear regression analysis revealed a significant negative association between FMD/NMD ratio and BPV, and this association remained significant after adjustment for age, body mass index, and mean BP levels. Conclusions FMD/NMD ratio is a better marker of endothelial function than FMD, and an increased visit-to-visit variability of BP is associated with a decreased endothelial function.
Subjects: Biology >> Bioengineering submitted time 2017-07-24 Cooperative journals: 《中国生物工程杂志》
Abstract： Objective: An IRES-based vector was constructed to achieve co-expression of two target genes with the screening marker gene promoted by the single promoter, and to improve the screening efficiency of multiple genes co-stable expression cell lines. Methods: A bicistronic expression element BamHI-MCS1-IRES-MCS2-IRES-BsiWI which has two multiple cloning sites was designed and synthesized. The vector named pLV-2MCS-Puro was constructed by inserting the element into the skeleton vector pLV-MCS-Puro which was constructed previously in our lab. The DsRed2 and EGFP genes were inserted simultaneously into the vector to test the screening efficiency of multiple genes co-stable expression cell lines. Results: The vector pLV-2MCS-Puro and the recombinant plasmid pLV-DsRed2-EGFP-Puro were constructed successfully. Transient transfection experiment showed that the vector can mediate co-expression of multiple genes. MDCK and Hela cell pools resistant to puromycin were obtained through transfection of the recombinant plasmid. The fluorescent inverted microscope showed that DsRed2 gene at the upstream of the IRES sequence and EGFP gene at the downstream of IRES sequence were co-expressed in cells, and the double positive rate was close to 100%. It indicated that this vector has high screening efficiency. The results of genomic PCR, RT-PCR and Western Blot showed that DsRed2 and EGFP genes were stably integrated into cell genome and the two proteins were expressed consistently. Conclusion: The IRES-based vector pLV-2MCS-Puro was successfully constructed and proved to be efficiently in screening multiple genes co-stable expression cell lines. This vector will have certain application prospects in studying protein interactions and constructing engineering cell lines.
Subjects: Astronomy >> Astrophysical processes submitted time 2019-07-09 Cooperative journals: 《天文研究与技术》
Abstract： 随着多波段时域天文学的快速发展，远程天文台逐渐显露出优势，成为时域天文学研究的重要工具。然而，国内还没有自主、成熟、稳定的系统可以应用到远程天文台的建设当中，为此中国虚拟天文台提出并设计了一套硬件集成系统以便于集成控制和扩展移植。电源模块是其中重要的组成部分，实现电源的集成控制将极大提升整个系统的稳定性。本文设计了一个闭环的电源集成控制模块，通过嵌入式技术实现了天文台各设备电源的集成控制、平顶的开关控制以及各个设备状态的监测，并提供多种控制模式。通过发送随机网络指令对该模块进行了24小时的连续测试，并测试了网络中断情况下短消息的控制。通过发送与监测数据的对比，结果表明系统具有良好的稳定性。
Subjects: Astronomy >> Astronomical Instruments and Techniques submitted time 2018-06-22 Cooperative journals: 《天文研究与技术》
Abstract： Spherical distance (Angular separation) calculation is commonly using in Astronomy and Geography. It is the foundation of object detecting, data query and cross-matching. The spherical distance can be computed by Spherical Geometry method, and people have deduced many formulas. But the precision of computer is limited, due to rounding error in the numerical computation. This article will inspect several widely used formulas, test and compare their results, and discuss their advantage and disadvantage. In addition, this article will demonstrate how to do distance calculation on several astronomical packages and databases. The purpose of this article is helping astronomers to find the suitable method to do their calculation.
