全文获取类型
收费全文 | 4437篇 |
免费 | 354篇 |
国内免费 | 231篇 |
专业分类
电工技术 | 42篇 |
综合类 | 217篇 |
化学工业 | 2344篇 |
金属工艺 | 545篇 |
机械仪表 | 78篇 |
建筑科学 | 50篇 |
矿业工程 | 128篇 |
能源动力 | 92篇 |
轻工业 | 26篇 |
水利工程 | 1篇 |
石油天然气 | 229篇 |
武器工业 | 22篇 |
无线电 | 110篇 |
一般工业技术 | 649篇 |
冶金工业 | 430篇 |
原子能技术 | 24篇 |
自动化技术 | 35篇 |
出版年
2024年 | 4篇 |
2023年 | 68篇 |
2022年 | 107篇 |
2021年 | 102篇 |
2020年 | 131篇 |
2019年 | 101篇 |
2018年 | 115篇 |
2017年 | 120篇 |
2016年 | 111篇 |
2015年 | 96篇 |
2014年 | 164篇 |
2013年 | 209篇 |
2012年 | 214篇 |
2011年 | 278篇 |
2010年 | 192篇 |
2009年 | 214篇 |
2008年 | 199篇 |
2007年 | 281篇 |
2006年 | 264篇 |
2005年 | 217篇 |
2004年 | 199篇 |
2003年 | 220篇 |
2002年 | 198篇 |
2001年 | 187篇 |
2000年 | 177篇 |
1999年 | 126篇 |
1998年 | 83篇 |
1997年 | 62篇 |
1996年 | 41篇 |
1995年 | 55篇 |
1994年 | 65篇 |
1993年 | 53篇 |
1992年 | 79篇 |
1991年 | 90篇 |
1990年 | 92篇 |
1989年 | 73篇 |
1988年 | 10篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1976年 | 3篇 |
1951年 | 2篇 |
排序方式: 共有5022条查询结果,搜索用时 31 毫秒
1.
Sk Tanbir Islam Sudip K. Samanta Santanu Das Himadri Chattopadhyay 《Journal of the American Ceramic Society》2022,105(7):4608-4620
The micro-powder injection molding (micro-PIM) process has the potential to bridge the gap between the design and manufacturing of micro-components that are often used in small and handy devices. Numerical modeling helps to analyze and overcome various difficulties of micro-PIM. In the present work, a numerical model is developed to predict the powder–binder separation (a common defect in PIM and especially severe in micro-PIM) during the injection of an alumina feedstock. A powder–binder separation criterion is proposed dealing with applied injection pressure and friction force between the powder and binder. An indirect comparison of feedstock travel time between two locations is used to validate the model. The predicted segregation from the simulated result is supported by a qualitative experimental measurement. The developed model can be used to optimize injection parameters to get a defect-free product. 相似文献
2.
Han Chen Shunzo Shimai Jin Zhao Xiaojian Mao Jian Zhang Guohong Zhou Shiwei Wang 《Journal of the European Ceramic Society》2021,41(6):3838-3843
Alumina platelets were arranged horizontally in submicron alumina particles by shear force in the flow of slurries during casting. The obtained alumina green bodies with platelets were pressureless-sintered in vacuum, producing ceramics with thoroughly oriented grains and high transmittance. The effects of sintering parameters on the densification, microstructure evolution, and orientation degree of alumina ceramics were investigated and discussed. The results showed that the densification, grain size, orientation degree, and in-line transmittance were increased with increasing sintering temperature. The enhancement of orientation degree was mainly coherent with grain growth. The grain-oriented samples exhibited a much higher in-line transmittance (at 600 nm) of 61 % than that of the grain random sample (29 %). Moreover, the transmission remained a high level in the ultraviolet range (<300 nm). 相似文献
3.
《Ceramics International》2022,48(9):12014-12027
The formed deposits wear out of refractory wall linings in the rotary kiln and may cause production disturbances. This study describes the chemical composition and mineralogical phase components at the deposit/refractory interface in the rotary kiln for fluxed iron ore pellets production. The main phases of refractory bricks are corundum and mullite, while the deposits mainly contain hematite and silicates. The main phases in the deposit/refractory brick contact zone are hematite, anorthite (CaAl2Si2O8), mullite, corundum, and silicates. Moreover, the hematite phases in the deposit/brick interface averagely contain 6.98 wt% Al and 1.38 wt% Ti. The silicates in the contact zone contain higher aluminium content and lower iron content than the silicates in the deposits. Finally, the thermodynamic analysis indicates that the main phases in the deposits can react with the refractory to form Al2Fe2O6, CaAl2Si2O8, feldspar, and liquid phases lead to the degradation of bricks in the kiln during the iron ore pellets production. 相似文献
4.
