首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   34篇
  免费   7篇
  国内免费   29篇
化学   63篇
力学   1篇
数学   1篇
物理学   5篇
  2023年   2篇
  2022年   2篇
  2020年   2篇
  2016年   1篇
  2015年   1篇
  2014年   1篇
  2009年   1篇
  2008年   1篇
  2007年   1篇
  2006年   3篇
  2005年   5篇
  2004年   5篇
  2003年   7篇
  2002年   1篇
  2001年   2篇
  2000年   9篇
  1999年   3篇
  1998年   5篇
  1997年   1篇
  1996年   2篇
  1995年   4篇
  1992年   1篇
  1990年   2篇
  1989年   1篇
  1988年   3篇
  1987年   2篇
  1983年   2篇
排序方式: 共有70条查询结果,搜索用时 31 毫秒
41.
 合成了Co-MCM-41和Co-MCM-48分子筛,并用X射线衍射、红外光谱和紫外-可见漫反射光谱等技术对样品进行了表征. 结果表明,部分Co离子掺杂进入了各分子筛的骨架中,在Co-MCM-41分子筛中只含有Co(Ⅱ),而在Co-MCM-48分子筛中只含有Co(Ⅲ). 分子筛中Co离子的价态不同是导致它们反应性能差异的根本原因.  相似文献   
42.
CO2重整甲烷制合成气催化剂六铝酸盐LaNiy/Al12-yO19-δ的研究   总被引:2,自引:2,他引:0  
A series of Ni modified hexaaluminates LaNi y Al 12- y O 19- δ ( y =0 3, 0 6, 0 9, 1 0) were prepared by decomposition of nitrates and calcination at high temperature. The crystalline structure and catalytic properties for CO 2 reforming of methane to synthesis gas were investigated by using XRD, XPS, TPR and TGA techniques. The results showed that a pure hexaaluminate LaNi y Al 12- y O 19- δ phase is formed only when y value is in 0< y ≤1. The reduced hexaaluminates LaNi y Al 12- y O 19- δ exhibit significant catalytic activity and stability for the reaction of CO 2 reforming of methane to synthesis gas at 780 ℃, and no deactivation resulting from carbon deposition is found. In the meantime, the catalytic activity is obviously affected by the modifier Ni in the hexaaluminate lattices. Under the same reaction conditions, the conversion of CH 4 and CO 2 increase with increase in the amount ( y value) of the modifier Ni.  相似文献   
43.
深黄被孢霉催化转化脂肪醇合成不饱和脂肪酸的初步研究   总被引:3,自引:0,他引:3  
The unsaturated fatty acids were biosynthesized by Mortierella isabellina grown on fatty alcohols (butanol, hexadecanol, octadecanol, etc) at 28 ℃ for 5 d and the fatty acid composition was analyzed by gas chromatography. The results showed that more lipid and higher content of the corresponding unsaturated fatty acids could be biosynthesized by the fungi grown on the long chain alcohols. Meanwhile, long chain alcohols were converted more quickly and had higher conversion. It suggests that long chain alcohols are more practical substrates.  相似文献   
44.
The decomposition of methane on Ni/a-Al2O3 modified by La2O3 and CeO2 with differ-ent contents has been investigated and the ralationship between methane decomposition and removal of carbon by CO2 over these catalyst has also been studied by pulse-chromatography. The catalysts were characterized by TPR and XRD. It was shown that Ni/a-Al2O3 could be promoted by adding La2O3, and the carbon species produced over this catalyst was activated and eliminated by CO2. But CeO2 would suppress the decomposition of methane over Ni crystallite. Both La2O3 and CeO2 can inhibit aggregation of the Ni particles. Decomposition of methane over the Ni-based catalysts is structure sensitive to a certain extent.  相似文献   
45.
Liu  Yan  Xu  Zhanlin  Cheng  Tiexin  Zhou  Guangdong  Wang  Junxia  Li  Wenxing  Bi  Yingli  Zhen  Kaiji 《Kinetics and Catalysis》2002,43(4):522-527
The amount of carbon deposited on hexaaluminate LaNiAl11O19 catalyst in CH4 decomposition and CO2 reforming of methane was determined by means of thermogravimetric analysis (TGA). The properties of carbon formed on the catalysts were characterized by X-ray photoelectron spectroscopy (XPS), temperature-programmed CO2 reaction (TPR-CO2), and temperature-programmed oxidation (TPO) techniques. The experimental results showed that hexaaluminate LaNiAl11O19 catalyst possessed high resistance to carbon deposition in CO2 reforming of methane to synthesis gas at high temperatures, and CO2 played an important role in eliminating carbon during the reaction. At least two forms of the deposited carbon, graphite and carbide, were produced during methane reforming with CO2.  相似文献   
46.
甲烷催化二氧化碳重整制合成气反应研究进展*   总被引:16,自引:0,他引:16  
本文参阅了甲烷催化二氧化碳重整制合成气反应研究方面50 余篇文献, 概述了近年来在该研究中催化剂活性组分选择、载体效应、助剂的作用、催化剂积炭行为和重整反应机理等方面的研究进展。  相似文献   
47.
The catalytic oxidative coupling of methane was studied over alkali, alkaline-earth and rare-earth metal oxides at 973 K under atmospheric pressure in a continuous flow fixed bed reactor. The catalysts used were prepared by impregnation method. Four alkaline-earth metal oxides were used as support. The temperature dependence of the catalytic properties and the phase composition of the catalysts were also detected.
, 973 - . . . .
  相似文献   
48.
CO2 reforming of CH4 over hexaaluminates LaNi x Mg1−x Al11O19+δ and LaNi x Mg0.8Al11.2−x O19+δ were studied. XRD analysis confirmed that modifier Ni as well as Mg was inlaid into the hexaaluminate lattice. Hexaaluminate LaNi x Mg1−x Al11O19+δ (1.0 ≥ x ≥ 0.4) showed better catalytic activities and higher resistance to carbon deposition, which was attributed to their pure magnetoplumbite-type structure. For this reaction, x-value between 0.6 and 0.4 was the most suitable.  相似文献   
49.
建立抑制电导离子色谱法测定蔬菜、药品和水中对氨基苯磺酸.以SH–AC–3型阴离子交换柱为分离柱,5.0 mmol/L Na2CO3–1.5 mmol/L NaHCO3为淋洗液,以1.0 mL/min的流量等度洗脱,对氨基苯磺酸与常见阴离子可实现完全分离,对氨基苯磺酸的色谱峰面积与质量浓度在0.05~100.0 mg/L...  相似文献   
50.
Summary Effect of KCl on the structure and the catalytic properties of CuCl2/γ-Al2O3 catalyst for ethane oxychlorination has been studied by means of solubility test, UV-vis spectroscopy, XRD, TPR, TEM and catalytic reaction. Addition of KCl decreases the interaction between active species CuCl2 and γ-Al2O3 and increases the catalytic properties by accelerating the Cu(II) → Cu(I) reduction step.  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