环Z/(2e)上本原序列最高权位的0,1分布

研究环Z/(2^e)上本原序列的最高权位序列a_e-1的0,1分布问题,给出了序列a_e-1在1个周期中0,1个数的比值的上下界,并显示出当e越大时,a_e-1的0,1个数的比值越接近1。     

A novel route to synthesize diphenylene by the catalytic effect of GaP nanocrystals

Diphenylene was synthesized directly from benzene under the catalytic effect of GaP nanocrystals, and the effect of GaP nanocrystals content was studied. The experimental results showed that no reactions took place without GaP nanocrystals. The more the GaP nanocrystals added, the more the reaction complete. Furthermore, at high temperatures (450-480℃), when the content of GaP nanocrystals was high enough, almost all benzene polymerized and the yield of diphenylene was rather high. On the contrast, even if there are enough GaP nanocrystals in the reaction mixture, almost no polymerization reaction took place at low temperature (for example, 250-300℃), and the yield of diphenylene was very poor. The analytical results of XRD, IR, elemental analysis and NMR proved that the sample was truly diphenylene.     

Hydroperoxide and endoperoxide lactones from photooxygenation of 3-alkylidenedihydrofuran-2,4-diones

3-Alkylidenedihydrofuran-2,4-diones 1 can be photooxygenated with O(2)/TBHP to hydroperoxides 3 which slowly decompose to diols 5. Stable endoperoxides 4 are best prepared by photooxygenation of 1 with 2 equiv of O(2) in the presence of CuSO(4) and p-TosOH following a nonradical mechanism. They are rapidly reduced by anhydrous FeBr(2) to give butenolide 9 indicating a potential antimalarial activity.     

Tipranavir analogous 3-sulfonylanilidotetronic acids: new synthesis and structure-dependent anti-HIV activity

Sulfonamide-containing tetronic acids 1, structural analogues of the HIV-1 protease inhibitor tipranavir, were synthesised in five steps including a microwave-assisted Claisen rearrangement of cinnamyl tetronates and a modified Charette cyclopropanation of the so-formed 3-allyltetronic acids. Compounds 1 with two non-H residues (R¹, R²) at C-5 of the tetronate core exhibited structure-dependent antiviral activity in two HIV strains. Derivatives 1c (R¹=R²=Me, R³=Cl) and 1d (R^1,2=(CH₂)₅, R³=Me) were most active (IC₅₀<10 μM) in the sensitive strain HIV_NL4-3.     

GrÖbner基推广及Z/(m)上多条序列综合算法

将GrÖbner基推广到环(Z/(P^e)[x₁,…,x_n])/I上,p是素数,e≥1,I是Z/(P^e)[x₁,…,x_n]的理想,应用推广的GrÖbner基理论,给出了环Z/(m)上多条序列的综合算法,算法复杂性是O(N²).     

Angular distribution of tensor polarizations in 2H(α, 5Heg.s)p from the sequential decay reaction 2H(α,p)5Heg.s(α)n

The sequential decay reaction ²H(α,p)⁵He^g.s(α)n has been studied at E_α = 22.5 MeV in kinematically complete p-α coincidence experiments with special regard to the tensor moments of even rank of the intermediate state ${}^5\text{He}{}^{\mathrm{<mtext>3</mtext><mtext>2?</mtext>}}$. From the measured absolute differential cross section of this reaction, the angular distributions of the second step for the ⁵He^g.s c.m. production angles from 45.6 to 119.8 were extracted. By applying Welton's formalism to the second step the tensor moments of even rank of the intermediate ⁵He system were deduced and compared to calculations in the cluster-model formalism. They as well as the absolute differential cross sections for ²H(α,pα)n were found to be in good agreement with the sequential decay model. Small deviations seem to arise from Coulomb interaction between p and α in the final channel and from the restriction to partial waves l ≦ 2.     

羟甲基环氧树脂的“邻位效应”的探讨

邻位羟甲基环氧树脂由于在其缩水甘油醚基的邻位引入了羟甲基而使环氧基反应活性提高。本文合成了邻位和对位羟甲基苯基缩水甘油醚作为模型化合物,通过差热分析和红外光谱研究了它们与4,4′-二氨基二苯甲烷的反应,并对Schwarzer提出的“邻位效应”进行了探讨。     

钇铝石榴石单晶缺陷的X射线透射形貌术观察

对提拉法生长的YAG单晶首次用X射线透射形貌术观察。揭示了YAG单晶的生长条纹、奇异小面以及垂直于生长条纹的位错线束等生长缺陷,并对这些缺陷作了简要的分析。 关键词：     

Catalytic Mechanism of Stereospecific Formation of cis-Configured Prenylated Pyrroloindoline Diketopiperazines by Indole Prenyltransferases

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