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141.
棉籽油间歇式酯交换反应动力学的研究 总被引:45,自引:0,他引:45
生物柴油(棉籽油甲酯)可以由棉籽油与甲醇在催化剂KOH存在下通过酯交换反应制得。故对棉籽油间歇式酯交换反应动力学进行了研究,并考察了反应温度和催化剂浓度对产物棉籽油甲酯浓度的影响。用液相色谱法分析棉籽油的组成;用气相色谱法分析产物中棉籽油甲酯的含量。由实验数据绘制的动力学曲线得到酯交换反应在开始阶段为准二级反应,以后紧接转为一级反应和零级反应,与文献报导的棕榈油酯交换反应动力学结果一致。由实验数据求出酯交换反应在开始阶段的动力学参数,35℃、45℃时的反应速率常数分别为0.9179Lmol-1min-1和1.049Lmol-1min-1,酯交换反应的活化能为10.88kJmol-1。根据实验结果得到棉籽油酯交换反应的最佳反应温度为45℃,最佳催化剂为1.1%KOH。 相似文献
142.
研究了甲基丙烯磺酸钠(SMAS)、丙烯酰胺(AM)与淀粉接枝共聚物的合成方法,接枝反应的影响因素和热稳定性。实验结果表明,该接枝反应基本符合自由基反应的一般规律,并且其聚合产物具有明显的抗高温能力。 相似文献
143.
Jianding Chen Christian Carrot Yvan Chalamet Jean‐Charles Majeste Mohamed Taha 《应用聚合物科学杂志》2003,88(5):1376-1383
Poly(n‐butyl methacrylate) (PBMA) composites with calcium carbonate (CaCO3) were prepared by in situ radical copolymerization of butyl methacrylate (BMA) and methacrylic acid (MA) with precipitated calcium carbonate. To compare the different rheological behaviors of the monomer mixtures with CaCO3 and the composites, the steady and dynamic viscosities of BMA/MA/CaCO3 and poly(BMA/MA/CaCO3) were measured by means of steady and oscillatory shear flows. The viscosity of the mixture BMA/MA/CaCO3 was found to increase evidently with the increasing of CaCO3%. The influence of MA% on viscosity of BMA/MA/CaCO3 was slight. During the in situ polymerization, the viscosity of the reacting system was measured to be enhanced by a factor of about 104 from the monomer/CaCO3 mixture to composites. The dependency of zero‐shear viscosity on molar mass of PBMA was also investigated. The relation between the zero‐shear viscosity and molar mass is η0 = 10?15 Mw3.5. The evolution of the viscosity with the temperature for both PBMA and its composites was obtained and time–temperature superposition was used to build master curves for the dynamic moduli. The flow activation energies were found to be 115.0, 148.6, and 178.7 kJ/mol for PBMA, composite PBMA/CaCO3 (90/10), and PBMA/MA/CaCO3 (89/1/10), respectively. The viscosity of the composites containing less than 10% CaCO3 was lower than that of pure PBMA with the same molar mass. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1376–1383, 2003 相似文献
144.
考察了负载型金属氧化物催化剂对碳酸二甲酯和丙醇气相酯交换合成碳酸甲丙酯的催化性能,并采用BET、XRD、CO2-TPD方法对催化剂进行了表征.结果表明,TiO2/Al2O3对反应具有较高的催化活性和稳定性.随着TiO2负载量的增加,催化剂的比表面积减小,而催化性能则随Ti负载量的增加先增加后减小,在Ti负载量为5%(wt)时活性达到最高,当Ti负载量低于5%(wt)时,TiO2可能以非晶态形式分散在Al2O3表面,而当Ti负载量高于5%(wt)时,TiO2以微晶的形式存在.CO2-TPD研究表明,负载量的改变对催化剂的碱性影响不明显. 相似文献
145.
146.
In drug delivery systems that use silicone elastomers as a diffusion matrix for the active drug, it is common to crosslink the material by the hydrosilylation reaction. In this platinum‐catalyzed reaction, vinyl groups on a polymer add to the methyl siloxane hydride (MHS) groups on a low molecular mass crosslinker. With an excess of crosslinker, a fast curing is achieved and a fully crosslinked material is formed. Unreacted MHS groups were shown to remain in the elastomer after curing because of the excess crosslinker. In this work, a simple procedure was developed to eliminate the unreacted MHS groups from the final product. We found that storage of the product at +40°C and 75% relative humidity for a few weeks will effectively destroy the residual MHS groups in the elastomer. The effects of varying levels of humidity, oxygen, and temperature on this postcuring procedure were studied. The amount of MHS groups was measured with NMR and IR spectroscopy. We also found that the hardness of the material increased by approximately 25% as a consequence of this postcuring treatment. This increase is probably due to a secondary crosslinking reaction between MHS and silanol groups. Heat treatment at higher temperatures led to an even further increase in the hardness and compression modulus. Because no MHS groups remained in the elastomer when this heat treatment was started, it is apparent that another secondary crosslinking reaction is occurring, probably silanol condensation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2254–2264, 2002 相似文献
147.
148.
Nutthakan Pongrakananon Nathaporn Somrang Worakanya Visitsart Pitt Supaphol Manit Nithitanakul Brian P. Grady 《应用聚合物科学杂志》2004,91(4):2216-2222
The effect of methyl acrylate content in ethylene–methyl acrylate–acrylic acid (E–MA–AA) terpolymers and acrylic acid content in ethylene–acrylic acid (E–AA) copolymers was investigated in blends of these two materials. The E–MA–AA terpolymer with 8 mol % methyl acrylate was not miscible with any E–AA material no matter what the AA content, whereas the terpolymer with only about 2 mol % methyl acrylate was miscible, at least to some extent, with the E–AA copolymer at high acrylic acid contents. Evidence supporting this conclusion derived from gloss, differential scanning calorimetry testing, and dynamic mechanical measurements. For the E–AA polymer material with the highest acid content, there was a synergistic effect for some properties at low added amounts of E–MA–AA copolymer; the tensile strength and hardness were 10% higher than values for the E–AA copolymer, even though the E–AA copolymer was much stiffer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2216–2222, 2004 相似文献
149.
150.
G.?BiresawEmail author A.?Adhvaryu S.?Z.?Erhan C.?J.?Carriere 《Journal of the American Oil Chemists' Society》2002,79(1):53-58
The steel/steel boundary friction properties of soybean oil (SBO) and high-oleic soybean oil (HOSBO) are compared. HOSBO is
significantly more saturated than SBO and more oxidatively stable. Changes in degree of unsaturation affect lateral interactions
of adsorbate molecules, which in turn affects their adsorption and, hence, their boundary lubrication properties. To investigate
this possibility, the free energies of adsorption (ΔG
ads) of SBO, HOSBO, and methyl laurate (ML) were determined from the analysis of friction-derived adsorption isotherms using
the Langmuir and Temkin adsorption models. The results showed a stronger adsorption for the vegetable oils than for ML, an
indication of multiple interactions between the ester groups of the triglycerides and the steel surface. The result also showed
no difference in the ΔG
ads values of SBO and HOSBO obtained using either the Langmuir or Temkin models. This was interpreted as an indication of the
lack of appreciable net lateral interaction between triglyceride adsorbates. 相似文献