In this study, pyrolysis of tomato waste has been performed in fixed bed tubular reactor at 500 °C, both in absence and presence of Cu/Al2O3 catalyst. The influences of heating rate, catalyst preparation method and catalyst loading on bio-oil yields and properties were examined. According to pyrolysis experiments, the highest bio-oil yield was obtained as 30.31% with a heating rate of 100 °C/min, 5% Cu/Al2O3 catalyst loading ratio and co-precipitation method. Results showed that the catalysts have strong positive effect on bio-oil yields. Bio-oil quality obtained from fast catalytic pyrolysis was more favorable than that obtained from non-catalytic and slow catalytic pyrolysis. 相似文献
5.
K. A. Unocic J. Bergholz T. Huang D. Naumenko R. Vaßen 《Energy Materials: Materials Science and Engineering for Energy Systems》2018,13(1):108-119
To fabricate oxide dispersion strengthened bond coatings, commercial Co–30wt-%Ni–20Cr–8Al–0?4Y powder was milled with 2% additions of Al2O3, Y2O3 or Y2O3 + HfO2. Low-pressure plasma sprayed, free-standing specimens were oxidised in air + 10%H2O at 1100 °C both isothermally (100 h) and in 500, 1?h cycles. Dry air cyclic testing conducted at both ORNL and FZJ showed remarkably similar results. In general, the water vapour addition caused more scale spallation. Two LPPS specimens without oxide additions were tested for comparison. The specimens with 2%Al2O3 addition exhibited the best behaviour as the powder already contained 0?4%Y. Additions of 2%Y2O3 and especially 1%Y2O3 + 1%HfO2 resulted in over-doping as evidenced by high mass gains and the formation of Y- and Hf-rich pegs. Scanning transmission electron microscopy of the isothermal specimens showed no Hf and/or Y segregation to the alumina scale grain boundaries in the over-doped specimens. 相似文献
6.
7.
In this investigation, low-cement castables were prepared using 70% alumina grog aggregates obtained from crushed alumina brick waste. The aggregates were thermally treated at 1550 °C for 3 h. Four types of low-cement castables were prepared with various types of aggregates (alumina grog with or without thermal treatment) and fillers (with or without zircon addition), and they were evaluated in terms of their physical, thermal, and chemical properties. Microstructural analysis via scanning electron microscopy (SEM) was performed on the castables before and after slag attack. Compared to the other fabricated castables, the thermally treated alumina grog castables with zircon showed better physical properties, such as a higher bulk density, cold crushing strength, and modulus of rupture and a lower apparent porosity and water absorption. In addition, they had a higher positive linear thermal expansion, refractoriness under load, permanent linear change, and hot modulus of rupture. The results of the SEM with energy dispersive X-ray analysis of the prepared castables confirmed that the mullite and anorthite phases were predominant when zircon was not added and the zircon–mullite phase additionally appeared upon the incorporation of zircon. A quantitative elemental analysis via X-ray fluorescence spectroscopy was employed to determine the composition of the castables. X-ray diffraction analysis showed that the alumina grog castables had a high mullite and low anorthite content, and the thermally treated alumina grog had a high anorthite, low mullite, and high zircon content. The improvement in the mechanical and thermo-mechanical properties of the castables with thermally treated alumina grog and added zircon can be attributed to the formation of the zircon–mullite phase with a low mullite phase content. 相似文献
8.
9.
10.
Georgia N Tomara Panagiota K Karahaliou Dimitris L Anastassopoulos Stavroula N Georga Christoforos A Krontiras Jozsef Karger‐Kocsis 《Polymer International》2019,68(5):871-885
Polyamide‐6 (PA‐6)/boehmite alumina (BA) nanocomposites were prepared via direct melt compounding. Structural, thermal and dielectric properties of ‘as‐received’ (including moisture) and ‘dried’ (thermally treated) specimens were examined. The BA nanofiller was homogeneously dispersed in the PA‐6 matrix. XRD and FTIR revealed that crystallization of PA‐6 in the γ phase was favoured over α phase with increasing BA content. The crystallinity index (CI) and the percentage of α and γ phases were also evaluated. Dried specimens exhibited a lower CI than as‐received specimens while the CI decreased with the addition of filler. Broadband dielectric spectroscopy revealed the presence of γ, β and α relaxations, the Maxwell–Wagner–Sillars effect and the contribution of conductivity relaxation in the as‐received samples. The drying procedure unmasked a double feature of both β and α modes. The results of the complementary techniques were analysed and the effects of moisture and/or the incorporation of BA nanofiller on the microstructure of the PA‐6 matrix are disclosed. © 2019 Society of Chemical Industry 相似文献