全文获取类型
收费全文 | 1416篇 |
免费 | 38篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 114篇 |
综合类 | 2篇 |
化学工业 | 316篇 |
金属工艺 | 53篇 |
机械仪表 | 46篇 |
建筑科学 | 26篇 |
矿业工程 | 1篇 |
能源动力 | 102篇 |
轻工业 | 85篇 |
水利工程 | 6篇 |
石油天然气 | 6篇 |
无线电 | 121篇 |
一般工业技术 | 315篇 |
冶金工业 | 95篇 |
原子能技术 | 66篇 |
自动化技术 | 109篇 |
出版年
2023年 | 4篇 |
2022年 | 13篇 |
2021年 | 12篇 |
2020年 | 7篇 |
2019年 | 20篇 |
2018年 | 18篇 |
2017年 | 13篇 |
2016年 | 31篇 |
2015年 | 15篇 |
2014年 | 33篇 |
2013年 | 67篇 |
2012年 | 60篇 |
2011年 | 66篇 |
2010年 | 61篇 |
2009年 | 67篇 |
2008年 | 60篇 |
2007年 | 60篇 |
2006年 | 49篇 |
2005年 | 44篇 |
2004年 | 55篇 |
2003年 | 48篇 |
2002年 | 49篇 |
2001年 | 37篇 |
2000年 | 47篇 |
1999年 | 34篇 |
1998年 | 49篇 |
1997年 | 36篇 |
1996年 | 39篇 |
1995年 | 30篇 |
1994年 | 29篇 |
1993年 | 22篇 |
1992年 | 14篇 |
1991年 | 11篇 |
1990年 | 13篇 |
1989年 | 13篇 |
1988年 | 16篇 |
1987年 | 16篇 |
1986年 | 12篇 |
1985年 | 19篇 |
1984年 | 22篇 |
1983年 | 19篇 |
1982年 | 20篇 |
1981年 | 21篇 |
1980年 | 17篇 |
1979年 | 15篇 |
1978年 | 17篇 |
1977年 | 11篇 |
1976年 | 5篇 |
1975年 | 14篇 |
1973年 | 4篇 |
排序方式: 共有1463条查询结果,搜索用时 15 毫秒
181.
182.
Michael Zeutzius Toshiaki Setoguchi Toshihiro Nakano Hideo Miyanishi Kunio Terao Saga University Honjo Saga - Japan 《热科学学报(英文版)》2000,(2)
~nonEmphasising time characterishcs and contIDI, onlyfew workll'v is av'ailable among the numerous reports onPulse combustors. Rare work deals with tWin Pulsecombustorsls] or combined pulse combustor-"dinesystemsl']. Kenffield15] obtained with a combinedconvenhonal Pulse combustor-tulbine system acombushon Pressals gain of 3-7% and a totalPerformance Of the combustor-"dine system for Pulsecombushon 40% higher than that of steady'combushonwhat aught also be due tO the brine characteristics.… 相似文献
183.
Yamamoto K Miyake H Kusunoki M Osaki S 《Journal of Bioscience and Bioengineering》2011,112(6):545-550
The structures of the E277A isomaltase mutant from Saccharomyces cerevisiae in complex with isomaltose or maltose were determined at resolutions of 1.80 and 1.40 Å, respectively. The root mean square deviations between the corresponding main-chain atoms of free isomaltase and the E277Α-isomaltose complex structures and those of free isomaltase and the E277A-maltose complex structures were found to be 0.131 Å and 0.083 Å, respectively. Thus, the amino acid substitution and ligand binding do not affect the overall structure of isomaltase. In the E277A-isomaltose structure, the bound isomaltose was readily identified by electron densities in the active site pocket; however, the reducing end of maltose was not observed in the E277A-maltose structure. The superposition of maltose onto the E277A-maltose structure revealed that the reducing end of maltose cannot bind to the subsite + 1 due to the steric hindrance from Val216 and Gln279. The amino acid sequence comparisons with α-glucosidases showed that a bulky hydrophobic amino acid residue is conserved at the position of Val216 in α-1,6-glucosidic linkage hydrolyzing enzymes. Similarly, a bulky amino acid residue is conserved at the position of Gln279 in α-1,6-glucosidic linkage-only hydrolyzing α-glucosidases. Ala, Gly, or Asn residues were located at the position of α-1,4-glucosidic linkage hydrolyzing α-glucosidases. Two isomaltase mutant enzymes – V216T and Q279A – hydrolyzed maltose. Thus, the amino acid residues at these positions may be largely responsible for determining the substrate specificity of α-glucosidases. 相似文献
184.