Subjects: Biology >> Ecology submitted time 2017-04-26 Cooperative journals: 《生态学报》
Abstract：苔藓物种多样性沿海拔梯度呈什么样的分布格局? 基于 53 个 20 m×20 m 样地，采集并鉴定了样地内所有生境中的苔藓 物种;采用多元回归树(multivariate regression trees， MRT)对苔藓植物进行分类;采用典范对应分析(canonical correspondence analysis， CCA)进行排序分析;用广义线性模型(Generalized Linear Model， GLM)研究苔藓物种多样性沿海拔的分布格局。 结果 如下:(1)采集的 1378 份苔藓植物标本经过鉴定，共有 33 科 89 属 240 种，其中藓类 226 种，苔类 14 种;(2)经交叉验证认为本 区苔藓植物可分为 4 类，I长肋青藓(Brachythecium populeum) +大叶匐灯藓(Plagiomnium succulentum) +圆叶匐灯藓 (Plagiomnium vesicatum) 群落，II灰白青藓(Brachythecium albicans) +宽叶青藓(Brachythecium curtum) +短肋羽藓(Thuidium kanedae)+平肋提灯藓(Mnium laevinerve) 群落，III短肋羽藓(Thuidium kanedae) +光萼叶苔(Jungermannia leiantha) +薄罗藓 (Leskea polycarpa) + 叉 肋 藓 ( Trachyphyllum inflexum) 群 落， IV 宽 叶 青 藓 ( Brachythecium curtum) + 垂 蒴 棉 藓 ( Plagiothecium nemorale)+全缘匐灯藓(Plagiomnium integrum) 群落;(3)海拔、坡度和坡向对苔藓物种分布的解释量为 7.29%;(4)苔藓物种多 样性随海拔的变化成明显的上升格局。 通过研究了解了小秦岭国家级自然保护区苔藓物种组成、群丛划分以及每种苔藓植物 的海拔分布范围;苔藓物种多样性随海拔的上升呈显著的上升格局，与乔木、灌木和草本的分布格局不同。 希望此研究能为苔 藓植物生态学研究和物种多样性保护提供参考。
Subjects: Astronomy >> Astrophysical processes submitted time 2018-11-01 Cooperative journals: 《天文研究与技术》
Abstract： 全天相机拍摄的全天空地基云图能够实时反应当地的云量信息，而云量是天文选 址时需要首先考虑的因素之一。在云量检测工作前对全天空地基云图根据图像质量，应用背景等因素进行自动化分类，实现鲁棒性高、适应性强的自动化分类算法，将减少图像分类 程中的人工成本，为天文选址提供重要帮助。本文实现了一种基于卷积神经网络分类模型的全天空地基云图自动化分类方法，采用雪龙号科考船搭载的全天相机数据进行了分类模型训练，并使用中科院云南天文台丽江观测站全天相机数据进行了验证，均取得了较好的分类效果，并证明该方法具有良好的可迁移性。
Subjects: Materials Science >> Nanoscience and Nanotechnology submitted time 2017-01-10
Abstract：采用低温 AlN 成核层在 Si(111)衬底上用金属有机化学气相沉积(MOCVD)设备摘要：采用低温 AlN 成核层在 Si(111)衬底上用金属有机化学气相沉积(MOCVD)设备生长了 GaN 薄膜。采用高分辨 X 射线衍射、椭圆偏振光谱仪和原子力显微镜研究了 AlN成核层的厚度对 GaN 外延层的影响。对 AlN 的测试表明，AlN 的表面粗糙度随着厚度增加而变大。对 GaN 的测试表明，所有 GaN 样品在垂直方向处于压应变状态，并且随 AlN 厚度增加而略有减弱。GaN 的(0002) ω扫描的峰值半宽(FWHM)随着 AlN 成核层厚度增加而略有升高，GaN(10-12) ω扫描的峰值半宽随着厚度增加而有所下降。(10-12) ω扫描的峰值半宽与 GaN 的刃型穿透位错密度相关。说明 AlN 成核层的厚度较大时，会降低刃型穿透位错密度，并减弱 c 轴方向的压应变状态。
Peer Review Status:
Awaiting Review
Subjects: Materials Science >> Nanoscience and Nanotechnology submitted time 2017-01-10
Abstract：摘要:在 Si(111)衬底上用金属有机化学气相沉积(MOCVD)设备生长了 AlN 和GaN 薄膜。采用高分辨 X 射线衍射、椭圆偏振光谱仪和原子力显微镜研究了AlN 缓冲层生长时的载气(H2)流量变化对 GaN 外延层的影响。椭圆偏振仪测试表明，相同生长时间内 AlN 的厚度随着 H2流量的增加而增加，即 H2流量增加会导致 AlN 的生长速率提高。原子力显微镜测试表明，随着 H2 流量的增加，AlN 表面粗糙度也呈上升趋势。对 GaN 的测试表明，随着 AlN 生长时的 H2流量增加，GaN 的(0002)和(10-12)的峰值半宽增加，即螺型穿透位错密度和刃型穿透位错密度增加。可能是由于 AlN 缓冲层厚度较大，导致 GaN 的晶体质量有所下降。实验表明，采用较低的 H2 流量生长 AlN 缓冲层可以控制 AlN 的生长速率，在一定程度上有助于提高 GaN 的晶体质量。
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2019-07-30 Cooperative journals: 《天文研究与技术》
Abstract：经过十余年的不断建设和发展，中国虚拟天文台（China-VO）已成为支撑天文学观测、研究、教学的重要技术和资源平台。随着多信使天文学和时域天文学时代的到来，虚拟天文台也需要升级自身的核心能力，以给天文工作者提供更精准的服务和技术支撑。为此，中国虚拟天文台团队结合天文学的发展方向和信息技术发展趋势梳理了一份核心技术需求清单，并以问卷的形式针对领域内专家和用户开展了调研。通过对调研结果的统计和分析，中国虚拟天文台明确了未来一段时期的主要努力方向和目标，计划采用平台化的开发模式，并开放第三方开发接口，以吸引更多感兴趣的开发者基于虚拟天文台资源做出实用的工具，更好地实现资源与技术向服务的快速转换。
Hits
Hits
Downloads
Comment