全文获取类型
收费全文 | 398篇 |
免费 | 16篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 43篇 |
化学工业 | 99篇 |
金属工艺 | 8篇 |
机械仪表 | 10篇 |
建筑科学 | 12篇 |
能源动力 | 26篇 |
轻工业 | 19篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 37篇 |
一般工业技术 | 85篇 |
冶金工业 | 20篇 |
原子能技术 | 19篇 |
自动化技术 | 35篇 |
出版年
2023年 | 10篇 |
2022年 | 9篇 |
2021年 | 16篇 |
2020年 | 8篇 |
2019年 | 7篇 |
2018年 | 22篇 |
2017年 | 10篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 17篇 |
2013年 | 32篇 |
2012年 | 22篇 |
2011年 | 37篇 |
2010年 | 22篇 |
2009年 | 24篇 |
2008年 | 28篇 |
2007年 | 13篇 |
2006年 | 15篇 |
2005年 | 11篇 |
2004年 | 1篇 |
2003年 | 6篇 |
2002年 | 11篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 12篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有415条查询结果,搜索用时 0 毫秒
101.
Application of B MAS-NMR to the characterization of boron in coal fly ash generated from Nantun coal
Boron and its compounds are environmentally hazardous substance and are well-known condensed products that appear in coal fly ash during combustion of coal in coal-fired electric power stations. In a previous study, we suggested that boron in coal fly ash obtained from Nantun coal in China, identified as Ash-N, may exist on the surface of relatively large coal fly ash particles or as very fine particles generated by homogeneous nucleation. Although the characterization of boron in coal fly ash is important for its effective stabilization or removal, its detection is quite difficult because of its low concentration in coal fly ash and its light atomic weight. In the present work, solid-state magic angle spinning nuclear magnetic resonance (MAS-NMR) technique has been applied to reveal the local chemical structures of boron in Ash-N. In the 11B MAS-NMR spectrum of Ash-N, two peaks which are attributed to a three-oxygen coordinated boron unit (BO3) and a four-oxygen coordinated boron unit (BO4) were observed with high resolution. We have estimated quadrupole parameters of the BO3 unit in Ash-N using computer simulation, and we have fingerprinted these moieties with the parameters of borates. The result of the present analysis shows that calcium- or magnesium-bearing orthoborate or pyroborate are the most likely forms of boron in Ash-N. 相似文献
102.
Kenji Shimomura Hiroyuki Koshino Arata Yajima Noriko Matsumoto Yuuma Kagohara Koichi Kamada Shunsuke Yajima Kanju Ohsawa 《Journal of chemical ecology》2010,36(8):824-833
Callosobruchus rhodesianus (Pic) (Coleoptera: Chrysomelidae: Bruchinae) is a pest of stored legumes through the Afro-tropical region. In laboratory bioassays, males of C. rhodesianus were attracted to volatiles collected from virgin females. Collections were purified by various chromatographic techniques, and the biologically active component isolated using gas chromatographic-electroantennographic detection analysis. Gas chromatography-mass spectrometry and NMR analyses suggested that the active compound was 2,3-dihydrohomofarnesal, i.e., 7-ethyl-3,11-dimethyl-6,10-dodecadienal. The structure was confirmed by non-stereoselective and enantioselective total synthesis. Using chiral gas chromatography, the absolute configuration of the natural compound was confirmed as (3S,6E)-7-ethyl-3,11-dimethyl-6,10-dodecadienal. Y-tube olfactomter assays showed that only the (S)-enantiomer attracted males of C. rhodesianus. The (R)-enantiomer and racemate did not attract males, suggesting that the (R)-enantiomer inhibits the activity of the natural compound. In combination with previous reports about sex attractant pheromones of congeners, we suggest that a saltational shift of the pheromone structure arose within the genus Callosobruchus. 相似文献
103.
