全文获取类型
收费全文 | 1706篇 |
免费 | 44篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 89篇 |
化学工业 | 263篇 |
金属工艺 | 75篇 |
机械仪表 | 42篇 |
建筑科学 | 24篇 |
能源动力 | 61篇 |
轻工业 | 116篇 |
水利工程 | 8篇 |
石油天然气 | 1篇 |
无线电 | 229篇 |
一般工业技术 | 318篇 |
冶金工业 | 408篇 |
原子能技术 | 54篇 |
自动化技术 | 71篇 |
出版年
2023年 | 6篇 |
2021年 | 22篇 |
2020年 | 16篇 |
2019年 | 15篇 |
2018年 | 28篇 |
2017年 | 24篇 |
2016年 | 24篇 |
2015年 | 18篇 |
2014年 | 40篇 |
2013年 | 78篇 |
2012年 | 41篇 |
2011年 | 70篇 |
2010年 | 58篇 |
2009年 | 57篇 |
2008年 | 62篇 |
2007年 | 68篇 |
2006年 | 66篇 |
2005年 | 69篇 |
2004年 | 45篇 |
2003年 | 43篇 |
2002年 | 53篇 |
2001年 | 27篇 |
2000年 | 33篇 |
1999年 | 47篇 |
1998年 | 155篇 |
1997年 | 111篇 |
1996年 | 77篇 |
1995年 | 48篇 |
1994年 | 48篇 |
1993年 | 39篇 |
1992年 | 21篇 |
1991年 | 20篇 |
1990年 | 20篇 |
1989年 | 11篇 |
1988年 | 21篇 |
1987年 | 20篇 |
1986年 | 12篇 |
1985年 | 18篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 10篇 |
1981年 | 15篇 |
1980年 | 11篇 |
1979年 | 10篇 |
1978年 | 10篇 |
1977年 | 11篇 |
1976年 | 12篇 |
1975年 | 4篇 |
1973年 | 5篇 |
1972年 | 4篇 |
排序方式: 共有1759条查询结果,搜索用时 31 毫秒
1.
Ichiro Fujii Shin Ariizumi Shintaro Ueno Chikako Moriyoshi Yoshihiro Kuroiwa Satoshi Wada 《Ceramics International》2018,44(9):10657-10662
We fabricated xBaTiO3 (BT)/(1-x)[BaTiO3-Bi(Mg1/2Ti1/2)O3-BiFeO3] (BT-BMT-BF)?+?0.1?wt%MnCO3 composites by spark plasma sintering and investigated the effect of BT content x, BT powder size, and BT-BMT-BF composition on piezoelectric properties. For xBT/(1-x)(0.3BT-0.1BMT-0.6BF) +?0.1?wt%MnCO3 (x?=?0–0.75) composites with a 0.5-µm BT powder, the dielectric constant was increased with x, and the relative density was decreased at x?=?0.67 and 0.75, creating optimum BT content of x?=?0.50 with a piezoelectric constant d33 of 107?pC/N. When a larger 1.5-µm BT powder was utilized for the composite with x?=?0.50, the d33 value increased to 150?pC/N due to the grain size effect of the BT grains. To compensate for a compositional change from the optimum 0.3BT-0.1BMT-0.6BF due to partial diffusion between the BT and 0.3BT-0.1BMT-0.6BF grains, a 0.5BT/0.5(0.275BT-0.1BMT-0.625BF)?+?0.1?wt%MnCO3 composite with the 1.5-µm BT powder was fabricated. We obtained an increased d33 value of 166?pC/N. These results provided a useful composite design to enhance the piezoelectric properties. 相似文献
2.
Shoji Nakamura Yuji Shibahara Atsushi Kimura Osamu Iwamoto Akihiro Uehara Toshiyuki Fujii 《Journal of Nuclear Science and Technology》2020,57(4):388-400
ABSTRACTThe thermal-neutron capture cross-section (σ0) and resonance integral (I0) were measured for the 135Cs(n,γ)136Cs reaction by an activation method and mass spectrometry. Because of difficulty in the preparation of pure 135Cs samples, we used 135Cs contained as an impurity in a normally available 137Cs standard solution. An isotope ratio of 135Cs and 137Cs in a standard 137Cs solution was measured by mass spectrometry to quantify 135Cs. Cesium-135 impurity along with the 137Cs standard solution was irradiated at the hydraulic conveyer of the research reactor in the Institute for Integral Radiation and Nuclear Science, Kyoto University. Wires of Co/Al and Au/Al alloys were used as neutron monitors to measure thermal-neutron fluxes and epi-thermal Westcott’s indices at an irradiation position. A gadolinium filter was used to measure the σ0, and a value of 0.133 eV was taken as the cut-off energy. Gamma-ray spectroscopy was used to measure induced activities of 137Cs, 136Cs and monitor wires. On the basis of Westcott’s convention, the σ0 and I0 values were derived as 8.57 ± 0.25 barn, and 45.3 ± 3.2 barn, respectively. The value of σ0 obtained in the present study agreed within the limits of uncertainties with the past-reported value of 8.3 ± 0.3 barn. 相似文献
3.
