全文获取类型
收费全文 | 4208篇 |
免费 | 106篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 87篇 |
综合类 | 8篇 |
化学工业 | 811篇 |
金属工艺 | 102篇 |
机械仪表 | 64篇 |
建筑科学 | 187篇 |
矿业工程 | 22篇 |
能源动力 | 62篇 |
轻工业 | 451篇 |
水利工程 | 20篇 |
石油天然气 | 10篇 |
无线电 | 339篇 |
一般工业技术 | 558篇 |
冶金工业 | 1158篇 |
原子能技术 | 26篇 |
自动化技术 | 415篇 |
出版年
2021年 | 52篇 |
2020年 | 49篇 |
2019年 | 41篇 |
2018年 | 65篇 |
2017年 | 45篇 |
2016年 | 57篇 |
2015年 | 50篇 |
2014年 | 64篇 |
2013年 | 193篇 |
2012年 | 92篇 |
2011年 | 157篇 |
2010年 | 106篇 |
2009年 | 121篇 |
2008年 | 132篇 |
2007年 | 124篇 |
2006年 | 134篇 |
2005年 | 120篇 |
2004年 | 93篇 |
2003年 | 95篇 |
2002年 | 106篇 |
2001年 | 70篇 |
2000年 | 59篇 |
1999年 | 84篇 |
1998年 | 162篇 |
1997年 | 121篇 |
1996年 | 105篇 |
1995年 | 69篇 |
1994年 | 82篇 |
1993年 | 93篇 |
1992年 | 70篇 |
1991年 | 50篇 |
1990年 | 67篇 |
1989年 | 67篇 |
1988年 | 65篇 |
1987年 | 52篇 |
1986年 | 40篇 |
1985年 | 68篇 |
1984年 | 74篇 |
1983年 | 66篇 |
1982年 | 58篇 |
1981年 | 51篇 |
1980年 | 55篇 |
1979年 | 48篇 |
1978年 | 50篇 |
1977年 | 62篇 |
1976年 | 75篇 |
1975年 | 48篇 |
1974年 | 44篇 |
1973年 | 36篇 |
1972年 | 42篇 |
排序方式: 共有4320条查询结果,搜索用时 15 毫秒
1.
2.
Amun Amri Ahmad Fadli Zhong-Tao Jiang Chun-Yang Yin M. Mahbubur Rahman Hantarto Widjaja Syamsu Herman Silvia Reni Yenti M. Miftahul Munir Gadang Priyotomo M. Iqbal Neni Frimayanti 《Ceramics International》2018,44(13):15274-15280
The copper and cobalt oxides composites coatings on aluminum substrates have been successfully synthesized via sol-gel method using nitrate-based sol precursors. The composites were characterized by X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), and UV–Vis–NIR spectrophotometry. The sol-gel reactions were discussed and Molecular Dynamics (MD) simulation was integrated into the study to predict molecules assembly properties. The XRD analyses revealed that the CuO and the Co3O4 composites were formed after the annealing process with the average difference of the calculated lattice parameters compared to ICDDs was 1.17%. The surface electronic structure was mainly consisted of tetrahedral Cu(I), octahedral Cu(II), tetrahedral Co(II), octahedral Co(III) as well as surface, sub-surface and lattice oxygen O?. The XRD, XPS and MD simulation results showed that there was minimal (or possibly non-existing) indication of copper-cobalt mixed phase oxides formations. FESEM and AFM surveys revealed that the coating had a porous surface composed of interlinked nanoparticles in the range of ~?10 to ~?40?nm. UV–Vis–NIR reflectance spectra showed that the sol precursors concentration and the dip-drying cycle significantly influenced the absorptance value with optimum absorptance (α) of 88.7% exhibited by coating synthesized using sol concentration of 0.1?M and 10 dip-drying cycles. High absorptance value and simplicity in the synthesis process render the coatings to be very promising candidates for solar selective absorber (SSA) applications. 相似文献
3.
4.
5.
6.
Hans-Jürgen Odenthal Herbert Pfeifer Ina Lemanowicz Rainer Gorissen 《Metallurgical and Materials Transactions B》2002,33(2):163-172
The present work describes quantitative digital particle image velocimetry measurements of a full-scale water model of a thin
slab mold. Different casting speeds and two submerged entry nozzles with one and two outlet ports have been investigated.
The flow pattern of the single-port nozzle shows a counterclockwise-rotating double vortex that is nearly steady-state but
leads to high stationary surface waves. The flow jets out of the two-port nozzle oscillate and produce a transient flow pattern
with low wave amplitudes. The amplitudes for the one-port nozzle show a linear variation with the volumetric flow rate. The
experimental results lead to a good interpretation of the flow phenomena and are used to validate steady-state numerical simulations
with the commercial program, CFX, on the basis of the Reynolds equations. To describe anisotropic turbulence effects, the
Reynolds stress model (RSM) is used for the flat single-port nozzle and the standard k-ɛ model for the mold flow. The calculated mean velocities and wave amplitudes, predicted from pressure distribution at the
water surface, are generally in the consensus of the experimental data.
An erratum to this article is available at . 相似文献
7.
8.
Herman Neufeld 《今日电子》2008,(9)
第一代NV SRAM模块问世近20年来,NVSRAM技术不断更新,以保持与各种应用同步发展,同时满足新的封装技术不断增长的需求。 相似文献
9.
The vicissitudes of the Israeli-Palestinian peace process since 1967 are analyzed using attitudes and related concepts where relevant. The 1967 war returned the two peoples' zero-sum conflict around national identity to its origin as a conflict within the land both peoples claim. Gradually, new attitudes evolved regarding the necessity and possibility of negotiations toward a two-state solution based on mutual recognition, which became the building stones of the 1993 Oslo agreement. Lacking a commitment to a final outcome, the Oslo-based peace process was hampered by reserve options, which increased avoidance at the expense of approach tendencies as the parties moved toward a final agreement. The resulting breakdown of the process in 2000 produced clashing narratives, reflecting different anchors for judgment and classical mirror images. Public support for violence increased, even as public opinion continued to favor a negotiated two-state solution. Reviving the peace process requires mutual reassurance about the availability of a partner for negotiating a principled peace based on a historic compromise that meets the basic needs and validates the identities of both peoples. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
Sood Johanna R.; Cisek Edward; Zimmerman Joan; Zaleski Ellen H.; Fillmore Herbert H. 《Canadian Metallurgical Quarterly》2003,48(1):44
Objective: To replicate and extend P. A. Lichtenberg and colleagues' (1996) cross-disciplinary intervention to improve physical and mental health among older adults. Participants: 14 depressed older adults (6 treatment, 8 control). Setting: The short-term rehabilitation unit of an urban nursing home. Intervention: Occupational therapists were trained to treat depression using pleasant events and cognitive-behavioral therapies. Outcome Measures: Geriatric Depression Scale, the Short Form-12, and the Multi-Level Assessment Instrument: Activities of Daily Living. Results: No significant group differences were found in physical or mental health. However, more control group members (75%) than treatment group members (33%) were depressed at study completion. Conclusions: The treatment of depressive symptoms can be integrated with a nonmental health treatment modality. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献