全文获取类型
收费全文 | 828篇 |
免费 | 33篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 62篇 |
化学工业 | 234篇 |
金属工艺 | 18篇 |
机械仪表 | 20篇 |
建筑科学 | 23篇 |
能源动力 | 68篇 |
轻工业 | 77篇 |
无线电 | 56篇 |
一般工业技术 | 136篇 |
冶金工业 | 21篇 |
原子能技术 | 48篇 |
自动化技术 | 99篇 |
出版年
2024年 | 3篇 |
2023年 | 11篇 |
2022年 | 18篇 |
2021年 | 29篇 |
2020年 | 19篇 |
2019年 | 15篇 |
2018年 | 21篇 |
2017年 | 19篇 |
2016年 | 22篇 |
2015年 | 21篇 |
2014年 | 29篇 |
2013年 | 62篇 |
2012年 | 48篇 |
2011年 | 87篇 |
2010年 | 58篇 |
2009年 | 46篇 |
2008年 | 39篇 |
2007年 | 47篇 |
2006年 | 36篇 |
2005年 | 33篇 |
2004年 | 22篇 |
2003年 | 19篇 |
2002年 | 25篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 12篇 |
1998年 | 13篇 |
1997年 | 11篇 |
1996年 | 5篇 |
1995年 | 11篇 |
1994年 | 4篇 |
1993年 | 9篇 |
1992年 | 2篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有862条查询结果,搜索用时 31 毫秒
811.
Aluminum covered with pore-sealed anodic oxide films was irradiated with a pulsed Nd-YAG laser to remove the oxide film at micro-areas. The specimen was re-anodized for long periods to examine the growth of porous anodic oxide films at the area where substrate had been exposed by measuring current variations and morphological changes in the oxide during the re-anodizing. The chemical dissolution resistance of the pore-sealed anodic oxide films in an oxalic acid solution was also examined by measuring time-variations in rest potentials during immersion.The resistance to chemical dissolution of the oxide film became higher with increasing pore-sealing time and showed higher values at lower solution temperatures. During potentiostatic re-anodizing at five 35-μm wide and 4-mm long lines for 72 h after the film was removed the measured current was found to increase linearly with time. Semicircular columnar-shaped porous type anodic oxide was found to form during the re-anodizing at the laser-irradiated area, and was found to grow radially, thus resulting in an increase in the diameter. After long re-anodizing, the central and top parts of the oxide protruded along the longitudinal direction of the laser-irradiated area. The volume expansion during re-anodizing resulted in the formation of cracks, parallel to the lines, in the oxide film formed during the first anodizing. 相似文献
812.
Mugihito Oshiro Hideaki Shinto Yukihiro Tashiro Noriko Miwa Tatsuya Sekiguchi Masahiro Okamoto Ayaaki Ishizaki Kenji Sonomoto 《Journal of Bioscience and Bioengineering》2009,108(5):376-384
We proposed a kinetic simulation model of xylose metabolism in Lactococcus lactis IO-1 that describes the dynamic behavior of metabolites using the simulator WinBEST-KIT. This model was developed by comparing the experimental time-course data of metabolites in batch cultures grown in media with initial xylose concentrations of 20.3–57.8 g/l with corresponding calculated data. By introducing the terms of substrate activation, substrate inhibition, and product inhibition, the revised model showed a squared correlation coefficient (r2) of 0.929 between the experimental time-course of metabolites and the calculated data. Thus, the revised model is assumed to be one of the best candidates for kinetic simulation describing the dynamic behavior of metabolites. Sensitivity analysis revealed that pyruvate flux distribution is important for higher lactate production. To confirm the validity of our kinetic model, the results of the sensitivity analysis were compared with enzyme activities observed during increasing lactate production by adding natural rubber serum powder to the xylose medium. The experimental results on pyruvate flux distribution were consistent with the prediction by sensitivity analysis. 相似文献
813.
Kenichi Haji Kimitaka Hirano Tatsuya Sakoda Masahisa Otsubo 《IEEJ Transactions on Electrical and Electronic Engineering》2009,4(6):793-795
To investigate the temperature distribution on the surface of a silicone rubber exposed to partial arc discharges, numerical analyses on thermal characteristics were carried out. The preliminary calculations indicated that there was no dependence of mesh and time step. The temperature on the specimen surface became high in the middle of the discharge gap while those at points of contact between an arc discharge and tips of glass-filter paper used as electrodes became low. The thermal diffusion from the points of contact between the arc discharge and the tips of glass-filter paper into electrolyte electrodes caused the temperature decrease at such points. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
814.
Detection of nitric oxide (NO) in marine phytoplankters 总被引:1,自引:0,他引:1
Kim D Kang YS Lee Y Yamaguchi K Matsuoka K Lee KW Choi KS Oda T 《Journal of Bioscience and Bioengineering》2008,105(4):414-417
In raphydophyte cell suspensions such as those of Chattonella marina, C. ovata and Heterosigma akashiwo, a gradual increase in NO-specific fluorescence intensity was observed, and the increase in the fluorescence intensity of each of these phytoplankters was completely inhibited in the presence of carboxy-PTIO, a specific NO scavenger. However, no such significant changes were observed in the case of other phytoplankter species. 相似文献
815.
