全文获取类型
| 收费全文 | 460篇 |
| 免费 | 10篇 |
| 国内免费 | 9篇 |
专业分类
| 电工技术 | 4篇 |
| 综合类 | 36篇 |
| 化学工业 | 96篇 |
| 金属工艺 | 12篇 |
| 机械仪表 | 8篇 |
| 建筑科学 | 44篇 |
| 矿业工程 | 56篇 |
| 能源动力 | 48篇 |
| 轻工业 | 30篇 |
| 石油天然气 | 23篇 |
| 武器工业 | 1篇 |
| 无线电 | 23篇 |
| 一般工业技术 | 35篇 |
| 冶金工业 | 17篇 |
| 原子能技术 | 17篇 |
| 自动化技术 | 29篇 |
出版年
| 2025年 | 2篇 |
| 2024年 | 3篇 |
| 2023年 | 3篇 |
| 2022年 | 12篇 |
| 2021年 | 16篇 |
| 2020年 | 13篇 |
| 2019年 | 11篇 |
| 2018年 | 17篇 |
| 2017年 | 17篇 |
| 2016年 | 6篇 |
| 2015年 | 14篇 |
| 2014年 | 28篇 |
| 2013年 | 35篇 |
| 2012年 | 25篇 |
| 2011年 | 32篇 |
| 2010年 | 29篇 |
| 2009年 | 29篇 |
| 2008年 | 25篇 |
| 2007年 | 31篇 |
| 2006年 | 23篇 |
| 2005年 | 22篇 |
| 2004年 | 10篇 |
| 2003年 | 11篇 |
| 2002年 | 12篇 |
| 2001年 | 8篇 |
| 2000年 | 9篇 |
| 1999年 | 10篇 |
| 1998年 | 2篇 |
| 1997年 | 2篇 |
| 1996年 | 2篇 |
| 1995年 | 2篇 |
| 1994年 | 1篇 |
| 1993年 | 1篇 |
| 1992年 | 4篇 |
| 1991年 | 3篇 |
| 1990年 | 2篇 |
| 1989年 | 3篇 |
| 1988年 | 1篇 |
| 1986年 | 2篇 |
| 1984年 | 1篇 |
排序方式： 共有479条查询结果，搜索用时 0 毫秒
31.
Selective epitaxial growth (SEG) silicon as sacrificial layer is proposed to circumvent junction leakage (Ijun) of bit line contact due to silicon substrate loss by high aspect ratio contact etching and spontaneous salicide formation. The result indicates that the appropriate SEG silicon in contact area significantly reduces Ijun about three orders compared with no SEG silicon. In addition, the SEG method provides acceptable Kelvin contact resistance. Furthermore, during salicide formation, the consumed ratio of titanium to silicon is 0.7. It is confirmed that the feasible approach not only prevents from Ijun deterioration but also adjusts contact resistance as well. 相似文献
32.
Polymer dispersed ferroelectric liquid crystal composite films consisting of varying polymer viscosities were prepared by polymerization induced phase separation (PIPS) technique. It was found that polymer viscosity influences the polarization switching and optical responses. A polymer dispersed ferroelectric liquid crystal film of low polymer viscosity shows faster switching, however a higher optical transmission at ~ 70% was observed in a higher polymer viscosity film. 相似文献
33.
34.
Li Xiao Fengxia Ling Lihua Tan Huabing Li Chun Hu Ying Luo Dang Tang Fuyou Liu Yashpal S. Kanwar Lin Sun 《Hemodialysis international. International Symposium on Home Hemodialysis》2015,19(4):E49-E53
We report the outcome of a 52‐year‐old patient with diabetic nephropathy and receiving maintenance hemodialysis (HD) using low molecular weight heparin (LMWH) as an anticoagulant for 2 years. He presented right lower limb pain accompanied with difficulty in walking for 2 months, and had no history of bleeding tendency or trauma. Physical examination revealed marked swelling and tenderness on his right lower limb. By ultrasound and magnetic resonance imaging (MRI) diagnoses, the calf hematoma was diagnosed and identified with venous thrombosis. Following treatment with heparin‐free HD, the swelling regressed and pain subsided, and a follow‐up MRI showed complete dissolution of hematoma. However, similar symptoms recurred in the right upper limb after 2 months without any predisposition, he was just placed on HD with LMWH, and symptoms regressed following the aforementioned therapy. This suggests that HD patients, especially with diabetic nephropathy having extremity hematoma, should be watched for the development of spontaneous hemorrhage that can be differentially diagnosed by imaging tests, such as MRI, and can be effectively treated with heparin‐free HD. 相似文献
35.
