On estimates for the Fourier-Bessel integral transform in the space <Emphasis Type="Italic">L</Emphasis><Subscript>2</Subscript>(ℝ<Subscript>+</Subscript>)

Two estimates useful in applications are proved for the Fourier-Bessel integral transform in L ₂(?₊) as applied to some classes of functions characterized by a generalized modulus of continuity.     

变系数反馈移位寄存器及其序列的几个性质

本文给出了一类新的密钥流生成器一变系数反馈移位寄存器,得到了该密钥流生成器序列的几个重要的密码学性质,并在文中给出了严格的数学证明。     

Operationally convenient asymmetric synthesis of (S)- and (R)-3-amino-4,4,4-trifluorobutanoic acid: Part II. Enantioselective biomimetic transamination of 4,4,4-trifluoro-3-oxo-N-[(R)-1-phenylethyl]butanamide

An asymmetric synthesis of (S)- and (R)-3-amino-4,4,4-trifluorobutanoic acid via DBU-catalyzed asymmetric 1,3-proton shift transfer reaction of (Z)-3-[(R)-1-phenylethylamino]-4,4,4-trifluoro-N-[(R)-1-phenylethyl]but-2-enamide has been developed. The intermediate Schiff base (S,R′)-9 was found to be relatively configurationally stable under the highly basic reaction conditions allowing preparation of the target amino acid in high chemical yield and enantioselectivity. This method was demonstrated to be practical for large (>25 g) scale synthesis of the target β-amino acid.     

六聚吡咯/丝组缀合物结构的NMR和 ESI-MS/MS表征

利用片断合成法合成了具有DNA切割能力的六聚吡咯/丝组缀合物, 检测了该化合物的¹H、¹³C NMR 和ESI-MS/ MS 图谱, 确证了该化合物的结构, 通过¹H-¹H COSY, HSQC,HMBC等2D NMR 技术对其¹H 和¹³C NMR 数据进行了归属和解析, 并探讨了其ESI-MS/ MS 质谱裂解规律.     

Epicocconone, A New Cell-Permeable Long Stokes' Shift Fluorescent Stain for Live Cell Imaging and Multiplexing

Epicocconone is a heterocyclic natural product from the fungus Epicoccum nigrum that fluoresces weakly in the green (520 nm). However, cells exposed to epicocconone rapidly absorb the dye and become bright orange fluorescent because the natural product reacts reversibly with proteins. The orange fluorescence is enhanced in lipophilic environments, allowing the visualization of membranous organelles and lipid rafts but does not stain oligonucleotides. As the unconjugated dye has no orange fluorescence, there is no need to wash out the excess fluorophore. Epicocconone is a neutral, non-toxic, small molecule that appears to diffuse readily into live of fixed cells without the need for permeabilization. These features enable the real-time imaging of live cells and the study of organelle movements. Cells stained with epicocconone are excitable by common lasers (UV, 405, 488, and 532 nm) and its long Stokes' shift allows multiplexing applications with more common short Stokes' fluorophores using a single light source.     

Simple Scheme for Realizing the General Conditional Phase Shift Gate and aSimulation of Quantum Fourier Transform in Circuit QED

We propose a theoretical scheme for realizing the generalconditional phase shift gate of charge qubits situated in ahigh-Q superconducting transmission line resonator. Thephase shifting angle can be tuned from 0 to 2π by simplyadjusting the qubit-resonator detuning and the interaction time.Based on this gate proposal, we give a detailed procedure toimplement the three-qubit quantum Fourier transform withcircuit quantum electrodynamics (QED). A careful analysis of thedecoherence sources shows that the algorithm can be achieved with ahigh fidelity using current circuit QED techniques.     

Coherent Control of the Goos-Hänchen Shifts in a Four-Level N Type Atomic Medium

The behavior of the Goos-Hänchen (GH) shifts of the reflected and transmitted probe light beams is theoretically investigated. In a fixed geometrical configuration, the effect of quantum interference induced by spontaneous emission on the phase control of the GH shifts is analyzed in this paper. It is found that in a four-level N-type atomic system as an intracavity medium, the GH shifts of the reflected and transmitted probe light beam are completely phase dependent.     

介质阻挡放电中点线放电的谱线线型及振动温度

在氩气/空气的混合气体近大气压介质阻挡放电中,首次观察到点状与线状放电共存的放电现象, 测量比较了点状与线状放电的谱线频移和振动温度。谱线频移的测量利用的是氩原子ArⅠ(2P₂→1S₅)的发射谱线,振动温度的测量利用的是氮分子第二正带系(C3Π_u→B3Π_g) 的发射谱线。结果表明：点放电中的ArⅠ(2P₂→1S₅)谱线的频移大于线放电谱线的频移,表明前者电子密度较高;而点放电振动温度低于线放电的振动温度。     

氢原子钟壁移的测量和消除

指出了克服氢原子钟壁移问题的必要性. 给出了一种测量氢钟壁移的简易方法,讨论了减小壁移的技术. 该文的方法和技术有助于进一步改善氢原子钟的长期稳定度.     

水溶性镧系位移试剂对羟基脯氨酸的手性识别

用¹H NMR和¹³ C NMR研究了水溶性镧系位移试剂Sm-pdta对反式-4-羟基脯氨酸的手性识别. 反式-4-羟基脯氨酸与Sm-pdta形成络合物后,其¹H NMR和¹³C NMR图谱的化学位移有所变化,手性碳附近的某些原子所对应的吸收峰裂分为2组信号,分别对应反式-4-羟基脯氨酸的两种对映异构体. 结果显示,对于反式-4-羟基脯胺酸, Sm-pdta是一个既方便又有效的手性位移试剂.