夫伦克耳激子的运动

本文从晶格模型出发,同时考虑周期场和电子-声子相互作用对激子能态的影响。夫伦克耳激子在晶格中运动有两种不同方式:在低温区,是能带传递;在高温区,是跳跃过程。     

Energy flow and community structure in freshwater ecosystems

The goal of this article is twofold: 1) It aims at providing an overview on some major results obtained from energy flow studies in individuals, populations, and communities, and 2) it will also focus on major mechanisms explaining community structures. The basis for any biological community to survive and establish a certain population density is on the one hand energy fixation by primary producers together with adequate nutrient supply and the transfer of energy between trophic levels (bottom-up effect). On the other hand, predator pressures may strongly control prey population densities one or more trophic levels below (top-down effect). Other interpopulation effects include competition, chemical interactions and evolutionary genetic processes, which further interact and result in the specific structuring of any community with respect to species composition and population sizes.     

合肥地区高校安居园工程可行性研究

文章针对合肥地区高校教师住房面积普遍偏小,尤其是中青年教师住房十分困难。经过对合肥地区高等院校教师现有住房情况的调研,提出了建造高等院校教师安居园工程的设想及实施方案,对实施“科教兴皖”的战略方针具有现实意义。     

贫困地区如何发展农业产业化（一）

山西省是全国主要的贫困省份之一。实施主导产业覆盖贫困乡村战略,搞农业产业化开发是山西省脱贫的有效途径。文章论述了贫困地区发展农业产业化的必要性及其难点,提出了贫困地区发展农业产业化的对策     

单模光纤的偏振特性分析

本文分析了性能不完善的单模光纤产生偏振特性的机理,并解释了偏振特性引起的几种物理现象,论证了性能完善的单模光纤不存在偏振特性。     

2,3-二羟基哌嗪与几种氨基化合物的缩合反应研究

由乙二胺与乙二醛的缩合物２,３－二羟基哌嗪,分别与甲酰胺、脲和乙二胺反应,制得２,４,７,９,１１,１４－六氮杂三环［８,４,０,０３,８］十四烷六盐酸盐四水合物（１）,２,５,７,９－四氮杂双环［４,３,０］壬－８－酮二盐酸盐－水合物（２）和２,５,７,１０－四氮杂双环［４,４,０］癸烷（３）。化合物１为未见文献报道的新化合物。化合物２的合成工艺条件优化后,反应得率与文献［１］相比有一定提高。化合物３的合成,由于将反应分为低温和高温两个缩合阶段,使反应得率提高到７７．５％。     

大立体角多参数电离室

因重离子核物理研究工作研究,研制成功灵敏区深庶３５ｃｍ的大立体角多参数电离室,可同 量信号△Ｅ、Ｅ和位置信号Ｘ、Ｙ等多项参数。     

The v-v energy transfer of highly vibrationally excited states (I)

The relaxation of the highly vibrationally excited CO (v = 1–8) by CO₂ is studied by timeresolved Fourier transform infrared emission spectroscopy (TR FTIR). 193 nm laser photolysis of the mixture of CHBr₃ with O₂ generates the highly vibrationally excited CO(v) molecules. TR FTIR records the intense infrared emission of CO(v→v-1). The vibrational populations of each level of CO(v) have been determined by the method of spectral simulation. Based on the evolution of the time resolved populations and the differential method, 8 energy transfer rate constants of CO(v = 1–8) to CO₂ molecules areobtained: (5.7±0.1), (5.9±0.1), (5.2±0.2), (3.4±0.2), (2.4±0.3), (2.2±0.4), (2.0±0.4) and (1.8±0.6) (10¹⁴ cm³ · molecule⁻¹ · s⁻¹), respectively. A two-channel energy transfer model can explain the feature of the quenching of CO(v) by CO². For the lower vibrational states of CO, the vibrational energy transfers preferentially to the u³ mode of CO² For the higher levels, the major quenching channel changes to the vibrational energy exchange between CO(v→v-1) and the u¹ mode of CO².     

The v-v energy transfer of highly vibrationally excited states (II)

The vibrational energy transfer from highly vibrationally excited CO to H₂O molecules is studied by time-resolved Fourier transform infrared emission spectroscopy (TR FTIR). Following the 193 nm laser photolysis of CHBr₃ and O₂ the secondary reactions generate CO(v). The infrared emission of CO(v → v−1) is detected by TR FTIR. The excitation of H₂O molecules is not observed. By the method of the spectral simulation and the differential technique, 8 rate constants for CO(v)/H₂O system are obtained: (1.7 ±0.1), (3.4 ±0.2), (6.2 ±0.4), (8.0 ±1.0), (9.0 ±2.0), (12 ±3), (16 ±4) and (18 ±7) (10¹³cm³ · molecule^-1· s^-1). At least two reasons lead to the efficient energy transfer. One is the contributions of the rotational energy to the vibational energy defect and the other is the result of the complex collision. With the SSH andab initio calculations, the quenching mechanism of CO(v) by H₂O is suggested.