全文获取类型
收费全文 | 1594篇 |
免费 | 80篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 34篇 |
综合类 | 4篇 |
化学工业 | 332篇 |
金属工艺 | 36篇 |
机械仪表 | 40篇 |
建筑科学 | 35篇 |
矿业工程 | 1篇 |
能源动力 | 110篇 |
轻工业 | 151篇 |
水利工程 | 28篇 |
石油天然气 | 42篇 |
无线电 | 257篇 |
一般工业技术 | 298篇 |
冶金工业 | 90篇 |
原子能技术 | 8篇 |
自动化技术 | 215篇 |
出版年
2024年 | 5篇 |
2023年 | 28篇 |
2022年 | 68篇 |
2021年 | 95篇 |
2020年 | 69篇 |
2019年 | 68篇 |
2018年 | 62篇 |
2017年 | 73篇 |
2016年 | 53篇 |
2015年 | 56篇 |
2014年 | 73篇 |
2013年 | 160篇 |
2012年 | 102篇 |
2011年 | 86篇 |
2010年 | 69篇 |
2009年 | 65篇 |
2008年 | 56篇 |
2007年 | 70篇 |
2006年 | 53篇 |
2005年 | 42篇 |
2004年 | 38篇 |
2003年 | 21篇 |
2002年 | 15篇 |
2001年 | 13篇 |
2000年 | 17篇 |
1999年 | 16篇 |
1998年 | 25篇 |
1997年 | 29篇 |
1996年 | 21篇 |
1995年 | 12篇 |
1994年 | 15篇 |
1993年 | 16篇 |
1992年 | 12篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 13篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1979年 | 5篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1963年 | 2篇 |
排序方式: 共有1681条查询结果,搜索用时 15 毫秒
31.
Conventional annealing is a slow, high temperature process that involves heating atoms uniformly, i.e., in both defective and crystalline regions. This study explores an electrical alternative for energy efficiency,where moderate current density is used to generate electron wind force that produces the same outcome as the thermal annealing process. We demonstrate this on a zirconium alloy using in-situ electron back scattered diffraction(EBSD) inside a scanning electron microscope(SEM) and juxtaposing the results with that from thermal annealing. Contrary to common belief that resistive heating is the dominant factor, we show that 5 × 10~4 A/cm~2 current density can anneal the material in less than 15 min at only135?C. The resulting microstructure is essentially the same as that obtained with 600?C processing for360 min. We propose that unlike temperature, the electron wind force specifically targets the defective regions, which leads to unprecedented time and energy efficiency. This hypothesis was investigated with molecular dynamics simulation that implements mechanical equivalent of electron wind force to provide the atomistic insights on defect annihilation and grain growth. 相似文献
32.
Md. Salah Uddin Afsar Mohammad Rashed Iqbal Faruque Sabirin Abdullah Mohammad Tariqul Islam 《计算机、材料和连续体(英文)》2023,76(1):455-469
This study proposed a new royal crown-shaped polarisation insensitive double negative triple band microwave range electromagnetic metamaterial absorber (MA). The primary purpose of this study is to utilise the exotic characteristics of this perfect metamaterial absorber (PMA) for microwave wireless communications. The fundamental unit cell of the proposed MA consists of two pentagonal-shaped resonators and two inverse C-shaped metallic components surrounded by a split ring resonator (SRR). The bottom thin copper deposit and upper metallic resonator surface are disjoined by an FR-4 dielectric substrate with 1.6 mm thickness. The CST MW studio, a high-frequency electromagnetic simulator has been deployed for numerical simulation of the unit cell in the frequency range of 4 to 14 GHz. In the TE mode, the offered MA structure demonstrated three different absorption peaks at 6.85 GHz (C-band), 8.87 GHz (X-band), and 12.03 GHz (Ku-band), with 96.82%, 99.24%, and 99.43% absorptivity, respectively. The electric field, magnetic field, and surface current distribution were analysed using Maxwell’s-Curl equations, whereas the angle sensitivity was investigated to comprehend the absorption mechanism of the proposed absorber. The numerical results were verified using the Ansys HFSS (high-frequency structure simulator) and ADS (advanced design system) for equivalent circuit models. Moreover, the proposed MA is polarisation and incident angle independent. Hence, the application of this MA can be extended to a great extent, including airborne radar applications, defence, and stealth-coating technology. 相似文献
33.
34.
