全文获取类型
收费全文 | 553篇 |
免费 | 47篇 |
国内免费 | 18篇 |
专业分类
电工技术 | 5篇 |
综合类 | 20篇 |
化学工业 | 281篇 |
建筑科学 | 3篇 |
矿业工程 | 2篇 |
能源动力 | 95篇 |
轻工业 | 7篇 |
石油天然气 | 144篇 |
一般工业技术 | 10篇 |
冶金工业 | 3篇 |
原子能技术 | 4篇 |
自动化技术 | 44篇 |
出版年
2023年 | 10篇 |
2022年 | 18篇 |
2021年 | 27篇 |
2020年 | 27篇 |
2019年 | 26篇 |
2018年 | 19篇 |
2017年 | 25篇 |
2016年 | 24篇 |
2015年 | 43篇 |
2014年 | 68篇 |
2013年 | 68篇 |
2012年 | 54篇 |
2011年 | 64篇 |
2010年 | 34篇 |
2009年 | 26篇 |
2008年 | 14篇 |
2007年 | 16篇 |
2006年 | 19篇 |
2005年 | 11篇 |
2004年 | 7篇 |
2003年 | 8篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
排序方式: 共有618条查询结果,搜索用时 15 毫秒
41.
The variation of moisture content in the biomass materials would affect the quality during the utilization of these materials as solid biofuel. The ability to predict the time-dependent moisture contents of the biomass via modeling can help to devise a better way to store and manage these biomass materials. In this study, pieces of aspen stems were subject to cycles of wetting and drying in lab-scale tests. A lumped mathematical model for simulating the moisture changes during storage was developed and calibrated using the experimental data. With the available weather data (air temperature, relative humidity, solar radiation, wind speed, and precipitation) as inputs, the model was then applied to estimate the moisture content of aspen (Populus tremuloides) during one year of storage in the field. Results showed that, for both uncovered bales and covered bales, the predicted moisture contents and the profiles were in good agreement with the measured in-field results. This lumped model may be used as a first approximation, and applied to estimate the moisture content of aspen or similar woody biomass materials during relatively long-term field storage. 相似文献
42.
煤制天然气过程模拟与?分析 总被引:1,自引:0,他引:1
煤制天然气过程具有设备流程简单、技术成熟可靠、单位热值投资成本低等优点。本文运用Aspen Plus软件建立煤制天然气流程的过程模型,并采用?分析法对系统主要单元进行计算分析,得出系统的?分布状况及各单元的?损失量。结果表明,低温甲醇洗单元的?效率最高,为98.22%,煤气化单元的?效率最低,为58.99%。同时,系统的?损失也主要发生在煤气化单元,占系统总?损失的72.69%。煤气化单元中主要的?损失是由于传热不可逆和化学反应的不可逆性引起的内部?损失,通过优化气化温度、汽氧摩尔比等方式改善气化炉的气化条件是提高气化?效率、降低系统?损失的关键。 相似文献
43.
在利用Aspen Plus软件对PVA醇解尾气吸收进行模拟研究时,计算出吸收剂用量和吸收塔填料层高度。现将在此基础上,利用灵敏度分析等方法对PVA醇解尾气吸收的模拟结果进行分析,将增加一台换热器使工艺流程优化,能让T1R塔顶出口甲醇含量下降,T2R的吸收负荷减轻,吸收剂水的用量下降到33 kmol/h。 相似文献
44.
基于Aspen Plus工作平台,运用Gibbs自由能最小化原理,对气流床粉煤气化过程进行了数值模拟,并对流程算法进行了改进。研究了氧煤比、蒸气煤比、压力及粉煤粒径对气化炉出口气体组成、温度、冷煤气效率、碳转化率及有效气产率的影响。结果表明:模拟值和实验值有良好的相似性;氧煤比对气化进程的影响较蒸汽煤比及其它操作条件更为显著;并确定了模拟煤种的最佳氧煤比是0.70~0.80kg/kg,气化炉出口CO+H2的最大干基体积分数为96.48%,冷煤气效率最高为83.56%,最大有效气产率为1.74m^3/kg;氧煤比每升高0.1kg/kg,气化炉出口温度升高约40℃,而蒸汽煤比每升高0.1kg/kg,气化炉出口温度降低约8℃。 相似文献
45.
Modeling of vapor-liquid equilibrium of gasoline-ethanol blended fuels for flash boiling simulations
K. Neroorkar 《Fuel》2011,90(2):665-673
Flash boiling is a physical phenomenon which governs the non-equilibrium phase change of a high temperature fluid as it is depressurized below its vapor pressure. The modeling of this process is of importance to a number of industrial applications and requires the vapor-liquid equilibrium properties of the fluid under consideration. The highly non-ideal nature of gasoline-ethanol fuel blends makes vapor-liquid equilibrium calculations extremely difficult for such fluids. A simple model known as GEFlash (Gasoline-Ethanol Flash), based on existing literature and fundamental chemical engineering thermodynamics is proposed to calculate the properties of gasoline-ethanol fuel blends that are required to perform flash boiling simulations. In addition, a second model based on the chemical engineering software Aspen Plus is also proposed and the predictions of the two models are validated against experimental data available in open literature. The results indicate that both models reproduce the trend in experimental data for vapor pressures and saturated liquid density for blends with different ethanol contents. The GEFlash model does not match the vapor mole fraction predictions of the Aspen Plus model for fuels with low ethanol content (E20 and E40). However, the vapor mole fractions for high ethanol content fuels (greater than E60) are accurate over the majority of the temperature range tested. 相似文献
46.
47.
48.
49.
萃取精馏分离甲基环己烷和甲苯工艺过程的模拟 总被引:5,自引:2,他引:3
利用Aspen Plus流程模拟软件,采用双塔流程,以苯酚为萃取剂,对萃取精馏分离甲基环己烷(MC)和甲苯(MB)的过程进行模拟计算,并用实验验证。考察了萃取精馏塔的萃取剂进料位置、原料进料位置、萃取剂与原料的摩尔比(溶剂比)和回流比等因素对分离效果的影响。在满足MC产品的纯度和收率均达到99%的条件下,模拟优化的结果为:理论塔板数为24块,原料在第17块板进料,萃取剂在第5块板进料,溶剂比3.08,回流比5。模拟结果与实验数据吻合较好,说明采用的模拟方法适用于MC和MB混合物萃取精馏过程的模拟。 相似文献
50.