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111.
金属助剂对Ni/SiO催化剂苯甲醚加氢脱氧性能的影响 《燃料化学学报》2018,46(1):75-83
采用等体积浸渍法制备了Ni/SiO2及Ni与金属助剂M(M=Fe、Co、Cu、Zn及Ga)物质的量比为30的Ni基双金属催化剂(记作Ni30M/SiO2),利用H2-TPR、XRD、H2化学吸附、NH3-TPD以及N2物理吸附-脱附等手段对催化剂进行了结构表征,研究了不同助剂对催化剂结构与苯甲醚加氢脱氧性能影响。结果发现,金属助剂影响了催化剂前驱体中镍物种的还原性能,表明金属助剂及镍之间存在一定相互作用。Ni30M/SiO2中Ni-M双金属晶粒粒径和Ni/SiO2中金属Ni晶粒粒径相近。由于表面张力较低的金属会在双金属晶粒表面富集,Ni30M/SiO2的H2化学吸附量不同程度地低于Ni/SiO2。另外,Ni30M/SiO2催化剂的酸量(尤其较弱酸中心酸量)高于Ni/SiO2。在300℃、常压、苯甲醚质量空速1.0 h-1及H2与苯甲醚物质的量比为25:1条件下考察了各催化剂苯甲醚的加氢脱氧性能。Ni30M/SiO2上苯甲醚转化率不同程度低于Ni/SiO2,原因在于Ni30M/SiO2催化剂H2化学吸附量较低。Ga及Zn改性催化剂上三苯(包括苯、甲苯及二甲苯)选择性分别为81.7%和76.8%,高于Ni/SiO2(71.5%),且Ni30Ga/SiO2及Ni30Zn/SiO2上三苯收率(分别为65.0%及63.8%)高于或接近于Ni/SiO2(63.7%)。Ni/SiO2及Ni30M/SiO2催化剂中,Ni30Zn/SiO2具有较高甲基转移能力及较低C-C键氢解活性。从提高碳收率、降低耗氢量角度而言,Ni30Zn/SiO2具有较佳的加氢脱氧性能,与Ni和Zn之间作用及Zn亲氧性高于Ni有关。 相似文献
112.
近年来, 甘油氢解的研究主要集中在生成 1,2-丙二醇和1,3-丙二醇二元醇. 与二元醇相比, 正丙醇也是一种昂贵的化学品, 用过量的甘油直接氢解合成高选择性的正丙醇将是一个非常好的生产途径. 因为铂金属具有较强的断 C-O 键的能力, 所以甘油氢解制正丙醇的催化剂主要采用铂作为活性组分. 本文以铂为活性组分, 采用浸渍法将其负载到不同 Zr/Al比的 Zr-Al 复合氧化物上制得 2.5%Pt/ZrxAl1-xOy催化剂, 并将其应用到甘油氢解反应中, 探讨了 Zr/Al 比对甘油氢解制正丙醇反应性能的影响.表征结果发现, 锆铝混合氧化物经过 400 ℃ 焙烧后为无定形态的复合金属氧化物, 载体中无单相氧化锆或氧化铝存在. 随着锆含量增加, 催化剂酸性位点向强酸方向移动. 不同 Zr/Al 比的锆铝混合氧化物负载铂催化剂的评价结果发现, 甘油转化率随催化剂中铝含量增加而增大; 锆铝比大于 5:5 时, 丙醇 (正丙醇+异丙醇) 的选择性很高, 普遍大于 87%; 锆铝比至 7:3 时, 正丙醇选择性最高. 通过 X 射线衍射、CO 化学吸附、H2程序升温还原、吡啶吸附、氨气程序升温脱附等方法对催化剂进行了表征, 发现随着锆铝混合氧化物中锆含量的增加, 催化剂的酸性位点向强酸方向移动, 调变 Zr/Al 比促进了铂颗粒的分散, 实现了催化剂表面酸量和强酸位点的定向调控. 当锆铝比增加至 7:3 时, 催化剂的强酸位点占总酸含量的91.2%. 对比催化剂酸性分析和反应结果可知, 催化剂表面的总酸含量高有助于甘油转化; 强酸位点有助于甘油深度脱水生成丙醇; 正丙醇的选择性则可能与 NH3脱附温度在 580 ℃ 处的强酸位和较大的 Pt 颗粒有关. 当 Zr/Al 比为 7:3 时, 催化剂表面强酸位点占 91.2%, 而强酸位点的增加有助于甘油的深度脱水形成正丙醇. 因此, 以 10% 甘油水溶液为原料, 在240 ℃和6.0 MPa 初始氢气压力条件下反应 8 h, 甘油转化率和正丙醇的选择性分别达到 81.2% 和 86.3%. 催化剂经过 5 次循环使用后, 甘油转化率和丙醇 (正丙醇+异丙醇) 选择性几乎不变, 但正丙醇的选择性略有降低. 使用 5 次后的催化剂表面的总酸量变化不大, 但酸分布变化较大, 即强酸比例下降. 可见, 催化剂活性变化小是由于其表面酸量变化不大, 而正丙醇选择性下降与强酸位点比例下降有关. 相似文献
113.
114.
Desulfurization of organic sulfides in hydrocarbon solvents in the presence of aqua complexes of metal chlorides H[MAlCl4OH] that exhibit lower acidity as compared to AlCl3 proceeds under mild conditions (450–525 K, atmospheric pressure) without external introduction of hydrogen. The process occurs with cleavage of C-S bonds and through intermediate formation of mercaptans to give H2S and the corresponding hydrocarbons. The reaction is accompanied by cleavage of C-C bonds in the groups surrounding the organosulfur moiety, in thiacyclane rings, as well as in hydrocarbon solvent molecules, resulting in the formation of a wide spectrum of gaseous and liquid products.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1998–2002, October, 1995. 相似文献
115.
