全文获取类型
收费全文 | 724篇 |
免费 | 28篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 79篇 |
综合类 | 1篇 |
化学工业 | 211篇 |
金属工艺 | 25篇 |
机械仪表 | 14篇 |
建筑科学 | 12篇 |
矿业工程 | 1篇 |
能源动力 | 20篇 |
轻工业 | 69篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 52篇 |
一般工业技术 | 112篇 |
冶金工业 | 19篇 |
原子能技术 | 16篇 |
自动化技术 | 119篇 |
出版年
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 13篇 |
2020年 | 8篇 |
2019年 | 18篇 |
2018年 | 17篇 |
2017年 | 15篇 |
2016年 | 18篇 |
2015年 | 16篇 |
2014年 | 24篇 |
2013年 | 38篇 |
2012年 | 30篇 |
2011年 | 54篇 |
2010年 | 41篇 |
2009年 | 32篇 |
2008年 | 36篇 |
2007年 | 36篇 |
2006年 | 36篇 |
2005年 | 20篇 |
2004年 | 25篇 |
2003年 | 25篇 |
2002年 | 25篇 |
2001年 | 8篇 |
2000年 | 13篇 |
1999年 | 19篇 |
1998年 | 18篇 |
1997年 | 18篇 |
1996年 | 15篇 |
1995年 | 11篇 |
1994年 | 16篇 |
1993年 | 9篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1974年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有753条查询结果,搜索用时 15 毫秒
51.
Nobuhiro Iwasa Tomoyuki Mayanagi Noriaki Ogawa Kentaro Sakata Nobutsune Takezawa 《Catalysis Letters》1998,54(3):119-123
Pd and Pt supported on ZnO, Ga2O3 and In2O3 exhibit high catalytic performance for the steam reforming of methanol, CH3OH+H2OCO2+3HH2, and the dehydrogenation of methanol to HCOOCH3, 2CH3OHHCOOCH3+2HH2. Combined results with temperature-programmed reduction (TPR) and XRD method revealed that Pd–Zn, Pd–Ga, Pd–In, Pt–Zn, Pt–Ga and Pt–In alloys were produced upon reduction. Over the catalysts having the alloy phase, the reactions proceeded selectively, whereas the catalysts having metallic phase exhibited poor selectivities. 相似文献
52.
Tomoyuki Kakigi Nozomi Miyoshi Kazuki Fujii Tatsuya Urakawa Akio Matsuura Takaharu Miura Masakazu Washio 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,265(1):118-124
Poly (tetrafluoroethylene-co-perfluoroalkylvinylether) (PFA) was irradiated by soft electron beam (soft-EB) under nitrogen gas atmosphere in solid-state and its molten state, respectively. The changes of thermal property and chemical structures of irradiated PFA in solid-state and molten state were studied by differential scanning calorimetric analysis (DSC) and solid-state 19F magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. By DSC analysis, the melting temperature shifted to lower temperatures, and crystallinity decreased with increasing soft-EB dose. By solid-state 19F MAS NMR spectroscopy, the new signals was observed and the detected new signals in irradiated PFA at 315 °C and at 30 °C were due to the tertiary carbon group with branching site (Y-type crosslinking site), perfluoro-propylene site and chain end methylene groups, respectively.Moreover, the molar ratio of perfluoroalkylvinylether (FAVE) structure to -CF2- units decreased with increasing dose. 相似文献
53.
Effects of magnetic field and hydrostatic pressure on martensitic transformations in some ferrous and nonferrous alloys have
been studied. The studies clarified the effects of magnetic field and hydrostatic pressure on martensitic transformation start
temperature, magnetoelastic martensitic transformation, morphology of martensites and transformation kinetics of athermal
and isothermal transformations. That is, transformation start temperatures of all the ferrous alloys examined increase with
increasing magnetic field, but those of non-ferrous, such as Ti-Ni and Cu-Al-Ni shape memory alloys, are not affected. On
the other hand, transformation start temperature decreases with increasing hydrostatic pressure in some ferrous alloys, but
increases in Cu-Al-Ni alloys. The magnetic field and hydrostatic pressure dependences of the martensitic start temperature
are in good agreement with those calculated by the equations proposed by our group. In the work on the Fe-Ni-Co-Ti alloy,
we found that magnetoelastic martensitic transformation appear. In addition, several martensite plates grow nearly parallel
to the direction of applied magnetic field in the specimen of an Fe-Ni alloy single crystal. Moreover, we found that the isothermal
process in an Fe-Ni-Mn alloy changes to the athermal one under magnetic field and the athermal process changes to the isothermal
one under hydrostatic pressure. Based on the facts, a phenomenological theory is constructed, which unifies the two transformation
processes. 相似文献
54.
