全文获取类型
收费全文 | 1346篇 |
免费 | 134篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 26篇 |
综合类 | 5篇 |
化学工业 | 360篇 |
金属工艺 | 57篇 |
机械仪表 | 62篇 |
建筑科学 | 7篇 |
能源动力 | 55篇 |
轻工业 | 141篇 |
水利工程 | 7篇 |
石油天然气 | 2篇 |
无线电 | 232篇 |
一般工业技术 | 307篇 |
冶金工业 | 30篇 |
原子能技术 | 53篇 |
自动化技术 | 141篇 |
出版年
2023年 | 3篇 |
2022年 | 12篇 |
2021年 | 30篇 |
2020年 | 16篇 |
2019年 | 34篇 |
2018年 | 46篇 |
2017年 | 38篇 |
2016年 | 62篇 |
2015年 | 56篇 |
2014年 | 73篇 |
2013年 | 86篇 |
2012年 | 83篇 |
2011年 | 127篇 |
2010年 | 77篇 |
2009年 | 97篇 |
2008年 | 92篇 |
2007年 | 78篇 |
2006年 | 56篇 |
2005年 | 38篇 |
2004年 | 42篇 |
2003年 | 55篇 |
2002年 | 38篇 |
2001年 | 39篇 |
2000年 | 29篇 |
1999年 | 33篇 |
1998年 | 22篇 |
1997年 | 10篇 |
1996年 | 18篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 13篇 |
1992年 | 3篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有1485条查询结果,搜索用时 15 毫秒
71.
Jo Wol Soon Kim Sung Dae Jeong Soo Kyung Oh Su Jung ParK Moon Taek Lee Chang Geun Kang Young- Rok Jeong Min Ho 《Food science and biotechnology》2022,31(4):433-441
Food Science and Biotechnology - Resveratrol is known to have anti-inflammatory properties. However, high-dose resveratrol is required for optimal anti-inflammatory effects. HS-1793 is a derivative... 相似文献
72.
Yifei Li Akshay Singh Kate Reidy Seong Soon Jo Frances M. Ross Rafael Jaramillo 《Advanced functional materials》2020,30(36)
The synthesis of large‐area TiS2 thin films is reported at temperatures as low as 500 °C using a scalable two‐step method of metal film deposition followed by sulfurization in an H2S gas furnace. It is demonstrated that the lowest‐achievable sulfurization temperature depends strongly on the oxygen background during sulfurization. This dependence arises because Ti? O bonds present a substantial kinetic and thermodynamic barrier to TiS2 formation. Lowering the sulfurization temperature is important to make smooth films, and to enable integration of TiS2 and related transition metal dichalcogenides—including metastable phases and alloys—into device technology. 相似文献
73.
Kyung Soon Jang Tae Won Kang Kee Sung Lee Chul Kim Tae-Woo Kim 《Journal of Mechanical Science and Technology》2010,24(6):1265-1271
Curved structural members are widely seen in our surroundings, such as railway supports in playgrounds resembling a c-ring
structure. The common geometry of the curved member consists of a segment of a circular ring with a uniform width. The curved
section is of constant width in most cardiovascular stents. This study focuses on curved strut members whose width changes
along the curved segment. The location of the maximum equivalent stress varies depending on the manner in which the width
changes. When the width is constant or larger toward the top, the maximum equivalent stress is developed at the top. Meanwhile,
when the area is reduced toward the bottom, the largest equivalent stress is developed some distance from the top. Simple
equations, based on the mechanics of materials and the theory of elasticity, were compared favorably with the results from
finite element analysis. Included are elaborations of the distribution of the change of stress. The suggested strategy of
changing the width, with refinements, could be applied to the optimal design of structural members, including pipes and medical
devices such as stents. 相似文献
74.
The current efficiency of polymer light-emitting diodes (PLEDs) were improved using a quantum dot interlayer between a hole transport layer and an emitting layer. The quantum dot interlayer played a role of controlling the hole transport in the PLEDs and enhanced the charge balance in the emitting layer. The current efficiency of the PLEDs was increased by more than 20% by the quantum dot interlayer. In particular, the efficiency improvement was significant at high luminance due to reduced efficiency roll-off in the quantum dot-embedded PLEDs. 相似文献
75.
Eun Kyoung Kim Jong Seok Bae Seung Soon Im Byoung Chul Kim Yang Kyoo Han 《应用聚合物科学杂志》2001,80(9):1388-1394
To obtain long branched polybutylene succinate (PBS), modified PBSs were prepared by introducing a branching agent, trimethylol propane (TMP), to the polycondensation system of succinic acid and 1,4‐butanediol. Molecular parameters such as absolute molecular weight and root‐mean‐square (RMS) radius of the modified PBSs were measured by gel permeation chromatography (GPC) with a multiangle laser light‐scattering (MALLS) detector. The RMS radius of TMP05, PBS prepared by incorporating 0.5 wt % TMP during polycondensation, was the smallest of all PBSs tested at the same molecular weight. The notable shear thinning and much reduced loss tangent for TMP05 qualitatively supported the difference in their molecular structures predicted by GPC. The analytical results indicated that introducing 0.5 wt % TMP produced PBS with chain branches long enough to produce molecular entanglements. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1388–1394, 2001 相似文献
76.