Motoi Oshima Wataru Shimada Shunsuke Hashimoto Atsushi Tani Kazunari Ohgaki 《Chemical engineering science》2010,65(20):5442-5446
Recrystallization in a tetragonal tetra-n-butyl ammonium bromide (hereafter, TBAB) semi-clathrate hydrate system has been investigated in TBAB aqueous solutions of two different concentrations (stoichiometric mole fraction for tetragonal TBAB hydrate formation and lower mole fraction than stoichiometric one) by use of optical microscopy. The recrystallization of TBAB hydrate has been observed under milder condition than that of the initial crystallization in both concentrations. In particular, solution of the lower concentration is easily recrystallized. This is the first observation of memory effect in a semi-clathrate hydrate system. In addition, the recrystallization occurs in the vicinity of the place where the last piece of initial crystal was dissociated. This implies that a small amount of residual structures remain in the dissociated water, but unfortunately they cannot be confirmed with Raman micro-spectroscopy. 相似文献
104.
Maeda D Mao TL Fukayama M Nakagawa S Yano T Taketani Y Shih IeM 《International journal of molecular sciences》2010,11(12):5120-5128
Recent genome-wide analysis has demonstrated that somatic mutations in ARID1A (BAF250) are the most common molecular genetic changes in ovarian clear cell carcinoma (OCCC). ARID1A mutations, which occur in approximately half of OCCC cases, lead to deletion of the encoded protein and inactivation of the putative tumor suppressor. In this study, we determined the significance of loss of ARID1A immunoreactivity with respect to several clinicopathological features in a total of 149 OCCCs. First, we demonstrated that ARID1A immunohistochemistry showed concordance with the mutational status in 91% of cases with 100% sensitivity and 66% specificity. Specifically, among 12 OCCC cases for which ARIDA mutational status was known, ARIDIA immunoreactivity was undetectable in all 9 cases harboring ARID1A mutations and was undetectable in one of 3 cases with wild-type ARID1A. With respect to the entire cohort, ARID1A immunoreactivity was undetectable in 88 (59%) of 149 OCCCs. There was no significant difference between ARID1A negative and positive cases in terms of histopathologic features, age, clinical stage, or overall survival. In conclusion, this study provides further evidence that mutations in ARID1A resulted in loss of ARID1A protein expression in OCCC, although no significant differences between ARID1A positive and negative cases were observed with respect to any clinicopathological features examined. 相似文献
105.
Masanobu Izaki Shunsuke SasakiFariza Binti Mohamad Tsutomu ShinagawaTakayuki Ohta Seiji WataseJunji Sasano 《Thin solid films》2012,520(6):1779-1783
The (111)-oriented Cu2O films with a 2.0-eV-bandgap energy were prepared by electrodeposition on a (111)-oriented Au/Si wafer substrate at the preparation temperatures from 298 to 323 K, and the structural, optical, and electrical characterizations were carried out by X-ray absorption spectra measurements, X-ray diffraction, scanning electron microscopic observations, optical absorption spectra, photoluminescence spectra measurements, and Hall effect measurements. The photoluminescence spectra and electrical characteristics changed depending on the temperature. The 1.52-eV-visible light that originated from the copper vacancies weakened with a decrease in the preparation temperature, and the emission of the slight 2.0-eV-visible light due to the recombination of excitons was observed for the Cu2O film prepared at 298 K. The hole density related to the copper vacancies decreased and the mobility increased with a decrease in the preparation temperature, and the maximum mobility of 21 cm2 V−1 s−1 could be obtained at 303 K. 相似文献
106.
Toshiyuki Kawai Mitsuru Takemoto Shunsuke Fujibayashi Masashi Neo Haruhiko Akiyama Seiji Yamaguchi Deepak K. Pattanayak Tomiharu Matsushita Takashi Nakamura Tadashi Kokubo 《Journal of materials science. Materials in medicine》2012,23(12):2981-2992
The effects of surface treatment on the bone-bonding properties of Ti metal were examined by both mechanical detaching test and histological observation after implantation into rabbit tibiae for various periods ranging from?4 to?26?weeks. The bone-bonding ability of Ti metal, which is extremely low as it is abraded, was hardly increased by simple heat treatment at 600?°C or treatment with H2SO4/HCl mixed acid alone, but was markedly increased by the heat treatment after the acid treatment. Even Ti metal that had been previously subjected to NaOH treatment showed considerably high bone-bonding ability after acid and heat treatments. Such high bonding abilities were attributed to their high apatite-forming ability in the body environment. Their high apatite-forming abilities were attributed to a high positive surface charge, and not to the type of crystalline phase or specific roughness of their surfaces. The present study has demonstrated that acid and subsequent heat treatments are effective for conferring stable fixation properties on Ti metal implants. 相似文献
107.
