全文获取类型
收费全文 | 1832篇 |
免费 | 53篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 111篇 |
综合类 | 6篇 |
化学工业 | 447篇 |
金属工艺 | 52篇 |
机械仪表 | 47篇 |
建筑科学 | 25篇 |
能源动力 | 77篇 |
轻工业 | 112篇 |
水利工程 | 7篇 |
石油天然气 | 3篇 |
无线电 | 157篇 |
一般工业技术 | 337篇 |
冶金工业 | 306篇 |
原子能技术 | 42篇 |
自动化技术 | 160篇 |
出版年
2023年 | 16篇 |
2022年 | 11篇 |
2021年 | 33篇 |
2020年 | 15篇 |
2019年 | 33篇 |
2018年 | 20篇 |
2017年 | 30篇 |
2016年 | 37篇 |
2015年 | 24篇 |
2014年 | 47篇 |
2013年 | 88篇 |
2012年 | 61篇 |
2011年 | 107篇 |
2010年 | 72篇 |
2009年 | 77篇 |
2008年 | 103篇 |
2007年 | 82篇 |
2006年 | 59篇 |
2005年 | 67篇 |
2004年 | 53篇 |
2003年 | 76篇 |
2002年 | 51篇 |
2001年 | 28篇 |
2000年 | 36篇 |
1999年 | 29篇 |
1998年 | 138篇 |
1997年 | 74篇 |
1996年 | 65篇 |
1995年 | 37篇 |
1994年 | 32篇 |
1993年 | 40篇 |
1992年 | 23篇 |
1991年 | 15篇 |
1990年 | 17篇 |
1989年 | 23篇 |
1988年 | 14篇 |
1987年 | 10篇 |
1986年 | 10篇 |
1985年 | 18篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 15篇 |
1981年 | 7篇 |
1980年 | 11篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1976年 | 18篇 |
1975年 | 9篇 |
1974年 | 6篇 |
1973年 | 4篇 |
排序方式: 共有1889条查询结果,搜索用时 171 毫秒
51.
Toshio Ogasawara Yuichi Ishida Takashi Ishikawa Takahira Aoki Toshiyuki Ogura 《Composites Part A》2006,37(12):2236-2240
Helium gas permeability of silicate clay (montmorillonite) particles/epoxy nanocomposites was examined. The incorporation of increasing amounts of montmorillonite particles reduced the helium gas permeability. Based on Fick’s law, gas permeation behavior of the nanocomposite was evaluated. With the increase of montmorillonite loading, gas diffusivity decreased, while gas solubility increased. Helium diffusion behavior is in agreement to the numerical results based on the Hatta–Taya–Eshelby theory. It has been revealed that dispersion of nanoscale platelets in polymer is effective in improving gas barrier property. 相似文献
52.
Yuichi Miyahara Kiyoshi Matsubara Zenji Horita Terence G. Langdon 《Metallurgical and Materials Transactions A》2005,36(7):1705-1711
The extrusion/equal channel angular pressing (EX-ECAP) processing procedure, in which magnesium-based alloys are subjected
to extrusion followed by ECAP, was applied to a Mg-7.5 pct Al-0.2 pct Zr alloy prepared by casting. Microstructural inspection
showed the EX-ECAP process was effective in reducing the grain size from ∼21 μm after extrusion to an as-pressed grain size of ∼0.8 μm. It is shown through static annealing that these ultrafine grains are reasonably stable up to 473 K, but grain growth occurs
at higher temperatures. Tensile specimens were cut from the billets prepared by EX-ECAP and testing showed these specimens
exhibited superplasticity at relatively low temperatures with maximum elongations up to >700 pct. By processing through EX-ECAP
to a higher imposed strain and thereby increasing the area fraction of high-angle boundaries, it is demonstrated that there
is a potential for achieving high-strain-rate superplasticity.
This article is based on a presentation made at the Symposium entitled “Phase Transformations and Deformation in Magnesium
Alloys,” which occurred during the Spring TMS meeting, March 14–18, 2004, in Charlotte, NC, under the auspices of the ASM-MSCTS
Phase Transformations Committee. 相似文献
53.
54.
Kiyoshi Matsubara Yuichi Miyahara Zenji Horita Terence G. Langdon 《Metallurgical and Materials Transactions A》2004,35(6):1735-1744
Experiments were conducted to evaluate the utility of a new processing procedure developed for Mg-based alloys in which samples
are subjected to a two-step processing route of extrusion followed by equal-channel angular pressing (designated as EX-ECAP).
