全文获取类型
收费全文 | 2184篇 |
免费 | 15篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 21篇 |
综合类 | 34篇 |
化学工业 | 1421篇 |
金属工艺 | 22篇 |
机械仪表 | 27篇 |
建筑科学 | 43篇 |
矿业工程 | 13篇 |
能源动力 | 95篇 |
轻工业 | 409篇 |
水利工程 | 3篇 |
石油天然气 | 8篇 |
武器工业 | 2篇 |
无线电 | 12篇 |
一般工业技术 | 60篇 |
冶金工业 | 20篇 |
原子能技术 | 6篇 |
自动化技术 | 7篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 14篇 |
2021年 | 20篇 |
2020年 | 27篇 |
2019年 | 18篇 |
2018年 | 27篇 |
2017年 | 46篇 |
2016年 | 41篇 |
2015年 | 44篇 |
2014年 | 95篇 |
2013年 | 635篇 |
2012年 | 67篇 |
2011年 | 132篇 |
2010年 | 79篇 |
2009年 | 72篇 |
2008年 | 90篇 |
2007年 | 143篇 |
2006年 | 101篇 |
2005年 | 72篇 |
2004年 | 85篇 |
2003年 | 54篇 |
2002年 | 66篇 |
2001年 | 66篇 |
2000年 | 26篇 |
1999年 | 24篇 |
1998年 | 25篇 |
1997年 | 21篇 |
1996年 | 20篇 |
1995年 | 14篇 |
1994年 | 20篇 |
1993年 | 6篇 |
1992年 | 19篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1982年 | 3篇 |
1981年 | 1篇 |
排序方式: 共有2203条查询结果,搜索用时 0 毫秒
71.
《Drying Technology》2013,31(1-2):305-315
Abstract Moisture is one of the most deteriorating factors of buildings. The deteriorating effect of moisture occurs mainly during the drying phase, not in the wetting phase. Environmental factors, such as air temperature, air humidity, and air velocity affect drying. An experimental air dryer of controlled drying air conditions was used to investigate the drying performance of 4 stone materials, 2 bricks, and 6 plasters. Drying kinetics was examined at 3 air temperatures, 5 air humidities, and 3 air velocities. A first-order kinetics model was obtained in which the drying time constant was a function of the drying conditions, and the equilibrium material moisture content was described by the modified Oswin equation. The parameters of the proposed model were found to be affected strongly by the material characteristics. 相似文献
72.
73.
Victor M. Monsalvo Angel F. Mohedano Juan J. Rodriguez 《Chemical Engineering Research and Design》2012
Sewage sludge was used as precursor to develop a potential inexpensive adsorbent by both simple drying and pyrolysis. The resulting materials were evaluated as adsorbents for the removal of 4-chlorophenol (4-CP) from aqueous solution. The dried biosolids showed a BET surface area lower than 3 m2/g, which yield a maximum adsorption capacity of 0.73 mmol 4-CP/g at pH 5.0 and 15 °C. The carbonization of biosolids under relatively mild conditions allowed obtaining materials with BET surface area up to 45 m2/g, which led to a significant increase of the maximum adsorption capacity (1.36 mmol 4-CP/g). The high ash content of the starting material (23%, d.b.) limits the development of porosity on a total dry-weight basis. Adsorption data were well fitted to the Redlich–Peterson isotherm equation whereas the most commonly used Langmuir and Freundlich equations were less satisfactory probably because of the occurrence of summative adsorption phenomenon. A thermodynamic study of the adsorption showed the spontaneous and exothermic nature of the process. Thus, simple drying and carbonization provide two ways of valorization of sewage sludge through its conversion into inexpensive low-rank adsorbents potentially useful for the removal of some hazardous water pollutants, like chlorophenols and related compounds. 相似文献
74.
Aditya Putranto 《Drying Technology》2014,32(2):208-221
The reaction engineering approach (REA) is examined here to investigate its suitability as the local evaporation rate to be used in multiphase drying. For this purpose, REA is first implemented to model the convective drying of materials with various thicknesses. The relative activation energy, as the fingerprint of REA, generated from one size of a material is used to model the convective drying of the same material with different thicknesses. Because the results indicate that REA parameters can model the drying of materials with various thicknesses, REA can be scaled down to describe the local evaporation rate (at the microscale as affected by local composition and temperature). The relative activation energy is used to describe the global drying rate in modeling the local evaporation rate. REA is combined with a system of equations of conservation of heat and mass transfer in order to yield the spatial reaction engineering approach (S-REA) as a nonequilibrium multiphase drying model. By using S-REA, the spatial profiles of moisture content, concentration of water vapor, temperature, and local evaporation rate can be generated, which can assist in comprehending the transport phenomena. 相似文献
75.
