首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 125 毫秒
1.
考察了焦煤中少量氧化铅添加剂对炼焦过程高温焦炉煤气硫化氢浓度以及对焦炭质量的影响。实验表明,煤中添加少量的氧化铅,可以达到焦炉粗煤气脱硫的目的,并且对焦炭的质量影响很小。针对实验所用的煤种,相当于焦煤质量的0.6%的氧化铅添加量在炼焦前期具有最佳的抑制硫释放的效果。炼焦后期,半焦中的硫化铅分解或铅转变为气态铅。气态铅和硫化氢在离开炼焦室时,由于煤气降低温度,又生成硫化铅。从而实现均相脱硫。焦炭中超过一半的铅可以挥发出去。在炼焦收缩阶段,半焦中过多的铅的存在不利于硫化铅的分解。  相似文献   

2.
L-核糖的合成研究进展   总被引:12,自引:1,他引:12  
L-核糖是合成L-核糖核苷抗病毒剂的重要中间体。综述了L-核糖的合成方法及 最新进展。重点讨论了L-核糖的化学合成方法,也介绍了L-核糖的微生物合成法。  相似文献   

3.
1.文摘应包含正文的要点。一般来说,文摘应包含研究对象(目的),研究方法(所用的设备、材料),结果与结论。2.文摘要尽量简短,尽可能删掉课题研究的背景信息。3.文摘中出现的数据应该是最重要、最关键的数据。4.不需要自己标榜自己的研究成果。  相似文献   

4.
1.文摘应包含正文的要点。一般来说,文摘应包含研究对象(目的),研究方法(所用的设备、材料),结果与结论。2.文摘要尽量简短,尽可能删掉课题研究的背景信息。3.文摘中出现的数据应该是最重要、最关键的数据。4.不需要自己标榜自己的研究成果。  相似文献   

5.
宋琦 《大学化学》2007,22(1):53-53
日本东京女子大学K.Shindo领导的研究小组开发了一种制造含有芳香化合物的吡啶甲酸的实用方法。这类化合物在自然界很少见,用常规方法合成时难度很大。但是它们可以用作合成医药和农药和其他化学物质的原料。这个小组通过把二苯基分解代谢的基因引入Escherichiacoli的方法,解决了这个问题。当微生物在含有两个苯环的芳族的培养基中繁殖时,能够把其中的一个苯环转变为吡啶甲酸(吡啶-2-羧酸)。图中所示是由7-羟基黄烷酮得到的产物。  相似文献   

6.
对水溶液体系中影响碱金属还原能力和还原活性的因素进行了理论分析。结果表明,碱金属的电极电势主要由焓控制,而离子的溶剂化焓对其还原能力影响很大。碱金属的活性顺序主要受第一电离能和原子化焓影响。还原能力和活性决定因素的差异导致碱金属电极电势和活性顺序的差异。  相似文献   

7.
2012年将迎来中国化学会80华诞。1932年,化学界的前辈们怀着拳拳爱国之心,抱着科学救国之志,自愿组成了这个学术团体。他们以民族大业为己任,对发展我国的化学化工和化学教育,做出了卓绝的贡献。在其后不到两年,本刊就作为中国化学会主办的学术刊物正式问世。忆往昔,岁月峥嵘,看今朝,前景辉煌。  相似文献   

8.
刘洪霖  陈念贻 《化学学报》1995,53(8):734-737
本文提出一种收敛的点电荷和Hartree-Fock表面势构成的自洽晶体场Madelung势用于原子簇量子化学从头计算。前者的计算类似于核吸引积分的单电子积分, 后者可以通过点群对称性操作从原子簇内的积分矩阵元得到。点电荷的大小和原子簇内对应的原子电荷相等, 其数目以晶体场势收敛为标准确定。介绍加速计算的程序技巧。该模型用于高温超导体YBa2Cu3O7的全电子从头计算并得到一些新结果。  相似文献   

9.
浅谈水的结构化学   总被引:6,自引:0,他引:6  
周公度 《大学化学》2002,17(1):54-63
水是地球上数量最多的分子型化合物。根据估算 ,地球上水的总量达 1 .4× 1 0 2 1kg。若地表平滑而没有起伏 ,地球表面将形成平均水深达 2 71 3m无边无际的汪洋。  在人们生活的环境中 ,随时随地都和水有着密切的关系。动植物的生存成长离不开水 ,人体中水占总质量的一半以上。工农业生产要依靠水 ,水是化学工业生产中最常用的试剂和溶剂 ,也是化学反应中最常用的一种化合物 ,化学科学的发展处处都和水有关。关于水的结构和性质的知识 ,是化学科学的重要基础内容。下面汇集作者近年编著教材时探讨有关水的结构化学的知识[1~ 5 ] ,以供…  相似文献   

10.
俄科学院约菲物理技术所和圣彼得堡国立化工制药学院的科研人员研究出了对爆轰纳米金刚石粒子进行辐照的光学方法。在许多刊物中,爆轰纳米金刚石的纳米粒子大小特征是根据动态光散射数据来计算的。研究表明,3~6 nm粒子的吸收光谱上有其显著特征。彼得堡研究者质疑该种方法是否适用于3~6 nm的粒子。因此俄研究人员开始做实验。通过实验证明能生产出更加纯的纳米金刚石悬浮细粉。  相似文献   

