全文获取类型
收费全文 | 1248篇 |
免费 | 22篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 32篇 |
综合类 | 2篇 |
化学工业 | 331篇 |
金属工艺 | 26篇 |
机械仪表 | 23篇 |
建筑科学 | 16篇 |
能源动力 | 27篇 |
轻工业 | 111篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
无线电 | 119篇 |
一般工业技术 | 236篇 |
冶金工业 | 235篇 |
原子能技术 | 28篇 |
自动化技术 | 81篇 |
出版年
2023年 | 10篇 |
2022年 | 15篇 |
2021年 | 24篇 |
2020年 | 3篇 |
2019年 | 9篇 |
2018年 | 16篇 |
2017年 | 21篇 |
2016年 | 19篇 |
2015年 | 17篇 |
2014年 | 28篇 |
2013年 | 52篇 |
2012年 | 42篇 |
2011年 | 59篇 |
2010年 | 43篇 |
2009年 | 45篇 |
2008年 | 48篇 |
2007年 | 48篇 |
2006年 | 47篇 |
2005年 | 31篇 |
2004年 | 40篇 |
2003年 | 32篇 |
2002年 | 60篇 |
2001年 | 39篇 |
2000年 | 23篇 |
1999年 | 25篇 |
1998年 | 103篇 |
1997年 | 60篇 |
1996年 | 48篇 |
1995年 | 27篇 |
1994年 | 23篇 |
1993年 | 22篇 |
1992年 | 13篇 |
1991年 | 18篇 |
1990年 | 14篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 12篇 |
1982年 | 11篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 16篇 |
1974年 | 3篇 |
1972年 | 5篇 |
排序方式: 共有1271条查询结果,搜索用时 15 毫秒
21.
Thermocapillary convection in a half‐zone liquid bridge of high Prandtl number fluid is widely known to exhibit a three‐dimensional oscillatory flow after the onset of oscillation. The oscillatory flow presents ‘standing’ and ‘traveling’ flows depending upon the temperature difference between the top and bottom rods. In the oscillatory state, the flow shows a modal structure with an azimuthal wave number that depends on the aspect ratio of the liquid bridge and the intensity of the thermocapillarity expressed by the Marangoni number. The present study attempted to control the azimuthal wave number by heating the free surface locally with a prescribed frequency and intensity. The flow in the liquid bridge exhibited different modal structures depending on the heating conditions and a relationship between the frequency and the modal structure was obtained. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(7): 460–469, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20086 相似文献
22.
The authors have proposed a method of reducing the energy consumption in residential buildings by providing household members with information on energy consumptions in their own houses. An on-line interactive “energy-consumption information system” that displays power consumptions of, at most, 18 different appliances, power and city-gas consumption of the whole house and room temperature, for the purpose of motivating energy-saving activities has been constructed and the effectiveness of the system investigated by installing it in 10 residential buildings. The experiment showed that energy-saving consciousness was raised and energy consumption was in fact reduced by the energy-saving activities of the household members. In this paper, the system is described in detail and the effectiveness of reducing energy-consumption of the whole house and for space heating will be discussed. Also the energy-saving activities in a certain household are shown by using load duration curves. 相似文献
23.
Marked low-loss coupling between a laser diode and a single-mode fibre has been realised, utilising a planoconvex, high-numerical-aperture graded-index rod lens with greatly improved small wavefront aberration. 相似文献
24.
Microwave holographic imaging method with improved resolution 总被引:6,自引:0,他引:6
A multifrequency holographic microwave imaging method with high resolving capability in both azimuth and range directions, is described. The method incorporates a synthetic aperture approach in pulse radar systems, originally designed for the pulse-echo imaging, in order to improve azimuth resolution. The imaging technique places no constraint on the waveform of a transmitted signal in use and allows the three-dimensional imaging. This paper develops 1) the general formula, which describes the relation between the transmitted and received signals, based on Kirchhoff diffraction theory, 2) a test function, which is the kernel of a linear operation for producing object images from received signals, and 3) a filter design technique for compressing the durations and suppressing the sidelobe levels of received signals. Numerical image reconstructions are presented for demonstrating high resolution capability of the method. 相似文献
25.
α-Tocopherol was reacted with methyl linoleateperoxyl radicals at 37°C. The peroxyl radicals were generated by the reaction
of methyl linoleate with a free radical initiator, 2,2′-azobis(2,4-dimethylvaleronitrile). The primary products of α-tocopherol with methyl linoleate-peroxyl radicals were isolated by
reversephase and normal-phase high performance liquid chromatography (HPLC), and their structures were characterized by ultraviolet
(UV), infrared (IR),1H and13C nuclear magnetic resonance (NMR) and mass spectrometry (MS). There were four stereoisomers of methyl 13-(8a-peroxy-α-tocopherone)-9(Z),11(E)-octadecadienoate and four stereoisomers of methyl9-(8a-peroxy-α-tocopherone)-10(E),12(Z)-octadecadienoate. 相似文献
26.