Mikihisa Saito Masaru Ishii Atsushi Ohnishi Fumiyuki Fujii Michihiro Matsui Daisuke Natsuno 《Electrical Engineering in Japan》2015,190(1):37-44
In recent years, frequent damage to wind turbines by winter lightning has been reported in the region along the Sea of Japan. It is a serious finding that lightning hits concentrate on wind turbines in this region. The authors investigated the increase rate of the frequency of lightning hits on wind turbines due to wind turbine construction by using LLS (lightning location system) data. As a result, an experimental formula to estimate the increase rate of the frequency of lightning hits on wind turbines as a function of parameters related to the construction conditions, namely the height of wind turbines, the height above sea level, and the latitude, is proposed. 相似文献
4.
Ryo Hashikawa Yasuhiro Fujii Atsushi Kinomura Takeshi Saito Arifumi Okada Takashi Wakasugi Kohei Kadono 《Journal of the American Ceramic Society》2019,102(4):1642-1651
Radiophotoluminescence phenomena have been widely investigated on various types of materials for dosimetry applications. We report that an aluminoborosilicate glass containing 0.005 mol% copper exhibits intense photoluminescence in the visible region induced by X-ray and γ-ray irradiation. The luminescence is assigned to the 3d94s1 → 3d10 transition of Cu+. The proportionality of the intensity of the induced photoluminescence to the irradiation dose was confirmed up to 0.5 kGy using 60Co γ-ray irradiation. Based on the spectroscopic results, a potential mechanism was proposed for the enhancement of the photoluminescence. The exposure to the ionizing radiation generates electron-hole pairs in the glass, and the electrons are subsequently captured by the Cu2+ ions, which are converted to Cu+ and emit the luminescence. For the glass containing 0.01 mol% copper, the pronounced enhancement of the photoluminescence was not observed because the reverse reaction, ie, the capture of the holes by the Cu+ ions, becomes prominent. The photoluminescence induced by the irradiation was stably observed for the glasses kept at room temperature and even for the glasses heat-treated at 150°C. However, the induced photoluminescence could be eliminated by the heat treatment at a temperature at 500°C, and the glass returned to the initial pre-irradiation state. The Cu-doped aluminoborosilicate glass is a potential candidate for use in dosimetry applications. 相似文献
5.
Tetsuji Kaneko Norihiko Tanaka Shinichi Ishioka Fujii Kazumi Yuichi Fukaya Katsuhiko Kumagai 《Journal of Nuclear Science and Technology》2019,56(9-10):873-880
ABSTRACTFukushima Daiichi nuclear power plants (1F) were damaged by unprecedented severe accident in the great east Japan earthquake, and seawater and freshwater had been injected as an emergency countermeasure for the core cooling. Although, the primary containment vessel (PCV) was not supposed to be exposed to diluted seawater, the PCV will be exposed to diluted seawater environment until fuel debris removal is completed. Therefore, it is necessary to establish a countermeasure of corrosion for the PCVs made of carbon steel. In this study, the effect of the addition of corrosion inhibitor, which is one of the corrosion countermeasures, was investigated by two types of corrosion tests. As a result of the immersion corrosion test, it was found that any of the three kinds of corrosion inhibitor could suppress corrosion of carbon steel. In addition, as a result of the inhibitor interim addition test, it was found that corrosion of carbon steel covered with corrosion products could be suppressed by optimizing the additive amount of corrosion inhibitor in the cooling water. 相似文献
6.
Fujii kazuyoshi 《景德镇陶瓷》2014,(4)
<正>吴也凡原创陶瓷艺术作品新加坡展选登——天驹系列No.5、No.6(55×112cm)景德镇陶瓷学院教授、景德镇中外陶瓷艺术协会艺术总监吴也凡博士(改革开放后厦门大学最早培养的几批博士之一)系晚清两房进士之后,1953年出身于名门艺术世家,自幼在当地名师指导下勤习书法与绘画,还受过良好的音乐教育。1966年开始的文化大革命摧残了一代人的梦想。1968年吴也凡通过亲友介绍在衡阳界牌的瓷厂学习画瓷,此后就一直与陶瓷美术有了不解之缘。文革动乱结束后,举国上下科技兴国,从1980 相似文献
7.
