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141.
林产化学加工学科的现况与发展前景 总被引:2,自引:0,他引:2
本文了介绍了并论述了林产化学加工学科所含的五个专业方向,木材化学加工工程,树木提取物化学工程,林产生物化工,木材保护与改性,林产化工装备与控制的研究内容,工业现状,存在问题与发展前景。 相似文献
142.
K. Luke 《Cement and Concrete Research》2004,34(9):1725-1732
Phase studies of calcium silicate hydrates formed at elevated temperature and pressure have been well documented. At 180 °C, the initially formed amorphous calcium silicate gel [C-S-H] transforms into well-defined crystalline phases, the stability of which is primarily dependent on the C/S ratio in the CaO-SiO2-H2O system and the hydrothermal conditions. Hillebrandite [C2SH], α-dicalcium silicate hydrate [α-C2SH] and β-tricalcium silicate [β-C6S2H3] are predominantly the stable phases in the lime-rich part of the CaO-SiO2-H2O system and are typically associated with high permeability and compressive strength retrogression. Gyrolite [C2S3H~2], tobermorite [C5S6H5], truscottite [C7S12H~3] and xonotlite [C6S6H] have all been reported to coexist stably in aqueous solution with silica in the silica-rich part of the CaO-SiO2-H2O system.The addition of excess silica to the CaO-SiO2-H2O system is usually in the form of silicon dioxide [SiO2], either as microsilica or quartz flour, which, in theory, should not affect the equilibrium chemistry. This has not been found to be the case, and metastable phases formed in the early stages of reaction modify the long-term stability and phase equilibrium. Pozzolanic materials that are predominantly alumino-silicates have also been investigated as a source of excess silica. Partial replacement of aluminum for silicon occurred, but had no apparent influence on the stability of the calcium silicate hydrates formed. 相似文献
143.
144.
水溶性聚合物在油田钻井液中的应用 总被引:3,自引:0,他引:3
介绍国内水溶性聚合物钻井液处理剂的研究与应用情况,水溶性聚合物可用泥浆降滤失剂,增粘剂,絮凝剂,降粘剂和防塌型,它包括天然高分子材料和合成聚合物。 相似文献
145.
Peter?S.?Piispanen Marcus?Persson Per?Claesson Torbj?rn?NorinEmail author 《Journal of surfactants and detergents》2004,7(2):147-159
Several novel and some previously known, mostly sugar-based, surfactants have been synthesized and some of their surface properties
have been characterized and compared with those of commercial nonylphenol ethoxylates. The surfactant solubility in water,
ethanol, and dodecane was studied. The properties of these compounds as emulsification agents in systems composed of the surfactant
with water/isopropyl myristate, water/rapeseed oil, and water/dodecane are presented. The aqueous solubility of the surfactants
follows the general trend expected from their hydrophilic-lipophilic balance according to Griffin (HLBG), but it is also clear
that the nature of the headgroup and the structure of the nonpolar part affect the solubility in a manner not aptured in the
standard HLBG concept. An ester or amine group as the connecting unit between the hydrophile and the hydrophobe produces a
more water-soluble surfactant than the corresponding amide derivative. Some effective emulsifiers were found. For instance,
the surfactants with a dehydroabietic nonpolar group appear to be promosing emulsifiers. Most sugar-based surfactants were
able to form macroemulsions of up to around 2 wt/vol% of oil. The stability of many of these amulsions was very high, extending
for months. 相似文献
146.
147.
Schistosome adults attract each other in vitro and the attraction is chemically mediated. InSchistosoma mansoni adults, excretory-secretory (ES) products of worms of one sex attract worms of the opposite sex, and at least the lipophilic fraction is attractive. Intra- and interspecific attraction occurs inSchistosoma mansoni, S. japonicum, andS. haematobium adults. Current knowledge of schistosome behavior in vitro is reviewed. 相似文献
148.
在现代社会中,平板电脑、智能手机在人们日常生活的方方面面发挥着巨大的作用。通过分析电子产品在儿童和青少年的视力、身体发育、社交能力和学习能力等方面的负面影响,提出了加强亲子陪伴、合理引导控制等应对措施。 相似文献
149.
Michael D. Dahlberg Richard L. Rohrer Daniel J. Fauth Richard Sprecher Gregory J. Olson 《Fuel》1993,72(12):1645-1649
A bacterium identified as Arthrobacter sp. was grown on dibenzothiophene (DBT) sulfone as a sole source of sulfur, producing sulfite and sulfate. Sulfur in DBT sulfone (1.0 mM) was nearly quantitatively converted to sulfate by the organism. The organism could also use DBT sulfone as a sole source of carbon and energy. There was evidence for transient accumulation of benzoic acid in the culture medium after growth of the cells slowed. The DBT sulfoxide analogue 9-fluorenone was converted by resting cells to a product identified as 1,10-dihydroxy-1,10-dihydrofluoren-9-one, suggesting that DBT sulfone may be metabolized via an angular hydroxylation resulting in carbon- sulfur bond cleavage. This strain of Arthrobacter showed no ability to desulfurize oxidized Illinois No. 6 coal. 相似文献
150.
介绍了甲醇的几种重要的下游产品,如甲醛、甲酸甲酯、甲胺等,提出应大力生产和发展甲醇下游产品,并进一步拓宽甲醇的应用领域,加快甲醇应用新技术的开发工作。 相似文献