The experiments were conducted using a Mg-0.6 wt pct Zr alloy and, for comparison purposes, samples of pure Mg. It is shown
that the potential for successfully using ECAP increases in both materials when adopting the EX-ECAP procedure. For the Mg-Zr
alloy, the use of EX-ECAP produces a grain size of ∼1.4 μm when the pressing is undertaken at 573 K. By contrast, using EX-ECAP with pure Mg at 573 K produces a grain size of ∼26
μm. Tensile testing of the Mg-Zr alloy at 523 and 573 K after processing by EX-ECAP revealed the occurrence of significantly
enhanced ductilities with maximum elongations of ∼300 to 400 pct. 相似文献
55.
Reiji Hattori Shuhei Yamada Yoshitomo Masuda Norio Nihei 《Journal of the Society for Information Display》2004,12(1):75-80
Abstract— We have developed new powder materials that exhibit liquid behavior, which can lead to the realization of novel bistable and reflective displays having paper‐white appearance, high contrast, and quick response. Two types of display were demonstrated, one had 160 × 160 array of pixels and the other had 320 × 320 in a 3.1‐in.‐diagonal viewable image size corresponding to 66 and 132 dpi, respectively. These displays were driven by passive‐matrix addressing. The displays showed a reflectivity of more than 41%, a contrast more than 1:10, and a pixel response time of less than 0.2 msec. The seven‐segment display for use in clocks was also demonstrated. 相似文献
56.
57.
The modeling of particle aggregation under a simple shear flow and the extension of the model to a stirred vessel is described. The model quantitatively demonstrates the change of the number of aggregates with time for each shear rate. This number increased with higher shear rate and, conversely, the aggregate size became small when raising the shear rate. This was because aggregates were broken by the stronger shear force. The number of aggregates for different impellers was determined. The shear rate was back‐calculated from the experimentally obtained aggregate size and the model equation. This shear rate was different from that estimated from the Metzner‐Otto method, consequently, some revisions of the Metzner‐Otto equation might be necessary for its application to particle aggregation. 相似文献
58.
59.
Nanoimprint lithography has two basic steps. The first is the imprint step in which a mold with nanostructures on its surface is pressed into a resin film on a substrate, followed by removal of the mold. The second step is the residual layer removal by a reactive ion etching (RIE). There is no report whether the properties of the imprinted structure after RIE change or not. In this work, the authors evaluated the Young’s modulus of the imprinted pillar after residual layer removal by RIE. In this experiment, hydrogen silsesquioxane (HSQ), a type of spin-on-glass, was used as an imprint material. The residual layer was etched by RIE using CHF3 gas. The Young’s modulus of imprinted pillar after RIE was measured via cantilever method. The Young’s modulus of HSQ pillar after RIE was twice as much as that of HSQ pillar before RIE. From the Fourier transform infrared measurement, it was founds the chemical structure of HSQ was changed by forming network structure due to heating by RIE plasma energy. These results indicate that the mechanical property of imprinted structure was changed in the residual layer removal step by using RIE. 相似文献
60.
Satoshi Nogami Katsuhiko Minoura Nao Kiminami Yui Kitaura Hiromasa Uchiyama Kazunori Kadota Yuichi Tozuka 《Advanced Powder Technology》2021,32(5):1750-1756
Although curcumin is considered to have various therapeutic effects, its use as a functional food or supplement is restricted owing to its low water solubility and bioavailability. To increase the solubility of curcumin in water, the use of polyvinylpyrrolidone (PVP) and vinylpyrrolidone-vinyl acetate copolymers with a pyrrolidone skeleton was noted to be promising. In particular, the bi-component formulations of curcumin/PVP prepared through spray drying exhibited an amorphous state in powder X-ray diffraction observations and temporally increased the apparent solubility of curcumin to over 5000 times that of untreated curcumin; nevertheless, after 24 h, the solubility decreased owing to the unstable supersaturated state of curcumin. The addition of α-cyclodextrin (α-CyD) in the bi-component curcumin/PVP formulation helped maintain the supersaturated state of curcumin, whereas the addition of β- and γ-CyD led to the collapse of the supersaturated state. The addition of α-CyD can likely help inhibit the nucleation and crystal growth of curcumin, through the interaction among the solubilized units of curcumin/PVP and α-CyD. 相似文献