全文获取类型
收费全文 | 206篇 |
免费 | 27篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 6篇 |
综合类 | 1篇 |
化学工业 | 72篇 |
金属工艺 | 14篇 |
机械仪表 | 3篇 |
建筑科学 | 5篇 |
能源动力 | 18篇 |
轻工业 | 22篇 |
水利工程 | 1篇 |
无线电 | 18篇 |
一般工业技术 | 41篇 |
冶金工业 | 4篇 |
原子能技术 | 3篇 |
自动化技术 | 26篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 6篇 |
2019年 | 4篇 |
2018年 | 13篇 |
2017年 | 11篇 |
2016年 | 20篇 |
2015年 | 4篇 |
2014年 | 23篇 |
2013年 | 13篇 |
2012年 | 22篇 |
2011年 | 17篇 |
2010年 | 16篇 |
2009年 | 17篇 |
2008年 | 11篇 |
2007年 | 6篇 |
2006年 | 11篇 |
2005年 | 6篇 |
2004年 | 3篇 |
2003年 | 7篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1991年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有234条查询结果,搜索用时 125 毫秒
61.
Yohei Abe Toru Kato Ken-ichiro Mori Shoma Nishino 《Journal of Materials Processing Technology》2014,214(10):2112-2118
Ultra-high strength steel sheets having low ductility were joined by mechanical clinching with dies for control of metal flow. The diameter and depth of the die were modified to relieve concentration of deformation of the sheets for avoidance of the occurrence of sheet fracture. As the tensile strength of the steel sheets increased, the interlock decreased due to small metal flow. Two kinds of the ultra-high strength steel sheets having different ductility were used. The ultra-high strength steel sheets having large ductility were successfully joined using die having modified shape, whereas the sheets having small ductility were not joined. The static and fatigue strengths of the mechanically clinched joint were compared with those of the resistance spot welded joint. Although the static load of the mechanically clinched joint was smaller than that of the resistance spot welded joint in both tension-shearing and cross-tension tests, the fatigue load of the clinched joint was larger in the large number of cycles. It was found that mechanical clinching has superior fatigue strength due to the large yield stress of the sheets and relaxation of the stress concentration. 相似文献
62.
Shunji Imai Yasuo Yoshioka Yuki Morishita Tokuyuki Yoshida Miyuki Uji Kazuya Nagano Yohei Mukai Haruhiko Kamada Shin-ichi Tsunoda Kazuma Higashisaka Yasuo Tsutsumi 《Nanoscale research letters》2014,9(1):651
Because of their useful chemical and physical properties, nanomaterials are widely used around the world - for example, as additives in food and medicines - and such uses are expected to become more prevalent in the future. Therefore, collecting information about the effects of nanomaterials on metabolic enzymes is important. Here, we examined the effects of amorphous silica particles with various sizes and surface modifications on cytochrome P450 3A4 (CYP3A4) activity by means of two different in vitro assays. Silica nanoparticles with diameters of 30 and 70 nm (nSP30 and nSP70, respectively) tended to inhibit CYP3A4 activity in human liver microsomes (HLMs), but the inhibitory activity of both types of nanoparticles was decreased by carboxyl modification. In contrast, amine-modified nSP70 activated CYP3A4 activity. In HepG2 cells, nSP30 inhibited CYP3A4 activity more strongly than the larger silica particles did. Taken together, these results suggest that the size and surface characteristics of the silica particles determined their effects on CYP3A4 activity and that it may be possible to develop silica particles that do not have undesirable effects on metabolic enzymes by altering their size and surface characteristics. 相似文献
63.
Kei Sato Dr. Yohei Katsuyama Kousuke Yokota Dr. Takayoshi Awakawa Dr. Takeaki Tezuka Dr. Yasuo Ohnishi 《Chembiochem : a European journal of chemical biology》2019,20(8):1039-1050
Fogacin and two novel fogacin derivatives, fogacins B and C, were isolated from the rare actinomycete Actinoplanes missouriensis. Biosynthesis of fogacin C apparently requires β alkylation of a polyketide chain. The fogacin biosynthetic type II polyketide synthase (PKS) gene cluster contains a hydroxymethylglutaryl-coenzyme A synthase (HCS) cassette, which is usually responsible for β alkylation in the type I PKS system. Another characteristic of the fog cluster is that it encodes two sets of ketosynthase (KS) and chain-length factor (CLF). Inactivation of either of the two KS genes in A. missouriensis and heterologous expression of the HCS cassette with either of the two KS-CLF genes in Streptomyces albus indicated that each KS-CLF had a different starter substrate specificity: one preferred an unusual β-alkylated starter and the other preferred a normal acetyl starter. This study expands knowledge of HCS cassette-dependent β alkylation into the type II PKS system and provides a natural example of combinatorial biosynthesis for producing diverse polyketides from different starter substrates. 相似文献
64.
