全文获取类型
收费全文 | 1219篇 |
免费 | 52篇 |
国内免费 | 19篇 |
专业分类
电工技术 | 63篇 |
综合类 | 1篇 |
化学工业 | 344篇 |
金属工艺 | 40篇 |
机械仪表 | 35篇 |
建筑科学 | 22篇 |
能源动力 | 67篇 |
轻工业 | 103篇 |
水利工程 | 2篇 |
石油天然气 | 2篇 |
无线电 | 94篇 |
一般工业技术 | 230篇 |
冶金工业 | 130篇 |
原子能技术 | 38篇 |
自动化技术 | 119篇 |
出版年
2023年 | 13篇 |
2022年 | 46篇 |
2021年 | 62篇 |
2020年 | 29篇 |
2019年 | 32篇 |
2018年 | 37篇 |
2017年 | 25篇 |
2016年 | 46篇 |
2015年 | 25篇 |
2014年 | 51篇 |
2013年 | 84篇 |
2012年 | 57篇 |
2011年 | 91篇 |
2010年 | 59篇 |
2009年 | 56篇 |
2008年 | 61篇 |
2007年 | 38篇 |
2006年 | 37篇 |
2005年 | 40篇 |
2004年 | 25篇 |
2003年 | 31篇 |
2002年 | 28篇 |
2001年 | 20篇 |
2000年 | 17篇 |
1999年 | 27篇 |
1998年 | 45篇 |
1997年 | 34篇 |
1996年 | 29篇 |
1995年 | 17篇 |
1994年 | 23篇 |
1993年 | 15篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1977年 | 6篇 |
1976年 | 11篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 4篇 |
1970年 | 3篇 |
排序方式: 共有1290条查询结果,搜索用时 31 毫秒
71.
Hiroki Ishikawa Ryoko Komaki Haruo Naitoh Akira Yamaba Hiroki Katoh 《Electrical Engineering in Japan》2010,173(1):51-59
This paper presents a current control design for switched reluctance motors (SRMs). The electric transfer characteristic of the motors is studied first. Their transfer function is shown to be expressible by a pure resistive component, which is not constant but varies depending on the motor current and speed. The current control design for SRMs follows the classical design technique used for DC machines, where the zeros of the PI controller cancel the poles of Ls+R. Because the transfer function of SRMs does not have any poles, an I controller is suitable for them. The integral gain should be adjusted in order to compensate the nonlinearity, that is, the variation in the equivalent resistor of the SRMs' transfer function. The values of the integral gain are tuned and tabulated for the motor speed and current. Simulation and experiment demonstrate that the current and speed of the SRMs present good responses without dependence on the motor speed and current. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(1): 51–59, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20987 相似文献
72.
Koh Matsumoto Kazutada Ikenaga Jun Yamamoto Kazuki Naito Yoshiki Yano Akinori Ubukata Hiroki Tokunaga Tadanobu Arimura Katsuaki Cho Toshiya Tabuchi Akira Yamaguchi Yasuhiro Harada Yuzaburo Ban Kousuke Uchiyama 《半导体学报》2011,32(1):21-23
Growth rate has a direct impact on the productivity of nitride LED production.Atmospheric pressure growth of GaN with a growth rate as high as 10μm/h and also Al0.1Ga0.9N growth of 1μm/h by using 4 inch by 11 production scale MOVPE are described.XRD of(002) and(102) direction was 200 arcsec and 250 arcsec, respectively.Impact of the growth rate on productivity is discussed. 相似文献
73.
Hironao Ogura Hiroki Ishida Ryuta Yokooji Hiroyuki Kage Yoshizo Matsuno Arun S. Mujumdar 《Drying Technology》2001,19(7):1461-1477
The authors have been studying Chemical Heat Pumps (CHP) from the viewpoints of energy saving and environmental impact. The CHP can store thermal energy in the form of chemical energy by an endothermic reaction, and release it at various temperature levels during heat demand periods by exo/endothermic reactions. The authors have proposed in an earlier study a novel chemical heat pump (CHP) system for environmentally-friendly effective utilization of thermal energy in drying as a chemical heat pump dryer (CHPD). In this exploratory study, we test the effectiveness of operating the proposed CHPDs experimentally. Basic experiments on the CHPDs such as hot dry air production for convective drying are performed on lab-scale CHPD apparatuses using gas-solid reactions in calcium oxide/calcium hydroxide reactant beds. The proposed CHPDs are found to produce hot air by CHP operation for drying. The temperature levels of the produced hot air and the reaction rates/conversions are as good as in the case of hot water supply system using basically same CHP operation. The cold heat for air dehumidification is also found to be generated/recovered by the same CHPD system. The generated heat amounts can be increased by changing the operating conditions although the heat recovery must be enhanced for practical application of CHPDs. 相似文献
74.
