全文获取类型
收费全文 | 2629篇 |
免费 | 70篇 |
国内免费 | 14篇 |
专业分类
电工技术 | 115篇 |
综合类 | 5篇 |
化学工业 | 817篇 |
金属工艺 | 60篇 |
机械仪表 | 99篇 |
建筑科学 | 39篇 |
能源动力 | 113篇 |
轻工业 | 222篇 |
水利工程 | 10篇 |
石油天然气 | 2篇 |
无线电 | 207篇 |
一般工业技术 | 484篇 |
冶金工业 | 236篇 |
原子能技术 | 127篇 |
自动化技术 | 177篇 |
出版年
2023年 | 18篇 |
2022年 | 30篇 |
2021年 | 52篇 |
2020年 | 27篇 |
2019年 | 28篇 |
2018年 | 49篇 |
2017年 | 29篇 |
2016年 | 58篇 |
2015年 | 38篇 |
2014年 | 79篇 |
2013年 | 157篇 |
2012年 | 108篇 |
2011年 | 142篇 |
2010年 | 103篇 |
2009年 | 144篇 |
2008年 | 158篇 |
2007年 | 134篇 |
2006年 | 131篇 |
2005年 | 97篇 |
2004年 | 75篇 |
2003年 | 83篇 |
2002年 | 79篇 |
2001年 | 59篇 |
2000年 | 46篇 |
1999年 | 63篇 |
1998年 | 117篇 |
1997年 | 79篇 |
1996年 | 63篇 |
1995年 | 46篇 |
1994年 | 34篇 |
1993年 | 40篇 |
1992年 | 26篇 |
1991年 | 28篇 |
1990年 | 20篇 |
1989年 | 21篇 |
1988年 | 12篇 |
1987年 | 23篇 |
1986年 | 21篇 |
1985年 | 30篇 |
1984年 | 35篇 |
1983年 | 19篇 |
1982年 | 16篇 |
1981年 | 17篇 |
1980年 | 13篇 |
1979年 | 13篇 |
1978年 | 12篇 |
1977年 | 9篇 |
1976年 | 11篇 |
1975年 | 5篇 |
1973年 | 5篇 |
排序方式: 共有2713条查询结果,搜索用时 15 毫秒
141.
Kiyoshi Hirao Koji Watari Manuel E. Brito Motohiro Toriyama Shuzo Kanzaki 《Journal of the American Ceramic Society》1996,79(9):2485-2488
Silicon nitride was fabricated by tape casting of α-Si3 N4 powder with 5 wt% Y2 O3 and 5 vol% rodlike β-Si3 N4 seed particles, followed by tape stacking, hot pressing under 40 MPa, and annealing at 1850°C for 2-66 h under a nitrogen pressure of 0.9 MPa. Silicon nitrides fabricated by this procedure exhibited a highly anisotropic microstructure with large elongated grains (developed from seed particles) uniaxially oriented parallel to the casting direction. Thermal conductivities parallel to the grain alignment were much higher than those measured in other directions and exhibited high values of up to 120 W/(m.K). The anisotropic thermal conductivity of the specimen could be explained by the rule of mixture, considering that large elongated grains developed from seeds have higher thermal conductivity than a small-grained matrix. 相似文献
142.
Munehisa Yasuniwa Shinsuke Tsubakihara Koji Iura Yoshinori Ono Yusuke Dan Kazuhisa Takahashi 《Polymer》2006,47(21):7554-7563
The crystallization behavior of poly(l-lactic acid) was studied in the range of 80-160 °C. The peak crystallization time (τp) was defined and obtained from the crystallization isotherm measured with a differential scanning calorimeter (DSC). Isothermal crystallization temperature (Tc) dependence of log(τp) discretely changed at 113 °C (= Tb). The linear growth rate of spherulite, G, was measured with a polarizing microscope. The Tc dependence of G and the size of the spherulite also discretely changed at Tb. Crystal structures for samples isothermally crystallized at temperatures which were higher and lower than Tb were orthorhombic (α-form) and trigonal (β-form), respectively. The discrete change of the crystallization behavior was explained by the formation of different crystal. 相似文献
143.
