全文获取类型
收费全文 | 5594篇 |
免费 | 519篇 |
国内免费 | 250篇 |
专业分类
电工技术 | 145篇 |
综合类 | 341篇 |
化学工业 | 1888篇 |
金属工艺 | 281篇 |
机械仪表 | 134篇 |
建筑科学 | 522篇 |
矿业工程 | 756篇 |
能源动力 | 212篇 |
轻工业 | 194篇 |
水利工程 | 114篇 |
石油天然气 | 1049篇 |
武器工业 | 17篇 |
无线电 | 129篇 |
一般工业技术 | 334篇 |
冶金工业 | 195篇 |
原子能技术 | 7篇 |
自动化技术 | 45篇 |
出版年
2024年 | 17篇 |
2023年 | 60篇 |
2022年 | 122篇 |
2021年 | 151篇 |
2020年 | 172篇 |
2019年 | 148篇 |
2018年 | 131篇 |
2017年 | 166篇 |
2016年 | 234篇 |
2015年 | 202篇 |
2014年 | 332篇 |
2013年 | 296篇 |
2012年 | 435篇 |
2011年 | 435篇 |
2010年 | 319篇 |
2009年 | 329篇 |
2008年 | 270篇 |
2007年 | 346篇 |
2006年 | 374篇 |
2005年 | 316篇 |
2004年 | 263篇 |
2003年 | 209篇 |
2002年 | 195篇 |
2001年 | 176篇 |
2000年 | 128篇 |
1999年 | 128篇 |
1998年 | 94篇 |
1997年 | 93篇 |
1996年 | 66篇 |
1995年 | 49篇 |
1994年 | 22篇 |
1993年 | 20篇 |
1992年 | 15篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 11篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 4篇 |
1980年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有6363条查询结果,搜索用时 15 毫秒
51.
Biomass is an often abundant, renewable, low ash and low sulfur fuel. Due to these properties, biofuels are promising alternatives for traditional petroleum-based fuel applications; however, traditional biofuels for internal combustion engines are not cost competitive with gasoline, diesel or fuel oils. One method to reduce the cost of biofuels is to use slurry fuels which have a potential lower cost than liquid biofuels due to high conversion efficiencies. Slurry biofuels, such as a mixture of corn and water, could provide a biofuel alternative for diesel engines, pressurized gasifiers and heating oil applications such as burners or gas turbines. Use of these biomass slurries poses important questions about their stability and suitability for practical applications in internal combustion engines and combustors.This work reports rheology data for stable corn-starch water slurries (CSWS) which used a polyacrylic acid thickener to eliminate settling of the slurry and to provide desirable shear-thinning behavior for most of the compositions evaluated. The effect of shear rate on the viscosity of the CSWS was studied using a BOHLIN-controlled stress (CS) rheometer. The well-known Ostwald—de Waele power law and Sisko models for viscosity fit the data. The effect of corn starch content, thickener content and temperature on the viscosity of CSWS was also studied. The favorable shear thinning properties were observed for starch contents up to 45% starch and should aid pumping, injection and spraying. The lower heating values of the slurries, however, are undesirably low. 相似文献
52.
V.A. de la Peña O’Shea M.C. Alvarez-Galvan J. M. Campos-Martin J. L. G. Fierro 《Catalysis Letters》2005,100(1-2):105-116
A 10 wt% Co/SiO2 catalyst was prepared by the incipient wet-impregnation method and tested in Fischer–Tropsch synthesis in a slurry reactor under conditions approaching industrial practice. The catalyst precursor was investigated by X-ray diffraction (XRD), temperature-programmed reduction (TPR), transmission electron microscopy (TEM) and photoelectron spectroscopy (XPS). The XPS and XRD techniques revealed the presence of a crystalline Co3O4 spinel-type phase, while-in addition-TEM and XPS analyses pointed to the formation of another amorphous Co3O4 spinel phase, both species interacting weakly with the silica substrate. The influence of total pressure on the conversion, selectivity and stability of the catalyst was studied. Upon increasing the overall pressure from 20 to 40 bar, not only activity increased but also the catalyst are not deactivating. These results are explained in terms of an increase of gases solubility in the solvent, this increment of CO concentration in the liquid phase favours carbonyl species formation and the cobalt particles segregation that implies an increase in the metal surface area. 相似文献
53.