11.
The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.  相似文献   

12.
The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.  相似文献   

13.
以α位(2,4-二特戊基)苯氧基邻苯二腈作为环合前体,制备了多种金属酞菁,产物经元素分析、紫外、红外、核磁氢谱等分析手段进行表征.并选择了部分酞菁进行溴化,其中着重研究了不同中心金属以及溴化对染料Q带吸收的影响.结果表明,酞菁染料的金属化对于其Q带吸收影响很大,多数染料金属化后会出现蓝移,而选择合适的条件进行溴化,可以使得金属酞菁的Q带吸收出现一定程度的红移,其中部分溴化金属酞菁的吸收波长与光信息产业中使用的近红外激光器很接近,具有潜在的实用价值.  相似文献   

14.
AgCuSe nanorods were prepared at room temperature by a redox reaction. The as-prepared product was characterized by X-ray powder diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy.X-ray powder diffraction shows that the as-prepared product is the tetragonal phase of AgCuSe. Transmission electron microscopy shows that the sample consists of nanorods with a diameter varying from 5 nm to 20 nm and a length varying from 200 nm to 600 nm. X-ray photoelectron spectroscopy shows that the purity of the sample is high. The formation mechanism of AgCuSe and the growth mechanism of AgCuSe nanorods were discussed.Thermodynamic calulations show that the final product in the synthetic system is pure AgCuSe. The solvent ethylenediamine did not only acts a didentate ligand to form relatively state Ag + and Cu + complexes, but also dissolved Se and enhanced the reactivity of Se. It played an important role in controlling the nucleation and growth of AgCuSe nanorods.  相似文献   

15.
用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.  相似文献   

16.
Applying calculus to the horizontal and vertical unit hyperbolas we derive the obtuse exterior and the acute angle of parallelism formulas for the arc length of a unit circle. When the analogous arc length of a hyperbola is figured, we further define metric distance with radian measure. Employing a non-conventional velocity of light formula, we explain several aspects of physics with a logical geometry. The hyperbolic geometry Lobacevskii angle of parallelism is mathematically measured to agree with the physical measure, without using the gravitational constant, but rather the electromagnetic spectrum and geodesics. Space is hereby measured with units of radians and time. Half-angle formulas for slopes and boosts pertain to spinor algebra. The new light velocity is justified when its derivative results in Einstein's mass–energy formula. Relativity is reformulated with these half-angle formulas.  相似文献   

17.
Trimethylsilylacetamide and trimethylsilyltrifluoroacetamide react with halogenodiorganylboranes to monomeric or dimeric amidoboranes depending on the organyl substituents. The compounds were characterized analytically and spectroscopically (NMR:1H,19F,11B; MS; IR).
21. Mitt.:A. Meller, W. Maringgele, K. Hennemuth undU. Sicker, J. Z. anorg. allg. Chem., im Druck.  相似文献   

18.
Góral, M. and Zawadzki, S., 1993. Vapour-liquid equilibria in nonpolar mixtures. II. Carbon tetrachloride with alkylbenzenes and n-alkanes at 313.15 K. Fluid Phase Equilibria, 90: 355-364.

Total vapour pressure measurements using a modified static method at 313.15 K are reported for binary mixtures of CCl4 with benzene, toluene, o-xylene, p-xylene, hexane, heptane, octane, nonane and decane. The results were correlated with the generalized Redlich-Kister equation for excess Gibbs energy. A comparison with literature vapour-liquid equilibrium data and excess enthalpy was made. Consistency within homologous series was checked. Predictions made using the UNIFAC method and the Hildebrand-Scatchard equation were compared.  相似文献   


19.
为了进一步探明葡萄糖在铂电极上的氧化机理,用循环伏安法(CV)在-0.9~0.4 V(相对于饱和甘汞参比电极)内研究了葡萄糖在铂电极上催化氧化行为,首次详细报道了葡萄糖在电化学氧化过程中的电位振荡现象,并用电流扫描法表征了葡萄糖的电位振荡情况.电流扫描结果表明,在较慢的电流扫描速度下,电极过程出现了明显的电位振荡.说明电极上产生了毒化中间物,电位振荡是由于毒化中间物在电极上的吸附和在高电位下氧化除去引起的.  相似文献   

20.
ZnO-MgO nanocomposite was prepared by glycine nitrate combustion method.Its photoluminescence property, the structure and annealing temperature dependence was studied by XRD, FTIR and SEM. The results show that the photoluminescence property of ZnO-MgO nanocomposite is greatly improved compared with that of pure ZnO. Under 325 nm laser excitation, the emission spectra of the 900 ℃ treated composite sample had an obviously enhanced ultraviolet (UV) band centered at 385 nm at room temperature. The luminescence intensity of the UV band became stronger with the increase of annealing temperatures and reached a maximum at 900 ℃ but decreased at 1000 ℃. The photoluminescence intensity was mainly affected by the grain size, the crystallization and the action between ZnO and MgO nanoparticles. In addition, an appropriate G/N value was favorable for improving the UV-PL properties of the nanocomposite samples.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号