Preparation and spectroscopic properties of 2'''',5''''-dideoxynucleosidylcobalamins

Two new coenzyme B12 analogues, 2',5'-dideoxycytidylcobalamin (2a) and 2',5'-dide-oxyuridinylcobalamin (2b), and two others, 2',5'-dideoxyadenosylcobalamin (2c), and 5'-deoxy-thymidylcobalamin (2d) were prepared by an improved method. All the four analogues were investigated by UV-vis and 2D 1H NMR spectroscopy. The comparisons and discussion about their spectroscopic properties were done.     

Methane Decomposition and C2 Hydrocarbon Formation under the Condition of DC Discharge Plasma

The infrared emission spectra of methane, H, CH and C2 hydrocarbons in natural gas were measured. The processes of methane decomposition and formation of C2 hydrocarbons were studied. The experiment shows that methane decomposition can be divided into three periods as the reaction proceeds.In the first period, a large number of free radicals were formed. While in the last period, the formation of C2 hydrocarbons and the decrease of free radicals were observed. The time and conditions of methane decomposition and formation of C2 hydrocarbons are different.     

Effect of TiO2 Support on the Composition, Morphology and Catalytic Property of the NiB Amorphous Alloy Catalyst

Both the unsupported and supported NiB amorphous alloy catalysts (NiB and NiB/TiO2)were prepared by the chemical reduction method. Their catalytic activities were tested by thehydrogenation of sulfolene. The interactions between the NiB alloy and TiO2 were discussed forthe first time by using XRD, ICP, SEM and TEM.     

Novel Transient Species of DNA Bases From Laser Photolysis

The laser photochemistry and photosensitization of DNA bases were carried out by using a nanosecond kinetic spectroscopy. A novel triplet state of thymine and its OH adduct were observed in N_2 and N_2O saturated aqueous solution respectively. The transient absorption spectra of triplet cytosine, cytidine and deoxycytidine monophosphoric acid were observed for the first time. Triplet guanosine was confirmed and its pK, value, 8.7, was obtained. Kinetic studies of the growth-decay of the above transient species were performed and their reaction mechanisms were elucidated in detail.     

Reactions in a Mixture of CH_4 and CO_2 under the Action of Microwave Discharge at Atmospheric Pressure

Reactions between CH_4 and CO_2 under the action of continuous microwave discharge at atmospheric pressure were studied in a special homemade reactor. The main products were CO and H2, while acetylene and ethylene were also found in the products. Experimental results show that conversions of CH4 and CO2 could be higher than 90% without the presence of any catalyst. Effects of CO2/CH4 molar ratio and total flow rate of the feed gas on the reaction were also investigated.     

Synthesis and characterization of semicarbazone metal complexes of Sn(IV) and Zr(IV)

Three semicarbazonyl ligands were synthesized and used to form six novel organometallic complexes with Ph2SnCl2 and Cp2ZrCl2. All these complexes were characterized by IR,1H NMR,MS and elemental analysis.     

Synthesis and structure determination of pyrazine-containing macrocyclic polyazomethines

<正>Two pyrazine-contairting macrocyclic polyazomethines 2 and 3 were synthesized by direct[2 + 2]and[3 + 3]condensation reactions between 2,2'-[pyrazine-2,3-diylbis(oxy)]dibenzaldehyde(1) and hydrazine.Both 2 and 3 were characterized by NMR, HRMS,and their structures were determined via X-ray crystal diffraction studies.     

Two New ent—Kauranoids from Isodon sculponeata

Two new ent-kauranc dierpenoids,sculponcatins L(1) and M (2) ,were isolated from the EtOAc extract of Isodon sculponeata.Their structures,were clucidated by spectroscopic cvidences.The cytotoxicities of 1 and 2 against human tumor cells k562 and T24 were tested.     

