全文获取类型
收费全文 | 2980篇 |
免费 | 66篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 133篇 |
综合类 | 4篇 |
化学工业 | 533篇 |
金属工艺 | 43篇 |
机械仪表 | 84篇 |
建筑科学 | 53篇 |
矿业工程 | 6篇 |
能源动力 | 74篇 |
轻工业 | 310篇 |
水利工程 | 8篇 |
石油天然气 | 7篇 |
无线电 | 397篇 |
一般工业技术 | 474篇 |
冶金工业 | 757篇 |
原子能技术 | 56篇 |
自动化技术 | 108篇 |
出版年
2023年 | 10篇 |
2022年 | 34篇 |
2021年 | 59篇 |
2020年 | 18篇 |
2019年 | 33篇 |
2018年 | 41篇 |
2017年 | 48篇 |
2016年 | 39篇 |
2015年 | 33篇 |
2014年 | 59篇 |
2013年 | 116篇 |
2012年 | 89篇 |
2011年 | 97篇 |
2010年 | 87篇 |
2009年 | 84篇 |
2008年 | 108篇 |
2007年 | 91篇 |
2006年 | 86篇 |
2005年 | 86篇 |
2004年 | 73篇 |
2003年 | 94篇 |
2002年 | 80篇 |
2001年 | 68篇 |
2000年 | 48篇 |
1999年 | 80篇 |
1998年 | 315篇 |
1997年 | 178篇 |
1996年 | 126篇 |
1995年 | 105篇 |
1994年 | 72篇 |
1993年 | 68篇 |
1992年 | 51篇 |
1991年 | 33篇 |
1990年 | 33篇 |
1989年 | 34篇 |
1988年 | 37篇 |
1987年 | 30篇 |
1986年 | 37篇 |
1985年 | 23篇 |
1984年 | 21篇 |
1983年 | 28篇 |
1982年 | 18篇 |
1981年 | 23篇 |
1980年 | 18篇 |
1979年 | 16篇 |
1978年 | 16篇 |
1977年 | 29篇 |
1976年 | 40篇 |
1975年 | 12篇 |
1971年 | 4篇 |
排序方式: 共有3047条查询结果,搜索用时 15 毫秒
51.
Chengzhou Li Yusuke Imai Yoshio Adachi Hiroshi Yamada Keiko Nishikubo Chao-Nan Xu 《Journal of the American Ceramic Society》2007,90(7):2273-2275
An organic aqueous solution of metal acetylacetonate precursors was subjected to spray pyrolysis in order to fabricate SrAl2 O4 :Eu (SAO) nanoparticles. Non-agglomerated luminescent SAO nanoparticles, having a spherical shape with a size of 10–30 nm, were achieved in a single step, while only submicrometer-sized SAO particles were obtained from the conventional ultrasonic pyrolysis of the metal nitrates. Without any post-annealing process, the as-prepared SAO nanoparticles were observed to exhibit a strong photoluminescence, which is comparable with that of the submicrometer-sized SAO particles. A mechanism for the formation of the nanoparticles is also discussed. 相似文献
52.
In order to obtain thermoplastic (before curing) and thermosetting (after curing) polyimides with high Tg for adhesive film, we prepared novel polyimides having phenylethynyl group in the side chain (44% of concentration of curing group) from asymmetric 2,3,3′,4′-biphenyltetracarboxylic dianhydride (a-BPDA), 3,4′-oxydianiline (3,4′-ODA) or 1,3-bis(4-aminophenoxy)benzene (1,3,4-APB) or 1,3-bis(3-aminophenoxy)benzene (1,3,3-APB), and 2,4-diamino-1-(4-phenylethynylphenoxy)benzene (mPDAp). Among three kinds of polymer, uncured polyimide of a-BPDA/1,3,4-APB; mPDAp had rather high Tg (265 °C, DMA) and thermoplasticity (E′ drop>103 at Tg). After curing reaction of phenylethynyl group, the Tg of the polyimide was increased dramatically (364 °C, DMA). The polyimide derived from 1,3,4-APB having less concentration of curing group (20%) was also prepared to improve further film flexibility and toughness. 相似文献
53.
The time dependency of the amounts of corrosion products and co-existing adsorbed water on copper in humid air containing SO2 was estimated from a series of in situ time-resolved IR-RAS spectra on the basis of the relations between the band intensities and the mass changes of the corrosion products, which were determined by simultaneous measurement of IR-RAS and QCM. The amounts of both corrosion products increased slowly at the initial stage and later increased rapidly. Although the relative humidity was kept constant, the amount of adsorbed water increased nearly the same behavior as that of corrosion products in the stage of relatively small amounts of corrosion products and later increased rapidly when the amounts of corrosion products increased. In humid air without SO2, sulfite gradually decomposed and some of it changed into sulfate. 相似文献
54.
A. Ohmori Z. Zhou K. Inoue K. Murakami T. Sasaki 《Journal of Thermal Spray Technology》1996,5(2):134-138
The penetration phenomena of liquid manganese (Mn) alloy into porous ZrO2 (8 vvt % Y2O3) coating plasma sprayed on SS400 steel substrate was studied by heating in a vacuum atmosphere. The improvement in mechanical
properties of the coating by heat treatment with liquid Mn alloys was examined. Liquid Mn alloys, such as Mn-Cu, Mn-Sn, and
Mn-In, rapidly penetrated the coating and formed a chemical bond between the coating and the substrate. The densification
of the ZrO2 coating occurred when ZrO2 particles were sintered with liquid Mn alloys that penetrated the porous coating. The dense coating was free of porosity,
and its hardness increased after heat treatment with Mn alloys, compared with assprayed ZrO2 coating. Moreover, the fracture toughness of the coating reached the same levels as those of sintered yttria-stabilized PSZ. 相似文献
55.
