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161.
M. Boudart 《Topics in Catalysis》1994,1(3-4):405-414
This is a personal account of the Havreholm Conference with a choice of topics dealing with catalytic ammonia synthesis. Among the general concepts that were retained are: the rate determining step with rates of adsorption and desorption of nitrogen; the direct activated dissociative adsorption of N2; the surface crystalline anisotropy of iron; the role of promoters in industrial iron based catalysts; and the atomic structure of the metallic surface on the industrial multiply promoted catalyst. Finally, a new isotope jump technique to measure an upper limit to the real turnover frequency is discussed. 相似文献
162.
Fresh leaves and volatile oil of the important weed Ageratum conyzoides in south China were highly inhibitory to seedling growth of various cultivated crops, especially in an adverse habitat. The constituents of the volatile oil were analyzed by GC-MS. Eleven components were identified and six main components, precocene I, precocene II, 3,3-dimethyl-5-tert-butylindone, -caryophyllene, -bisabolene, and fenchyl acetate, were isolated by means of column chromatography. Precocene I, precocene II, -caryophyllene, and 3,3-dimethyl-5-tert-butylindone inhibited seedling growth of acceptor plants. Inhibitory activity of the volatile oil was more intense than that of the pure components. Fenchyl acetate and -bisabolene have no inhibitory activity, but when mixed with precocene II, they increased the inhibitory activity to growth of acceptor seedling plants. Experiments show that allelopathic synergism exists among allelochemicals of Ageratum conyzoides. 相似文献
163.
V. E. Sokolov E. S. Albone P. F. Flood P. F. Heap M. Z. Kagan V. S. Vasilieva V. V. Roznov E. P. Zinkevich 《Journal of chemical ecology》1980,6(4):805-825
The sulfur-rich anal sac secretion of the mink,Mustela vison, consisted of immiscible lipid (1.7% sulfur) and aqueous (0.7% sulfur) phases. Light and electron microscopy revealed secretory tissue of two types, sebaceous (holocrine) and apocrine. A major input of sulfur into the sac appeared to be associated with glycoprotein granules present in the apical portions of the apocrine cells as X-ray energy probe microanalysis showed these to contain relatively high levels of sulfur. The lipid of the secretion, presumed to be largely of sebaceous origin, consisted mainly of wax monoesters, while the aqueous phase contained volatile fatty acids, ammonia, and amines, including putrescine (1,4-diaminobutane). The identity of the major headspace volatiles was confirmed by NMR, MS, and Raney nickel desulfuration as being 2,2-dimethylthiacyclobutane and 3,3-dimethyl-1, 2-dithiacyclopentane. These compounds were not detected by GC-MS in the headspace volatiles of the anal sac secretions of eight other mustelid species examined. Other sulfur compounds detected included isomeric dimethylthiacyclobutanes, a number of disulfides and 3-methyl-but-3-enyl methyl sulfide (isopentenyl methyl sulfide). The significance of these findings is discussed. 相似文献
164.
T. Watanabe P. Chairoj H. Tsuruta W. Masarngsan C. Wongwiwatchai S. Wonprasaid W. Cholitkul K. Minami 《Nutrient Cycling in Agroecosystems》2000,57(1):55-65
Nitrous oxide (N2O) emission from fertilized maize fields was measured using a closed chamber at four experimental sites in Thailand. The average measured N2O flux from unfertilized plots through crop season was 4.16 ± 1.52, 5.05 ± 1.65, 5.25 ± 1.68 and 6.74 ± 2.95 g N2O-N m-2 h-1, at Nakhon Sawan, Phra Phutthabat, Khon Kaen and Chiang Mai, respectively. Increased N2O emissions by the application of nitrogen fertilizer were 0.22–0.44, 0.19–0.38%, 0.12–0.24 and 0.08–0.15% of the applied N, respectively. Compared to other data, N2O emission rate to applied nitrogen was not significantly different between the data of Thailand and the Temperate Zone. 相似文献
165.
生物脱氮工艺的新发展-半硝化和厌氧氨氧化 总被引:13,自引:0,他引:13
传统生物脱氮工艺耗能多,反硝化时还消耗碳源,半硝化一厌氧氨氧化(SHARON-ANAMMOX)是一种全新的脱氮工艺,其原理是首先由亚硝化细菌将废水中1/2氨氮氧化为NO2^-,剩余的氨氮与所生成的NO2^-以等摩尔比例ANAMMOX菌作用生成N2,因耗能少且不消耗碳源,故具有可持续发展意义。 相似文献
166.
含氨废水处理技术及工艺设计方案 总被引:14,自引:1,他引:14
本文根据氮肥厂废水的特点,研究了高浓度氨氮废水的处理方法-吹脱法的除氨机理和氨氮去除率的影响因素。针对pH值和温度对氨氮去除率的影响,我们做了实验,结果表明若去除率要达到90%以上,pH值必须大于12且温度高于90C。同时可以用CaO将废水的pH值调节到12以上。最后,针对这种废水的处理设计了可行的工艺方案。 相似文献
167.
168.
B. S. Goodrich E. R. Hesterman K. S. Shaw R. Mykytowycz 《Journal of chemical ecology》1981,7(5):817-827
A study has been made of the volatile constituents in the vapors collected from fecal pellets of wild rabbits,Oryctolagus cuniculus. Measurements of changes in the heart rates of adult male rabbits exposed to the effluent of a gas chromatographic capillary column were used to indicate the presence of compounds which may be of behavioral significance. Combined with the use of high-resolution columns in gas chromatography and gas chromatography-mass spectrometry, this approach has implicated several classes of compounds, including volatile fatty acids and phenols, which in certain absolute or relative concentrations may be involved in the formation of signals of territorial importance. 相似文献
169.
Michael addition of ethyl acrylate and acetone over solid bases 总被引:1,自引:0,他引:1
The catalytic behaviour of the superbases Na/NaOH/-Al2O3 and CsxO/-Al2O3 as well as of the basic zeolites Na/NaX and CsxO/CsX were investigated in the Michael addition of ethyl acrylate and acetone. The reactions were carried out in the liquid phase at catalyst loadings varying from 0.05 to 0.1 mol ester/g catalyst. 相似文献
170.