全文获取类型
收费全文 | 1044篇 |
免费 | 45篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 40篇 |
化学工业 | 284篇 |
金属工艺 | 23篇 |
机械仪表 | 12篇 |
建筑科学 | 21篇 |
矿业工程 | 1篇 |
能源动力 | 47篇 |
轻工业 | 129篇 |
水利工程 | 7篇 |
石油天然气 | 1篇 |
无线电 | 74篇 |
一般工业技术 | 205篇 |
冶金工业 | 115篇 |
原子能技术 | 46篇 |
自动化技术 | 86篇 |
出版年
2023年 | 13篇 |
2022年 | 22篇 |
2021年 | 33篇 |
2020年 | 22篇 |
2019年 | 20篇 |
2018年 | 22篇 |
2017年 | 27篇 |
2016年 | 35篇 |
2015年 | 22篇 |
2014年 | 46篇 |
2013年 | 67篇 |
2012年 | 67篇 |
2011年 | 78篇 |
2010年 | 45篇 |
2009年 | 64篇 |
2008年 | 51篇 |
2007年 | 46篇 |
2006年 | 46篇 |
2005年 | 39篇 |
2004年 | 31篇 |
2003年 | 23篇 |
2002年 | 23篇 |
2001年 | 10篇 |
2000年 | 16篇 |
1999年 | 13篇 |
1998年 | 37篇 |
1997年 | 30篇 |
1996年 | 16篇 |
1995年 | 13篇 |
1994年 | 16篇 |
1993年 | 11篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1972年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有1091条查询结果,搜索用时 31 毫秒
101.
102.
Yasumasa Takao Kiyotaka Shuzenji Takeshi Tachibana 《Journal of the American Ceramic Society》2008,91(1):311-314
Spherical powders of aluminum oxynitride/nitride are directly prepared by flame synthesis in which oxygen serves as an indispensable reactant. Nonoxide powders are commonly nonspherical, and the particle sizes of these powders are less than submicrometers. The major limiting factors for the synthesis are the free energy, reaction temperature, and reaction rate. The innovative issue related to this flame technology that is assisted by plasma is the ambivalence of the reducing gas atmosphere over 1500 K. The chemical equilibrium calculated indicates that the plasma heating compensates for the lack of reaction temperature under a low-oxygen condition. This burner realizes a high-speed reaction with the help of the reactive species in the arcs. 相似文献
103.
Akira Tachibana Kazuo Tohiguchi Takayuki Ueno Yuichi Setogawa Ayako Harada Toshizumi Tanabe 《Journal of Bioscience and Bioengineering》2009,107(6):668-669
Ligation-independent cloning (LIC) is a useful method for efficient directional cloning of a PCR product. LIC requires a specially designed vector containing a long stretch of sequence that is missing any one of the four nucleotides. When the linearized vector is treated with T4 DNA polymerase, in the presence of the absent base, long single-stranded overhangs are generated that are suitable for cloning. In this study, long and efficient sticky ends for LIC were produced by sequential T4 DNA polymerase treatments at non-specific sequences on a commercially available vector. All restriction enzyme sites become available in the current LIC. 相似文献
104.
105.
106.
Masahiro Tabata Yoshikazu Nishida Tatsuya Kodama Keisuke Mimori Takashi Yoshida Yutaka Tamaura 《Journal of Materials Science》1993,28(4):971-974
An oxygen-deficient Mn(II) ferrite (Mn0.97Fe2.02O3.92) was synthesized and its reactivity to reduce CO2 gas into carbon was studied at 300°C. The oxygen-deficient Mn(II) ferrite was obtained by flowing H2 gas through Mn(II) ferrite with a nearly stoichiometric composition of Mn0.97Fe2.02O4.00 at 300° C. The lattice constant of the oxygen-deficient Mn(II) ferrite (0.8505nm) is larger than that of the Mn(II) ferrite with a nearly stoichiometric composition (0.8498nm). The chemical composition of the Mn(II) ferrite changed from Mn0.97Fe2.02O4.00 to Mn0.97Fe2.02O3.92 during the H2 reduction process, indicating that the oxygen is deficient in the spinel structure of the Mn(II) ferrite. This was confirmed by Mössbauer spectroscopy and X-ray diffractometry. The efficiency of CO2 decomposition into carbon at 300°C with the oxygen-deficient Mn(II) ferrite was much lower by about 105 than that of oxygen-deficient magnetite. This is considered to be due to the difference in electron conductivity between Mn(II) ferrite and magnetite, which determines the reductivity for CO2 into carbon by donation of an electron at the adsorption site. 相似文献
107.
108.
The adsorption abilities of chitin and its congeners with two series of degrees of deacetylation prepared by two different deacetylation procedures were compared. Among the polysaccharides obtained by the heterogeneous method, those with higher amino group content had higher adsorption ability. Plots of collection percentages versus amino group content, however, did not give straight lines. The plot for the chelation on the congeners that were prepared by homogeneous hydrolysis had a maximum at about 50% amino group content, and the value was higher than that for the sample with the highest amino group content, which was prepared by heterogeneous hydrolysis. These results suggest that the polysaccharides with about 50% amino group content obtained by the homogeneous procedure are potentially useful for the removal of metals. 相似文献
109.
The deformation field in notched metal sheets stretched under tension was analysed experimentally. The results of strain distribution were explained by using the result of the near-tip deformation field of non-linear elastic material, combined with a simple model of the plastic state under a mixed plane stress and plane strain condition. Next, the relationship among fracture mechanics parameters, i.e. the notch-tip opening displacement, the notch-tip contraction and was established based on the rigid plastic strip model. Finally, the effect of the specimen thickness on the toughness value at crack initiation and instability was discussed by improving Bluhm's idea that the total fracture resistance was the sum of the fracture work for slant and flat fractures. 相似文献
110.
Y. Iwasa T. Hasegawa T. Koda Y. Tokura H. Tachibana Y. Kawabata 《Synthetic Metals》1992,50(1-3):415-421
We have investigated the ↑χ(3)(−3ω; ω, ω, ω)↑ spectra of polysilane films by means of third-harmonic generation. The fundamental photon energy is scanned from 0.56 to 2.2 eV. The ↑χ(3)↑ spectra show three structures, which are assigned to three- and two-photon excitonic resonances. These features indicate that the predominant excited states involved in the non-linear optical response of polysilanes are composed of three levels: the lowest one-photon allowed exciton, a one-photon forbidden exciton, and another higher-lying one-photon allowed state. 相似文献