The rates of absorption of oxygen into aqueous cuprous chloride solutions containing hydrochloric acid were measured at 15, 25 and 35°C using a baffled agitated vessel operated batchwise and the experimental results were analyzed with the chemical absorption theory. The reaction between oxygen and cuprous chloride was found to be second order, i.e. first order with respect to oxygen and CuCl2? ion which is the actual reactive species in aqueous cuprous chloride solutions containing hydrochloric acid. The reaction rate constants were calculated and correlated as a function of temperature. 相似文献
55.
56.
Noriaki Ozaki Hiroko Tokoro Yoshiho Hamada Asuka Namai Tomoyuki Matsuda Souhei Kaneko Shin‐ichi Ohkoshi 《Advanced functional materials》2012,22(10):2089-2093
The crystal structure, magnetic properties, and temperature‐ and photoinduced phase transition of [{CoII(4‐methylpyridine)(pyrimidine)}2{CoII(H2O)2}{WV(CN)8}2]·4H2O are described. In this compound, a temperature‐induced phase transition from the CoII (S = 3/2)‐NC‐WV(S = 1/2) [high‐temperature (HT)] phase to the CoIII(S = 0)‐NC‐WIV(S = 0) [low temperature (LT)] phase is observed due to a charge‐transfer‐induced spin transition. When the LT phase is irradiated with 785 nm light, ferromagnetism with a high Curie temperature (TC) of 48 K and a gigantic magnetic coercive field (Hc) of 27 000 Oe are observed. These TC and Hc values are the highest in photoinduced magnetization systems. The LT phase is optically converted to the photoinduced phase, which has a similar valence state as the HT phase due to the optically induced charge‐transfer‐induced spin transition. 相似文献
57.
New catalytic technologies in Japan 总被引:9,自引:0,他引:9
Recent trends in R&D of catalytic technology in Japan (cleaner and more efficient production, environmental catalysts, and recycling processes) are overviewed and examples of recent achievements are listed. Examples are then described as zeolite-catalyzed organic reactions recently commercialized and expected to be commercialized: hydration of cyclohexene, synthesis of pyridine derivatives and gas-phase Beckmann rearrangement of cyclohexanone oxime. Finally, as an example of environmental catalysts, the NOx storage–reduction type three-way automobile catalyst, is introduced. 相似文献
58.
Synthesis of ethanol by hydrogenation of carbon dioxide has been investigated by developing the novel composite catalysts. The three different kinds of elementary reaction functions for ethanol synthesis were undertaken. The catalytic functions are partial reduction of CO2 to CO, C–C bond formation, and –OH group insertion. For this purpose, supported Rh catalyst, Fe-based modified Fisher–Tropsch catalyst, and Cu-based modified methanol synthesis catalyst were combined by different ways. As a result, high space–time yields of ethanol as high as 0.8–0.9 kg/l h were obtained. 相似文献
59.
Tajima T Sakata W Wada T Tsutsui A Nishimoto S Miyake M Takaguchi Y 《Advanced materials (Deerfield Beach, Fla.)》2011,23(48):5750-5754
A coaxial nanohybrid consisting of a single-walled carbon nanotube (SWCNT), fullerodendron, and SiO(2) shows high-efficiency light-driven hydrogen evolution from water. Upon visible light irradiation, SWCNT/fullerodendron/SiO(2) coaxial nanohybrid shows hydrogen evolution activity in the presence of methyl viologen (MV(2+)), benzyldihydronicotinamide (BNAH), and a colloidal polyvinyl alcohol(PVA)-Pt. 相似文献
60.
Oxygen potentials of oxide nuclear fuels are important thermodynamic data in development of nuclear fuel technologies. Minor actinide bearing MOX (mixed oxide) fuels have been developed as sodium cooled fast reactor fuels. Content of Am which is one of the minor actinide elements causes oxygen potentialto increase. The effects of the oxygen potential increase on the irradiation behavior were evaluated. Profiles of temperature and O/M (oxygen-to-metal) ratio in the pellets were evaluated to better understand the irradiation behavior. From these data, local oxygen potential in the radial direction of the pellets was calculated, and was compared with free energy of compounds composed of fission products. Based on this comparison, it was concluded that Cs2MoO4 was likely formed at pellet periphery of (U07Pu03)O1.98 and (U0.66Pu03Amoo16Npo.016)Ol.976 The extent of cladding tube inner surface oxidation was predicted by using the calculated oxygen potential. No significant difference between irradiation behaviors of (Uo.7Puo3)O2_x and (U0.66PUo 3Amo.016Npo.016)O2.x pellets was confirmed. 相似文献