Synthesis of Tin Oxide Through Thermal Decomposition of Sn2 （NH4）2 （ C2 O4 ）3 and Its Gas Sensing Property

Nanocrystalline tin oxide samples were prepared by using Sn2 （NH4 ）2 （C2O4）3 as the precursor. The thermal decompositions were respectively conducted at 250,450 and 650 ℃. TG-DTA, XRD, TEM, FTIR were used to characterize the samples. The indirect heating sensors by using these materials as sensitive bodies were fabricated on an alumina tube with Au electrodes and platinum wires. Sensing properties of these sensors were investigated. It was found that the tin oxide sample obtained by thermal decomposition at 450 ℃ has a higher sensitivity to C2H5OH and a higher selectivity to hexane and ammonia than those obtained via the conventional precipitate method and the working temperatures needed were greatly decreased.     

PREPARATION AND THE CULTURE OF LO2 CELLS ON PVA—BASED MICROCARRIERS

Using polyvinyl alcohol(PVA) as raw material and vacuum pump oil as oil phase medium,PVA-based microcarriers were prepared by suspension method,The diameters of the beads were 100-180um,LO2 cells were cultured on PVA-based microcarriers and cytodexⅢ microcarriers.Morphology,attachment and growth rate of LO2 cells were studied.     

芥子气过氧化物消毒产物的气相色谱-质谱测定

采用气相色谱-质谱(GC-MS)技术对芥子气的过氧化物消毒产物进行了分离和检测。不完全消毒定性检测到芥子气的6种氧化产物,未检测到其水解产物。增加消毒剂用量和延长消毒时间都会使消毒产物进一步氧化,最终变成二乙烯基砜、氯乙基乙烯基砜和芥子砜3种消毒产物。定量分析得出,1 mol芥子气生成的最终消毒产物分别为二乙烯基砜0.193 mol,氯乙基乙烯基砜0.145 mol,芥子砜0.504 mol。3种化合物线性范围1~30 mg/L,加标回收率在57%~78%之间,相对标准偏差小于3.1%,检出限均为0.5 mg/L。     

多重射流燃烧反应制备的TiO2/ SiO2纳米复合颗粒的形态和结构

TiO₂-SiO₂ nanocomposite particles were prepared in premixed H₂ / Air flame, and the morphology and structure of these nanocomposites were characterized by FTIR, XRD, TEM and HRTEM. The morphology of SiO₂ / TiO₂ nanocomposites was different from that of pure TiO₂ or SiO₂ nanoparticles, and the chemical bond of Ti-O-Si was found in the nanocomposites indicating that the TiO₂ / SiO₂ nanocomposites were not merely a physical mixture of TiO₂ and SiO₂. TiO₂ nanocrystalline grains with sizes of 1～2 nm were homogeneously dispersed in the amorphous SiO₂ matrix when TiCl₄ and SiCl₄ were mixed at molecular level in the flame. The particle size and rutile content decreased with increasing of SiO₂ molar ratio.     

纳米SnO2@TiO2包覆催化剂的制备及表征

采用活性层包覆法在自制细SnO2胶体粒子表面包覆TiO2,制备出SnO2@TiO2包覆型复合催化剂,以其对有机磷农药DDVP的降解效果作为评价光催化活性的标准,对制备条件进行了优化,并用XRD、TEM和BET等手段对样品进行了表征,结果表明,SnO2胶体乙醇溶液含水量20％,钛酸丁酯质量分数为34.5％。灼烧温度680℃时制得TiO2含量56.45％的包覆样品SnO2@TiO2为纳米级粒子,且其光催化活性最佳。     

5-氟尿嘧啶短肽的合成及其抗肿瘤活性研究

5-氟尿嘧啶乙酸对-硝基苯酯和5-氟尿嘧啶丙酸对-硝基苯酯分别与三种二肽反应,制备了五个5-氟尿嘧啶二肽(4 a-e)。以5-氟尿嘧啶的氨基酸对-硝基苯酯(2 a-c)分别和三种二肽反应,制得四个5-氟尿嘧啶三肽(5 a-d)。产物经元素分析、NMR、IR和UV鉴定。初步动物试验表明:5-氟尿嘧啶丙酰甘-苯丙二肽,5-氟尿嘧啶乙酰甘-甘-苯丙三肽和5-氟尿嘧啶乙酰缬-亮-甘三肽对小白鼠移植性艾氏腹水癌有一定的抑制作用。     

