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61.
Yin Zhong Shen Sung Ho Kim Hai Dong Cho Chang Hee Han Woo Seog Ryu 《Nuclear Engineering and Design》2009,239(4):648-68
One of the reasons that ferritic/martenstic steels have been considered as candidate materials for nuclear power reactors is their superior creep resistance at elevated temperature. The creep rupture strength of 9% chromium steel could be improved by a fine dispersion of secondary precipitate phase. The precipitate phases in extra-low carbon 9% chromium steel with tempered conditions were investigated by transmission electron microscope and energy-dispersive X-ray analysis. The steel specimens were normalized and then tempered at different temperatures. Niobium-rich MN nitrides (Nb0.6V0.3Cr0.1)N, and two kinds of vanadium nitrides, (V0.6Nb0.2Cr0.2)N and (V0.45Nb0.45Cr0.1)N having a f.c.c. crystal structure, were identified in the steel specimens tempered at 600-780 °C, and 750 or 780 °C respectively. Hexagonal chromium-rich M2N precipitate phases with different lattice parameters, a = 2.80 Å/c = 4.45 Å and a = 7.76 Å/c = 4.438 Å, were determined in the tempered steel specimens. The M2N phase showed a decrease/an increase in its chromium/vanadium content as the tempering temperature was increased. The influence of precipitates and heat treatment conditions on the high temperature properties of 9% Cr steel was discussed. 相似文献
62.
Jina Ryu Mats Brittberg Bomi Nam Jinyeong Chae Minju Kim Yhan Colon Iban Martin Magneli Eiji Takahashi Bharti Khurana Charles R. Bragdon 《International journal of molecular sciences》2022,23(5)
Cartilage lesions are difficult to repair due to low vascular distribution and may progress into osteoarthritis. Despite numerous attempts in the past, there is no proven method to regenerate hyaline cartilage. The purpose of this study was to investigate the ability to use a 3D printed biomatrix to repair a critical size femoral chondral defect using a canine weight-bearing model. The biomatrix was comprised of human costal-derived cartilage powder, micronized adipose tissue, and fibrin glue. Bilateral femoral condyle defects were treated on 12 mature beagles staged 12 weeks apart. Four groups, one control and three experimental, were used. Animals were euthanized at 32 weeks to collect samples. Significant differences between control and experimental groups were found in both regeneration pattern and tissue composition. In results, we observed that the experimental group with the treatment with cartilage powder and adipose tissue alleviated the inflammatory response. Moreover, it was found that the MOCART score was higher, and cartilage repair was more organized than in the other groups, suggesting that a combination of cartilage powder and adipose tissue has the potential to repair cartilage with a similarity to normal cartilage. Microscopically, there was a well-defined cartilage-like structure in which the mid junction below the surface layer was surrounded by a matrix composed of collagen type I, II, and proteoglycans. MRI examination revealed significant reduction of the inflammation level and progression of a cartilage-like growth in the experimental group. This canine study suggests a promising new surgical treatment for cartilage lesions. 相似文献
63.
Kyunghyun Ryu George E. Zacharakis-Jutz Song-Charng Kong 《International Journal of Hydrogen Energy》2014
The effect of combustion of hydrogen generated by an ammonia dissociation catalyst on engine performance and exhaust emissions in a spark-ignition engine using ammonia-gasoline was investigated. An ammonia dissociation catalyst coated with 2% ruthenium on 3.175-mm alumina pellets were used in order to analyze the effect of the catalyst as an ammonia cracker to decompose ammonia into hydrogen and nitrogen. Results show that combustion of hydrogen generated by an ammonia dissociation catalyst resulted in improved engine performance and reduced exhaust emissions. The conversion rate of ammonia into hydrogen was affected by the flow rate of ammonia, and the catalyst was very effective at low to medium flow rates, resulting in significantly increased engine power and decreased fuel consumption. With the use of the catalyst, emissions of CO, HC, NH3 and NOx were reduced considerably. Overall, it was demonstrated the ammonia dissociation catalyst can enable ammonia to be used as a hydrogen carrier for use in internal combustion engines effectively. 相似文献
64.
Seismic Fragility of Steel Piping System Based on Pipe Size,Coupling Type,and Wall Thickness 总被引:1,自引:0,他引:1
In this study, a probabilistic framework of the damage assessment of pipelines subjected to extreme hazard scenario was developed to mitigate the risk and enhance design reliability. Nonlinear 3D finite element models of T-joint systems were developed based on experimental tests with respect to leakage detection of black iron piping systems, and a damage assessment analysis of the vulnerability of their components according to nominal pipe size, coupling type, and wall thickness under seismic wave propagations was performed. The analysis results showed the 2-inch schedule 40 threaded T-joint system to be more fragile than the others with respect to the nominal pipe sizes. As for the coupling types, the data indicated that the probability of failure of the threaded T-joint coupling was significantly higher than that of the grooved type. Finally, the seismic capacity of the schedule 40 wall thickness was weaker than that of schedule 10 in the 4-inch grooved coupling, due to the difference in the prohibition of energy dissipation. Therefore, this assessment can contribute to the damage detection and financial losses due to failure of the joint piping system in a liquid pipeline, prior to the decision-making. 相似文献
65.