75.
76.
Kameda Atsushi Yamamoto Masahito Uejima Hiroki Hagiya Masami Sakamoto Kensaku Ohuchi Azuma 《Natural computing》2005,4(2):103-126
In this paper, we propose a new architecture for a multi-state DNA machine whose conformation of repeated hairpin structures changes sequentially in response to input oligomers. As an application of the machine, we also propose molecular memory in which the machine is used as a memory unit. Addressing in the memory is realized through state transitions of the machine. We then describe a method for designing DNA sequences of the machine, which exhaustively checks conformational changes of the machine by dividing its secondary structure into hairpin units. The method is based on the minimum free energy of the structure, the structure transition paths, and the total frequency of optimal and suboptimal structures. DNA sequences designed by the method were tested in a chemical experiment in which a machine consisting of two hairpins was actually constructed. As a result, we verified that the multi-state DNA machine realized the expected changes in its secondary structure. 相似文献
77.
Mitsutoshi Miyasaka Hiroyuki Hara Hiroki Takao Simon Tam Rob Payne Prem Rajalingham Satoshi Inoue Tatsuya Shimoda 《Journal of the Society for Information Display》2005,13(3):187-191
Abstract— Thin‐film transistors (TFTs) are field‐effect transistors that can be used to create large‐scale‐integrated (LSI) circuits. The combination of high‐performance TFTs and transfer technology of the TFTs has the potential to foster the rise of a new flexible microelectronics industry. This paper discusses the current status of flexible microelectronics, using a TFT fingerprint sensor (FPS) as an example. Technology used in active‐matrix displays can easily be applied to the TFT FPS. TFT technology should not be confined to the display industry; its use should be expanded into the semiconductor industry. With the result presented in this paper, we declare a new era of flexible microelectronics open. 相似文献
78.
HT Nagasawa JF Cohen AM Holleschau WB Rathbun 《Canadian Metallurgical Quarterly》1996,39(8):1676-1681
A marked age-related decrease in glutathione (GSH) levels as well as depression of gamma-glutamylcysteine synthetase activity are factors that are believed to render the aged lens more susceptible to oxidative stress and, therefore, to cataractogenesis. Providing gamma-L-glutamyl-L-cysteine, the dipeptide precursor of GSH, would effectively bypass the compromised first step in its biosynthesis and should protect the lens from GSH depletion. Accordingly, some bioreversible sulfhydryl-, amino-, and C-terminal carboxyl-protected prodrug forms of this dipeptide were prepared. Sulfhydryl protection was in the form of an acetyl thioester, while the carboxyl group was protected as the ethyl ester. These prodrugs were evaluated for their GSH-enhancing activity in cultured human and rat lenses in vitro using an assay that measured the incorporation of [14C]glycine into lens GSH. Ethyl S-acetyl-gamma-L-glutamyl-L-cysteinate (2) raised GSH levels in human lenses by 25% and in rat lenses by >150%. These data suggest that 2 may have potential as an anticataract agent since ethyl gamma-L-glutamyl-L-cysteinate (1a), the des-S-acetyl analog of 2, had been shown (by others) to protect against experimental rodent cataracts. GSH augmentation by 1a was 2% in human lenses and 25% in rat lenses, considerably less than that shown by 2. 相似文献
79.
Internal oxidation was observed in gold-rich alloys as substrates for porcelain veneers in dental restorations, which contain small amounts of Fe and Sn. The internal oxidation proceeded with oxygen ions diffusing to the inner part of the alloy through Fe2O3 formed at the grain boundaries of the alloy matrix. SnO2 was formed internally together with the Fe2O3. The external oxidation zone was composed of only Fe2O3 in a wide range of Fe and Sn concentrations. Fe3O4 was formed with Fe2O3 in the Sn-rich composition range by reduction of Fe2O3 in the presence of Sn. A band mainly composed of SnO2 was formed at the inside of the internal oxidation zone in the composition range where Fe3O4 formed. In the Sn-rich alloys this internal oxidation band of SnO2 moved to the external oxidation zone. 相似文献
80.
Koizumi H Yamamoto T Maki A Yamashita Y Sato H Kawaguchi H Ichikawa N 《Applied optics》2003,42(16):3054-3062
We will briefly review the present status of optical topography and then discuss the method of improving practicality, i.e., the signal-to-noise (S/N) ratio and the spatial resolution in observations of higher-order brain functions. The optimum wavelength pair improved the S/N ratio sixfold for deoxyhemoglobin, and new configurations of light irradiation and detection positions doubled the spatial resolution. We also report on developing application fields of optical topography. This modality will bridge the gap between natural sciences, neuroscience, and pedagogy, and show actual real-time brain activity. 相似文献