Tiered Electron Anions in Multiple Voids of LaScSi and Their Applications to Ammonia Synthesis 下载免费PDF全文
Jiazhen Wu Yutong Gong Takeshi Inoshita Daniel C. Fredrickson Junjie Wang Yangfan Lu Masaaki Kitano Hideo Hosono 《Advanced materials (Deerfield Beach, Fla.)》2017,29(36)
Electrides—compounds in which electrons localized in interstitial spaces periodically serve as anions—have attracted broad attention for their exotic properties, such as extraordinary electron‐donating ability. In our efforts to expand this small family of phases, LaScSi emerges as a promising candidate. Its electron count is 2e? f.u.?1 in excess of that expected from the Zintl concept, while its structure offers interstitial spaces that can accommodate these extra electrons. Herein, this potential is explored through density functional theory (DFT) calculations and property measurements on LaScSi. DFT calculations (validated by heat capacity and electrical transport measurements) reveal electron density peaks at two symmetry‐distinct interstitial sites. Importantly, this electride‐like character is combined with chemical stability in air and water, an advantage for catalysis. Ru‐loaded LaScSi shows outstanding catalytic activity for ammonia synthesis, with a turnover frequency (0.1 s?1 at 0.1 MPa, 400 °C) an order of magnitude higher than those of oxide‐based Ru catalysts, e.g., Ru/MgO. As with other electrides, LaScSi's ability to reversibly store hydrogen prevents the hydrogen poisoning of Ru surfaces. The better performance of LaScSi, however, hints at the importance of the high concentration (>1.6 × 1022 cm?3) and tiered nature of its anionic electrons, which offers guidance toward new catalysts. 相似文献
185.
Fumito Kitatani Hideo Harada Shinji Goko Nobuyuki Iwamoto Hiroaki Utsunomiya Hidetoshi Akimune 《Journal of Nuclear Science and Technology》2016,53(4):475-485
The 77Se (γ, n) cross section was measured for the energy range from 7.6 to 13.8 MeV by using quasi-monochromatic laser-Compton scattering γ-rays. The advanced method to deduce γ-ray strength functions from (γ, n) cross section was developed. By utilizing the method, the γ-ray strength functions of 77, 78, 80Se were deduced so as to reproduce the 77, 78, 80Se (γ, n) cross sections measured in this work and previous systematic measurements. The inverse (n, γ) cross sections for 76, 77, 79Se isotopes were calculated using the statistical model calculation code CCONE with the deduced γ-ray strength functions. The uncertainty of the calculated 79Se(n, γ)80Se cross section was evaluated by comparing the calculations and the experimental data on 76, 77Se (n, γ) cross sections. 相似文献
186.
