用原生质体融合技术选育2－酮基－L－古龙酸高产菌株的研究

对革兰氏阳性的地衣芽孢杆菌（Ｂａｃｉｌｌｕｓｌｉｃｈｅｎｉｆｏｒｍｉｓ）Ｈ１９和革兰氏阴性的２－酮基－Ｌ－古龙酸产生菌Ｓ１９的原生质体的制备条件进行了研究，并采用聚乙二醇作诱导剂进行了两菌株的原生质体融合，用链霉素作为抗性标记对融合子进行了选择。从１７株产生２－酮基－Ｌ－古龙酸的融合子中选出了一株连续传代八次产酸高且产量稳定的融合子１５号。融合子１５号具有两个亲本菌株所具有的一些特性。

车载容迟网络中一种基于真实轨迹的车辆移动模型

车辆移动模型的选择会严重影响车载容迟网络中关键技术的仿真研究结果.现有车辆移动模型大多属于合成移动模型,不符合真实环境.基于车辆真实移动轨迹建立车辆移动模型,考虑了道路拓扑选择、车辆速度控制、车辆初始位置选择以及路口转向选择等因素.在此基础上,进一步分析了模型对实际车辆行为模拟的接近程度、车辆的分布特性,以及基于该模型的网络连接特性.结果表明,提出的模型能够真实地逼近现实环境中车辆的实际行为.

经济全球化下的区域经济空间结构演化研究评述

近50年以来,交通与通讯技术的迅猛发展使以往许多限制生产活动区位选择的本地化生产要素丧失了固有的垄断性,国际金融市场自由化降低了资本流通的障碍,标准化生产减少了对工人特殊技能的依赖,因此跨国公司可以在全球范围组织生产活动,但是技术创新和知识创新又极大地突出了地区企业集聚、地区创新环境的重要性。因此在经济全球化时期,生产活动的空间区位呈现出复杂的集聚或扩散趋势,区域经济空间结构表现为特殊的形式和规律。在最近20年的地理学研究中,出现了大量关于经济全球化时代区域空间结构的讨论。以跨国公司对生产活动空间区位的影响为主线,对近10年来国内外关于经济全球化时期区域空间结构研究的主要热点问题和观点予以综述。

农业干旱风险评估研究综述

对农业干旱风险致险性、脆弱性及损失模型等方面进行了深入系统的回顾与评述,阐述了农业干旱风险研究的前沿领域和学术问题,展望了农业干旱风险未来的发展趋势:农业干旱致险性评估的关键是构建合适的干旱指标,目前干旱评估指标很多,大致可分为水分变异程度指标、干旱发展过程指标和干旱空间差异指标三类,但多数指标对农业干旱成灾过程反映不足,在评估方法上对农业干旱灾害机理认识不深入,成为了农业致险性评估的瓶颈;农业干旱脆弱性通常决定着农业干旱风险的高低,其中,灌溉能力、技术、资金等是影响农业脆弱性高低的重要因子,而定量刻画农

太阳辐射对长白山阔叶红松林净生态系统碳交换的影响

太阳辐射是植物进行光合作用的前提条件,因此成为影响植被吸收大气CO2的重要环境因子。该研究基于30min通量和常规气象数据,以相对辐射和晴空指数为指标,分析了2003～2006年生长旺季(6～8月)太阳辐射的改变对长白山阔叶红松(Pinuskoraiensis)林净生态系统碳交换(Netecosystemexchange,NEE)的影响。结果表明:天空有一定云层的覆盖对阔叶红松林碳的净吸收有明显的促进作用。4年里6～8月间生态系统最大光合速率在天空有云覆盖时较晴空条件下分别提高了34%、25%、4%和11

磺化POSS的合成及其与聚电解质的组装

合成了具有立方笼状结构的磺化八苯取代倍半硅氧烷(SOPS),经红外光谱(FTIR)及核磁共振波谱(NMR)分析,确认了产物的结构。用携带负电荷的SOPS与聚丙烯胺(PAH)进行层层组装,制备了纳米复合超薄膜。

Studies on the components of crude and processed Fructus Corni by ESI-MSn

The components of crude and processed Fructus Corni were investigated by means of electrospray ionization-tandem mass spectrometry(ESI-MSn) technique in the negative ion mode. Compared with those of crude Fructus Corni, the chemical components of the processed Fructus Corni were changed both in quality and in quantity. From the ESI-MS spectra of the crude and processed Fructus Corni, six peaks were selected to establish the characteristic ESI-MS peaks. Several factors in the processing procedure were examined.

