空间F^＊上一类积分方程解的存在和唯一性

本文在引文［１—４］的基础出上，首次在空间~Ｆ＊上构造性的建立了一类积分方程。并获得了这类积分方程解的存在和唯一性定理。     

受乳糖启动子控制的基因表达过程的优化

借助于ＳＤＳ－聚丙烯酰胺凝胶电泳分析方法，对乳糖诱导的由乳糖启动子控制的大肠杆菌ＲＮＡ聚合酶σ７０因子基因表达过程进行了优化研究．结果表明，含此融合基因的大肠杆菌菌株ＢＬ２１（ＤＥ３）ｐＧＥＭＤ的生长量达到ＯＤ６００ｎｍ＝１．０时，用终浓度为０．０８％的乳糖进行连续５ｈ的诱导，可使大肠杆菌ＲＮＡ聚合酶σ７０因子基因的表达量达到最大，并达到ＩＰＴＧ同样的诱导效果．流加低浓度的乳糖溶液能增加σ７０因子的合成量，但是促进作用不很显著．     

Ge_xSi_(1-x)/Si超晶格中周期不均匀对折叠声学声子拉曼线宽的影响

本文报导了在 Ge_Si_(1-x)/Si 超晶格中观察到了超晶格周期不均匀导致的折叠声学声子拉曼谱线展宽,这种谱线展宽与折叠指数(m)有关,折叠声学声子的谱线越宽,m 相同的折叠声学声子具有相同的线宽。     

Crystallization of (Bi,Nd)4Ti3O12 films in N2 environment by chemical solution deposition

(Bi,Nd)₄Ti₃O₁₂ (BNT) ferroelectric films were deposited on Pt/Ti/SiO₂/Si substrates by chemical solution deposition and crystallized in an N₂ environment after pre-annealing in air at 500 °C. The effect of crystalline temperature on the structural and electrical properties of the BNT films was studied. The BNT films annealed in N₂ in the temperature range of 630 °C to 670 °C were crystallized well and the average grain size increased with increasing crystalline temperature, while the remanent polarization and dielectric constant of the films are not a monotonic function of the crystalline temperature. The BNT films crystallized at 650 °C have the largest remanent polarization value of 2P_r=63.6 μC/cm², a dielectric constant of 344 at 10 kHz, and a fatigue-free characteristic. A positive correlation between the remanent polarization and the dielectric constant of the BNT films has been observed. PACS 81.20.Fw; 81.40.Ef; 77.84.-s     

q-deformed boson-realization model applied to vibrational spectrum of sulfur dioxide

Aq-deformed boson-realization model is presented to study both stretching and bending vibrations of sulfur dioxide, where Fermi resonances are taken into account. Our results are compared with those of other models.     

A Monte Carlo study of the thermal properties of Cu3Au low index surfaces

The thermal dependencies of composition and order of the (111), (100) and (110) Cu₃Au surfaces are studied at the atomic scale by means of Monte Carlo simulations in the “transmutational” ensemble at constant volume. The question addressed is the extent to which such simulations carried on with a model N-body potential designed on the basis of bulk energetic and mechanical properties allow predictions consistent with experimental observations of the surface. Although the currently available experimental data still leave unanswered questions, many of them allow for comparison with modelling. Qualitative agreement is found for temperature dependencies of both surface composition and order, and the simulation results are discussed in detail. Some clear discrepancies are found as well, in particular (but not only) in the case of the (110) surface and its first neighbouring layer. Although the origin of such differences is not yet clear, it is suggested that they may serve to assess and to improve the model in the light of quantitative surface studies.     

Asymptotically optimal production policies in dynamic stochastic jobshops with limited buffers

We consider a production planning problem for a jobshop with unreliable machines producing a number of products. There are upper and lower bounds on intermediate parts and an upper bound on finished parts. The machine capacities are modelled as finite state Markov chains. The objective is to choose the rate of production so as to minimize the total discounted cost of inventory and production. Finding an optimal control policy for this problem is difficult. Instead, we derive an asymptotic approximation by letting the rates of change of the machine states approach infinity. The asymptotic analysis leads to a limiting problem in which the stochastic machine capacities are replaced by their equilibrium mean capacities. The value function for the original problem is shown to converge to the value function of the limiting problem. The convergence rate of the value function together with the error estimate for the constructed asymptotic optimal production policies are established.     

空间应用的低温工质

介绍了低温流体在低温低压近临界区以及稀薄状态下的特殊性质,并详细介绍了几种低温工质的特点以及它们在空间技术中的应用。