Rapid Reconstitution of Biosynthetic Machinery for Fungal Metabolites in Aspergillus oryzae: Total Biosynthesis of Aflatrem 下载免费PDF全文
Koichi Tagami Dr. Atsushi Minami Ryuya Fujii Dr. Chengwei Liu Dr. Mizuki Tanaka Prof. Dr. Katsuya Gomi Prof. Dr. Tohru Dairi Prof. Dr. Hideaki Oikawa 《Chembiochem : a European journal of chemical biology》2014,15(14):2076-2080
Reconstitution of the biosynthetic machinery for fungal secondary metabolites in Aspergillus oryzae provides an opportunity both for stepwise determination of the biosynthetic pathways and the total biosynthesis of fungal natural products. However, to maximize the utility of the reconstitution system, a simple and rapid strategy for the introduction of heterologous genes into A. oryzae is required. In this study, we demonstrated an effective method for introducing multiple genes involved in the biosynthesis of fungal metabolites by using the expression vectors pUARA2 and pUSA2, each of which contains two cloning sites. The successful introduction of all the aflatrem biosynthetic genes (seven genes in total) after two rounds of transformation enabled the total biosynthesis of aflatrem. This rapid reconstitution strategy will facilitate the functional analysis of the biosynthetic machinery of fungal metabolites. 相似文献
8.
Tetsuo Fukuchi Takayuki Ozeki Mitsutoshi Okada Tomoharu Fujii 《IEEJ Transactions on Electrical and Electronic Engineering》2016,11(4):391-400
A thermal barrier coating (TBC) is applied to high‐temperature components in gas turbines, and consists of a ceramic topcoat and a metallic bondcoat. Various kinds of TBC degradation and damage occur in high‐temperature components during service, such as topcoat thinning, topcoat delamination, and formation of a thermally grown oxide (TGO) layer below the topcoat, each of which can be examined using a suitable nondestructive inspection technique. Topcoat thinning can be detected by topcoat thickness measurement using terahertz waves, which are electromagnetic waves in the frequency region between optical and radio waves. The measurement resolution is about 10 μm, which is comparable to microscopic observation of the cross section in destructive inspection. Topcoat delamination can be detected by active thermography, in which the topcoat surface is scanned by a heating laser and the surface temperature distribution is measured by a thermal infrared camera. The combination of temperature peak and residual thermal image detection is effective in eliminating false detection. The TGO layer can be detected using photoluminescence, in which the Cr3+ ions included as an impurity in Al2O3 are detected. Since delamination tends to occur at locations at which the TGO layer has grown, TGO layer detection provides an effective method to select regions where delamination has occurred or is likely to occur. An inspection flow based on these techniques is proposed, which is expected to aid the establishment of condition‐based maintenance strategies of high‐temperature components. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
9.
Preparation of Morphology‐Controlled Plate‐Like Sodium Niobate Particles by Hydrothermal Synthesis 下载免费PDF全文
Sodium niobate (NaNbO3) particles with plate‐like morphology and hexagonal unit cells were prepared by the hydrothermal method. The result of SEM showed that the hexagonal NaNbO3 were characterized by plate‐like morphology with a diameter of 5–15 μm and a thickness of 1–2 μm. The crucial influences on the morphology and crystal phase of the NaNbO3, such as concentration of [OH?], surfactant, and K+:Na+ ratio, were established. By further calcination treatment, the plate‐like hexagonal NaNbO3 particles could be completely transformed into perovskite structure without morphology change. The XRD and EBSD results indicate that the major face of the calcined particles is parallel to the crystallographic (001)pc (pseudo cubic index) plane. Compared with the traditional high‐temperature molten salt method, this work provides a simpler way to prepare the template for fabricating textured ceramics. 相似文献
10.
Compression molding and melt‐spinning of the blends of poly(lactic acid) and poly(butylene succinate‐co‐adipate) 下载免费PDF全文
Weraporn Pivsa‐Art Sommai Pivsa‐Art Kazunori Fujii Keiichiro Nomura Kiyoaki Ishimoto Yuji Aso Hideki Yamane Hitomi Ohara 《应用聚合物科学杂志》2015,132(16)
Poly(lactic acid) (PLA) is a biobased polymer made from biomass having high mechanical properties for engineering materials applications. However, PLA has certain limited properties such as its brittleness and low heat distortion temperature. Thus, the aim of this study is to improve toughness of PLA by blending with poly(butylene succinate‐co‐adipate) (PBSA), the biodegradable polymer having high toughness. Polymer blends of PLA and PBSA were prepared using a twin screw extruder. The melt rheology and the thermal property of the blends were examined. Further the blends were fabricated into compression molded parts and melt‐spun fiber and were subjected to tensile and impact tests. When the PBSA content was low, PBSA phase was finely dispersed in the PLA matrix. On the other hand, when the PBSA content was high, this minor phase dispersed as a large droplet. Mechanical properties of the compression molded parts were affected by the dispersion state of PBSA minor component in PLA matrix. Impact strength of the compression molded parts was also improved by the addition of soft PBSA. The improvement was pronounced when the PBSA phase was finely dispersed in PLA matrix. However, the mechanical property of the blend fibers was affected by the postdrawing condition as well as the PBSA content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41856. 相似文献