全文获取类型
收费全文 | 2448篇 |
免费 | 80篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 147篇 |
综合类 | 2篇 |
化学工业 | 476篇 |
金属工艺 | 104篇 |
机械仪表 | 63篇 |
建筑科学 | 35篇 |
能源动力 | 108篇 |
轻工业 | 151篇 |
水利工程 | 10篇 |
石油天然气 | 4篇 |
无线电 | 270篇 |
一般工业技术 | 488篇 |
冶金工业 | 433篇 |
原子能技术 | 85篇 |
自动化技术 | 164篇 |
出版年
2023年 | 15篇 |
2021年 | 47篇 |
2020年 | 25篇 |
2019年 | 30篇 |
2018年 | 40篇 |
2017年 | 43篇 |
2016年 | 49篇 |
2015年 | 35篇 |
2014年 | 70篇 |
2013年 | 121篇 |
2012年 | 73篇 |
2011年 | 135篇 |
2010年 | 110篇 |
2009年 | 96篇 |
2008年 | 112篇 |
2007年 | 108篇 |
2006年 | 89篇 |
2005年 | 95篇 |
2004年 | 70篇 |
2003年 | 78篇 |
2002年 | 71篇 |
2001年 | 37篇 |
2000年 | 51篇 |
1999年 | 62篇 |
1998年 | 182篇 |
1997年 | 125篇 |
1996年 | 84篇 |
1995年 | 58篇 |
1994年 | 56篇 |
1993年 | 43篇 |
1992年 | 29篇 |
1991年 | 25篇 |
1990年 | 22篇 |
1989年 | 20篇 |
1988年 | 22篇 |
1987年 | 21篇 |
1986年 | 13篇 |
1985年 | 19篇 |
1984年 | 16篇 |
1983年 | 17篇 |
1982年 | 14篇 |
1981年 | 16篇 |
1980年 | 14篇 |
1979年 | 11篇 |
1978年 | 10篇 |
1977年 | 13篇 |
1976年 | 13篇 |
1975年 | 6篇 |
1974年 | 6篇 |
1973年 | 5篇 |
排序方式: 共有2540条查询结果,搜索用时 31 毫秒
1.
Ryo Hashikawa Yasuhiro Fujii Atsushi Kinomura Takeshi Saito Arifumi Okada Takashi Wakasugi Kohei Kadono 《Journal of the American Ceramic Society》2019,102(4):1642-1651
Radiophotoluminescence phenomena have been widely investigated on various types of materials for dosimetry applications. We report that an aluminoborosilicate glass containing 0.005 mol% copper exhibits intense photoluminescence in the visible region induced by X-ray and γ-ray irradiation. The luminescence is assigned to the 3d94s1 → 3d10 transition of Cu+. The proportionality of the intensity of the induced photoluminescence to the irradiation dose was confirmed up to 0.5 kGy using 60Co γ-ray irradiation. Based on the spectroscopic results, a potential mechanism was proposed for the enhancement of the photoluminescence. The exposure to the ionizing radiation generates electron-hole pairs in the glass, and the electrons are subsequently captured by the Cu2+ ions, which are converted to Cu+ and emit the luminescence. For the glass containing 0.01 mol% copper, the pronounced enhancement of the photoluminescence was not observed because the reverse reaction, ie, the capture of the holes by the Cu+ ions, becomes prominent. The photoluminescence induced by the irradiation was stably observed for the glasses kept at room temperature and even for the glasses heat-treated at 150°C. However, the induced photoluminescence could be eliminated by the heat treatment at a temperature at 500°C, and the glass returned to the initial pre-irradiation state. The Cu-doped aluminoborosilicate glass is a potential candidate for use in dosimetry applications. 相似文献
2.
3.
Nayve R. Fujii M. Fukugawa A. Takeuchi T. Murata M. Yamada Y. Koyanagi M. 《Journal of microelectromechanical systems》2004,13(5):814-821
This paper describes the fabrication and characterization of a thermal ink jet (TIJ) printhead suitable for high speed and high-quality printing. The printhead has been fabricated by dicing the bonded wafer, which consists of a bubble generating heater plate and a Si channel plate. The Si channel plate consists of an ink chamber and an ink inlet formed by KOH etching, and a nozzle formed by inductively couple plasma reactive ion etching (ICP RIE). The nozzle formed by RIE has squeezed structures, which contribute to high-energy efficiency of drop ejector and, therefore, successful ejection of small ink drop. The nozzle also has a dome-like structure called channel pit, which contributes to high jetting frequency and high-energy efficiency. These two wafers are directly bonded using electrostatic bonding of full-cured polyimide to Si. The adhesive-less bonding provided an ideal shaped small nozzle orifice. Use of the same material (Si substrate) in heater plate and channel plate enables the fabrication of high precision long printhead because no displacement and delamination occur, which are caused by the difference in thermal expansion coefficient between the plates. With these technologies, we have fabricated a 1" long printhead with 832 nozzles having 800 dots per inch (dpi) resolution and a 4 pl. ink drop volume. 相似文献
4.
