全文获取类型
收费全文 | 787篇 |
免费 | 50篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 11篇 |
综合类 | 1篇 |
化学工业 | 183篇 |
金属工艺 | 26篇 |
机械仪表 | 16篇 |
建筑科学 | 27篇 |
能源动力 | 61篇 |
轻工业 | 60篇 |
水利工程 | 11篇 |
石油天然气 | 4篇 |
无线电 | 85篇 |
一般工业技术 | 141篇 |
冶金工业 | 29篇 |
原子能技术 | 2篇 |
自动化技术 | 181篇 |
出版年
2024年 | 4篇 |
2023年 | 26篇 |
2022年 | 46篇 |
2021年 | 50篇 |
2020年 | 33篇 |
2019年 | 34篇 |
2018年 | 55篇 |
2017年 | 43篇 |
2016年 | 41篇 |
2015年 | 27篇 |
2014年 | 42篇 |
2013年 | 64篇 |
2012年 | 47篇 |
2011年 | 48篇 |
2010年 | 40篇 |
2009年 | 31篇 |
2008年 | 27篇 |
2007年 | 29篇 |
2006年 | 20篇 |
2005年 | 25篇 |
2004年 | 13篇 |
2003年 | 10篇 |
2002年 | 11篇 |
2001年 | 10篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 8篇 |
1997年 | 3篇 |
1996年 | 9篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1976年 | 3篇 |
排序方式: 共有838条查询结果,搜索用时 31 毫秒
61.
Tanvi Bhasin Ashish Agarwal Sujata Sanghi R.K. Kotnala Jyoti Shah Manisha Yadav Muskaan Tuteja 《Ceramics International》2018,44(7):7629-7636
Multiferroic composites of spinel ferrite and ferroelectric xCoFe2O4 – (1-x)Na0.5Bi0.5TiO3 (with x = 0.10,0.30,0.50) were efficiently prepared by standard solid state reaction mechanism. X-ray diffractometer was used to analyze crystal structure of the prepared composites. The observed XRD patterns of the composites comprise peaks of both the phases i.e. ferrite and ferroelectric, with no sign of secondary peaks. Rietveld refinement of XRD data further confirms the coexistence of these two phases with cubic (Fd3m) and rhombohedral (R3c) symmetry corresponding to ferrite and ferroelectric phase respectively. The 3-dimensional overview of crystal structure of pure CoFe2O4 and Na0.5Bi0.5TiO3 and of composite 0.50CoFe2O4?0.50Na0.5Bi0.5TiO3 is generated by using refined parameters. The dielectric constant (ε´) and dielectric loss (tanδ) values were recorded as a function of frequency ranging from 100?Hz to 7?MHz and at different temperatures. Both ε´ and tanδ follow dispersion pattern at lower frequencies while show frequency independent behavior at higher frequencies. The magnetic evaluation carried by analyzing M-H hysteresis loop reveals the ferrimagnetic characteristics of these composites. The highest value of magnetic moment is 1.12μB observed for composite 0.50CoFe2O4 – 0.50Na0.5Bi0.5TiO3. Magnetoelectric (ME) voltage coefficient (α) was also demonstrated to observe the interaction between ferrite and ferroelectric phases. The highest value of α (72.72μV/Oe cm) is obtained for low ferrite composition 0.10CoFe2O4 – 0.90Na0.5Bi0.5TiO3, which suggests the dependence of magnetoelectric response on the resistivity of the composites. 相似文献
62.
63.
64.
The inhibition effect of all the three Mannich bases against the corrosion of mild steel in 1 M HCl solution was studied by
weight loss, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and atomic force microscopy techniques.
Data obtained from EIS studies were analyzed to model the corrosion inhibition process through appropriate equivalent circuit
models. The adsorption of Mannich bases obeyed Langmuir adsorption isotherm. Both thermodynamic and activation parameters
were calculated and discussed. Polarization curves indicate that they are mixed type of inhibitors. All the Mannich bases
were adsorbed physically at lower concentration, whereas chemisorption was favored at higher concentration. The results obtained
from weight loss, EIS, and Potentiodynamic polarization are in good agreement. 相似文献
65.
The price of oil could play a significant role in influencing the expansion of biofuels, but this issue has yet to be fully investigated in the literature. Using a global computable general equilibrium (CGE) model, this study analyzes the impact of oil price on biofuel expansion, and subsequently, on food supply. The study shows that a 65% increase in oil price in 2020 from the 2009 level would increase the global biofuel penetration to 5.4% in 2020 from 2.4% in 2009. If oil prices rise 150% from their 2009 levels by 2020, the resulting penetration of biofuels would be 9%, which is higher than that would be caused by current mandates and targets introduced in more than forty countries around the world. The study also shows that aggregate agricultural output drops due to an oil price increase, but the drop is small in major biofuel producing countries as the expansion of biofuels would partially offset the negative impacts of the oil price increase on agricultural outputs. An increase in oil price would reduce global food supply through direct impacts as well as through the diversion of food commodities and cropland towards the production of biofuels. 相似文献
66.
Yadav Ashish Mohan Tripathi Kuldeep Narayan Sharma S. C. 《The Journal of supercomputing》2022,78(3):4236-4260
The Journal of Supercomputing - With the rapid increase in the functionality of IoT applications, the services provided by edge/IoT devices have surged in the recent past. Fog computing is gaining... 相似文献
67.
Swarnkar Rishabh Das Ashish Prasad Shashi Bhushan 《Russian Journal of Non-Ferrous Metals》2021,62(3):333-340
Russian Journal of Non-Ferrous Metals - This paper investigates the effects of brass interlayer on the microstructural and mechanical properties of friction stir welded AA 6082-T6. To analyze the... 相似文献
68.
Multimedia Tools and Applications - Digital image communication over public networks requires a high level of security to protect picture elements that represent information. Security is an... 相似文献
69.
Pandey Chandrasen Baghel Neeraj Dutta Malay Kishore Srivastava Ashish Choudhary Nandlal 《Multimedia Tools and Applications》2021,80(9):13407-13427
Multimedia Tools and Applications - Viral infection in crops is something that may lead to a huge loss in crop yield as there are no known recovery procedures. Also, at the onset of yellowing in a... 相似文献
70.
Proof-of-concept has been demonstrated for a process that will utilize nutrients from sludge liquor, natural light, and CO2 from biogas to grow microalgae at wastewater treatment plants. This process will reduce the impact of returning side-streams to the head of the plant. The produced algae will be fed to anaerobic digesters for increased biogas production. Dewatering of anaerobically digested sludge in centrifuges produces reject water with extremely low transmittance of light. A pretreatment procedure was developed that improved light transmittance for reject water from the FREVAR, Norway, wastewater treatment plant from 0.1% T to 77% T (670 nm, 1 cm path). Chlorella sp. microalgae were found to be suitable for growth in this pre-treated reject water. Typical nitrogen removal was 80-90 g N/kg TSS of produced microalgae. The microalgae were successfully harvested by chemically assisted flocculation followed by straining through a 33 microm sieve cloth, achieving up to 99% recovery. Harvested algae were anaerobically co-digested with wastewater sludge. The specific methane gas production (mL CH4/g VS fed) for the algae varied from less than 65% to 90% of the specific methane gas production for the wastewater sludge, depending on digester temperature, retention time and pre-treatment of the algae biomass. 相似文献