Sujan Kumar Roy Md. Khademul Islam Molla Keikichi Hirose Md. Kamrul Hasan 《International Journal of Speech Technology》2011,14(4):339-349
A novel and robust pitch estimation method is presented in this paper. The basic idea is to reshape the speech signal using
a combination of the dominant harmonic modification (DHM) and data adaptive time domain filtering techniques. The noisy speech
signal is filtered within the ranges of fundamental frequencies to obtain the pre-filtered signal (PFS). The dominant harmonic
(DH) of the PFS is determined and enhanced its amplitude. Normalized autocorrelation function (NACF) is applied to that modified
signal. Then empirical mode decomposition (EMD) based data adaptive time domain filtering is applied to the NACF signal. Partial
reconstruction is performed in EMD domain. The pitch period is determined from the partially reconstructed signal. The experimental
results show that the proposed method performs better than the other recently developed methods for noisy and clean speech
signals in terms of gross and fine pitch errors. 相似文献
35.
S. Islam Z. Bano I. Siddique A.M. Siddiqui 《Computers & Mathematics with Applications》2011,61(6):1507-1516
The steady flow of a non-Newtonian fluid when slippage between the plate and the fluid occurs is considered. The constitutive equations of the fluid are modeled for a fourth-grade non-Newtonian fluid with partial slip; they give rise to nonlinear boundary value problems. Analytical solutions are obtained using powerful analytic techniques for solving nonlinear problems, homotopy perturbation and optimal homotopy asymptotic methods. The results obtained are compared with the numerical results and it is shown that solutions exist for all values of the non-Newtonian parameters. The solutions valid for the no-slip condition for all values of the non-Newtonian parameters can be derived as special cases of the present analysis. Finally the solutions are discussed using a graphical approach. 相似文献
36.
Mursalin Akon Towhidul Islam Xuemin Shen Ajit Singh 《Peer-to-Peer Networking and Applications》2010,3(2):83-99
In this paper, we introduce Systematic P2P Aided Cache Enhancement or SPACE, a new collaboration scheme among clients in a computer cluster of a high performance computing facility to share their caches
with each other. The collaboration is achieved in a distributed manner, and is designed based on peer-to-peer computing model.
The objective is to provide (1) a decentralized solution, and (2) a near optimal performance with reasonably low overhead.
Simulation results are given to demonstrate the performance of the proposed scheme. In addition, the results show that SPACE
evenly distributes work loads among participators, and entirely eliminates any requirement of a central cache manager. 相似文献
37.
38.
Md Baharul Islam Wong Lai-Kuan Wong Chee-Onn 《Multimedia Tools and Applications》2017,76(7):9517-9542
The advancement of digital photography and the popularity of photo sharing social media such as Instagram and Facebook have undoubtedly stimulated growing interest in aesthetics quality improvement. One aspect of photography that contributes to high quality photos is image composition; the spatial arrangement of photo subjects in the image frame. Professional photographers often apply a wealth of photographic composition rules, e.g., rule of thirds, visual balance and simplicity to capture compelling photos. In the recent years, aesthetics-driven recomposition that attempts to computationally modify the composition of an image to mimic a professional photo has started to receive considerable research interest. Researchers have proposed numerous recomposition techniques that utilize a single or a combination of multiple image operators, i.e., cropping, warping and patch rearrangement operators, to modify the composition of an image. In this paper, we present a survey on the state-of-the-arts aesthetic-driven image recomposition. We define the image recomposition problem, outline its objectives, and provide a comprehensive review of the existing image recompositoin techniques, together with a detailed analysis of the effectiveness of each technique in achieving the recomposition objectives. This survey is intended as a good reference for researchers interested in image recomposition. 相似文献
39.
A more efficient and secure ID-based remote mutual authentication with key agreement scheme for mobile devices on elliptic curve cryptosystem 总被引:1,自引:0,他引:1
Recently, Yang and Chang proposed an identity-based remote login scheme using elliptic curve cryptography for the users of mobile devices. We have analyzed the security aspects of the Yang and Chang's scheme and identified some security flaws. Also two improvements of the Yang and Chang's scheme have been proposed recently, however, it has been found that the schemes have similar security flaws as in the Yang and Chang's scheme. In order to remove the security pitfalls of the Yang and Chang and the subsequent schemes, we proposed an enhanced remote user mutual authentication scheme that uses elliptic curve cryptography and identity-based cryptosystem with three-way challenge-response handshake technique. It supports flawless mutual authentication of participants, agreement of session key and the leaked key revocation capability. In addition, the proposed scheme possesses low power consumption, low computation cost and better security attributes. As a result, the proposed scheme seems to be more practical and suitable for mobile users for secure Internet banking, online shopping, online voting, etc. 相似文献
40.