Ogawa Kazuhiro Minkov Dorian Shoji Tetsuo Sato Minoru Hashimoto Hideo 《NDT & E International》1999,32(3):1369
Nondestructive evaluation of thermal barrier coating (TBC) degradation during service operation has received a wide attention for service life prediction of advanced gas turbines. In this work, TBC on nickel base superalloy degraded at various degrees by thermal aging is investigated. Particularly, TBC and Metal–Chromium–Aluminum–Yttrium alloy (McrAlY) (M indicates iron (Fe), cobalt (Co), nickel (Ni) or these combinations) bond coating interface where a detrimental reaction takes place and forms various reaction products during thermal aging, is studied in detail. Formation kinetics and physical properties of the reaction layer are evaluated by means of Impedance Spectroscopy (IS). Specimens aged at higher temperature and a longer aging time shows larger impedance. The impedance behavior of TBC and bond coating is found to be markedly changed by the formation of the reaction layer. Physical properties and thickness of the reaction layer are evaluated using the change of the impedance. A mechanistic interpretation of the cause of change in the physical properties and IS behavior are described. 相似文献
187.
An ultrafast X‐ray computed tomography (CT) scanner has been developed. This scanner overcomes problems that occur in a transient or unsettled state, which make the conventional CT scanner inappropriate. To reduce the scanning time, this X‐ray CT system uses electronic switching of electron beams for X‐ray generation instead of the mechanical motion adopted by conventional CT scanners. The mechanical motion is a major obstacle to improving scanning speed. A prototype system with a scanning time of 3.6 ms was initially developed and confirmed to measure the dynamic events of two‐phase flow. However, an increased scanning speed is generally required for practical use in the thermal hydraulics research field. Therefore, an advanced type which can operate under the scanning time of 0.5 ms and can measure two‐phase flow with a velocity up to 4 to 5 m/s was developed. © 2000 Scripta Technica, Heat Trans Asian Res, 29(3): 155–165, 2000 相似文献
188.
Takashi Kosaka Nobuyuki Matsui Yo‐Ichi Taniguchi Hideo Do‐meki 《Electrical Engineering in Japan》2000,130(1):118-128
Although the reluctance motors are attractive from the standpoints of simple construction and drive electronics, the relatively high torque ripple and acoustic noise are major drawbacks. These drawbacks limit motor applications. In this paper, the torque ripple suppression of the reluctance motor under the sinusoidal current drive is examined. The analysis shows that the torque ripple is caused by the spatial harmonics of inductance. One approach is based on the compensation current generated with the spatial harmonics of inductance. Another is based on the modification of rotor tooth configuration to eliminate the spatial harmonics. According to the proposed strategies, torque ripple suppression characteristics can be evaluated at the design stage of the motor. Both approaches have been verified by experiments. © 1999 Scripta Technica, Electr Eng Jpn, 130(1): 118–128, 2000 相似文献
189.
Kenichi Yamazaki Toshihisa Iwamoto Tadashi Kawamoto Hideo Fujinami 《Electrical Engineering in Japan》2000,131(2):12-19
We have studied experimentally the shielding method of ELF magnetic field applied to the source of line conductors. For the single‐phase line current, it appears to be difficult to achieve effective shielding. On the other hand, for the balanced three‐phase conductors, including triangle and twisted configuration, a certain reduction of generated magnetic field was achieved by adjusting the configuration of conductors or by surrounding the conductors with cylindrical shielding materials made of ferromagnetic materials or nonferromagnetic metals. Normalized characteristics between phase current, distance between source current and observation point, distance between phase conductors, and the pitch of twisted cable were derived. In addition, the effect of unbalanced current was also investigated. © 2000 Scripta Technica, Electr Eng Jpn, 131(2): 12–19, 2000 相似文献
190.
This paper presents a new methodology for the inverse analysis of time-dependent two-phase Stefan problems. The problem considered here is that of determining the time dependence of a phase-change interface at several observed temperatures. In our method, imaginary heat sources are arranged in an imaginary domain and then the phase-change interface is identified as the isothermal surface at the melting temperature by controlling the imaginary heat source intensities. Using delta-function imaginary heat sources and their corresponding Green functions, which are pre-calculated numerically, it is shown that the phase-change interface is determined non-iteratively at each time step. We offer numerical examples to demonstrate the capability of the proposed method. © 1998 Scripta Technica, Heat Trans Jpn Res, 27(3): 179–191, 1998 相似文献