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1.
Monodisperse poly(vinyl acetate) (PVAc) microspheres with high molecular weight obtained by suspension polymerization of vinyl acetate were saponified in alkaline aqueous solution to keep their spherical structure. The saponification was restricted on the surface of the PVAc microspheres and obtained particles had skin/core structure. Various poly(vinyl alcohol) (PVA) microspheres with different diameters and degrees of saponification (DSs) were obtained. The conversion of PVAc to PVA during the heterogeneous surface saponification time were examined by nuclear magnetic resonance spectroscopy and after 72 h hydrogel type PVA microspheres completely saponified were obtained. The crystal melting temperatures of the microspheres obtained by the saponification were measured a constant value of 238°C irrespective of varying DS, and the peaks became enlarged as reaction time. Iodine complexes were formed in saponified microspheres with DS of 41% and 99% by immersing them in I2/KI aqueous solution and decomposed by the reduction of I2 in the complexes to 2I? using sodium sulfite to confirm whether the skin formed through the saponification was composed of PVA with high VA content. Obviously, characteristic blue color developments owing to I5?‐PVA complexes were observed in both saponified regions and a red in the PVAc core. Consequently, it was concluded that the PVA skins formed by heterogeneous surface saponification had high DSs. Such complexes endowed polymeric microspheres a good radiopacity which would be useful in clinical treatment of vascular diseases and were examined by X‐ray irradiation image. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
2.
F. R. van de Voort J. Sedman G. Emo A. A. Ismail 《Journal of the American Oil Chemists' Society》1992,69(11):1118-1123
A simple, rapid and reproducible method of determining the iodine value (IV) and saponification number (SN) for fats and oils
was developed with an attenuated total reflectance/Fourier transform infrared spectrometer and commercially available triglycerides
as calibration standards. Partial least squares was used to determine the spectral regions correlating with the known chemical
IV and SN values, and the calibration set was augmented with additional standards generated by spectral co-adding techniques.
The calibration model obtained was used to analyze commercially available fats and oils with a wide range of IV and SN values,
and the results were compared to the values obtained by American Oil Chemists’ Society methods. With the spectrometer calibrated
and programmed, IV and SN results could be obtained within 2–3 min per sample, a major improvement over conventional wet chemical
methods. 相似文献
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以歧化松香为主要原料,在较低的温度(75~95℃)下,溶入KOH水溶液,并进行皂化反应,制备固体份质量分数45%的歧化松香钾皂。研究了反应温度、皂化时间、pH值、添加复合助剂TX-A对反应速度、去氢枞酸钾含量,以及黏度、结晶、胶凝等产品性能的影响。得出歧化松香钾皂化的较佳制备条件为:pH值为10.36,皂化时间分别为120 min(未加TX-A)、98 min(加TX-A),反应温度85℃,TX-A加入量为反应物质量的0.2%。制备出的歧化松香钾皂产品,在性能上完全符合行业标准ZBB 72003-84的要求,并且结晶、胶凝性质有所改善,加纳色号标准降低两个等级。 相似文献
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分析了环己酮生产环己烷皂化废碱液焚烧排放烟气时有臭味及蒸发器列管严重结垢的原因和机理.对皂化废碱液蒸发浓缩技术进行了改进:将外加热式管内沸腾升膜蒸发器改造为外加热式管外沸腾强制循环蒸发器,并在皂化废碱液中添加蒸发助剂.实施后明显抑制了蒸发器列管结垢趋势,焚烧炉烟气臭气消除,运行周期达到1个月以上;清洗蒸发器时,只需用稀碱液和水循环清洗,避免了频繁打开蒸发器机械清洗. 相似文献
8.
微波化学研究中的关键问题之一是对化学反应过程中的介电系数进行跟踪和测量.本文采用开槽同轴谐振探头首次测量了乙酸乙酯皂化反应对微波的反射系数,并用遗传算法获得了微波频率下该反应的等效介电系数.结果发现等效介电系数实部随温度的变化趋势符合L Onsager和Debye理论对极性混合溶液的描述;等效介电系数虚部因极化损耗和欧姆损耗随温度变化而相应变化;而等效介电系数实部随时间的变化与L Onsager极性混合溶液等效介电系数理论的描述相反. 相似文献
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Ga?lle?Poulenat Sabine?Sentenac Zéphirin?Mouloungui'ephirin.mouloungui@ensiacet.fr" title="z 'ephirin.mouloungui@ensiacet.fr" itemprop="email" data-track="click" data-track-action="Email author" data-track-label="">Email author 《Journal of surfactants and detergents》2003,6(4):305-310
Sodium, lithium, and calcium soaps obtained by saponification of high-oleic sunflower oil were studied by Fourier-transform
infrared spectroscopy. Spectra of crude mixtures containing soap, glycerin, residual alkali, and triacylglycerols were compared
to those of pure soaps obtained from fatty acids. The infrared spectra of crude soaps showed the same characteristic bands
as pure ones. The absorption bands of asymmetric (ω2) and symmetric (ω1) stretching vibrations of the carboxylate group indicated that the metal-oxygen bonds of these soaps had an ionic character
whose strength differed from one cationic counterion to another. Once the characteristic absorption bands of the soaps were
assigned, a kinetics study of saponification was performed. Saponification by sodium, anhydrous lithium, and calcium hydroxides
was an autocatalytic reaction, characterized by an S-shaped kinetics curve, whereas saponification by aqueous lithium hydroxide
was stoichiometric. The structure of the metal-oxygen bond played a role in the kinetic mechanisms. 相似文献