Qusai M. Mistarihi Wooseong Park Kyungseok Nam Mohd‐Syukri Yahya Yonghee Kim Ho Jin Ryu 《国际能源研究杂志》2018,42(6):2141-2151
In this paper, the fabrication of novel burnable absorber fuel concepts with oxide pellets, containing either a lumped Gd2O3 rod, a mini‐pellet, or a spherical particle in the centerline of the oxide pellet, is investigated to propose the lumped Gd2O3 burnable absorber fuel concept to improve nuclear fuel performance with longer fuel cycle lengths and better fuel utilization. The unique characteristic of the lumped Gd2O3 burnable absorber fuel is its high spatial self‐shielding factor that reduces its burnout rate and, therefore, improves the reactivity control. Oxide pellets containing lumped Gd2O3 were fabricated by using a combination of cold isostatic pressing and microwave sintering at 1500°C to understand the potential technical issues in the fabrication of duplex burnable absorber fuel. The effect of the sintering temperature on the densification and phase transformation of 8 wt.% yttria‐stabilized zirconia, a surrogate for UO2, was investigated. Spherical Gd2O3 particles were fabricated by the drip casting of a Gd2O3‐based Na alginate solution. The fabrication of duplex oxide pellets by using presintered Gd2O3 mini‐pellets resulted in internal cracks at the interface between the Gd2O3 and 8 wt.% yttria‐stabilized zirconia layers because of the mismatch of their densification. However, the formation of interfacial cracks was eliminated by controlling the initial sintered density of the lumped Gd2O3. 相似文献
66.
In oxy‐coal combustion for carbon capture and storage, oxygen and recirculated CO2 are used as oxidizers instead of air to produce CO2‐rich flue gas. Owing to differences between the physical and chemical properties of CO2 and N2, the development of a burner and boiler system based on fundamental understanding of the flame type, heat transfer, and NOx emission is required. In this study, computational fluid dynamic analysis incorporating comprehensive coal conversion models was performed to investigate the combustion characteristics of a 30 MWth tangential vane swirl pulverized coal burner. Various burner design parameters were evaluated, including the influence of the burner geometry on the swirl strength, direct O2 injection, and O2 concentrations in the primary and secondary oxidizers. The flame characteristics were sensitive to the oxygen concentration in the primary oxidizer. The performance of direct O2 injection around the primary oxidizer with low O2 concentration was dependent on the mixing of the fuel and oxidizer. The predictions showed that swirl number adjustment and careful direct oxygen injection design are essential for retrofitting air‐firing pulverized coal burners as oxy‐firing burners. 相似文献
67.
Jeong Chang Hee Ryu Haram Zhang Ting Lee Chi Ho Seo Han Geuk Han Sung Gu 《Food science and biotechnology》2018,27(5):1419-1427
Food Science and Biotechnology - Yogurt is a fermented dairy food produced by growth of lactic acid bacteria (LAB). Green tea is associated with beneficial health effects. Thus, the aim of this... 相似文献
68.
Food Science and Biotechnology - The aim of this study was to evaluate the effects of green tea contents (0, 5, 10, and 15%) on texturization and antioxidant properties of textured vegetable... 相似文献
69.
Seung‐Hun Ryu Dong‐Uk Park Eun Lee Soyoung Park So‐Yeon Lee Sungsu Jung Sang‐Bum Hong Jihoon Park Soo‐Jong Hong 《Indoor air》2019,29(5):735-747
Since around the year 2000, hundreds of people in Korea have developed humidifier disinfectant‐associated lung injury (HDLI). We collected all HD exposure‐related information from the field investigations into the locations in which the 1199 registered patients had used HD. Among the people who registered, 38% (1st round = 214, 2nd = 73, 3rd = 166) were confirmed as HDLI patients. Children aged under eight years old made up the highest proportion of HDLI cases (N = 279, 62%), followed by pregnant women (N = 31, 7%). One hundred thirty‐three (29%) of the confirmed HDLI patients died. Fifty‐seven percent of HDLI patients (N = 259) developed HDLI after <1 year of HD use. The number of HDLI patients who used only the Oxy Saksak HD brand was found to be 176 (39%), followed by the brands Cefu (N = 27, 6%) and Aekyung (N = 22, 5%). HD products containing only polyhexamethylene guanidine phosphate (PHMG‐P) were the most frequently used among HDLI patients (N = 234, 52%), followed by oligo (2‐(2‐ethoxy)ethoxyethyl) guanidinium (PGH) (N = 27, 6%) and a mixture of chloromethylisothiazolinone (CMIT) and methylisothiazolinone (MIT) (N = 26, 6%). The average PHMG‐P inhalation level estimated from the patient group classified as suffering lung injury definitely associated with HD use was 145.1 μg/m3 (N = 91, SD = 395.1 μg/m3), higher than levels estimated from both the probable and possible HDLI patient groups. In conclusion, HD exposure‐related variables, including type of HD brand and estimated inhalation HD level, were associated with the risk of HDLI. 相似文献
70.
Wireless Networks - With the increase in the number of mobile devices such as tablets and smart watches, mobile social networks (MSNs) provide great opportunities for people to exchange... 相似文献