Spheroidization of Al grains is required for the production of semi-solid slurry either by a partial solidification route or partial re-melting route. In this research, A356 aluminum alloy was deformed and partially re-melted to semi-solid state. A segregation sensitive reagent (Weck’s reagent) was used to reveal the inner microstructure of Al grains for the better understanding of the microstructure evolution during partial re-melting. Optical microstructure observation showed that the previously compressed Al dendrites were actually “fractured” during heat treatment and such “fractured” dendrites contributed to the refinement and spheroidization of Al grains. Further study of this phenomenon indicates that the “fractures” are actually migrating high-angle grain boundaries, which was related to the recrystallization that occurred during heat treatment. Moreover, the growth layer of Al grains formed during water quenching is clearly visualized after being etched by Weck’s reagent. Consequently, precise evaluation of solid fractions through image analysis was realized by excluding growth layer when measuring the area of solid phase. 相似文献
65.
66.
Improvement of stretch flangeability of ultra high strength steel sheet by smoothing of sheared edge
Ken-ichiro Mori Yohei Abe Yoshio Suzui 《Journal of Materials Processing Technology》2010,210(4):653-659
Stretch flangeability of an ultra high strength steel sheet having small ductility was increased by improving quality of a sheared edge. The effect of the quality of the sheared edge on the stretch flangeability of the high strength steel sheets was examined from expansion of a sheared hole with a conical punch. The quality of the sheared edge varied with the clearance between the punch and die, and the quality influenced the limiting expansion ratio. It was shown from measurement of surface of the sheared edge that the limiting expansion ratio of the sheared ultra high strength steel sheet is dependent on the macroscopic unevenness and hardness of the sheared edge and not on the microscopic roughness. The macroscopic unevenness of the sheared edge was eliminated by smoothing the edge with a conical punch. It was found that the smoothing of the sheared edge is effective in improving the stretch flangeability of the ultra high strength steel sheet. 相似文献
67.
Yusuke Wakikawa Tadaaki Ikoma Yohei Yamamoto Takanori Fukushima Takuzo Aida 《Synthetic Metals》2010,160(3-4):275-279
By means of the integral mode time-of-flight measurement of the drift motion of the photoinjected charge at room temperature, we observed magnetic field effect (MFE) on the photocharge in self-assembled nanotube of hexabenzocoronene (HBC) at the configurations where the magnetic field is parallel and perpendicular to the electric field. The detected MFEs are interpreted in terms of two mechanisms that are caused by the fast charge transportation (Hall effect) and the spin selective recombination (electron–hole (e–h) pair mechanism). A high mobility in the nanotubes of π-stacked HBC was implied from the Hall data. The time dependence of the low field MFE due to the e–h pair mechanism clarified the recombination from both the singlet and triplet e–h pairs with the initial rate of ~108 s?1. 相似文献
68.
In this paper, a system identification method for hybrid systems switched by the magnitude of velocity and displacement is proposed. First, it is shown that the regression vector space of a mechanical system switched by the magnitude of velocity cannot be separated by a hyperplane. Then a method based on support vector machines with a polynomial kernel is proposed. The effectiveness of the proposed method is shown by simulations and experiments. 相似文献
69.
Satomi T Ueno K Fujita Y Kobayashi H Tanaka J Mitamura Y Tateishi T Otsuka H 《Journal of nanoscience and nanotechnology》2006,6(6):1792-1796
Polypyridine grafted with poly(ethylene glycol) (Py-g-PEG) have been synthesized. Radical copolymerization of methyl-terminated PEG macromonomer with 4-pyridylmethyl methacrylate homogeneously proceeded and the obtained copolymer spontaneously adsorbs from aqueous solution onto gold surfaces, where the pyridine parts act as the multipoint anchor to the surface and the PEG parts provide the strong steric repulsion between the chains. As a result, the highly protein repellent and stable surface was constructed through multipoint pyridine attachment as compared with singlepoint pyridine attachment. Py-g-PEGs thus synthesized are promising material to functionalize metal and semiconductor material and to self-assemble into micelle in biotechnological and biomedical field. 相似文献
70.