Vertical structure p-type permeable metal-base organic transistors based on N,N '-diphentyl-N,N '-bis(1-naphthylphenyl)-1,1 '-biphenyl-4,4 '-diamine

In this article, vertical structure p-type permeable-base organic transistors were proposed and demonstrated. A hole-type organic semiconductor N,N-'-diphentyl-N,N-'-bis(1-naphthylphenyl)-1,1(')-biphenyl-4,4(')-diamine was used as emitter and collector. In the permeable-base transistors, the metal base was formed by firstly coevaporating Al and Ca in vacuum and then annealing at 120 degrees C for 5 min in air, followed by a thin Al deposition. These devices show a common-base current gain of near 1.0 and a common-emitter current gain of similar to 270.

Structure and mechanical properties of extruded Mg-Gd based alloy sheet

The Mg-8Gd-2Y-1Nd-0.3Zn-0.6Zr (wt.%) alloy sheet was prepared by hot extrusion technique, and the structure and mechanical properties of the extruded alloy were investigated. The results show that the alloy in different states is mainly composed of alpha-Mg solid solution and secondary phases of Mg5RE and Mg24RE5 (RE = Gd, Y and Nd). At aging temperatures from 200 degrees C to 300 degrees C the alloy exhibits obvious age-hardening response. Great improvement of mechanical properties is observed in the peak-aged state alloy (aged at 200 degrees C for 60 h), the ultimate tensile strength (sigma(b)), tensile yield strength (sigma(0.2)) and elongation (epsilon) are 376 MPa, 270 MPa and 14.2% at room temperature (RT), and 206 MPa. 153 MPa and 25.4% at 300 degrees C, respectively, the alloy exhibits high thermal stability.

Temperature and pressure dependence of phase separation of trans-decahydronaphthalene/polystyrene solution

The cloud-point temperatures (T-c1's) of ti-ans-decahydronaphthalene (TD)/polystyrene (PS, M-w = 270 kg/mol) solutions were determined by fight scattering measurements over a range of temperatures (1-16 degreesC), pressures (100-900 bar), and compositions (4.2-21.6 vol% polymer). The system phase separates upon cooling and the T-c1 was found to increase with the rising pressure for the constant composition. In the absence of special effects this finding indicates positive excess volumes. The special attention was paid to the demixing temperatures as a function of the pressure for the different polymer solutions and the plots in the T-volume fraction plane and P-volume fraction plane. The cloud-point curves of polymer solutions under changing pressures were observed for different compositions, demonstrates that the TD/PS system exhibits UCST (phase separation upon cooling) behavior. With this data the phase diagrams under pressure were calculated applying the Sanchez-Lacombe (SL) lattice fluid theory. Furthermore, the cause of phase separation, i.e., the influence of Flory-Huggins (FH) interaction parameter under pressure was investigated.

Pressure effects on the thermodynamics of trans-decahydronaphthalene/polystyrene polymer solutions: Application of the Sanchez-Lacombe lattice fluid theory

The cloud-point temperatures (T-cl's) of trans-decahydronaphthalene(TD)/polystyrene (PS, (M) over bar (w) = 270 000) solutions were determined by light scattering measurements over a range of temperatures (1-16degreesC), pressures (100-900 bar), and compositions (4.2-21.6 vol.-% polymer). The system phase separates upon cooling and T-cl was found to increase with rising pressure for constant composition. In the absence of special effects, this finding indicates positive excess volume for the mixing. Special attention was paid to the demixing temperatures as a function of pressure for different polymer solutions and the plots in the T-phi plane (where phi signifies volume fractions). The cloud-point curves of polymer solutions under different pressures were observed for different compositions, which demonstrated that pressure has a greater effect on the TD/PS solutions when far from the critical point as opposed to near the critical point. The Sanchez-Lacombe lattice fluid theory (SLLFT) was used to calculate the spinodals, the binodals, the Flory-Huggins (FH) interaction parameter, the enthalpy of mixing, and the volume changes of mixing. The calculated results show that modified PS scaling parameters can describe the thermodynamics of the TD/PS system well. Moreover the SLLFT describes the experimental results well.