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971.
结合点正则变换(PCT)与分析转移矩阵(ATM)两种方法,得到了零势场中变质量粒子的束缚能谱.通过计算变质量粒子穿透零势场的概率,发现并解释了透射谱中共振峰与本征能量的一一对应关系.  相似文献   
972.
针对氧碘化学激光器的金属喷管在使用过程中需加热保温且存在结构复杂、故障率高等问题,初步选择了几种可用于加工无加热喷管的非金属材料,并以kW级氧碘化学激光器为原型,以聚酰亚胺为例,对激光器运行条件下的喷管温度场进行数值模拟,以验证此种非金属无加热喷管的可行性。结果表明:与金属喷管相比,非金属喷管在不加热保温的情况下能够有效阻止热量传递,防止碘蒸气冷却凝结,满足激光器喷管的使用要求。  相似文献   
973.

Background  

Opioid agonist drugs produce analgesia. However, long-term exposure to opioid agonists may lead to opioid dependence. The analgesic and addictive properties of opioid agonist drugs are mediated primarily via the mu-opioid receptor (MOR). Opioid agonists appear to alter neuronal morphology in key brain regions implicated in the development of opioid dependence. However, the precise role of the MOR in the development of these neuronal alterations remains elusive. We hypothesize that identifying and characterizing novel MOR interacting proteins (MORIPs) may help to elucidate the underlying mechanisms involved in the development of opioid dependence.  相似文献   
974.
<正>A non-destructive technique for subsurface measurements is proposed by combining light scattering method with laser confocal scanning tomography.The depth and distribution of subsurface defect layers are represented in term of scattered light intensity pattern,and three types of fused silica specimens are fabricated by different grinding and polishing processes to verify the validity and effectiveness.By using the direct measurement method with such technique,micron-scale cracks and scratches can be easily distinguished,and the instructional subsurface defect depths of 55,15,and 4μm are given in real time allowing for an in-process observation and detection.  相似文献   
975.
We report the design and fabrication of a novel and fully integrated polymer-based centrifugal microfluidic disc for rapid automatic allergens detection. All essential steps for a single test including flow valving, sequencing, mixing, separation, extraction, and sedimentation for final detection are automatically conducted within 30 min on a centrifugal microfluidic disc. Our design features a siphon-based valving and analyte extraction structure where the released analyte is separated and subsequently extracted by a siphon valve into the detection chamber. Incorporating the siphon valve and a series of capillary valves, we realize automated detection of allergic reaction on a centrifugal microfluidic disc.  相似文献   
976.
Let be a domain in , . Let be a divergence form uniformly elliptic operator with Dirichlet boundary conditions on and Neumann boundary conditions on , where is a closed subset of . We prove intrinsic ultracontractivity for the semigroup associated to the Schrödinger operator , where is a potential in the Kato class, provided that is locally Lipschitz and is given by the boundary of either a Hölder domain of order or a uniformly Hölder domain of order , . Our results extend to the mixed boundary case the results of Bañuelos, Bass and Burdzy, Bass and Hsu, and Davies and Simon.  相似文献   
977.
Quantized rotation of atoms from photons with orbital angular momentum   总被引:1,自引:0,他引:1  
We demonstrate the coherent transfer of the orbital angular momentum of a photon to an atom in quantized units of variant Planck's over 2pi, using a 2-photon stimulated Raman process with Laguerre-Gaussian beams to generate an atomic vortex state in a Bose-Einstein condensate of sodium atoms. We show that the process is coherent by creating superpositions of different vortex states, where the relative phase between the states is determined by the relative phases of the optical fields. Furthermore, we create vortices of charge 2 by transferring to each atom the orbital angular momentum of two photons.  相似文献   
978.
Coordination of the carbocyclic ring of hydroquinones to electrophilic transition-metal fragments such as Mn(CO)3+ and Rh(COD)+ produces stable pi-bonded eta6-complexes that are activated to facile reversible deprotonation of the -OH groups. The deprotonations are accompanied by electron transfer to the transition metal, which acts as an internal oxidizing agent or electron sink. With manganese as the metal, the resulting eta5-semiquinone and eta4-quinone complexes have been used to synthesize one- two- and three-dimensional polymeric metal-organometallic coordination networks. With rhodium as the metal, the pi-quinonoid complexes have been demonstrated to play a unique role in multifunctional C-C coupling catalysis and in the synthesis of new organolithium reagents. Both classes of pi-quinonoid complexes appear to have significant applications in nanochemistry by providing an excellent vehicle for templating the directed self-assembly of nanoparticles into functional materials.  相似文献   
979.
Two cyclic diarylheptanoids, garugamblin-3 (1) and acerogenin L (2), isolated from the MeOH extract of the fruits of Alnus japonica Steud., inhibited human low-density lipoprotein (LDL) oxidation in the thiobarbituric acid-reactive substance assay with IC50 values of 2.9 and 1.7 microM, respectively, and they also inhibited cell-mediated LDL oxidation more than five times more strongly than that of a well-known antioxidant, probucol, at a concentration of 10 microM. 1 had no effect on the anti-atherogenesis in low-density lipoprotein receptor- deficient mice.  相似文献   
980.
Novel Zn1-xMnxSe one-dimensional nanostructures-straight nanowires (x = 0.1 and 0.3), zigzagged nanobelts (x = 0.4), and toothed nanosaws (x = 0.4)-were synthesized using the chemical vapor deposition method. They all consisted of single-crystalline wurtzite ZnSe crystals, irrespective of the Mn content. In particular, the nanosaws have a unique structure in which double-sided teeth are rooted in the nanowire core and bent so as to align as two parallel rows. The long axis is parallel to the [010] direction, and all of the teeth have the [0001] growth direction. The X-ray diffraction pattern confirms the formation of wurtzite ZnSe crystal and the decrease of the lattice constant owing to Mn doping. The Mn2+ emission at 2.1 eV (appeared below 100 K), originating from the d-d (4T1 --> 6A1) transition, proves the effective substitution of Mn2+ ions at the tetrahedral coordinate sites.  相似文献   
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