全文获取类型
收费全文 | 1997篇 |
免费 | 34篇 |
专业分类
电工技术 | 100篇 |
综合类 | 1篇 |
化学工业 | 333篇 |
金属工艺 | 32篇 |
机械仪表 | 35篇 |
建筑科学 | 23篇 |
能源动力 | 46篇 |
轻工业 | 94篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 446篇 |
一般工业技术 | 301篇 |
冶金工业 | 461篇 |
原子能技术 | 41篇 |
自动化技术 | 114篇 |
出版年
2023年 | 6篇 |
2022年 | 23篇 |
2021年 | 28篇 |
2020年 | 11篇 |
2019年 | 17篇 |
2018年 | 12篇 |
2017年 | 14篇 |
2016年 | 44篇 |
2015年 | 21篇 |
2014年 | 29篇 |
2013年 | 52篇 |
2012年 | 50篇 |
2011年 | 58篇 |
2010年 | 34篇 |
2009年 | 47篇 |
2008年 | 66篇 |
2007年 | 46篇 |
2006年 | 42篇 |
2005年 | 42篇 |
2004年 | 57篇 |
2003年 | 76篇 |
2002年 | 58篇 |
2001年 | 66篇 |
2000年 | 43篇 |
1999年 | 58篇 |
1998年 | 190篇 |
1997年 | 122篇 |
1996年 | 98篇 |
1995年 | 85篇 |
1994年 | 49篇 |
1993年 | 53篇 |
1992年 | 33篇 |
1991年 | 39篇 |
1990年 | 29篇 |
1989年 | 40篇 |
1988年 | 40篇 |
1987年 | 19篇 |
1986年 | 29篇 |
1985年 | 35篇 |
1984年 | 26篇 |
1983年 | 16篇 |
1982年 | 19篇 |
1981年 | 22篇 |
1980年 | 15篇 |
1979年 | 14篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1976年 | 17篇 |
1974年 | 4篇 |
1973年 | 5篇 |
排序方式: 共有2031条查询结果,搜索用时 15 毫秒
21.
22.
Yasuyuki Itoh Tohru Sugawara 《Journal of Infrared, Millimeter and Terahertz Waves》1996,17(2):465-475
This paper describes a quasi-optical method for the conversion of modes transmitted through highly oversized circular waveguides. A waveguide-mode is radiated once from a waveguide cut in the form of a radiation beam, which is then properly shaped by two curved mirrors and directed back into the waveguide. The curved mirror shapes are iteratively and automatically determined for given propagation distances using the design technique for phase correction mirrors. The proposed method gives favorable results in designing a waveguide expander/reducer, a TE01-TE02 mode converter, and a TE01-HE11 mode converter. 相似文献
23.
K. Nakano S. Tomiya M. Ukita H. Yoshida S. Itoh E. Morita M. Ikeda A. Ishibashi 《Journal of Electronic Materials》1996,25(2):213-216
Using electroluminescence (EL) topography and transmission electron microscopy (TEM), we investigated the nonluminescent regions
which form while current is being injected into ZnMgSSe/ZnSSe/ZnCdSe-based blue light emitters. Small dark spots were observed
just after turn-on and spread out forming rough nonluminescent triangles in the <100> directions in the EL image of the active
region. TEM studies showed that the small dark spots are pre-existing stacking faults originating at the substrate/epitaxial
layer interface. The nonluminescent triangles were found to be a dense region of dislocation dipoles and dislocation loops.
Each dipole was aligned along two <110> directions in the {111} planes. The Burgers vectors were of the type a/2<011> inclined
at 45° to the (001) junction plane. 相似文献
24.
Masaru Itoh 《The Structural Design of Tall and Special Buildings》1992,1(2):119-132
This paper summarizes the results of the wind design carried out for the Act Tower building in Japan. Wind tunnel tests were performed in order to estimate the building response for different wind directions. Undesirable building motion perceived by building occupants is also studied and antivibration systems have been installed to solve this problem. 相似文献
25.
Masahiro Baba Goh Itoh Haruhiko Okumura 《Journal of the Society for Information Display》2007,15(3):205-211
Abstract— In this paper, a software‐processed edge‐ and level‐adaptive overdrive (SELAO) method, which is a novel overdrive technique that utilizes not only a temporal change of gray levels but also a spatial edge intensity of motion pictures, is proposed. The SELAO method is a software video‐processing technology to improve motion‐picture quality rendered on LCDs more than is possible with a conventional SLAO method without edge‐adaptive overdrive, and it works in real time on commonly used personal computers (PCs). 相似文献
26.
27.
The biopsy specimens were homogenized and diluted ten-fold serially in Hank's solution. Each dilution samples were streaked on Skirrow's selective medium. The plates were incubated at 37 degrees C 5 to 7 days under micro-aerobic condition and counting the viable cell of H. pylori. The positive rate of specimens with H. pylori in active gastric ulcer tissue (62.0%) was higher than that in scarred tissue (51.9%). Number of H. pylori viable cells in active ulcer tissue was significantly larger than in scarred tissue. The positive correlation between Raw's gastritis score of specimens from patients with erosive gastritis and number of H. pylori viable cells was clearly noticed. 相似文献
28.
Kakitsuka T. Shibata Y. Itoh M. Kadota Y. Tohmori Y. Yoshikuni Y. 《Quantum Electronics, IEEE Journal of》2002,38(1):85-92
In order to achieve an accurate design of polarization-insensitive semiconductor optical amplifiers based on tensile strained bulk InGaAsP, the reduction of strain in the active layer of the buried heterostructure and its influence on polarization sensitivity are analyzed numerically for the first time. The gain calculation, including the strain distribution in the active layer, is examined based on the k · p method for the different active layers. It is found that the strain introduced during the epitaxial growth is strongly reduced after regrowth of the burying layer. In an active layer having the aspect ratio of 1 : 4, the strain reduction causes more than a 0.5-dB deviation in the polarization sensitivity of the gain. From a comparison with the experimental results, it is shown that including the effect of the burying layer in the calculation gives an accurate determination of the amount of strain for the polarization independence 相似文献
29.
30.
N Cho Y Nara M Harada T Sugo Y Masuda A Abe K Kusumoto Y Itoh T Ohtaki T Watanabe S Furuya 《Canadian Metallurgical Quarterly》1998,46(11):1724-1737
On the basis of structural information for the cyclic hexapeptide endothelin (ET) receptor antagonist, TAK-044, a series of thieno[2,3-d]pyrimidine-2,4-dione derivatives bearing a carboxyl group and aromatic rings that were important for receptor binding were designed, synthesized, and evaluated for ET receptor binding affinities and inhibitory activities against ET-induced vasoconstriction. Optimization of each substituent in the thieno[2,3-d]pyrimidine ring led to the discovery of a novel and potent nonpeptide ET receptor antagonist, 6-(4-methoxymethoxyphenyl)-5-methylsulfonylaminomethyl-1-(2- methylthiobenzyl)-2,4-dioxo-1,2,3,4-tetrahydrothieno[2,3-d]p yrimidine-3- acetic acid (32 g), which binded to human ETA and ETB receptor subtypes with affinities (IC50) of 7.6 and 100 nM, respectively. Compound 32 g effectively antagonized ET-induced vasoconstriction and the inhibitory effect mediated by the ETB receptor was more potent than that of bosentan, while the inhibitory effect mediated by the ETA receptor was slightly less potent than that of bosentan. 相似文献