全文获取类型
收费全文 | 2618篇 |
免费 | 115篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 140篇 |
综合类 | 3篇 |
化学工业 | 753篇 |
金属工艺 | 56篇 |
机械仪表 | 82篇 |
建筑科学 | 76篇 |
能源动力 | 116篇 |
轻工业 | 318篇 |
水利工程 | 12篇 |
石油天然气 | 1篇 |
无线电 | 130篇 |
一般工业技术 | 537篇 |
冶金工业 | 125篇 |
原子能技术 | 119篇 |
自动化技术 | 275篇 |
出版年
2023年 | 23篇 |
2022年 | 25篇 |
2021年 | 80篇 |
2020年 | 25篇 |
2019年 | 37篇 |
2018年 | 84篇 |
2017年 | 54篇 |
2016年 | 106篇 |
2015年 | 52篇 |
2014年 | 100篇 |
2013年 | 180篇 |
2012年 | 161篇 |
2011年 | 194篇 |
2010年 | 139篇 |
2009年 | 160篇 |
2008年 | 178篇 |
2007年 | 124篇 |
2006年 | 105篇 |
2005年 | 101篇 |
2004年 | 86篇 |
2003年 | 76篇 |
2002年 | 84篇 |
2001年 | 53篇 |
2000年 | 34篇 |
1999年 | 50篇 |
1998年 | 68篇 |
1997年 | 47篇 |
1996年 | 42篇 |
1995年 | 23篇 |
1994年 | 36篇 |
1993年 | 26篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 9篇 |
1989年 | 16篇 |
1988年 | 10篇 |
1987年 | 13篇 |
1986年 | 16篇 |
1985年 | 18篇 |
1984年 | 9篇 |
1983年 | 15篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1976年 | 8篇 |
1975年 | 3篇 |
1973年 | 2篇 |
排序方式: 共有2743条查询结果,搜索用时 62 毫秒
131.
Kiyotaka Onitsuka Atsushi Shimizu Fumie Takei Shigetoshi Takahashi 《Journal of Inorganic and Organometallic Polymers and Materials》2009,19(1):98-103
A novel multifunctional initiator has been developed by peripheral modification of a Pt-acetylide dendrimer. Pd–Pt μ-ethynediyl
units were introduced to the first-generation dendrimer by a divergent method. The dendritic initiator was applicable to the
living polymerization of aryl isocyanides, producing high molecular weight polymers with a narrow polydispersity index in
quantitative yields. The 31P NMR spectrum of the resulting polymer suggested that all Pd–Pt μ-ethynediyl units in the dendritic molecule actually functioned
as an initiator. 相似文献
132.
Ken‐Ichiro Ishimori Tsuyoshi Yaita Takaumi Kimura Takashi Yamada Satoshi Shinoda 《溶剂提取与离子交换》2013,31(4):489-500
The extraction equilibria of Am(III) and Eu(III) by using a tripodal ligand, tris(2‐pyridylmethyl)amine (tpa), with various lipophilic anions have been investigated. The extractability of both Am(III) and Eu(III) was increased by the combination of tpa and counteranions due to a synergistic effect. The separation factors between Am(III) and Eu(III) were also increased from 7.6 to 49 by the combination of counteranions and organic solvents. The extraction equilibria of Am(III) and Eu(III) with tpa in 1,2‐dichloroethane were determined by slope analysis. It was found that three anions and one molecule of the ligand coordinated to Am(III) and Eu(III) was extracted regardless of the anions. 相似文献
133.