Cynthia Salas 《Drying Technology》2014,32(3):301-310
Tectona grandis and Gmelina arborea are common in commercial reforestation in the tropics. However, color variations, moisture content, and drying defects are also present in dried lumber. Moisture content variations, drying defects, and color changes were evaluated in the present work for three drying methods (kiln, solar, and air drying) during three seasons (dry, rainy, and transition season) in Costa Rica. According to the results, kiln drying had the fastest drying times, regardless of the season. On the other hand, air drying had slower drying time and higher final moisture content. With regard to defects, kiln drying produced the highest number and magnitude of defects in both species, whereas air drying showed the lowest quantity and severity of defects. No variations due to the drying methods or the season were observed in check and split, though solar drying presented intermediate values in all drying defects. The seasons of the year did not present any effect on drying defects. Finally, T. grandis dried lumber is darker than green lumber, and dried G. arborea wood is clearer. In addition, there is an increase in red ( a * ) and yellow ( L * ) tonalities, and color changes (Δ E * ) are considered perceptible or very perceptible in both species. No differences were found among the three drying methods in Δ E * , although the season of the year affected dif L * and dif C * significantly. 相似文献
76.
Nan Fu Meng Wai Woo Sean Xu Qi Lin Zihao Zhou Xiao Dong Chen 《Chemical engineering science》2011,(8):138
Droplets with different initial sizes, which are typical in conventional liquid atomization for spray drying applications, will result in varying drying and crust formation histories. It is essential for any droplet drying model to accurately capture such fundamental phenomena. This study used a newly constructed glass-filament single droplet rig to evaluate the applicability of the Reaction Engineering Approach (REA) in describing such effect. For the three initial sizes (1, 2 and 3 μL) tested, the glass filament gravimetric method clearly distinguished the different drying kinetics and the crust formation phenomenon, delineated by the drying behavior. Analysis from the drying kinetics revealed that the main premise of the REA, which utilizes a material-specific master activation energy curve, is applicable to droplets of different initial sizes at all the three air temperatures tested. This allowed the REA to accurately predict the different temperature and moisture histories given by droplets with different initial sizes. The result supports the REA as a good modeling approach for a wide range of initial droplet conditions. A new master curve approach was proposed to predict the diameter change of droplets with different initial concentrations. Validation with the current and past experimental data revealed that this approach has strong potential to account for the different feed concentrations typically found in spray drying applications. 相似文献
77.
以高性能混凝土用胶凝材料为研究对象,研究了粉煤灰、矿粉在不同养护湿度和温度下对水泥浆体变形性能的影响规律.结果表明:饱水养护时,粉煤灰的掺入降低了水泥浆体的水养膨胀变形;养护温度升高、粉煤灰掺量增加,水泥浆体水养膨胀变形降低幅度增大,但不同水养温度下掺入矿粉对水泥浆体膨胀变形无明显影响;密封养护时,掺入粉煤灰可有效抑制... 相似文献
78.
模拟含硼废液喷雾干燥试验 总被引:1,自引:0,他引:1
研究了三种喷雾干燥方式处理模拟含硼废液试验的性能和影响因素.三种喷雾干燥方式为:旋转式雾化并流喷雾干燥、气流式雾化并流喷雾干燥和气流式雾化混合流动喷雾干燥.对于硼浓度21 000 ppm(10-6)的模拟含硼废液,在供料温度为62~64 ℃,干燥塔进出口温度分别为210~220 ℃和110~120 ℃,压空流量为8.0 m3/h,雾化器转速为73.0 m/s的条件下,三种喷雾干燥方式均得到了流动性良好的粉体,粉体中占总质量95%的粉体粒径在0.356~0.061 mm之间.三种喷雾干燥方式处理模拟含硼废液的减容系数在0.22~0.27之间,气流式雾化并流喷雾干燥方式、气流式雾化混合流动喷雾干燥方式和旋转式雾化并流喷雾干燥方式的废液处理能力依次增大,所得粉体的含水率依次增大. 相似文献
79.
In the last rice harvest season, experimental results have been obtained on the efficiency and drying quality of a solar assisted heat pump drying prototype system. The system has been operated as a solar and heat pump system and drying curves for the different options have been obtained. The advantage of the low temperature and better control in the drier shows that the heat pump assisted solar drying system is an excellent alternative to traditional drying systems. 相似文献
80.
水性丙烯酸树脂及其水性油墨性能研究 总被引:2,自引:0,他引:2
水性油墨的抗水性和耐酸碱性是直接制约水性油墨应用性能的重要指标,本研究采用甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)为硬软单体,以丙烯酸(AA)、丙烯酸羟丙酯(HPA)为功能单体,采用乳液聚合法制备一种高固含量、耐酸碱性和抗水性优良、成膜性较好的水性丙烯酸树脂,并用这种树脂配制水性油墨;讨论了各单体用量对树脂膜抗水性和耐酸碱性的影响,以及油墨其他相关成分对油墨干燥速度、抗水性和光泽度的影响.研究表明,当MMA∶BA质量比为3∶2,AA和HPA含量分别为3.6%和6.7%时,树脂获得良好的抗水性;当助溶剂异丙醇含量为5%,分散剂用量为颜料和填料总量的3%,pH值为8.5~9.0,油墨中水的含量为25%时,油墨具备较好的干燥速度、抗水性和光泽度等性能. 相似文献