5.
K. Fujii J. Fujimoto H. Hayashii R. Kajikawa Y. Masatani H. Ozaki A. Sugiyama R. Suzaki S. Suzuki T.Y. Tsukamoto T.F. Tsukamoto S. Uno S. Iwata 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1985,236(1):55-63
We constructed and tested a prototype gas sampling electromagnetic calorimeter of the Pb-proportional tube sandwich type. The calorimeter uses conductive plastic tubes and cathode pad readout with a tower structure which resulted in reasonable energy and spatial resolutions for electrons in the momentum range 0.5–4.0 GeV/c; /c). This paper describes the test and the performance studied under various conditions. 相似文献
6.
Tatara Takako Fujii Tomiko Kawase Tokuzo Minagawa Motoi 《Journal of the American Oil Chemists' Society》1985,62(6):1053-1058
Journal of the American Oil Chemists' Society - Kinetic parameter of hydrolysis, degree of hydrolysis, pH and temperature characteristics and positional specificity of hydrolysis of seven kinds... 相似文献
7.
H Kuniyasu W Yasui F Shimamoto K Fujii M Nakahara T Asahara K Dohi E Tahara 《Canadian Metallurgical Quarterly》1996,46(12):1005-1010
A rare case of hepatoblastoma in a 61-year-old Japanese housewife is described. This liver tumor mainly consisted of two tissue components: embryonal hepatocytes and primitive mesenchymal tissue. Fetal hepatocytes with alpha-fetoprotein production, gland formation, cartilage and osteoid were also found in a small portion. Molecular analysis by slot blot method revealed increased copy numbers of c-met and K-sam proto-oncogenes and cyclin D1 genes. These findings suggest that alterations of these oncogenes might play a role in the development of adult hepatoblastoma. 相似文献
8.
A new mathematical model for study of an interface crack between two dissimilar elastic half planes is proposed. A process zone is formed along the interface between the physical crack and the continuous part. Both the crack opening (and sliding) displacement with a smooth shape and the finite magnitude of stress concentration appear in this zone. The analytical model is expressed by closed elastic solutions using complex variables, but with no oscillations at the crack tip. 相似文献
9.
The effects of carbon-fiber chips and carbon brushes as additives on the thermal conductivity enhancement of phase change materials (PCMs) using in latent heat thermal energy storage are investigated experimentally and numerically by considering the wall effect of the additives. The carbon-fiber chips are effective for improving the heat transfer rate in PCMs. However, the thermal resistance near the heat transfer surface is higher than that for the carbon brushes. As a result, the overall heat transfer rate for the fiber chips is lower than that for the carbon brushes. Consequently, the carbon brushes are superior to the fiber chips for the thermal conductivity enhancement under the present experimental conditions. The carbon brushes are moreover applied to the packed beds of particles to overcome their low thermal conductivity in chemical heat pump/storage. The carbon brushes essentially improve the heat transfer characteristics in the packed beds, though the thermal resistance is observed because the particles obstruct contact between the fibers and the heat transfer surfaces. 相似文献
10.
Yukio Sato Tomohito Tanaka Fumiyasu Oba Takahisa Yamamoto Yuichi Ikuhara Taketo Sakuma 《Science and Technology of Advanced Materials》2003,4(6):137
SrTiO3 and ZnO bicrystals with various types of boundaries were fabricated in order to examine their current–voltage characteristics across single grain boundaries. Their grain boundary structures were also investigated by high-resolution transmission electron microscopy. In Nb-doped SrTiO3, electron transport behaviors depend on the type of boundaries. Random type boundaries exhibit highly non-linear current–voltage characteristics, while low angle boundaries show a slight non-linearity. On the contrary, undoped ZnO does not exhibit non-linear current–voltage characteristics in any type of boundaries including random ones. It is suggested that the differences observed in current–voltage properties between the two systems are mainly due to the difference in the accumulation behavior of acceptor-like native defects at grain boundaries. A clear non-linearity is obtained by means of Co-doping even for the highly coherent Σ1 boundary in a ZnO bicrystal. This is considered to result from the production of acceptor-like native defects by Co-doping. 相似文献