《Advanced Powder Technology》2022,33(3):103454
This study examines the effects of intrinsic properties, particle size, and specific surface area (SSA) of coal on spontaneous combustion. Moreover, it analyzes the underlying mechanism of spontaneous combustion from particle size, SSA and gas adsorption perspectives. The susceptibility of coal to spontaneous combustion is studied by wet-oxidation potential (WOP) method. Coal residues left after the WOP experiment are analyzed for change in structural and compositional behaviour. The study revealed an inverse relationship between the particle size and SSA of coal. Spontaneous combustion susceptibility increased with increase in volatile matter and decreased with increase in fixed carbon content of coal. The optimum moisture content of coal resulting maximum spontaneous combustion tendency is determined 6%. Decrease in particle size and increase in SSA augmented the spontaneous combustion propensity of coal. With decrease in coal particle size from 425 to 850 to < 38 µm, the mean D50 value decreased by 27 times, the mean SSA increased by 42 times and coal spontaneous combustion susceptibility increased almost by 2 times. Critical coal particle size is determined 38–74 µm (D50 = 50.56 µm), below which no appreciable change in oxidation rate is observed. Moreover, two models are developed to predict the spontaneous combustion susceptibility of coal based on particle size (D50) and SSA. 相似文献
36.
《International Journal of Hydrogen Energy》2022,47(77):33135-33152
Self-ignition may occur during hydrogen storage and transportation if high-pressure hydrogen is suddenly released into the downstream pipelines, and the presence of obstacles inside the pipeline may affect the ignition mechanism of high-pressure hydrogen. In this work, the effects of multiple obstacles inside the tube on the shock wave propagation and self-ignition during high-pressure hydrogen release are investigated by numerical simulation. The RNG k-ε turbulence model, EDC combustion model, and 19-step detailed hydrogen combustion mechanism are employed. After verifying the reliability of the model with experimental data, the self-ignition process of high-pressure hydrogen release into tubes with obstacles with different locations, spacings, shapes, and blockage ratios is numerically investigated. The results show that obstacles with different locations, spacings, shapes and blockage ratios will generate reflected shock waves with different sizes and propagation trends. The closer the location of obstacles to the burst disk, the smaller the spacing, and the larger the blockage ratio will cause the greater the pressure of the reflected shock wave it produces. Compared with the tubes with rectangular-shaped, semi-circular-shaped and triangular-shaped obstacles, self-ignition is preferred to occur in tube with triangular-shaped obstacles. 相似文献
37.
A phaser-based processing technique was adopted in an UWB over fiber system employing SOA. The target is to simultaneously reduce the ASE noise impact and nonlinear effects inherent to optical amplification. Experimental results prove the effectiveness of chirping in terms of cross correlation and bit error rate. 相似文献
38.
《Journal of the European Ceramic Society》2020,40(6):2323-2330
The occupationally disordered structures and associated local polar fluctuations in lead-free relaxors determine their electrical properties that are also sensitive to external stimuli. These stimuli can lead to phase transitions, and the associated enhancement in the electro-mechanical responses necessitate a better understanding of these transitions. Here we report a non-canonical spontaneous phase transition from a relaxor to a ferroelectric phase in (Na1/2Bi1/2)TiO3-BaTiO3 with temperature. With the help of experiments (dielectric permittivity, diffraction, differential scanning calorimetry, polarization and Raman spectroscopy), a complete picture of the temperature evolution of relaxor behavior leading to this spontaneous phase transition has been reported. Furthermore, it has been shown that internal chemical pressure from oxygen vacancies can be utilized to tailor these phase transitions. Finally, an electric field-temperature phase diagram has been proposed with an emphasis on the influence of the defect chemistry. This work provides new insights into the origin of these spontaneous phase transitions. 相似文献
39.
《矿业科学技术学报(英文版)》2020,30(4):525-531
An increase in methane, spontaneous fire and bumping hazards in Polish hard coal mines, observed in the last two decades, led to the need to elaborate the tools allowing proper selection of a range of preventive measures to fight them at the stage of designing coal extraction. Designing the production of a coal seams in the conditions of associated methane and spontaneous fires hazards in Polish hard coal mines requires elaboration of the design standards for coal panels in gassy coal seams. This paper presents the guidelines on how to design production in the conditions of associated methane and spontaneous fire hazards.Presented tools and methodology since the very first research were many times verified by daily mining operations in the conditions of associated methane and spontaneous fire hazards, which confirms their significant contribution to the development of safe and economical mining operations. 相似文献
40.
The characterization of the physical and chemical properties of coal on a standard provides an understanding of its characteristics towards spontaneous combustion. The trend of linear relationships between coal recording standards (% air-dried (ad), % dry (db) and % dry ash free (daf) basis) of 30 selected coal samples from the Witbank coalfields and spontaneous combustion liability indices were evaluated. The spontaneous combustion liability indices of these samples were evaluated by crossing point temperature (XPT), Stage II Slope, FCC (Feng, Chakravorty, Cochrane) and the Wits-Ehac tests, while the coal properties were determined from the proximate and ultimate analyses. The results obtained from these coal properties were related to different liability indices to develop trends of linear relationships using regression analysis. The ad basis indicated higher correlation coefficients than the db and daf basis for the XPT and FCC index, while the daf showed higher correlation coefficients than the ad and db basis for the Wits-Ehac index. It was found that the trend of linear relationships of these coal properties differs from one liability index to the next. The XPTs showed a better trend followed by the Stage II Slope on the coal properties among the spontaneous combustion liability indices evaluated. 相似文献