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981.
Two complemental 2′-phosphorothioate oligo-DNA compounds were used as linker molecules to provide the necessary symmetry-breaking mechanism to direct the assembly of 13 nm Au nanoparticles into aggregates with anisotropic optical properties. 相似文献
982.
983.
984.
Brown CN Awes TC Beddo ME Brooks ML Bush JD Carey TA Chang TH Cooper WE Gagliardi CA Garvey GT Geesaman DF Hawker EA He XC Isenhower LD Kaplan DM Kaufman SB Kirk PN Koetke DD Kyle G Lee DM Lee WM Leitch MJ Makins N McGaughey PL Moss JM Mueller BA Nord PM Papavassiliou V Park BK Peng JC Petitt G Reimer PE Sadler ME Sondheim WE Stankus PW Thompson TN Towell RS Tribble RE Vasiliev MA Webb JC Willis JL Wise DK Young GR;FNAL E/NuSea Collaboration 《Physical review letters》2001,86(12):2529-2532
We present a measurement of the polarization observed for bottomonium states produced in p-Cu collisions at square root of s = 38.8 GeV. The angular distribution of the decay dimuons of the Upsilon(1S) state shows no polarization at small values of the fractional longitudinal momentum x(F) and transverse momentum p(T) but significant positive transverse production polarization for either p(T)>1.8 GeV/c or for x(F)>0.35. The Upsilon(2S+3S) (unresolved) states show a large transverse production polarization at all values of x(F) and p(T) measured. These observations challenge NRQCD calculations of the polarization expected in the hadronic production of bottomonium states. 相似文献
985.
Ying-guang Shi 《计算数学(英文版)》2001,19(2):151-156
1. IntroductionThis note deals with convergence of (0,1,2,3) illterpolation on an arbitrary system of nodes.Fisrt we illtroduce some definitions and notations.LetGiven a fiXed even integer m, let Ajk 6 Pm.--1 (the set of polynomials of degree at most mn-- 1)satisfyThen the (0,1,...,m--1) Hermite--Fej6r type illterpolation for f 6 C[--1, 1] is defined byand the (0,1,...,m--1) Hernilte interpolation for f e Cd--'[--1, 1] is defined by(of. [6]). We also need a well known fact:where 11' 11 sta… 相似文献
986.
氧化钼-二氧化钛复合膜的可见光致变色性能研究 总被引:3,自引:0,他引:3
采用溶胶凝胶法制备了一系列氧化钼-二氧化钛纳米复合物, 用柠檬酸作分散剂, 将得到的纳米复合物粉末分散成溶胶, 涂膜制备了具有可见光变色性能的均匀透明的光致变色(λ≥420 nm)复合膜. 通过红外、XPS、ESR测定表明, 在氧化钼、二氧化钛复合界面上生成了Mo—O—Ti键, 此键的存在是该复合膜具有可见光致变色响应的内在原因. 在可见光的照射下, 电子从二氧化钛的价带经由Mo—O—Ti键, 被激发到氧化钼的导带上. 研究了光致变色过程的动力学, 发现光致变色反应的速率取决于膜中复合物的摩尔比([MoO3]/[TiO2])以及电荷转移能量(CTE). 相似文献
987.
根据研究发现, 在有醇作助表面活性剂的CTAB反胶束中木素过氧化物酶(LiP)不能表现活力, 而在水介质中CTAB对LiP的催化活性影响又不是很大. 为了揭示其中醇的影响, 本工作就不同碳链长度的醇对LiP酶催化性能的影响进行了研究. 由于CTAB反胶束体系中醇浓度较高, 且碳原子数大于4的直链醇在水中的溶解度又很小, 为此采用了LiP可在其中显示催化活性的CTAB正胶束、AOT反胶束和Brij30反胶束作介质, 通过研究这些介质中不同链长的醇对LiP催化活力的影响, 来探讨CTAB反胶束中木素过氧化物酶(LiP)不能表现活力的原因. 结果表明, 不管表面活性剂聚集体的结构、电性质及反胶束大小如何, 只要醇的浓度超过500 mmol•L-1 (丁醇≥1200 mmol•L-1), LiP在上述原本可显示活力的介质中均无催化活性. 据此推测CTAB反胶束中木素过氧化物酶(LiP)不能表现活力的原因主要是由助表面活性剂醇造成的. 相似文献
988.
Fig. The absorption 《科学通报(英文版)》2000,45(10):914-920
Histidine coordinated to Chi a is a distinct characteristic of Chl ain vivo. By using histidine analogue of 1-methylimidazole (C4H6N22) and measuring the UV/vis absorption, CD and MCD spectra of the interaction between C4H6N2 and Chl a in CCI4, we have obtained that: (i) In pure CCl4 solvent, Chl a molecule is in five-coordinate state, and two Chl a molecules form an asymmetric compact-dimer with strong
coupling interaction. We propose that the two Chl a molecules are connected by two unequally coordinated Mg-O bonds (the two
oxygen atoms come from the C=O of C131 keto and C17 ester, respectively); (ii) when the molar ratio of C4H6N2/Chl a is 0.5 or 1 (corresponding to 2Chl a · 1C4H6N2 and 2Chl a · 2C4H6N2, respectively), significant changes have been observed in the absorption, CD and MCD spectra, which indicate that the Chl
a remains in dimer form, but the coupling interaction between them reduces greatly. We postulate that C4H6N2 replaces the ligation of C=O of C17 ester and C131 keto to Mg atoms sequentially. The two Chl a molecules linked by two weakly interacted Mg…O bonds form a relaxed-dimer. The
structure of the model is essentially similar to that of the primary electronic donor, P680, of photosystem II in high plants and algae. 相似文献
989.
. 《科学通报(英文版)》2000,45(15):1351-1354
The Raman spectra of two one-dimensional silicon nanowire samples with different excitation wavetengths were measured and
an abnormal phenomenon was discovered that the Raman spectral features change with the wavetengths of excitation. Closer analysis
of the crystalline structure of samples and the changes in Raman spectral features showed that the abnormal behavior is the
result of resonance Raman scattering setection effect. 相似文献
990.
1.IntroductionManyscientificandengineeringproblemscallbereducedtoexteriorboundaryvalueproblemsofpartialdifferentialequations.Althoughthenumericalmethodstosolveboundaryvalueproblems,suchasthefiniteelementmethodandthefinitedifferencemethod,areveryeffectiveonboundeddomains,yetweoftenfinditdifficulttousethemtodealwithunboundedproblems.Theboundaryreductionisaforcefulmeanstosolvesomeproblemsoverunboundeddomains.Amongmanyboundaryreductions,thenaturalboundaryreductionfoundedbyK.FengandD.H.Yuhassomed… 相似文献