A scaled quantum mechanical force field for the sulfuryl halides. I. The symmetric halides SO2X2 (X=F, Cl, Br)

Force fields and vibrational wavenumbers were calculated for the molecules SO2X2 (X=F, Cl, Br) using DFT techniques. The previously available experimental data and assignments for SO2F2 and SO2Cl2 were compared with the theoretical results and revised, and new low temperature infrared and Raman data were obtained for SO2Cl2. These data were subsequently used in the definition of scaled quantum mechanics force fields for such molecules. Adjusted wavenumbers were also predicted for the still unknown SO2Br2. A comparison is made with results published for the VO2X2- anions.     

Nitration Reaction Catalyzed by Horseradish Peroxidase in the Presence of H2O2 and NaNO2

The enzymatic nitration of phenol and m-cresol catalyzed by horseradish peroxidase was studied in the presence of H2O2 and NaNO2. The results showed that the nitration products of phenol were 2-nitro and 4-nitrophenols. There was also a small amount of by-products of hydroquinone and catechol. The influences of various reaction parameters, including pH, organic solvent type, and concentrations of NaNO2 and H2O2, on the nitration products were investigated. The yields of 4-nitrophenol and 2-nitrophenol were 14% and 12%, respectively. The nitration products of m-cresol were 4-nitro-m-cresol and 6-nitro-m-cresol, and the yields of 4-nitro-m-cresol and 6-nitro-m-cresol were 19% and 30%, respectively.     

NH_2基态和激发态的SAC－CI和量子拓扑方法研究

ＮＨ_２基态和激发态的ＳＡＣ－ＣＩ和量子拓扑方法研究郑世钧，蔡新华，宋天乐，孟令鹏，中迁博，波田雅彦（河北师范学院化学系，石家庄，０５００９１）（京都大学工程学院京都，日本）关键词ＳＡＣ－ＣＩ方法，激发态，电子密度，拓扑分析用量子拓扑学方法研究激发态...     

钛铝载体的合成及负载CuO对NO催化性能研究

以TiCl4为原料合成了TiO2/[[alpha]]-Al2O3载体. 在色谱-微反流动法反应装置上考察了CuO/15%(w, 下同)TiO2/[alpha]-Al2O3系列催化剂对NO+CO 的反应性能. 结果表明上述催化剂对NO+CO 反应表现出较好的活性, 其中12%CuO/15%TiO2/[alpha]-Al2O3反应活性最佳. 空气和H2 预处理后, NO 完全转化的温度分别为300C[[deg]]和275C[deg].通过H2-TPR、XRD 和FT-IR 等技术表征, 发现适量TiO2能促进CuO 在钛铝载体上的分散. TPR 结果显示12%CuO/15%TiO2/[alpha]-Al2O3在整个TPR 过程中出现四个还原峰, 琢和酌还原峰分别是钛铝载体表面裸露的TiO2上高度分散的CuO 和晶相CuO 的还原；茁和啄还原峰为钛铝载体上高度分散的CuO 和晶相CuO 的还原. FT-IR实验表明NO和CO 在经H2气氛预处理的催化剂表面上吸附较强, 且生成了N2O 和NO2等物种；NO+CO混合气在经空气和H2预处理的催化剂表面吸附时, 出现了N2O吸收峰, 峰温分别为200C[deg]和150C[deg].     

Ru-Re/SiO2催化剂上丙三醇氢解制丙二醇:催化剂的酸性质与Re组分的作用

考察了Ru-Re/SiO2 组分催化剂的酸性质,并探讨了Re组分在丙三醇氢解制丙二醇反应中对提高该催化剂性能所起的作用.本文采用氨气程序升温脱附法和吸附吡啶原位红外光谱法表征了双组分Ru.Re/SiO2和单组分Ru/SiO2、Re/SiO2催化剂的酸性质,并比较了催化剂在丙三醇氢解反应中的催化性能.结果显示,Ru-Re...