The micellar properties of aqueous binary mixed solutions for two systems consisting of sodium cholate (NaC)-octaoxyethylene
glycol mono n-decyl ether (C10E8) and sodium glycocholate (NaGC)-C10E8 have been studied on the basis of surface tensions, polarity of the micelle interior and the mean aggregation number. Application
of two theoretical treatments, based on regular solution and excess thermodynamic quantities for critical micellar concentration
(CMC) data from surface tension curves of two mixed systems showed that the mole fraction of each bile salt in the mixed micelles
near the CMC is lower than that of the corresponding prepared mole fraction in the mixed solution. The polarity of the interior
suggested that the hydrophobicity of intramicelles increased with the increase of the mole fraction of bile salt in the mixed
solution and that the mixed micelles become dramatically more hydrophobic at a mole fraction of 0.68 for NaGC−C10E8 system and 0.75 for NaC−C10E8 system, respectively. This implies that the micelles become richer in the bile salt molecules and the tendency appears strongly
for NaGC−C10E8 system due to the strong cohesion between the conjugated glycines in the NaGC molecules. The decrease of aggregation number
with the increase of the mole fraction of bile salts shows that the micelles approach those of the single system of each bile
salt. This supports the previously mentioned facts. 相似文献
27.
Toshiki Ueno Takeru Nakaki Taisei Mukogawa Shuonan Dong Hiroki Kurita Keisuke Otsuka Kanjuro Makihara Fumio Narita 《Advanced Engineering Materials》2023,25(19):2300185
In this study, the Fe–Co alloy is combined with cobalt ferrite (CoFe2O4) and nickel (Ni) to form Fe–Co/CoFe2O4 and Fe–Co/Ni clad sheets and their energy-harvesting performance is evaluated. The Fe–Co/CoFe2O4 clad sheet exhibits an output voltage of 4.229 mV and an output power of 6.89 nW at a wind speed of 10 m s−1. The energy-harvesting performance of both these clad sheets cannot be quantitatively compared owing to their different thicknesses, which result in varying volume and distance from the neutral plane. Nevertheless, the values of output voltage and power for Fe–Co/CoFe2O4 are higher than those for Fe–Co/Ni (2.107 mV and 0.294 nW). 相似文献
28.
Shin-ichiro Sekimiya Eikoh Kobayashi Nobukatsu Nemoto Yukihiko Ueno Koji Ikeda Nobuo Takamiya 《Polymer Bulletin》1991,27(1):37-40
Summary Liquid crystalline side-chain polysiloxanes were prepared without metal complex catalyst. Mesogenic groups such as cholesteryl, 4-cyano-4-biphenyl and 4-methoxy-4-biphenyl group were introduced into polysiloxane by esterification and from DSC measurements they were compatible with other liquid crystalline polysiloxanes reported previously. 相似文献
29.
The effect of NH4F addition on the high-anodic behaviors of various DSA-type electrodes was investigated in a mixture of sulfuric acid and ammonium sulfate. The pronounced effect of NH4 addition was observed on DSA-type Ti/RuO2, Ti/IrO2?TiO2 electrodes, but not observed on the other electrodes studied. The close relationship was found between the increment of the electrode potential caused by the NH4 addition and the quantity of F? adsorbed on the electrode surface. The effect of NH4F addition was considered to be resulted from the adsorption of F? on the electrode surface, and the presence of adsorbed F? was directly proved. 相似文献
30.
Masaaki Takehisa Sueo Machi Hiromasa Watanabe Takashi Ueno Seiichi Takahashi Ryoji Tsuchiya Kanji Otaguro Isao Motoda Yoshio Takasaka Kazukiyo Miyanaga Waichiro Kawakami Kouichi Yamaguchi Takanobu Sugo Hayato Nakajima Terutaka Watanabe Chuhei Hinachi 《应用聚合物科学杂志》1979,24(3):853-864
Radiation-induced bulk polymerization of ethylene was carried out with use of a pilot plant with a 10 liter reactor at pressures of 225–400 kg/cm2, temperatures of 30–95°C, ethylene feed rates of 5–28 kg/hr, and dose rate of 3.8 × 105 rad/hr. Characteristics of the process are mild polymerization conditions and capability of producing medium density polyethylene in powder form. The spacetime yield and molecular weight of polymer were in the range of 3.5 to 13.1 g/liter hr and 2.2 × 104 to 14 × 104, respectively. The space-time yield increased with mean residence time and 2.4 powders of pressure, and decreased with temperature. Molecular weight changed similarly with the reaction conditions. These results were consistent with those of the bench plant experiment and the scale effect was small. Polymer deposit to the reactor wall limited a period of continuous operation of the plant. The amount of deposited polymer was increased with the square of reaction time. The rate of polymer deposit was proportional to polymer concentration and to the cube of pressure. The polymer deposit cannot be solved in the bulk process. 相似文献