Norihiko L. Okamoto Tatsuya Koyama Kyosuke Kishida Katsushi Tanaka Haruyuki Inui 《Acta Materialia》2009,57(17):5036-5045
Phase relationships of manganese-substituted ruthenium sesquisilicide alloys have been investigated by using X-ray powder diffraction and scanning and transmission electron microscopy. A series of chimney–ladder phases Ru1?xMnxSiy (0.14 ? x ? 0.97, 1.584 ? y ? 1.741) are formed over a wide compositional range between Ru2Si3 and Mn4Si7. The compositions of these chimney–ladder compounds deviate slightly from the composition line connecting Ru2Si3 and Mn4Si7, which corresponds to the ideal composition line satisfying VEC (valence electron counting) = 14 rule. The occurrence of this compositional deviation is discussed in terms of the VEC rule and the atomic packing. The thermoelectric properties of the directionally solidified Ru1?xMnxSiy alloys (0.55 ? x ? 0.90) have also been investigated as a function of the Mn content and temperature. The dimensionless figure of merit (ZT) for those alloys with a high Mn content (x ? 0.75) increased with the increase in Mn content. The ZT value for a crystal with x = 0.90 was as high as 0.76 at 874 K. 相似文献
816.
Nobuyuki Gokon Shin-ichi Inuta Shingo Yamashita Tsuyoshi Hatamachi Tatsuya Kodama 《International Journal of Hydrogen Energy》2009,34(17):7143
Composite materials with alkali carbonate and magnesia have been examined for high-temperature thermal storage in solar tubular reformers. The concept of a double-walled reactor tube involves packing a molten-salt/ceramic composite material into the annular region between internal catalyst tube and exterior solar-absorber wall. In this paper, the shape and interior structure of the reactor tube are newly designed for use in solar cavity-type reformers using straight reactor tubes. Na2CO3, K2CO3, and Li2CO3 composite materials with magnesia were tested as thermal storage media for CO2 reforming of methane during cooling mode of the reactor tube at a laboratory scale. The efficiency of Na2CO3/MgO composite with various MgO contents was also estimated. Composite materials of Na2CO3 80–90 wt% and MgO 20–10 wt% were successfully delayed the cooling of the catalyst bed and sustained methane conversion at >90%. A solar cavity-type reformer consisting of multiple straight reactor tubes is expected to enable stable operation of the solar reforming process under fluctuating solar insolation during cloud passage. 相似文献
817.
Koji Takahashi Norsyazwan Hilmi Yohei Ito Tatsuya Ikuta Xing Zhang 《International Journal of Thermophysics》2009,30(6):1864-1874
The small size of nanomaterials deposited by either focused ions or electron beams has prevented the determination of reliable
thermal property data by existing methods. A new method is described that uses a suspended platinum hot film to measure the
thermal conductivity of a nanoscale deposition. The cross section of the Pt film needs to be as small as 50 nm × 500 nm to
have sufficient sensitivity to detect the effect of the beam-induced nanodeposition. A direct current heating method is used
before and after the deposition, and the change in the average temperature increase of the Pt hot film gives the thermal conductivity
of the additional deposited material. In order to estimate the error introduced by the one-dimensional analytical model employed,
a two-dimensional numerical simulation was conducted. It confirmed the reliability of this method for situations where the
deposit extends onto the terminals by (1 μm or more. Measurements of amorphous carbon (a-C) films fabricated by electron beam
induced deposition (EBID) produced thermal conductivities of 0.61 W · m−1 · K−1 to 0.73 W · m−1 · K−1 at 100 K to 340 K, values in good agreement with those of a-C thin films reported in the past. 相似文献
818.
819.
Microstructure and mechanical properties of diffusion bonded SiC/steel joint using W/Ni interlayer 总被引:1,自引:0,他引:1
This paper describes the design and examination of W/Ni double interlayer to produce a joint between SiC and ferritic stainless steel. Diffusion bonding was performed by a two steps solid state diffusion bonding process. Microstructural examination and mechanical properties evaluation of the joints show that bonding of SiC to steel was successful. EDS and XRD analysis revealed that W5Si3 and WC were formed at SiC/W interface. The diffusion products at W/Ni interface, Ni-rich solid solution Ni(W) or intermetallic compound Ni4W, was found to be dependent on the second step joining temperature. Neither intermediate phases nor reaction products was observed at Ni/steel interface for the joints bonded at the temperature studied. The average tensile strength of 55 MPa which is insensitive to the second step process was measured for as-bonded SiC/steel joint and the failure occurred at SiC/W interface. The hardness near the various bonded interfaces was also evaluated. 相似文献
820.
Mikio Yoshida Shingo Nakatsukasa Masaaki Nanba Kuniaki Gotoh Tatsuya Zushi Yasuo Kubo Jun Oshitani 《Advanced Powder Technology》2010,21(1):69-74
In order to decrease Cl content in waste plastics, dry density float-sink separation of Cl-contained and Cl-free plastics was explored using a semi-continuous rotating-type gas–solid fluidized bed separator with silica sand. The separator has two distinctive features: (1) the plastics can be fed at a middle height of the sand bed, and (2) when the plastics are recovered with the sand from a container after the float-sink, the recovery height of the sand bed can be changed to designate the plastics as floaters or sinkers. The waste plastics of Cl content = 5.4 wt% were used in this study. The separation was investigated by changing the experimental conditions. As a result, the float-sink of the plastics was affected by the air velocity for fluidization, the float-sink time and the feed amount of plastics. The possible causes of the effects were discussed by focusing on the apparent density of fluidized bed, the fluidization intensity, the size segregation of fluidized particle, the shape of the plastics, and the interactions between the plastics during the float-sink. When the recovery height was changed at the adjusted conditions, the Cl content in the floaters was successfully decreased to be 0.4–0.85 wt%, at which the recovery of the Cl-free plastics was 40–60%. 相似文献