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排序方式: 共有363条查询结果,搜索用时 15 毫秒
71.
Kikuo Wakino Hirohumi Sunahara Yasunobu Yoneda Yukio Sakabe Kimihide Sugo 《Integrated ferroelectrics》2013,141(3):269-282
Abstract Low temperature fired ceramics based on alumina/glass added oxide ceramics have been developed and are being used by several companies as substrates for high density assembled modular packaging.1–3 The features of low temperature fireable substrates are the cofireability with highly conductive metals such as Ag, Ag-Pd, or Cu, and the cofireability with other passive component materials for L, C, R and relatively low dielectric constant elements. But most of these substrates have the disadvantage that their thermal expansion coefficient is not perfectly compatible with Si or GaAs. This paper reports the results of a newly developed cordierite/glass based substrate employing Cu as the surface and internal conductors and having the freedom of tuning the thermal expansion coefficient by changing the composition. The ceramic composition with adjustable thermal expansion coefficient value of 3 to 7 ppm/°C can be manufactured and easily matched with the thermal expansion coefficient of Si or GaAs without a big change of electrical performance. 相似文献
72.
Takashi Ogi Ratna Balgis Kikuo Okuyama Naoko Tajima Heru Setyawan 《American Institute of Chemical Engineers》2013,59(8):2753-2760
Platinum‐deposited titanium nitride (Pt/TiN) nanoparticle aggregates with high porosities were successfully prepared via a self‐assembly‐assisted spray pyrolysis method. The addition of formic acid (HCOOH) had a significant influence on the process, promoting the simultaneous formation of metallic Pt and reduction on the surface of the TiN support material. Complete reduction of the Pt/TiN nanoparticle aggregates improved the catalytic activity. The electrochemical surface area (ECSA) of Pt/TiN with HCOOH (Pt/TiNw/HCOOH) was 87.15 m2/g‐Pt, which was higher than that of Pt/TiN without HCOOH (Pt/TiNw/o‐HCOOH). The catalytic durability of Pt/TiNw/HCOOH was twice that of Pt/TiNw/o‐HCOOH. An effective strategy for obtaining carbon‐free catalysts with high activities and durabilities was identified. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2753–2760, 2013 相似文献
73.
Shoji Asai Takayuki Yamazaki Akira Miyazaki Taikan Suehara Toshio Namba Tomio Kobayashi Haruhiko Saito Takatoshi Idehara Isamu Ogawa S. Sabchevski 《Journal of Infrared, Millimeter and Terahertz Waves》2012,33(7):766-776
Positronium is an ideal system for research on QED, especially in a bound state. A discrepancy (3.9σ) is found recently between measured HFS values and the QED prediction (including up-to O(α
3 log α
− 1), where α is the fine-structure constant.). It might be due to a contribution of unknown new physics or common systematic problems
in all the previous measurements. A new method to measure HFS directly is performed using a high power gyrotron. The transition
from ortho-positronium to para-positronium has been observed with 5 σ CL, which is the first observation of M1 transition in (sub)Terahertz region. New technologies of high power gyrotrons are
developed for precision spectroscopy. 相似文献
74.
Takashi Sasaoka Hideki Shimada Takayuki Sasaki Masatomo Ichinose Kikuo Matsui 《煤炭学报(英文版)》2008,14(3):365-368
The size distribution of a muck pile depends not on only the blasting standard but also on the mechanical properties, joint
system, and crack density of the rock mass. As, the cracks in the rock masses are especially heavily developed at the limestone
quarries in Japan, they, along with the joints, have a large impact on the effects of blasting, such as the size of the muck
pile. Therefore, if the joint system and/or crack density in a rock mass can be determined and quantitatively evaluated, the
blasting operation can be conducted more effectively, efficiently and safely. However, guidelines for designing appropriate
blasting standards based on the rock mass conditions have not yet been scientifically developed. Therefore, blasting tests
were conducted on different mines and faces, under different geological conditions and blasting standards, in order to determine
the impacts of each factor on the effects of blasting. Summarized the results of a series of blasting tests and described
the impacts of geological conditions on the size of the muck pile produced by blast.
Bhandari S. Engineering rock blasting operations, 1997. 相似文献
75.
Atsuhito Honda Masaki Kawano Masayoshi Ishida Keiji Sato Michiro Komatsubara Isamu Ohyama 《材料科学技术学报》2000,16(2):238-243
1. IntroductionThe total performance of inverter power supplieshas improved drastically as a result of the development of colltrol methods, higher performance in semiconductors, and higher speed, higher integration, andlower cost in integrated circuits, making it possible touse the inverter drive method in a wide range of rotating machinery which requires smaller size and/or variable speed drives. In line with these trends, magneticloss under nonsinusoidal waveform excitation, including lower … 相似文献
76.
