燃料气中H_2、N_2、O_2、CH_4、CO、O_2的全分析

从生物质汽化制取的燃料气，其主要成份是 CO_2、H_2、O_2、N_2、CH_4、CO 六种气体。但在不同的工艺条件下，各组份的含量差异很大。在工艺试验中，需要及时监测各种组份含量的变化，摸索最佳工艺条件，这就要求缩短分析周期。为此我们改装了一台 SP-2307色谱仪。用 Ar 作载气，只用一个热导检测器，一次进样就可完成上述六种气体的分析。改装时增加气体自动进样系统，提高了分析的准确度。

量子阱共振腔增强型光电探测器的高功率特性

通过测量1.55 μm量子阱共振腔增强型光电探测器的光电流随反向电压和光功率的变化关系,以及模拟能带结构、电场分布等特性,研究了量子阱共振腔增强型光电探测器的高功率特性.分析了光电流的产生机制,测量了1.064 μm量子阱共振腔增强型光电探测器的光电响应,模拟了具有不同势垒高度的量子阱共振腔增强型光电探测器的光电响应.从实验和模拟两方面证明了量子阱的势垒高度是影响量子阱共振腔增强型光电探测器高功率特性的最主要因素.

High-Power and High-Efficiency 650nm-Band AlGaInP Visible Laser Diodes Fabricated by Ion Beam Etching

High power and high-slope efficiency 650nm band real-refractive-index ridge waveguide AlGaInP laser diodes with compressive strained MQW active layer are formed by pure Ar ion beam etching process.Symmetric laser mesas with high perpendicularity,which are impossible to obtain by traditional wet etching method due to the use of a 15°-misoriented substrate,are obtained by this dry etching method.Laser diodes with 4μm wide,600μm long and 10%/90% coat are fabricated.The typical threshold current of these devices is 46mA at room temperature,and a stable fundamental-mode operation over 40mW is obtained.Very high slope efficiency of 1.4W/A at 10mW and 1.1W/A at 40mW are realized.

~(19)F+~(93)Nb耗散反应产物不重复截面的分析

完成了19F +93 Nb耗散反应产物激发函数的两次独立测量 ,入射束流的能量从 10 2MeV到10 8MeV ,步长 2 5 0keV .实验结果在一些相同能量点两次测量的截面不能重复 .分析表明 :能量自关联函数的离散程度大约相当于随机计数率引起的离散程度的 3倍 ;激发函数曲线相对于能量平均本底的几率分布 ,有大约 2 1髎超出了标准高斯分布宽度的 3倍 ;两次测量得到的截面之差的几率分布大约有 18髎也超出了标准高斯分布宽度的 3倍 .可见 ,两次测量的19F +93 Nb耗散反应产物激发函数的截面不重复性具有明确的统计意义 ,其来源不是计数率的随机涨落 .

历史时期黄土高原生态环境建设分析

采用科学史观简要分析了黄土高原生态环境演变的历史过程。通过分析认为 ,历史时期的黄土高原生态环境演变不再单纯表现为自然过程 ,而是与人类活动密切相关的人地互动过程。人为因素黄土高原生态环境历史演变具有双重意义 ,既通过耕种对自然环境破坏 ,还进行农业生态环境建设 ,提高土地承载能力 ,其主要是由不同的环境观和社会因素造成的。人类对生态环境影响以资源利用为主 ,有意识的建设活动较少 ,农业生态环境建设成就巨大 ,生态环境演变具有明显历史进程 ,被动的生态环境保护和恢复对生态环境演变有特殊意义 ,历史时期黄土高原农业生态环境建设实践及其成效在农田水利环境、土壤环境、水土保持等方面表现突出。历史时期生态环境建设研究具有现实意义 ,在当今西部大开发机遇下 ,应借鉴历史经验 ,加快黄土高原生态环境建设。建议采用科学的环境观指导实践 ,加大科技投入和市场调剂 ,减小黄土高原地区粮食压力 ,实现较劣土地的生态恢复 ,使自然生态环境修复和农业生态环境建设同步进行 ,建设结构合理的水土保持型大农业生态环境。

水稻外观品质稳定性分析及G×E互作与气候因子的关系

基于AMM I模型,研究了25个水稻品种外观品质性状与环境的交互作用,并对参试品种垩白品质性状的稳定性、G×E互作与气候因子的关系及气候生态适应性进行了探讨。结果表明,稻米长、宽及长宽比的G×E互作效应差异不显著,垩白率和垩白度的G×E互作效应达到了1%的显著水平。在此基础上将参试品种分为稳定性最好垩白适中、稳定性适中垩白较小及稳定性和垩白性状均较差三类。垩白品质性状的iPCA与水稻生育期内的气温、日照、降雨的相关分析表明气候因子是决定G×E互作的一项重要环境因子。据此得到不同品种对气候因子的最佳品质适应性,如品种V 9和V 24(沈农9819和0142)的垩白率对温度较低的环境,V 23(盐优5858)的垩白度对相对寡照高温的环境具有特殊适应性,在实际生产中选择与这些品种有负向互作的地点可获得较低的稻米垩白率和垩白度。

Biodegradable amphiphilic polymer-drug conjugate micelles

The coupling of drugs to macromolecular carriers received an important impetus from Ringsdorf's notion of polymer-drug conjugates. Several water-soluble polymers, poly(ethylene glycol), poly[N-(2-hydroxypropyl) methacrylamidel, poly(L-glutamic acid) and dextran, are studied intensively and have been utilized successfully in clinical research. The promising results arising from clinical trials with polymer-drug conjugates (e.g., paclitaxel, doxorubicin, camptothecins) have provided a firm foundation for other synthetic polymers, especially biodegradable polymers, used as drug delivery vehicles. This review discusses biodegradable polymeric micelles as an alternative drug-conjugate system. Particular focus is on A-B or B-A-B type biodegradable amphiphilic block copolymer such as polylactide, morpholine-2,5-dione derivatives and cyclic carbonates, which can form a core-shell micellar structure, with the hydrophobic drug-binding segment forming the hydrophobic core and the hydrophilic segment as a hydrated outer shell. Polymeric micelles can be designed to avoid uptake by cells of reticuloendothelial system and thus enhance their blood lifetime via the enhanced permeability and retention effect.

Submesoscale activity over the shelf of the northern South China Sea in summer: simulation with an embedded model

We applied a primitive equation ocean model to simulate submesoscale activities and processes over the shelf of the northern South China Sea (NSCS) with a one-way nesting technology for downscaling. The temperature and density fields showed that submesoscale activities were ubiquitous in the NSCS shelf. The vertical velocity was considerably enhanced in submesoscale processes and could reach an average of 58 m per day in the subsurface. At this point, the mixed layer depth also was deepened along the front, and the surface kinetic energy also increased with the intense vertical movement induced by submesoscale activity. Thus, submesoscale stirring/mixing is important for tracers, such as temperature, salinity, nutrients, dissolved organic, and inorganic carbon. This result may have implication for climate and biogeochemical investigations.