全文获取类型
收费全文 | 756篇 |
免费 | 16篇 |
专业分类
电工技术 | 29篇 |
综合类 | 2篇 |
化学工业 | 161篇 |
金属工艺 | 9篇 |
机械仪表 | 25篇 |
建筑科学 | 3篇 |
能源动力 | 16篇 |
轻工业 | 61篇 |
无线电 | 44篇 |
一般工业技术 | 141篇 |
冶金工业 | 183篇 |
原子能技术 | 45篇 |
自动化技术 | 53篇 |
出版年
2022年 | 3篇 |
2021年 | 11篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 16篇 |
2013年 | 31篇 |
2012年 | 22篇 |
2011年 | 42篇 |
2010年 | 15篇 |
2009年 | 21篇 |
2008年 | 24篇 |
2007年 | 24篇 |
2006年 | 22篇 |
2005年 | 44篇 |
2004年 | 24篇 |
2003年 | 26篇 |
2002年 | 17篇 |
2001年 | 19篇 |
2000年 | 18篇 |
1999年 | 28篇 |
1998年 | 73篇 |
1997年 | 42篇 |
1996年 | 28篇 |
1995年 | 25篇 |
1994年 | 26篇 |
1993年 | 21篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1983年 | 9篇 |
1982年 | 2篇 |
1981年 | 8篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 15篇 |
1975年 | 6篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有772条查询结果,搜索用时 15 毫秒
61.
62.
Yasuhisa Ishikawa Akihiko Iwai Susumu Nishiwaki Tadashi Koshizuka Tsuneharu Teranishi Kyouichi Uehara 《Electrical Engineering in Japan》2004,146(2):20-26
Investigations were conducted on the VFT (Very Fast Transient) surges that propagate into a 500‐kV transformer. The disconnector restriking surge and ground fault surged were discussed. It was regarded that a large part of the surge voltage was applied just at the entrance of the transformer winding for the VFT surges. Thus, an equivalent circuit that models the windings was used for the analysis. The overvoltages that appear between the first winding sections at the entrance of the transformer were computed. The following was established. (1) The overvoltage between the first winding sections becomes greater when the magnitude of the voltage change at the transformer terminal is larger. The overvoltage between the first winding sections is not affected by the magnitude of the transformer terminal voltage. (2) For the disconnectors that are not connected directly to the transformer, the voltage change at the transformer terminal is not so large. (3) In the case of a ground fault at the GIS near the transformer, the voltage change at the transformer terminal is the same as that for a disconnector directly connected to the transformer. (4) In actual GIS, the disconnector that is connected directly to the transformer is not usually used. In this situation, the overvoltages that threaten the transformer insulation will not be generated by the restriking of the disconnectors. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(2): 20–26, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10225 相似文献
63.
64.
65.
Based on the present state of the art of the separation technology, recycling of fission-product rare elements (FRE) in the FBR spent fuel is discussed. The rad.-waste fractionation is in accordance with the present society's trend toward zero-emission, and the mean of salt-free method utilizing electrochemistry agrees with the principles of the newly established green chemistry. A catalytic electrolytic extraction method is proposed to separate the target, radioactive but potentially strategic elements, Pd, Ru, Rh, Re (Tc), Te and Se dissolved in the HLLW. It avoids secondary waste arising. This method is particularly feasible for the separation of Pd where cyclic reaction of metal cations such as Pd(II) or Fe(II), acting as promoters or mediators and already contained in HLLW, accelerates the electrochemical deposition of Ru, Rh and Re. Elemental separation not only offers alternative material resources to meet expanding demands for catalysts in Fuel Cell/Soft Energy system but is also the first step for transmutation or other selective strategies for waste management of long-lived fission products (LLFP). 相似文献
66.
Okuyama H. Miyajima T. Morinaga Y. Hiei F. Ozawa M. Akimoto K. 《Electronics letters》1992,28(19):1798-1799
The continuous wave operation of an ZnSe/ZnMgSSe laser diode was achieved for the first time at 77 K. Blue stimulated emission was observed at a wavelength of 447 nm and the threshold current density was 225 A/cm/sup 2/.<> 相似文献
67.
Novel system of electro-catalysts was developed for methanol oxidation reaction (MOR) in direct methanol fuel cells. Mixture of platinum tetraammine complex with cobalt quinolyldiamine complex with various mixing ratio was supported on graphite powder, and heat treated at 400-1000 °C in argon atmosphere. Powder thus obtained was put on a graphite disk electrode, and tested for electrochemical MOR in acid media. Although the cobalt complex itself showed almost no catalytic ability for MOR, it enhanced the activity of Pt more than several 10-fold when it was mixed with Pt. MOR performance was best exploited at about equal mixing ratio of platinum and cobalt complexes. Compared with platinum-ruthenium alloy catalysts, the new catalysts exhibited promising catalytic ability. The present investigation revealed good potentiality of organic complex catalysts in combination with metal catalysts for MOR, which opens the way to synthesize and develop a new class of electro-catalysts of low cost through wide range of molecular designing. 相似文献
68.
K Shirotani K Takahashi K Ozawa T Kunishita T Tabira 《Canadian Metallurgical Quarterly》1997,240(3):728-731
Mutations in the presenilin 1 (PS1) and presenilin 2 (PS2) genes are associated with early-onset autosomal dominant familial Alzheimer's disease, and the gene products are endoproteolytically processed to yield N-terminal fragments (NTF) and C-terminal fragments (CTF). We have studied the cleavage site of the PS2 protein in stably transfected human neuroblastoma cells. The 23 kD PS2-CTF was isolated by a combination of anion exchange chromatography and affinity chromatography and directly sequenced. The N-terminus of the PS2-CTF started at residue 307, which indicated that the cleavage occurs between Lys306 and Leu307 in the proximal portion of the large hydrophilic loop. This site is close to the cleavage positions observed in the PS1 protein. 相似文献
69.
In the negative feedback model, loss of endogenous glucocorticoids up-regulates the expression of glucocorticoid receptor mRNA. To elucidate further the effect of chronic lack of glucocorticoids on the expression of glucocorticoid receptor mRNA and protein, in situ hybridization and immunohistochemical methods were used to examine the long-term alteration of glucocorticoid receptor mRNA and its immunoreactivity in the forebrain of adrenalectomized rats. Constant lack of glucocorticoids resulted in marked decrease in the expression of glucocorticoid receptor mRNA and disappearance of glucocorticoid receptor immunoreactivity in many forebrain structures. In particular, in the suprapyramidal blade of the hippocampal granule cell layer and cerebral cortex, many cells showed almost no glucocorticoid receptor mRNA signals. These results suggest that long-term loss of endogenous glucocorticoids down-regulates the levels of glucocorticoid receptor mRNA, leading to reduction in the synthesis of glucocorticoid receptors in the rat forebrain. Therefore, the presence of endogenous glucocorticoids is vital to the continued expression of glucocorticoid receptor mRNA. 相似文献
70.
M. Ozawa A. Tadano R. Aogaki N. Kino J. Li K. Kishio K. Kitazawa 《Fullerenes, Nanotubes and Carbon Nanostructures》1997,5(3):567-591
Fullerenol, C60 (OH)n (n is about 24), was investigated by using electrochemical techniques on Platinum electrode in aqueous solutions. Fullerenol was found to promote hydrogen adsorption during cathodic polarization, while its electrochemical inertness was observed within the potential window of water. This effect was involved by the formation of multi-layer adsorption of fullerenol on Pt surface. 相似文献