首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   583172篇
  免费   8410篇
  国内免费   2169篇
电工技术   11219篇
综合类   547篇
化学工业   83309篇
金属工艺   24674篇
机械仪表   18692篇
建筑科学   12667篇
矿业工程   2557篇
能源动力   16146篇
轻工业   46954篇
水利工程   5556篇
石油天然气   8814篇
武器工业   21篇
无线电   72242篇
一般工业技术   115619篇
冶金工业   114008篇
原子能技术   12023篇
自动化技术   48703篇
  2021年   4918篇
  2020年   3881篇
  2019年   4990篇
  2018年   8317篇
  2017年   8303篇
  2016年   8894篇
  2015年   5914篇
  2014年   9611篇
  2013年   28493篇
  2012年   15566篇
  2011年   21149篇
  2010年   16879篇
  2009年   18935篇
  2008年   19674篇
  2007年   19450篇
  2006年   17600篇
  2005年   15853篇
  2004年   14969篇
  2003年   14843篇
  2002年   13704篇
  2001年   13604篇
  2000年   12291篇
  1999年   13473篇
  1998年   35588篇
  1997年   24661篇
  1996年   18893篇
  1995年   14489篇
  1994年   12762篇
  1993年   12696篇
  1992年   9119篇
  1991年   8746篇
  1990年   8435篇
  1989年   8007篇
  1988年   7693篇
  1987年   6715篇
  1986年   6606篇
  1985年   7561篇
  1984年   6854篇
  1983年   6171篇
  1982年   5737篇
  1981年   5836篇
  1980年   5459篇
  1979年   5219篇
  1978年   5173篇
  1977年   6133篇
  1976年   8460篇
  1975年   4448篇
  1974年   4199篇
  1973年   4233篇
  1972年   3579篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Journal of Materials Science: Materials in Electronics - The Co1?xZnxFe2O4 (Co–Zn) ferrite nanoparticles with x varying from 0.0 to 0.4 have been manufactured by facile chemical...  相似文献   
2.
Journal of Materials Science: Materials in Electronics - The ZnO and TiO2 nanopowders have been prepared by means of the pulsed laser reactive ablation of metallic (Zn, Ti) targets. The Structural,...  相似文献   
3.
Journal of Materials Science: Materials in Electronics - Non-volatile organic memory devices were fabricated using polystyrene sulfonate (PSS)?+?nitrogen-doped multi-walled carbon...  相似文献   
4.
Journal of Materials Science: Materials in Electronics - In the recent years, metal oxides have attracted more interest for researchers because of their applications in energy and...  相似文献   
5.
Journal of Materials Science: Materials in Electronics - A mixed solution of 2-aminopyridine and succinic acid, with a 1:1 molar ratio, was kept at room temperature to develop a 2-aminopridinium...  相似文献   
6.

The non-centrosymmetric space group organic nonlinear optical single crystal of 4-chloro-2-nitroaniline (4Cl2NA) was developed by slow evaporation method at 40 °C. Grown 4Cl2NA was monoclinic structure with Pc space group which was recognized by single-crystal XRD analysis. An intermolecular contact of 4Cl2NA was visually analysed by Hirshfeld surface analysis. Active functional groups and their respective vibrations were identified by FTIR and FT-Raman spectral analysis. Optical properties were evaluated by UV–Visible spectral analysis. Thermal TG/DTA thermogram analysis and mechanical Vickers hardness analysis revealed that the synthesis material was thermally stable up to 115 °C and mechanical work hardness coefficient (n?=?2.98) confirmed the grown crystal was soft material. Laser beam-irradiated LDT analysis expressed the laser utility limitation of the 4Cl2NA crystal. The NLO second harmonic generation efficiency was tested by Kurtz Perry powder method.

  相似文献   
7.
8.

Real-time continuous and remote health monitoring has become widespread due to the developments in Wireless body area networks (WBANs). Based on the criticality of health data to be transmitted, regular healthcare data and critical emergency health data must be provided differential service. In this paper, we consider the beyond WBAN communication in a system comprising multiple WBANs with different quality of service (QoS) requirements and multiple access points (APs), and propose two hybrid approaches for resource allocation. In the first approach, the AP association to the WBANs and channel allocation to the APs are done jointly and is modelled as an optimization problem, which is computationally complex and it also requires global network information. In order to reduce the involvement of APs in making decisions for resource allocations of WBANs, the problem is reformulated as a Stackelberg game with price update, which guarantees QoS of the critical users. A learning based algorithm, namely distributed learning for Pareto optimality, is used by the normal users, in this second approach. The performance of both the proposed approaches are evaluated and compared, in terms of the throughput of the critical and normal users as well as the QoS guarantee of the critical users.

  相似文献   
9.
Duparc  Estelle  Möller  Frederik  Jussen  Ilka  Stachon  Maleen  Algac  Sükran  Otto  Boris 《Electronic Markets》2022,32(2):727-745
Electronic Markets - The open-source paradigm offers a plethora of opportunities for innovative business models (BMs) as the underlying codebase of the technology is accessible and extendable by...  相似文献   
10.
Inorganic Materials - We have studied the effect of annealing on the chemical and physical properties of mineral-like host matrices for immobilization of the rare-earth–actinide fraction from...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号