The present work analyzes the effect of various factors on the hydration of pentasodium triphosphate. The experimental method
is based on application of the hydration test. Technical-quality products with different proportions of phase I and phase
II have been used. The variables studied are phase I/phase II ratio, initial temperature, particle size, stirring rate and
composition of the slurry (presence of hexahydrate crystals and water hardness). The results have been discussed according
to a kinetics model that includes a series of stages of a physical nature (dissolution of anhydrous salt and the crystallization
of the hexahydrate), as well as of a chemical nature (solvation of the ions in solution). Crystallization of the hexahydrate
may be the controlling stage in the process. 相似文献
54.
本实验采用牛、猪、羊三种骨头通过高温煅烧制备骨灰瓷原料。采用XRD和SEM方法表征三种骨灰料的晶相结构和显微结构。实验结果表明 :三种骨灰料经 14 0 0℃煅烧后均存在Ca1 0 (PO4 ) 6(OH) 2 、α -Ca3(PO4 ) 2 种晶相。在 132 0℃煅烧的三种骨灰料中 ,按牛、猪、羊顺序 ,Ca1 0 (PO4 ) 6 (OH) 2 含量分别为 87 2 %、89 1%、71 9% ;β-Ca3(PO4 ) 2 含量最高 ,其可塑性和成瓷性能好 ,从晶相上考虑选择羊骨为较佳的骨灰瓷原料。从白度和透光度上考虑选择牛骨为较佳原料。随着煅烧温度升高 ,三种骨头料的β-Ca3(PO4 ) 2 含量增加 ,羊骨和牛骨中的Ca1 0 (PO4 ) 6 (OH) 2 含量减少 ,而猪骨的Ca1 0(PO4 ) 6 (OH) 2 含量反而增加。因此煅烧温度升高对羊骨和牛骨有利 ,而对猪骨不利 相似文献
55.
新型多喷嘴对置式水煤浆气化技术工业化应用 总被引:3,自引:0,他引:3
煤气化技术是实现煤炭洁净利用的关键。介绍了新型多喷嘴对置式水煤浆气化炉流场、煤气化机理及其工业化应用概况。通过工业化运行结果表明:该装置气化效率高,交叉流式洗涤冷却水分布器的水均布,气化炉运转平稳,负荷可调节范围大,洗涤、冷却性能好,该技术打破了国外对水煤浆气化技术的垄断。 相似文献
56.
Copper depassivation and repassivation characteristics in potassium sorbate solutions, subsequent to mechanical abrading are reported. The identification of copper repassivation kinetics obtained subsequent to mechanical damage of copper protective films formed in sorbate based solutions is discussed. The repassivation rate of copper in sorbate based solutions was measured by means of a slurryjet system capable of measuring single particle impingments on microelectrodes. Copper repassivation rates measured by this slurryjet system in sulfate solutions containing 10 g L−1 potassium sorbate were found to be in the range of 0.5-1.5 ms. An increase in the potassium sorbate concentration leads to a decrease in copper repassivation time at potentials ranging from 200 to 600 mVAg/AgCl. The impingement angle between the copper surface and a single abrasive particle has no impact on copper repassivation time nor peak current (Imax) values. XPS studies revealed that copper passivation in potassium based solution was due to the formation of a thin film which is constituted of: Cu2O, Cu(OH)2 and Cu(II)-sorbate, while copper(II)-sorbate is mainly present at the top levels of the passive film. It is therefore recommended that the use of potassium sorbate as a passivating component in conjunction with the addition of strong oxidizing agents in chemical mechanical planarization (CMP) slurry design should be considered. 相似文献
57.
通过选用特定的小分子单体,采取分段聚合方式,合成具有特定官能团的化合物,用作水煤浆分散悬浮剂。 相似文献
58.
通过对湿法PU合成革用聚氨酯(PU)树脂浆料配方的改进,降低了浆料的生产成本,浆料的后期加工性能提高,并且PU膜的性能也有所改善。 相似文献
59.
60.
石灰乳输送泵的失效分析与优化设计 总被引:1,自引:0,他引:1
结合某水泵厂提供的石灰乳输送泵的设计资料,根据试制的离心渣浆泵出现的失效现象,分析失效原因,研究改进方法,为低比转数离心渣浆泵的设计提出优化设计意见。 相似文献