全文获取类型
收费全文 | 1277篇 |
免费 | 18篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 46篇 |
综合类 | 6篇 |
化学工业 | 221篇 |
金属工艺 | 30篇 |
机械仪表 | 42篇 |
建筑科学 | 24篇 |
能源动力 | 36篇 |
轻工业 | 109篇 |
水利工程 | 4篇 |
石油天然气 | 4篇 |
无线电 | 183篇 |
一般工业技术 | 189篇 |
冶金工业 | 311篇 |
原子能技术 | 27篇 |
自动化技术 | 65篇 |
出版年
2023年 | 2篇 |
2022年 | 11篇 |
2021年 | 14篇 |
2020年 | 10篇 |
2019年 | 5篇 |
2018年 | 13篇 |
2017年 | 16篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 25篇 |
2013年 | 44篇 |
2012年 | 45篇 |
2011年 | 55篇 |
2010年 | 42篇 |
2009年 | 40篇 |
2008年 | 41篇 |
2007年 | 37篇 |
2006年 | 41篇 |
2005年 | 44篇 |
2004年 | 37篇 |
2003年 | 39篇 |
2002年 | 42篇 |
2001年 | 31篇 |
2000年 | 32篇 |
1999年 | 42篇 |
1998年 | 119篇 |
1997年 | 68篇 |
1996年 | 64篇 |
1995年 | 52篇 |
1994年 | 37篇 |
1993年 | 36篇 |
1992年 | 15篇 |
1991年 | 20篇 |
1990年 | 21篇 |
1989年 | 26篇 |
1988年 | 12篇 |
1987年 | 12篇 |
1986年 | 14篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1975年 | 3篇 |
1973年 | 2篇 |
排序方式: 共有1297条查询结果,搜索用时 218 毫秒
91.
Weiwu Chen Soshu Kirihara Yoshinari Miyamoto 《Journal of the American Ceramic Society》2007,90(1):92-96
Three-dimensional (3D) photonic crystals with a diamond structure made from 40 vol% TiO2 –acrylate dielectric composites were formed by means of a CAD/CAM micro-stereolithography system. The lattice constant of the diamond unit cell was 500 μm and the forming accuracy was 10 μm. The photonic band gap in the Γ–X 〈100〉 direction measured by terahertz-time-domain spectroscopy appeared at 280–360 GHz, which agreed fairly well with the band gap calculated by the plane wave expansion method. 相似文献
92.
Takai Y. Fujita M. Nagata K. Isa S. Nakazawa S. Hirobe A. Ohkubo H. Sakao M. Horiba S. Fukase T. Takaishi Y. Matsuo M. Komuro M. Uchida T. Sakoh T. Saino K. Uchiyama S. Takada Y. Sekine J. Nakanishi N. Oikawa T. Igeta M. Tanabe H. Miyamoto H. Hashimoto T. Yamaguchi H. Koyama K. Kobayashi Y. Okuda T. 《Solid-State Circuits, IEEE Journal of》2000,35(2):149-162
This paper describes three circuit technologies indispensable for high-bandwidth multibank DRAM's. (1) A clock generator based on a bidirectional delay (BDD) eliminates the output skew. The BDD measures the cycle time as the quantity charged or discharged of an analog quantity, and replicates it in the next cycle. This achieves a 0.18-mm 2, two-cycle-lock clock generator operating from 25 to 167 MHz with a 30-ps resolution. (2) A quad-coupled receiver eliminates the internal skew caused by the difference between a rise input and a fall input by 40%. (3) An interbank shared redundancy scheme (ISR) with a variable unit redundancy (VUR) efficiently increases yield in multibank DRAM's. The ISR allows redundancy match circuits to be shared with two or more banks. The VUR allows the number of units replaced to be variable. These circuit technologies achieved a 250-Mb/s/pin, 8-bank, 1-Gb double-data-rate synchronous DRAM 相似文献
93.
H Miyamoto H Yamamoto K Arima J Fujii K Maruta K Izu T Shiomori S Yoshida 《Canadian Metallurgical Quarterly》1997,63(7):2489-2494
The presence of PCR inhibitors in water samples is well known and contributes to the fact that a practical PCR assay has not been developed for legionella surveillance. In this study, we devised a new seminested PCR assay for detection of Legionella spp. in water samples as a means of overriding the PCR inhibitors without loss of sensitivity. The seminested PCR assay utilized primers to amplify the 16S rRNA gene (LEG primers) of 39 Legionella spp. The assay was specific to legionellae, and the sensitivity was 1 fg of extracted Legionella DNA in laboratory examination. To evaluate the feasibility and sensitivity of the PCR assay in identifying the presence of legionellae, it was used to survey Legionella contamination in the water of 49 cooling towers of 32 hospitals. A commercially available EnviroAmp Legionella kit and a culture method were also used in the survey for comparison with the seminested PCR assay. The detection rates of legionellae in the samples were 91.8% (45 of 49) by the PCR assay and 79.5% (39 of 49) by the culture method. The EnviroAmp kit revealed that 30.6% of the water samples (15 of 49) contained inhibitors of the PCR amplification. However, the seminested PCR assay could produce the Legionella-specific DNA bands in 14 of the 15 samples. Although 8 of the 14 samples were positive in the first-step PCR, 6 of the 14 samples became positive in the second-step PCR. These results suggest that the effect of PCR inhibitors in samples, if any, can be reduced because of the dilution of the sample in the second-step PCR and that sensitivity of detection can be increased by the second-step PCR. Thus, the seminested PCR assay with LEG primers to amplify the 16S rRNA gene of 39 Legionella spp. was a practical and sensitive method to detect Legionella spp. in water samples. 相似文献
94.