Takatsuki S Nemoto S Sasaki K Maitani T 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2003,44(2):89-95
An LC/MS method was developed for the determination of acrylamide (AA) in processed or cooked foods. AA was extracted with a mixture of water and acetone from homogenized food samples after the addition of 13C-labeled acrylamide (AA-1-(13)C) as an internal standard. The extract was concentrated, washed with dichloromethane for defatting, and cleaned up on Bond Elut C18, PSA and ACCUCAT cartridge-columns, and then AA was determined by LC/MS in the selected ion recording (SIR) mode. For the LC/MS analysis, four LC columns were connected in-line and the flow of the mobile phase was switched according to a time-program. Monitoring ions for AA were m/z 72 and 55, and those for AA-1-(13)C were m/z 73 and 56. AA and AA-1-(13)C were determined without interference from the matrices in all samples. The recoveries of AA from potato chips, corn snack, pretzel and roasted tea spiked at the level of 500 ng/g of AA were 99.5-101.0% with standard deviations (SD) in the range from 0.3 to 1.6%. The limits of detection and quantification of the developed method were 9 and 30 ng/g for AA in samples, respectively. The method was applied to the analysis of AA in various processed or cooked food samples purchased from retail markets. High levels of AA were found in potato chips and French-fried potato (467-3,544 ng/g). Fried and sugar-coated dough cakes (karinto) contained 374 and 1,895 ng/g. Corn snacks contained 117-535 ng/g of AA. Roasted foods (such as roasted sesame seed, roasted barley (mugi-cha), roasted tea (hoji-cha), coffee beans and curry powder) contained 116-567 ng/g of AA. Foods made from fish, egg and meat contained lower levels of AA than the plant-based foods. Foods containing much water showed a tendency to have low levels of AA compared with dry foods. The proposed method was applicable to the analysis of AA in variety of processed foods. 相似文献
134.
Takashi MINAMI Shohei ARAI Naoki KENMOCHI Hiroaki YASHIRO Chihiro TAKAHASHI Shinji KOBAYASHI Tohru MIZUUCHI Shinsuke OHSHIMA Satoshi YAMAMOTO Hiroyuki OKADA Kazunobu NAGASAKI Yuji NAKAMURA Kiyoshi HANATANI Shigeru KONOSHIMA Fumimichi SANO 《等离子体科学和技术》2013,(3):240-243
A new high repetition rate Nd:YAG Thomson scattering system is developed for the Heliotron J helical device.A main purpose of installing the new system is the temporal evolution measurement of a plasma profile for improved confinement physics such as the edge transport barrier (H-mode) or the internal transport barrier of the helical plasma.The system has 25 spatial points with ~10mm resolution.Two high repetition Nd:YAG lasers (>550mJ@ 50Hz) realize the measurement of the time evolution of the plasma profile with ~10ms time intervals.Scattered light is collected by a large concave mirror (D=800 mm,f/2.25) with a solid angle of ~100 mstr and transferred to interference filter polychromators by optical fiber bundles in a staircase form.The signal is amplified by newly designed fast preamplifiers with DC and AC output,which reduces the low frequency background noise.The signals are digitized with a multi-event QDC,fast gated integrators.The data acquisition is performed by a VME-based system operated by the CINOS. 相似文献
135.
Iron–Nitrogen‐Doped Vertically Aligned Carbon Nanotube Electrocatalyst for the Oxygen Reduction Reaction 下载免费PDF全文
Satoshi Yasuda Atom Furuya Yosuke Uchibori Jeheon Kim Kei Murakoshi 《Advanced functional materials》2016,26(5):738-744
A highly active iron–nitrogen‐doped carbon nanotube catalyst for the oxygen reduction reaction (ORR) is produced by employing vertically aligned carbon nanotubes (VA‐CNT) with a high specific surface area and iron(II) phthalocyanine (FePc) molecules. Pyrolyzing the composite easily transforms the adsorbed FePc molecules into a large number of iron coordinated nitrogen functionalized nanographene (Fe–N–C) structures, which serve as ORR active sites on the individual VA‐CNT surfaces. The catalyst exhibits a high ORR activity, with onset and half‐wave potentials of 0.97 and 0.79 V, respectively, versus reversible hydrogen electrode, a high selectivity of above 3.92 electron transfer number, and a high electrochemical durability, with a 17 mV negative shift of E 1/2 after 10 000 cycles in an oxygen‐saturated 0.5 m H2SO4 solution. The catalyst demonstrates one of the highest ORR performances in previously reported any‐nanotube‐based catalysts in acid media. The excellent ORR performance can be attributed to the formation of a greater number of catalytically active Fe–N–C centers and their dense immobilization on individual tubes, in addition to more efficient mass transport due to the mesoporous nature of the VA‐CNTs. 相似文献
136.