Isolated mixing region in agitated vessel with rotated two-bladed paddle impeller and no baffle was visualized experimentally and its structural property was investigated in detail. A set of thin filaments spirally wrapping around the core of the toroidal isolated mixing region is observed under low Reynolds number conditions, which is smaller than 60. Three-dimensional geometrical structure of filament in isolated mixing region depends on the periodical perturbations caused by the rotating impeller. We have succeeded in the determination of three-dimensional geometrical structure of filament in isolated mixing region based on relation between the movement of fluid particle and filament numbers and/or wire turns. Interestingly, the wire turns of filaments are opposite to movements of fluid particles. 相似文献
108.
Fukushima T Kosaka A Yamamoto Y Aimiya T Notazawa S Takigawa T Inabe T Aida T 《Small (Weinheim an der Bergstrasse, Germany)》2006,2(4):554-560
Free-radical polymerization of an imidazolium ion-based ionic liquid bearing a methacrylate group, gelling with single-walled carbon nanotubes (SWNTs), allows fabrication of a mechanically reinforced, electroconductive soft material (bucky plastic). A film sample of this material displays an excellent conductivity of 1 S cm(-1) and a 120-fold enhancement of the Young's modulus at a 7 wt % content of SWNTs. The conductivity is temperature-dependent in the range 5-300 K, suggesting that the conductive process involves carrier hopping. Scanning electron and atomic force micrographs of a bucky plastic film display the presence of crosslinked networks consisting of finely dispersed SWNTs. Such nanotube networks, developed in the polymer matrix, likely suppress slipping of entrapped polymer molecules via a strong interfacial interaction and also facilitate intertubular carrier transport. Although a bucky plastic derived from a vinylimidazolium ion-based ionic liquid monomer shows a comparable conductivity to that of the methacrylate version, the film is brittle irrespective of the presence or absence of SWNTs. 相似文献
109.
Mamoru Kimura Kazumasa Ide Kazuo Nishihama Motoo Futami Masaya Ichinose Tetsuo Fujigaki Motonobu Iizuka Kazuhiro Imaie Yasuomi Yagi Jyunji Tamura 《Electrical Engineering in Japan》2007,161(1):51-57
This paper focuses on selection of wind turbine generation systems that include generators, converters, and gears. We study three systems: a permanent magnet generator (PMG) system, a doubly‐fed generator (DFG) system, and a synchronous generator (SYG) system in terms of the system efficiencies and running costs. The system efficiencies and running costs are calculated by considering the relationship between wind power and wind conditions. According to these results, the one‐step gear PMG system is the best choice for a large wind turbine system. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(1): 51–57, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20506 相似文献
110.
Sanggil Han Shunsuke Yamamoto Anastasios G. Polyravas George G. Malliaras 《Advanced materials (Deerfield Beach, Fla.)》2020,32(48):2004790
Transistor-based ion sensors have evolved significantly, but the best-performing ones rely on a liquid electrolyte as an internal ion reservoir between the ion-selective membrane and the channel. This liquid reservoir makes sensor miniaturization difficult and leads to devices that are bulky and have limited mechanical flexibility, which is holding back the development of high-performance wearable/implantable ion sensors. This work demonstrates microfabricated ion-selective organic electrochemical transistors (OECTs) with a transconductance of 4 mS, in which a thin polyelectrolyte film with mobile sodium ions replaces the liquid reservoir. These devices are capable of selective detection of various ions with a fast response time (≈1 s), a super-Nernstian sensitivity (85 mV dec−1), and a high current sensitivity (224 µA dec−1), comparing favorably to other ion sensors based on traditional and emerging materials. Furthermore, the ion-selective OECTs are stable with highly reproducible sensitivity even after 5 months. These characteristics pave the way for new applications in implantable and wearable electronics. 相似文献