Koji Fushimi Takatoshi Shimada Hiroki Habazaki Hidetaka Konno Masahiro Seo 《Electrochimica acta》2011,(4):1773
Depassivation–repassivation of iron surfaces in boric–borate solutions were investigated by using the micro-indentation test. A pair of current peaks due to repair of the passive film following rupture of the film were observed during a series of indenter drives, i.e., loading and unloading of the indenter. The shape of the current peak depended on environmental conditions (conductivity and pH of the solution) and substrate conditions (mechanical processing history, alloyed element) as well as indentation conditions (repetition, maximum depth, and maximum load). Plastic deformation of the surface was accompanied by surface depassivation, while no depassivation occurred during the elastic deformation, indicating that the passive film on iron has a ductile property. The solution conditions did not affect the scale of depassivation but affected the rate of repassivation. Dislocations in the substrate made surface depassivation difficult but enhanced reactivity during the repassivation. The test also revealed that type-312L stainless steel has high corrosion resistance in a concentrated NaCl solution. 相似文献
144.
Koji Takahashi Sota Watanabe Yoshio Urabe Masakazu Hisatsune 《Nuclear Engineering and Design》2009,239(12):2719-2727
Low cycle fatigue tests were conducted using 100A elbow specimens made of STPT410 carbon steel with local wall thinning. Local wall thinning by erosion/corrosion was simulated by machined pipe wall thinning. The local wall thinning areas were located at three different areas, called extrados, crown and intrados. The elbow specimens were subjected to cyclic in-plane bending under displacement control without internal pressure. The effects of eroded conditions, such as eroded ratio, eroded angle and position, on the low cycle fatigue behavior and fatigue life were discussed by using experimental results and finite element analyses. Also the location of crack initiation and the crack growth direction could be predicted by three dimensional elasto-plastic finite element analyses. In addition, the safety margin of eroded elbows against seismic loading was discussed by comparing the fictitious stress of elbows with the allowable stress limit demanded by the design code. 相似文献
145.
Monosodium glutamate (GluNa)-compounded starch was prepared by heat-moisture treating a mixture of tapioca starch and GluNa. GluNa-compounded starch exhibited a higher gelatinization temperature and reduced swelling and solubility, essentially lower hardness of the granule center, and paste viscosity than those of the heat-moisture treated tapioca starch and the untreated starch. However, its appearance, unit chain length distribution, and α-amylase digestibility were similar to those of the heat-moisture treated tapioca. It is thus concluded that GluNa compounding is useful for providing a unique type of starch that possesses a less swollen and viscous texture than that produced with simple heat-moisture treatment. 相似文献
146.
147.
Carbon Nanotubes: Simple Salt‐Coordinated n‐Type Nanocarbon Materials Stable in Air (Adv. Funct. Mater. 18/2016) 下载免费PDF全文
148.
Satoshi Someya Satoshi Yoshida Takahide Tabata Koji Okamoto 《International Journal of Heat and Mass Transfer》2009,52(19-20):4236-4243
The basic characteristics of the reacting mixing flow of two streams were investigated. The reaction between aqueous solutions of ammonia and acetic acid, which produces ammonium acetate, was investigated in terms of the effect on the fluid–fluid interface of the mixing flow relative to fluids that did not react. The reaction between these solutions was negligibly exothermic, and there were minimal differences in density. The velocity field in the reacting mixing flow was quantitatively measured using high-speed time-resolved particle image velocimetry (PIV) and the behavior of the mixing flow was qualitatively investigated using laser-induced fluorescence (LIF). The jet width, the velocity field, the kinetic energy and the turbulent intensities are qualitatively estimated and discussed. It was found that the chemical reaction resulted in the suppression of the mixing flow. 相似文献
149.
Yuji Tatemoto Yoshiyuki Bando Koji Oyama Keiji Yasuda Masaaki Nakamura Yasuhiro Sugimura Masahito Shibata 《Drying Technology》2001,19(7):1287-1303
The effects of operational conditions on the drying performance in closed superheated steam drying were examined theoretically and experimentally. The vapor generated from the sample was circulated in the drying chamber. In the theoretical analysis, the replacement of air with vapor in drying chamber and the convective vapor transfer in sample were considered. At the start of drying, the drying chamber was filled with air. As the drying proceeded, the air was replaced with the vapor generated from sample. The calculated results explained the characteristics of experimental data. The pore diameter of sample had little effect on the drying characteristics. During the internal evaporation period, the evaporation occurred in the narrow zone, which moved from the surface to the bottom of sample. The convective vapor transfer in sample had a significant influence on the drying performance. The excess increments in temperature and velocity of drying gas hardly contributed to shortening the drying time. 相似文献
150.