Ryu Komatsu Ryo Nakazato Takeru Sasaki Akio Suzuki Naoyuki Senda Takuya Kawata Yasuhiro Jimbo Tomoya Aoyama Naoto Ohno Susumu Kawashima Hisao Ikeda Shingo Eguchi Yoshiharu Hirakata Shunpei Yamazaki Takashi Shiraishi Seiji Yasumoto Masataka Nakada Masataka Sato Chris Bower Darryl Cotton Andrew Matthews Piers Andrew Catalin Gheorghiu Johan Bergquist 《Journal of the Society for Information Display》2015,23(2):41-49
In this study, a 5.9‐inch foldable active‐matrix organic light emitting diode (AMOLED) display was developed. A folding test was performed repeatedly. The display survived the folding test (100,000 folds) with a curvature radius of 2 mm. To protect an organic light emitting diode (OLED) against moisture, inorganic passivation layers are provided on the upper and lower sides of the flexible display. Using our transfer technology, high density passivation layers can be obtained. The measured water vapor transmission rate of the layer is 7 × 10?6 g/m2?day or less, which improves OLED reliability. With these techniques, we have developed a book‐type display, which is repeatedly foldable like a book, and a tri‐fold display including a display area, which is foldable in three. 相似文献
56.
We experimentally found the unexpected phenomena of scattering in laminated polarization splitters (LPS's) composed of a-Si:H-SiO(2) multilayer and studied its mechanism. The scattering phenomena strongly depend on the incident angle and polarization of the incident light. To reduce the scattering loss in LPS's, a multilayer with flat layer boundaries is fabricated with rf bias sputtering. As a result, the insertion loss of the LPS is reduced to ~ 1 × 10(-3) dB/ μm, which is acceptable for practical uses. 相似文献
57.
Formation of Mutagens from the Photooxidations of 2-4-Ring PAH 总被引:1,自引:0,他引:1
58.
Theoretical analysis of the spatial phase-matching loci for second-harmonic generation and multiwave-mixing interactions 总被引:1,自引:0,他引:1
We report a theoretical analysis on spatial noncolinear phase matching of multiwave mixing and its application to a second-harmonic-generation (SHG) experiment. From the numeric calculations, the noncolinear phase-matching properties in general situations were determined. The theory gives the applicability for all noncolinear phase matching. Fine coincidences between theoretical calculations and observed spatial loci on noncollinear phase-matching SHG were confirmed. Relations that allow the calculation of the noncollinear phase-matching angle for any case of SHG are established. As an example, the noncolinear phase-matched SHG pattern on a screen is calculated numerically in the case of SHG of 1064 nm from a Nd:YAG laser under the phase-matched condition for two organic nonlinear crystals: 1-(2-thienyl)-3-(4-methyphenyl) propene-1 (TC-28), which is biaxial, and (2-furyl) methacrylic anhydride (FMA), which is uniaxial. Experimental results compared quite favorably with the theoretical analysis. Noncolinear phase matching may be of great practical interest in optical multiwave-mixing processes, such as optical parametric oscillation and optical parametric amplification. This technique also can be used for the measurement of crystal optical constants. 相似文献
59.
Kojima Masami Tasaki Takafumi Suzuki Yukihisa Kamijo Toshio Hada Aki Kik Alfred Ikehata Masateru Sasaki Hiroshi 《Journal of Infrared, Millimeter and Terahertz Waves》2022,43(3-4):260-271
Journal of Infrared, Millimeter, and Terahertz Waves - Millimeter waves (MMW) absorbed by skin or cornea may induce damage by heat. We have developed a 60 GHz MMW exposure-induced eye... 相似文献
60.
Chung Loong Yiin Suzana Yusup Armando T. Quitain Yoshimitsu Uemura Mitsuru Sasaki Tetsuya Kida 《Clean Technologies and Environmental Policy》2018,20(9):1987-2000
Recently, the development of efficient and environmentally benign solvents has received great attention to replace current harsh organic solvents. In this context, low-transition-temperature mixtures (LTTMs) have emerged as favorable green solvents for biomass delignification. Palm oil biomass, empty fruit bunch (EFB) was pretreated with commercial l-malic acid and microwave hydrothermally extracted cactus malic acid-derived LTTMs at 60, 80, and 100 °C. The LTTMs applied in this study were derived from malic acid–choline chloride–water and malic acid–monosodium glutamate–water with a molar ratio of 2:4:2 and 3:1:5, respectively. Three first-order reactions were used to express the delignification kinetic model of EFB. The first term was based on the initial stage and assigned as infinite due to the fast rate of delignification which could not be detected. The second and third terms were proportional to bulk and residual delignification stages. A good agreement was obtained between the kinetic model and the experimental data obtained in this study with R2?≥?0.91. The activation energies for the delignification reactions using l-malic acid and cactus malic acid-based LTTMs in the bulk and residual stages were approximated as 36–56 and 19–26 kJ/mol and 34–90 and 47–87 kJ/mol, respectively. 相似文献