Catalytic transfer hydrogenation of mycoepoxydiene 总被引:1,自引:0,他引:1
Haiyan Chen Yongcheng Lin Guangying Chen Guping Hu Li Wang L. L. P. Vrijmoed 《Chemistry of Natural Compounds》2006,42(4):407-409
Catalytic transfer hydrogenation with hydrogenolysis of mycoepoxydiene (1) by ammonium formate/10% Pd-C gave a new compound, deacetylhexahydromycoepoxydiene (2), whose structure was determined by spectroscopic and X-ray diffraction experiments. In the primary bioassay, 1, 2 and hexahydromycoepoxydiene (3) showed anticancer activities against HeLa in vitro. The IC50 (μg/mL) values were 5.5, 50, and >100, respectively.
Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 331–332, July–August, 2006. 相似文献
116.
Dimitri I. Kochubey Vladimir A. Rogov Vera P. Babenko 《Reaction Kinetics and Catalysis Letters》2007,90(1):167-177
The rate of thiophene decomposition was shown to be independent of the type of chalcogens used in catalysts MoX2/Al2O3, where X = S, Se. On the contrary, the rate of selenophene decomposition was shown to be higher on catalysts MoSe2 than that on MoS2. This observation suggests that the decomposition proceeds on anion vacancies. The decomposition of either thiophene over
MoSe2 or selenophene over MoS2 results in the formation of partially substituted chalcogenides. At that, the molar ratios of the substituted chalcogen to
Mo were shown to coincide in both cases. The fact that the rate of the thiophene decomposition does not depend on the degree
of anion exchange indicates that the decomposition is not associated with hydrogenolysis. 相似文献
117.
J. J. Calvino M. A. Cauqui G. Cifredo J. M. Rodríguez-Izquierdo H. Vidal 《Journal of Sol-Gel Science and Technology》1994,2(1-3):831-836
The influence of the preparation method on the microstructure and catalytic behavior of Rh and Ni dispersed on TiO2-SiO2 aerogels is investigated.The autoclave method has been followed to prepare titania-silica aerogels with TiO2 contents ranging between 0 and 10 mole %. These aerogels have been used as matrices to disperse catalytically active metals: Rh and Ni. The metals can be deposited by impregnation of aerogels, or alternatively, can be added into the hydrolysis water used in the synthesis of gels. The resulting catalysts present surface areas higher than 550 m2·g–1.The percentage of titania, the method followed for the introduction of the metal, and the nature of the metal itself affect both the activities and selectivities of the catalysts in the hydrogenolysis of n-butane. Thus, the presence of titania in Rh catalysts increases the activity values, and the samples prepared by impregnation present selectivities towards ethane higher than 80%. Whereas, the rhodium catalysts in which the metal has been introduced before gelling, do not orientate the reaction in favor of a definite product. For the case of Ni, it is quite frequent to obtain high selectivities towards the breakdown of the C-C terminal bonds. In summary, the preparation methods allow to modulate into very broad limits the catalytic behavior of the samples. 相似文献
118.
Soldatenkov A. T. Soldatova S. A. Ryashentseva M. A. Ntaganda Zh. Zvolinskii O. V. Smirnova E. N. Kharlamova M. D. 《Russian Chemical Bulletin》2002,51(11):2116-2120
Condensation of 5,6-dihydroindolo[2,1-a]isoquinoline with aromatic aldehydes in trifluoroacetic acid afforded 12-arylidene-5,6-dihydroindolo[2,1-a]isoquinolinium trifluoroacetates. Hydrogenolysis of these salts on rhenium heptasulfide at elevated temperature and hydrogen pressure yielded indolo[2,1-a]isoquinolines, while reduction with sodium borohydride gave 12-arylmethylindoloisoquinolines. Photoluminescence was found for some indolo[2,1-a]isoquinolines. 相似文献
119.
3-Amino-2-(isoxazol-3-yl)-4-methoxymethyl-6-methylthieno[2,3-b]pyridine was synthesized by the reaction of 2(1H)-thioxopyridine-3-carbonitrile with 3-chloromethylisoxazole in the presence of two equivalents of KOH. Boiling of 3-amino-2-(isoxazol-3-yl)-4-methoxymethyl-6-meth-ylthieno[2,3-b]pyridine with Raney nickel results in 4-aminothieno[2,3-b;4,5-b′]dipyridine or 5-(4-amino-2-pyridyl)pyridine depending on the reaction conditions.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 669–670, March, 2008. 相似文献
120.
采用等体积浸渍法制备了Ni-WO3/SBA-15催化剂,将其应用于纤维素的水相氢解.考察了温度对纤维素水解和其形貌的影响及Ni、WO3含量等对纤维素转化行为的影响.XRD表征结果表明,随着温度的升高纤维素颗粒粒径逐渐变小并趋于均一,结晶状态逐渐由晶型变为无定型态.H2-TPR结果表明,Ni和WO3间存在较强的相互作用,这种相互作用提高了W物种对C-C键的解离性能,同时,提高了Ni物种的加氢活性,促进了纤维素向乙二醇的转化.在3%Ni-15%WO3/SBA-15催化剂上,反应条件为230 ℃、6.0 MPa、6.0 h时,纤维素完全转化,乙二醇的产率达到70.7%. 相似文献