This paper proposes a distributed borrowing addressing (DIBA) scheme to solve problems of failure in address assignments resulting from limited tree depth and width when the distributed address assignment mechanism is used in a ZigBee/IEEE 802.15.4 wireless sensor network. DIBA is a method of borrowing addresses from neighbor nodes for newly entering nodes and assigning the borrowed addresses. Its network or sensing coverage can increase with almost the same overhead as the existing method. DIBA is a simple and lightweight means of addressing and routing, making it suitable for wireless sensor networks. Simulations showed that DIBA is a distributed addressing scheme with consistently excellent performance. 相似文献
77.
The effect of tool edge radius on the chip formation behavior of tool-based micromachining 总被引:2,自引:1,他引:1
Keng Soon Woon Mustafizur Rahman 《The International Journal of Advanced Manufacturing Technology》2010,50(9-12):961-977
Chip formation behavior of micromachining is governed by the tool edge radius effect as reflected by the characteristic changes in plastic deformation at varying combinations of tool edge radius, r, and undeformed chip thickness, a. At high a/r above unity, concentrated plastic deformation takes place at the primary and secondary deformation zones akin to conventional macromachining. Decreasing a/r below unity promotes localized deformation ahead of the tool edge radius, with the expansion in fraction of the primary deformation zone and the simultaneous shrinkage in fraction of the secondary deformation zone following the reductions in total tool–chip contact length. Further decrease of a/r below a critical threshold brings forth a total suppression of secondary deformation zone and resulted in an ultimate localization of plastic deformation ahead of the tool edge radius. This is perceived as a transition in chip formation mechanism from concentrated shearing to a thrust-oriented behavior. 相似文献
78.
Polypyrrole (PPy) microstructures with diverse shapes were synthesized in an aqueous inorganic salt medium including organic crystals and pyrrole (Py). A series of sulfobenzoic acid salt forms with various cations (K+, Na+, Li+, NH4+) in different positions (para, meta, ortho) of the sulfonate group on the benzene ring were used to form organic crystals as sacrificial templates. Using these crystals, we produced five different shapes of PPy microstructures (hexagonal microplates, curled nanofibers, lozenge-shaped microplates, rigid rods, parallelogram microplates), which replicated the shapes of the organic crystal templates through electrostatic interaction between the anionic crystal surfaces and the cationic PPy chains. In contrast, PPy that was polymerized without crystals showed bulky agglomerates of 200-500 nm size. The electrical properties were dictated by the molecular structures of the organic salt molecules used. While the highest conductivity (200.3 Scm−1) was observed in PPy using crystals of para-linked 4-sulfobenzoic acid monopotassium salt, the lowest conductivity (0.8 Scm−1) was observed in PPy prepared in the presence of crystals of ortho-linked 2-sulfobenzoic acid monoammonium salt. 相似文献
79.
In this work, we investigated the effects of quantum dot (QD) annealing (as-grown, 600°C-annealed, and 750°C-annealed) on the preliminary performances of 1.3-μm InAs-InGaAs-GaAs quantum dot electroabsorption modulators (QD-EAMs). Both extinction ratio and insertion loss were found to vary inversely with the annealing temperature. Most importantly, the 3-dB response of the 750°C-annealed lumped-element QD-EAM was found to be 1.6 GHz at zero reverse bias voltage - the lowest reverse bias voltage reported. We believe that this work will be beneficial to researchers working on on-chip integration of QD-EAMs with other devices since energy consumption will be an important consideration. 相似文献
80.
Ultra-thin polypyrrole nanosheets (UPNSs) are fabricated by organic crystal surface-induced polymerization (OCSP) of pyrrole in an aqueous suspension containing hydrated crystals of sodium decylsulfonate (C10SO3Na) below the Krafft temperature using FeCl3 as an oxidant. The hydrated C10SO3Na crystals are used as templates through electrostatic binding of the cationic polypyrrole (PPy) chains oxidized by Fe(III) ions on the anionic C10SO3Na crystal surface. The resulting UPNSs have a single layer thickness of ∼21 nm, widths between 2 and 6 μm, and lengths greater than 10 μm. The UPNSs are composed of a single continuous PPy domain. Moreover, the UPNSs exhibit higher conductivity (30.6 Scm−1) and longer conjugation lengths than the PPy nanoparticles (2.4 Scm−1) prepared using emulsion polymerization. We systematically investigate the UPNSs as gas sensors for detecting and quantifying toxic gases such as HCl and NH3. The UPNSs exhibit much higher gas sensitivity and faster response times compared with the PPy nanoparticles. 相似文献