全文获取类型
收费全文 | 8972篇 |
免费 | 732篇 |
国内免费 | 139篇 |
专业分类
电工技术 | 161篇 |
综合类 | 372篇 |
化学工业 | 4116篇 |
金属工艺 | 112篇 |
机械仪表 | 148篇 |
建筑科学 | 352篇 |
矿业工程 | 118篇 |
能源动力 | 374篇 |
轻工业 | 2902篇 |
水利工程 | 74篇 |
石油天然气 | 92篇 |
武器工业 | 14篇 |
无线电 | 83篇 |
一般工业技术 | 612篇 |
冶金工业 | 213篇 |
原子能技术 | 25篇 |
自动化技术 | 75篇 |
出版年
2024年 | 63篇 |
2023年 | 122篇 |
2022年 | 189篇 |
2021年 | 235篇 |
2020年 | 276篇 |
2019年 | 262篇 |
2018年 | 287篇 |
2017年 | 400篇 |
2016年 | 357篇 |
2015年 | 297篇 |
2014年 | 482篇 |
2013年 | 1542篇 |
2012年 | 530篇 |
2011年 | 571篇 |
2010年 | 369篇 |
2009年 | 362篇 |
2008年 | 330篇 |
2007年 | 422篇 |
2006年 | 437篇 |
2005年 | 355篇 |
2004年 | 303篇 |
2003年 | 255篇 |
2002年 | 219篇 |
2001年 | 228篇 |
2000年 | 161篇 |
1999年 | 153篇 |
1998年 | 126篇 |
1997年 | 120篇 |
1996年 | 81篇 |
1995年 | 71篇 |
1994年 | 44篇 |
1993年 | 47篇 |
1992年 | 37篇 |
1991年 | 20篇 |
1990年 | 24篇 |
1989年 | 12篇 |
1988年 | 11篇 |
1987年 | 4篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1951年 | 1篇 |
排序方式: 共有9843条查询结果,搜索用时 15 毫秒
21.
22.
混凝土早期收缩开裂是加剧混凝土劣化并导致最终失效的一个重要因素.分析混凝土早期的自由收缩量值是进行收缩开裂研究的基础。为此,基于湿度扩散理论建立了混凝士早期的自生收缩与干燥收缩计算分析模型,经实例验证,计算结果与试验结果有较好的一致性。 相似文献
23.
发展我国冻干蔬菜产业大有可为 总被引:1,自引:0,他引:1
本文介绍了真空冷冻干燥食品的发展现状、特点及其工艺流程 ,着重讨论了发展冻干食品工业的广阔前景 相似文献
24.
Sucrose crystallization in thin films (50–55 μm) was studied, using a videomicroscopy technique, at conditions encountered during hard panning processes. No nucleation occurred in unseeded films, while a linear increase in seeded crystals occurred during drying. Crystal growth rate increased with temperature (25–30°C) and with air velocity (2.4–12.5 m/sec), but did not change with varying sucrose concentrations (70–76% w/w) and relative humidities (0–66% at 30°C). FD & C Yellow No. 5 food coloring in the dye form (0.05–0.5 g/100 mL) showed no effects while similar concentrations in the lake form inhibited crystal growth rate. 相似文献
25.
快干性瓦楞纸箱粘合剂的研制 总被引:1,自引:0,他引:1
本文叙述了快干性瓦楞纸箱粘合剂的配制及工艺过程。实验结果表明,该粘合剂具有快的干燥速度和良好的性能 相似文献
26.
《Drying Technology》2007,25(12):1949-1958
A mathematical model for through drying of paper at constant pressure drop was developed. The model is based on physical properties; hence, basis weight, pressure drop, drying air temperature, pore size distribution, initial gas fraction, and tortuosity are important input parameters to the model. The model was solved for different combinations of the variables basis weight, drying air temperature, and pressure drop corresponding to industrial conditions and the results were compared with data from bench-scale experiments. The simulations show that the drying rate curve is very sensitive to the air flow rate and that correctly modeling the correlation between pressure drop and air flow rate is the most important factor for a successful model for through drying. The model was tuned by adjusting the parameters initial gas fraction and tortuosity in order to give the best possible fit to experimental data. For a given basis weight and pressure drop, different drying air temperatures resulted in relatively constant values of the fitted parameters. This means that the model can well predict the effects of changes in drying air temperature based on a tuning of the model performed at the same basis weight and pressure drop. However, for a given basis weight, an increase in pressure drop yielded fitted parameters that were somewhat different; i.e., a lower initial gas fraction and a higher tortuosity, a change that increases the resistance to air flow. This implies that the correlation between pressure drop and air flow rate in the model does not quite capture the nonlinear relationship shown by the experiments. 相似文献
27.
Thermal history and solute precipitation behavior of suspended solution droplets of sodium chloride (NaCl), magnesium sulphate (MgSO4), and zirconium hydroxychloride (ZrO(OH)Cl) evaporating at atmospheric and reduced pressures are studied. Experimental measurements on the variation of droplet diameter, solution concentration, and temperature during the evaporation period are presented and discussed. The results of solute precipitation behavior in solution droplets observed under an optical microscope are displayed and discussed. Results indicate that reducing the pressure (∼ 33 kPa) results in a change in the solution droplet evaporation rate, but the thermal histories of a particular solution droplet are similar at the atmospheric and reduced pressures. At atmospheric and reduced pressures used in this study, the d2 law for solution droplets is valid at early stages of the evaporation and before the solute precipitation initiates. Drying of MgSO4 and ZrO(OH)Cl solution droplets results in the formation of spherical particles, whereas drying of spherical NaCl solution droplets results in the formation of cubic particles. 相似文献
28.
High-temperature and controlled humidity treatment before drying has proven to be highly effective in preventing surface checks by forming drying sets in the surface layer of boxed-heart square timber in Japan. In this study, we examined the differences of the surface drying sets on sugi timber under different treatment temperatures. As a result, the width of a surface check after drying was much smaller at a treatment temperature of 120°C than at 80°C, and this indicates that the drying set with 120°C treatment would be larger than that with 80°C treatment. Also we observed that treatment temperature had a greater effect on the drying set as the drying advanced. 相似文献
29.
微波干燥原理及其应用 总被引:31,自引:1,他引:30
介绍了微波干燥的原理和主要特点及其应用的现状,并且给出了微波干燥经济核算的计算方法。 相似文献
30.
Drying of textile bobbins was carried out on two kinds of laboratory-scale dryers: in a cross circulation drying rig, atmospheric pressure heating air is used, while in the through circulation drying apparatus, the heating air is pressurized before the drying process takes place. In both cases, a bobbin was fitted with seven thermocouples, placed in a plane normal to the bobbin axis but at different radial distances, in order to provide temperature data during the drying process. In cross circulation drying, plots of temperature against time indicated the presence of two moving fronts, one starting from inside the bobbin, another from the outside, while in through circulation drying, similar plots showed the presence of an evaporation front, moving from inside the bobbin to the outside. In both canes, numerical models were developed to simulate the drying processes. 相似文献