Satoshi Someya Satoshi Yoshida Takahide Tabata Koji Okamoto 《International Journal of Heat and Mass Transfer》2009,52(19-20):4236-4243
The basic characteristics of the reacting mixing flow of two streams were investigated. The reaction between aqueous solutions of ammonia and acetic acid, which produces ammonium acetate, was investigated in terms of the effect on the fluid–fluid interface of the mixing flow relative to fluids that did not react. The reaction between these solutions was negligibly exothermic, and there were minimal differences in density. The velocity field in the reacting mixing flow was quantitatively measured using high-speed time-resolved particle image velocimetry (PIV) and the behavior of the mixing flow was qualitatively investigated using laser-induced fluorescence (LIF). The jet width, the velocity field, the kinetic energy and the turbulent intensities are qualitatively estimated and discussed. It was found that the chemical reaction resulted in the suppression of the mixing flow. 相似文献
137.
Wenxi Tian Yuki Ishiwatari Satoshi Ikejiri Masanori Yamakawa Yoshiaki Oka 《Nuclear Engineering and Design》2009,239(11):2382-2390
In present study, the collapse of void bubble in liquid has been simulated using moving particle semi-implicit (MPS) code. The liquid is described using moving particles and the bubble–liquid interface was set to be vacuum pressure boundary without interfacial heat mass transfer. The topological shape of bubble can be traced according to the motion and location of interfacial particles. The time dependent bubble diameter, interfacial velocity and bubble collapse time were obtained under wide parametric range. The comparison with Rayleigh and Zababakhin's prediction showed a good agreement which validates the applicability and accuracy on MPS method in solving present momentum problems. The potential void induced water hammer pressure pulse was also evaluated which is instructive for further material erosion study. The bubble collapse with non-condensable gas has been further simulated and the rebound phenomenon was successfully captured which is similar with vapor-filled cavitation phenomenon. The present study exhibits some fundamental characteristics of void bubble hydrodynamics and it is also expected to be instructive for further applications of MPS method to complicated bubble dynamics problems. 相似文献
138.
Satoshi Tanaka Atsushi Makiya Zenji Kato Keizo Uematsu 《Journal of the European Ceramic Society》2009,29(5):955-959
A rotating magnetic field was used to fabricate c-axis oriented zinc oxide. The influence of rotating speed on orientation structure was also examined. The aligned axes had the largest diamagnetic susceptibility, which axis was difficult to align with a static magnetic field. In c-axis oriented ZnO, the degree of orientation (Lotgering factor) in the green compact ranged from 0.2 to 0.5 along c-axis. The Lotgering factor increased with rotating speed. For all samples with the rotating magnetic field, the degrees of orientation increased up to above 0.9 after sintering at 1573 K. 相似文献
139.
Sunnam Kim Wataru Inoue Satoshi Hirano Ryohei Yagi Yutaka Kuwahara Tomonari Ogata Seiji Kurihara 《Polymer》2014
Three type polymers containing the same azobenzene side chain group with different backbone structures, poly(DMAz6Fm), poly(DMAz6It) and poly(MAz6Ac) derived respectively from fumaric acid, itaconic acid and acrylic acid, were synthesized. The dependence of photo-response properties on the polymeric architecture was investigated for the solutions and films. By irradiation of the linearly polarized light (436 nm), uniaxial orientations of the thin films were induced and anisotropic properties were investigated by measurements of the order parameters and birefringence values. 相似文献
140.
The authors propose a new design concept for controlling the deflection of a micro-membrane with the aid of its thickness distribution for realizing a prescribed design in the MEMS. As an example, the authors treat a micro air pump that comprises a micro-membrane. The membrane is actuated by an electrostatic force. The membrane deflects and thus the deflection is influenced by the air pressure and the electrostatic field. This is a highly complicated system. To find out a proper thickness distribution, the authors use the genetic algorithm that is appropriate to reduce the searching space of solution. 相似文献