Hiroyuki Mishima Mituo Kakei Toshio Yasui Saori Miyamoto Yasuo Miake Takaaki Yanagisawa 《Frontiers of Materials Science in China》2008,2(2):179-181
The present study was aimed at examining the nature of apatite crystal in the tooth apparatus of a conodont fossil using transmission
electron microscopy (TEM), scanning electron microscopy (SEM), laser Raman microprobe spectrometry and electron-probe microanalysis
(EPMA). The hard tissue of the condont consisted of 2 layers and the organization varied with the size of the crystal. Higher
magnification showed that the crystals were observed in the lattice of (100) and the central dark lines were not present.
Ca, P, and F were detected in the crystal using EPMA. Our results indicate that the apatite crystal in conodont fossils is
not hydroxyapatite but fluorapatite. 相似文献
95.
Naoki Mizuta Kiyotaka Matsuura Soshu Kirihara Yoshinari Miyamoto 《Materials Science and Engineering: A》2008,492(1-2):199-204
Feasibility of a new method of titanium aluminide coating on titanium surface based on a reaction between aluminum liquid beads and the surface of titanium substrate has been studied using a computer-aided three-dimensional microwelder (3DMW) designed by the present authors. A predetermined length of thin aluminum wire was fed onto the substrate surface, and a spark was stricken from a thin electrode of a W-Ce2O3 alloy to make a small aluminum liquid bead on the substrate surface and to simultaneously melt a small area of the substrate surface beneath the bead. All conditions including the length of the wire feeding, the position of the electrode, electric power, etc. had been programmed beforehand. The liquid bead containing aluminum and titanium rapidly solidified on the titanium substrate surface producing titanium aluminides on it. Repetition of the aluminum wire feeding, the electrode positioning and the spark striking produced a coating layer consisting of sub-layers of TiAl3, TiAl and Ti3Al from the surface side to the substrate side. Vickers hardness and wear resistance of the coated sample were remarkably improved. 相似文献
96.
A novel chirped return-to-zero transmitter with a simplified configuration that uses an electro-absorption modulator is proposed. Using this transmitter, high fibre input power is achieved (up to +14 dbm) in repeaterless 20 Gbit/s transmission over standard singlemode fibres 相似文献
97.
Microstructure Development and Dielectric Properties of Potassium Strontium Niobate Ceramics 总被引:1,自引:0,他引:1
Toshio Kimura Seiji Miyamoto Takashi Yamaguchi 《Journal of the American Ceramic Society》1990,73(1):127-130
Sintering of a KSr2 Nb5 O15 powder compact at 1350°C resulted in a duplex structure. Prefiring of the compact between 1200° and 1300°C inhibited the abnormal grain growth responsible for the duplex structure. The Curie temperature and dielectric constant were dependent on the microstructure. 相似文献
98.
Shimizu N. Harada Y. Miyamoto N. Hosoya M. Goto E. 《Electron Devices, IEEE Transactions on》1989,36(6):1175-1181
The fundamental characteristics are described of the quantum flux parametron (QPF), measured by a method in which the output signals of the QFP are detected with a DC SQUID. The DC SQUID linearly and continuously converts the output current of the QFP to voltage, allowing the output signal of the QFP to be measured as the voltage of the DC SQUID. The fundamental characteristics of the QFP have been experimentally confirmed in detail 相似文献
99.
A new formulation in which the assumed stress field is divided into membrane and bending stress fields is developed. A family of effective shell elements of hybrid/mixed finite element method that accounts for transverse shear deformations is proposed based on a modified Hellinger–Reissner variational principle. In this paper, the present shell elements possess different three-field assumptions, which are described by compatible displacement, incompatible displacement, and stress fields. Several benchmark problems are conducted to test both the accuracy and reliability of the proposed shell elements. Numerical analyses show that the present shell elements pass all the patch tests, do not contain any spurious zero energy modes, and have no lock phenomena even for very thin plate and shell. Further insight into the performance of the present shell elements is gained to demonstrate the high accuracy of the elements by several folded-plate structure problems. The numerical results demonstrate the validity, reliability, and applicability of the present elements. The present elements are valid for thick as well as thin shell structures. 相似文献
100.
Soichiro Nakamura Yasuhiro Suzuki Eri Ishikawa Toshiharu Yakushi Hao Jing Takahide Miyamoto Kiyoshi Hashizume 《Food chemistry》2008
A major allergenic protein of buckwheat, Fag e 1 prepared from common buckwheat (Fagopyrum esculentum), was covalently linked with food-grade polysaccharides, arabinogalactan or xyloglucan through the controlled dry-heating at 60 °C under 65% relative humidity. The introduction of polysaccharide chain onto the molecular surface of Fag e 1 reduced the allergenicity of Fag e 1. The results revealed that the Maillard-type glycosylation of Fag e 1 with polysaccharides brought about a drastic reduction of the reactivity against human sera of buckwheat-allergy subjects, using immuno dot-blotting, QCM analysis and ELISA. In addition, the glycosylation of Fag e 1 yielded a great improvement of its surface functionality. Solubility of Fag e 1 at the neutral pH was substantially increased up to 13.5 times and 9.6 times by the conjugation with arabinogalactan and xyloglucan, respectively. Emulsifying properties of Fag e 1 were also improved by the glycosylation, of which both emulsifying activity and emulsion stability were more than 6 times higher than those of the native protein. 相似文献