Agus Purwanto Wei-Ning Wang Takashi Ogi I. Wuled Lenggoro Eishi Tanabe Kikuo Okuyama 《Journal of Alloys and Compounds》2008,463(1-2):350-357
High luminance Y3Al5O12:Ce3+ (YAG:Ce) nanoparticles were prepared from urea-added nitrate aqueous precursor by flame-assisted spray pyrolysis (FASP). The addition of urea into nitrate precursor plays an important role in YAG:Ce nanoparticle formation and in improving its optical performance. The decomposition and combustion of urea in the flame zone provides additional heat to the particles, which coupled with the evolution of large volumes of gasses, contributes to nanoparticle formation. The as-prepared nanoparticles are hexagonal YAlO3, that are nearly spherical, rough on the surface and dense—and they can be converted to YAG:Ce after being annealed at 1200 °C for 4 h. The heat-treated particles are single crystalline, smooth in surface and dense with an average size around 50 nm. The optimum cerium-doping concentration of YAG:Ce nanoparticles is 4.0 at.%, which exhibits quantum efficiency of 45.0%. This quantum efficiency is comparable with that of YAG:Ce nanoparticles produced from other processes. The efficient emission of YAG:Ce nanoparticles also originates from a relatively good distribution of Ce ions incorporated into the host material of YAG as evidenced from the elemental mapping analysis. 相似文献
77.
Synthesis of nanocrystalline GaN from Ga2O3 nanoparticles derived from salt-assisted spray pyrolysis
Takashi Ogi Yutaka Kaihatsu Ferry Iskandar Eishi Tanabe Kikuo Okuyama 《Advanced Powder Technology》2009,20(1):29-34
Gallium nitride (GaN) nanoparticles were successfully produced from nano-sized gallium oxide (Ga2O3) particles under a flow of ammonia gas. The gallium oxide nanoparticles were prepared by salt-assisted spray pyrolysis (SASP). Highly crystalline Ga2O3 nanoparticles with an average diameter of approximately 10 nm were obtained at various temperatures when a flux salt (LiCl, 5 mol/l) was added to the precursor solution. The effects of the crystallinity of the Ga2O3 particles and nitridation time on transformation to GaN were characterized using X-ray diffraction and scanning/transmission electron microscopy. Highly crystalline GaN nanoparticles with a mean size of 23.4 nm and a geometric standard deviation of 1.68 nm were obtained when Ga2O3 nanoparticles with relatively low crystallinity were used as the starting material. The resulting GaN nanoparticles showed a photoluminescence peak at 364 nm under UV excitation at 254 nm. 相似文献
78.
Based on finite-difference time-domain(FDTD) method,the wave propagation and localization in two-dimensional defect-containing piezoelectric phononic crystals are investigated when the mechanical-electrical coupling is taken into account.The characteristics of localized defect modes are studied,and the effects of the number and direction of defects on the defect modes and transmission coefficients are discussed.Numerical results of defect modes and transmission coefficients are presented for BaTiO3/polymer piezocomposite,and from which we can see that the number and direction of defects have pronounced effects on the defect modes and transmission coefficients.The results also show the existence of elastic wave localization in piezoelectric phononic crystals containing defects. 相似文献
79.
Isamu Kobayashi 《Information Systems》1987,12(4):343-352
In classical database theory, relational calculus has long been used in expressing query formulae and integrity constraints. In fact, relational calculus formulae are much easier to deal with than first-order formulae when evaluating queries and validating database updates in the database environment. In deductive databases, however, first-order calculus is preferred because it is convenient when proof procedures are involved. Since both situations should coexist in advanced information systems, it is very desirable to devise a conversion procedure between relational calculus and first-order calculus. In this paper, interpretation of first-order formulae in the database environment is discussed first, then tuple calculus, an extension of relational calculus, is presented. This extension enables us to describe query formulae and general rules necessary in advanced information systems, in particular, dealing with complex objects. Finally, a conversion algorithm from first-order formulae into tuple calculus formulae is presented. Several application issues are also included. 相似文献
80.
The reactivity of the formate ions on Ni/SiO2 catalyst was examined during the course of the formic acid decomposition. It is of great interest to note that the reactivity was markedly increased by the presence of formic acid in the ambient gas compared to that at the same coverage under vacuum. It is accordingly suggested that the formate ion behaves as reaction intermediate through the interaction between the formic acid molecules in the ambient gas. 相似文献