我国宜一步到位发展高速磁悬浮列车——先行建设宁沪杭甬高速磁悬浮列车线

高速磁悬浮列车是 2 1世纪新型的、理想的交通工具 ,具有较多的优越性 ,其技术已趋成熟。我国应跨越轮轨铁路 ,一步到位发展磁悬浮列车。长江三角洲地区经济、社会飞速发展 ,区域需要建立快速、安全、舒适、清洁、节能的高速主通道。先在沪宁线或沪杭甬线上建试验段 ,然后建设宁—沪—杭—甬高速磁悬浮列车线 ,成为区域内实现 2小时经济圈的主通道     

pH-/temperature-sensitive carboxymethyl chitosan/poly(N-isopropylacrylamide-co-methacrylic acid) IPN: preparation,characterization and sustained release of riboflavin

Dual crosslinked pH-/temperature-sensitive interpenetrating polymer networks (IPN) were prepared by free-radical copolymerization of N-isopropylacrylamide and methylacrylic acid (MAA) using N,N′-methylenebisacrylamide as a crosslinker in carboxymethyl chitosan (which was crosslinked by Ca²⁺) aqueous solution. Scanning electron microscopy was used to observe the morphologies of the IPN at different pH values and temperatures. The effects of MAA content and environmental pH on the “pH-/temperature-induced” phase transition behavior of the IPN hydrogels were investigated. The phase transition temperature was adjusted to 37 °C by changing the MAA content. The effects of drug-loaded content, crosslinking density, environmental pH, and temperature on the drug release behavior of the drug-loaded IPN hydrogel were also explored. Based on results, the hydrogel possessed pH/temperature sensitivity. The swelling ratio and phase translation temperature of the hydrogel were lower at lower pH. These values were lowest at pH 3.0. The release behavior of riboflavin was dependent on preparation condition, environmental pH, and temperature. Drug cumulative release was only 6 % at pH 1.8 for 2 h. The drug cumulative release was 13 % before the drug-loaded hydrogel reached the position with pH 6.8. The drug release rate was higher at lower temperature. Therefore, dual-crosslinked hydrogel holds much potential as a drug site-specific carrier.     

调频数字激励器的测量

目前,很多新型调频发射机采用数字激励器,声音质量得到明显改善,技术指标也相应提高,使传统的测量方法和测试仪器受到了一定的限制。本文主要对调频数字激励器几项重要指标的测量进行讨论。     

Eu2O3掺加硼磷酸锂发光玻璃的性能研究

以氧化硼、磷酸二氢铵、碳酸锂、氧化铕为原料,通过高温熔融法制备了发光硼磷酸锂玻璃,确定了Li2O-B2O3-P2O5基础玻璃系统组成;在不同组成系统中掺加Eu2O3,确定发光强度最大的硼磷酸锂系统组成。荧光测试结果表明,Li2O-B2O3-P2O5∶Eu体系中,Eu发光既有613nm的窄带光谱(Eu3+),也有380～550nm的宽带光谱(Eu2+),Eu2+发光强度高于Eu3+发光强度,表明主要以Eu2+形式存在。在Li2O-B2O3-P2O5∶Eu体系中,0.4Li2O-0.4B2O3-0.2P2O5∶Eu体系的Eu2+发光最强。证明Eu2O3在硼磷酸锂玻璃主要以Eu2+存在。     

利用液面推算油层静压方法初探

胜坨油田进入特高含水期后,开采难度日益加大,各种动态监测技术的综合运用显得尤为重要。油井压力的录取是油田开发重要的动态监测手段,压力资料是确定油藏合理注采比、制定注采调整方案的重要依据。在分析传统的推算静压方法的基础上,探索出不停井用利动液面推算静压的新方法。只要取得油井动液面或套压资料,就可以应用该方法推算油层静压,减少高产井关井造成的产量损失。     

与Na(4d)—Na(4f)碰撞能量转移相关联的两步混合激发四波混频

运用与Na_2(A~1∑~+)和Na(4d)相联属的等频两步混合共振四波混频过程,产生了在322.2nm—325.2nm区内可调谐的紫外相干辐射。实验同时表明,该可调谐相干辐射的强度与钠原子4d→4f碰撞能量转移过程密切有关。     

Phosphorylation analysis of G protein-coupled receptor by mass spectrometry: identification of a phosphorylation site in V2 vasopressin receptor

Phosphorylation plays vital roles in the regulation and function of the V2 vasopressin receptor (V2R), a G protein-coupled receptor (GPCR) that is responsible for maintaining water homeostasis in the kidney. Through a combination of immunoaffinity purification, immobilized metal affinity chromatography, and nanoflow liquid chromatography tandem mass spectrometry, we identified a novel phosphorylation site (Ser(255)) in the third intracellular loop of human V2R. We showed that the third intracellular loop could be phosphorylated in vitro by protein kinase A, but not by Akt kinase, although sequence motif analysis predicated otherwise. The analytical procedures and methodologies described in this study should be generally applicable for identifying the endogenous phosphorylation sites in other GPCRs, overcoming the limitations of conventional approaches such as sequence motif analysis and site-directed mutagenesis.     

培育中心镇是中国城镇化的必然规律

我国小城镇量大面广,地域差异大。如何通过中心镇培育,建设一批中小城市,是中国城镇化进程中的战略问题。论文阐述了培育中小城市的目标要求,分析当前中心镇培育工作的发展优势和制约因素,中心镇培育中小城市是当前面临的历史机遇,提出培育中心镇是中国城镇化的必然规律。     

Analysis of nonpremixed multiregion laminar flames through biofuel porous particles considering the effect of heat recirculation

In this study, a comprehensive analysis is conducted to evaluate the effects of heat recirculation and particle porosity on combustion characteristics of multizone counterflow nonpremixed flames fed with porous biofuel particles. For this purpose, the structure of flame contains preheat, postvaporization, and oxidizer zones. Additionally, Lycopodium is considered as the volatile biofuel, especially due to its appreciable flammability and dispensability. Dimensionalized and nondimensionalized forms of mass and energy conservation equations are scrutinized in each zone. To explore of the thermal recirculation effect, a specific term is included in the energy conservation equation. The variation of several parameters, including flame temperature, particle radius, mass fraction of the gaseous fuel and oxidizer, mass particle content, equivalence ratio, and particle porosity, is studied in this work considering and ignoring the thermal recirculation impact. As a result, increasing heat recirculation coefficient from $k=0$ to 1 will rise the flame temperature and shift the flame position to the left side (fuel nozzle). Furthermore, consideration of the thermal heat recirculation will improve the gaseous fuel production in the preheat and postvaporization zones. Additionally, an increase in mass concentration and reduction of particles radius and porosity would lead to a rise in the flame temperature.     

VB环境下刀具数据库管理系统的开发

随着现代数控技术的不断发展和普遍应用,刀具数据库的开发与管理有了极其重要的意义和实际的研究价值.本文在VB环境下,利用开放式数据库互联(ODBC),通过数据库关联和程序设计完成了具有较高适应性的刀具数据库管理系统.通过链接、访问及维护刀具数据库,可有效加强对刀具的管理及合理利用.