全文获取类型
收费全文 | 2945篇 |
免费 | 217篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 51篇 |
综合类 | 8篇 |
化学工业 | 735篇 |
金属工艺 | 46篇 |
机械仪表 | 68篇 |
建筑科学 | 113篇 |
矿业工程 | 4篇 |
能源动力 | 231篇 |
轻工业 | 361篇 |
水利工程 | 46篇 |
石油天然气 | 19篇 |
无线电 | 411篇 |
一般工业技术 | 557篇 |
冶金工业 | 113篇 |
原子能技术 | 15篇 |
自动化技术 | 397篇 |
出版年
2024年 | 6篇 |
2023年 | 72篇 |
2022年 | 130篇 |
2021年 | 253篇 |
2020年 | 161篇 |
2019年 | 137篇 |
2018年 | 196篇 |
2017年 | 164篇 |
2016年 | 178篇 |
2015年 | 128篇 |
2014年 | 179篇 |
2013年 | 240篇 |
2012年 | 188篇 |
2011年 | 226篇 |
2010年 | 135篇 |
2009年 | 140篇 |
2008年 | 88篇 |
2007年 | 83篇 |
2006年 | 76篇 |
2005年 | 54篇 |
2004年 | 42篇 |
2003年 | 45篇 |
2002年 | 27篇 |
2001年 | 19篇 |
2000年 | 18篇 |
1999年 | 18篇 |
1998年 | 27篇 |
1997年 | 15篇 |
1996年 | 19篇 |
1995年 | 13篇 |
1994年 | 6篇 |
1993年 | 10篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 6篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有3175条查询结果,搜索用时 31 毫秒
991.
Md. Zaidul I. S. Nik Norulaini Mohd. Omar A. K. Hiroaki Yamauchi Takahiro Noda 《Starch - St?rke》2007,59(6):269-276
Multiple linear regression equations were developed to correlate the granule size distribution, composition, and minerals content with the Rapid Visco Analyser (RVA) pasting properties of potato starches of different cultivars. From the experimental values and the values of the regression coefficients, it could be observed that a higher level of amylose resulted in a lower peak viscosity (PV) and breakdown (BD) and higher setback (SB) and peak viscosity temperature (PVT) in the potato starches. The reverse was observed when the phosphorus content was higher. Smaller granule size was associated with a decrease in the PVT, whereas larger granules demonstrated higher PV, BD, and SB values in the potato starches. A higher calcium content was associated with a decrease in PV and an increase in BD, SB, and PVT. On the other hand, higher potassium was associated with an increase in PV, BD, SB, and PVT. The sodium contents demonstrated a higher PV and SB, and the reverse was observed in the BD and PVT. It is difficult to conclude the precise role of magnesium ions to the RVA properties although as divalent cations, they may have similar effect as calcium. From the positive and negative values of the regression coefficients it was shown that the correlation is useful for determining more precise values of the RVA pasting properties using a multiple linear regression equation. The correlations were also useful for predicting the effects of the starch composition and minerals on the RVA pasting properties. 相似文献
992.
Wireless Personal Communications - The current state of aerosols retention and loading over West Africa requires urgent consideration to avert environmental disaster which include telecommunication... 相似文献
993.
994.
995.
Electrowetting-induced microwater droplet transports in parallel-plate and open-plate electrowetting-on-dielectrode (EWOD) have been studied numerically. The governing equations for three-dimensional transient microfluidic flow are solved by a finite volume scheme with a two-step projection method on a fixed computational domain. The free surface of the droplet is tracked by the coupled level set and volume-of-fluid (CLSVOF) method with the surface tension force determined by the continuum surface force (CSF) model. The results of the numerical model have been validated with published experimental data and the physics of droplet transport have been investigated. A parametric study has been performed in which the effects of voltage amplitude, channel gap, and electrode size have been examined. 相似文献
996.
Dan Deng Xingwang Li Varun Menon Md Jalil Piran Hui Chen Mian Ahmad Jan 《Digital Communications & Networks》2022,8(4):415-421
Non-Orthogonal Multiplex Access (NOMA) can be deployed in Unmanned Aerial Vehicle (UAV) networks to improve spectrum efficiency. Due to the broadcasting feature of NOMA-UAV networks, it is essential to focus on the security of the wireless system. This paper focuses on maximizing the secrecy sum rate under the constraint of the achievable rate of the legitimate channels. To tackle the non-convexity optimization problem, a reinforcement learning-based alternative optimization algorithm is proposed. Firstly, with the help of successive convex approximations, the optimal power allocation scheme with a given UAV trajectory is obtained by using convex optimization tools. Afterwards, through plenty of explorations of the wireless environment, the Q-learning networks approach the optimal location transition strategy of the UAV, even without the wireless channel state information. 相似文献
997.
Pristine polyelectrolyte multilayers (PEMs) composed of poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS) were treated with an anionic surfactant to prepare rough and porous templates formed by surfactant-induced polyelectrolyte (PE) desorption from pristine film. These templates served as a base substrate for the growth of fresh multilayers using the same polyelectrolyte pair. Growth solutions with or without NaCl salt were used for the formation of fresh multilayers. The growth behavior of fresh multilayers on rugged PEMs was much different than that of a conventional film. The fresh multilayers on templates showed both nonlinear and linear growth behaviors and their surface morphologies differed from those of the rugged template or the pristine film. Unique adsorption behaviors were also observed when PEs were adsorbed onto the templates. UV-Vis spectroscopy and atomic force microscopy (AFM) were employed to study the entire system. These results of the present study offer a unique perspective on the usual model of PEM growth, and provide an alternative route for construction of PEMs with different architectures. 相似文献
998.
999.
Saqib Ali Anjum Naveed Md Asri Bin Ngadi Junaid Ahsenali Chaudhry 《Wireless Personal Communications》2014,75(4):1983-2003
The Quality of Service of Multi-Channel Multi-Radio Wireless Mesh Networks is adversely affected by the complex behavior of interference patterns present between the sender and receiver of a link. This behavior is usually captured using wireless channel interference models. The accuracy of the interference model is highly dependent on the interaction of the Carrier Sense Multiple Access with Collision Avoidance Medium Access Control (CSMA/CA MAC) protocol based on the geometric location of the sender and receiver of the link. Therefore, this paper presents a nomenclature of interference modeling schemes available in Wireless Mesh Network (WMN) literature with respect to the geometric location of the sender and receiver of a link. The behavior and limitations of each model are analyzed with the help of empirical examples. The results indicate that Garetto’s model of interfering links is the best choice to model wireless channel interference in WMNs. In addition, this study provides an interference analysis of Garetto’s model for the two link case by computing the conditional packet loss probability of each class of interfering link. The probability analysis concluded that the links with disconnected senders are highly interfering compared to sender connected links. Further, the analysis will assist researchers and engineers in relay node placement, capacity analysis, channel assignment, and topology control schemes in the WMN. 相似文献
1000.
Wanzi Xie Hongbo Wang Hongying Yang Zhihui Yang Jingjing Zhang Md Kamruzzaman 《Color research and application》2022,47(1):40-48
The color depth, an important attribute of color, can reflect the amount of dye partly, which has important functions on the evaluation of color-fastness and strength of dyes, dyeing effect of fabric, computer color matching, and so on. Natural Color System, an internationally accepted color system, orders colors by three parameters (blackness, chromaticness, and hue). The color depth has not been specified within the Natural Color System. This article tries to find the regularity of the sample with equal-depth in Natural Color System. Firstly, 1950 color samples in Natural Color System were measured using an X-Rite Color i7 Spectrophotometer, and their color depths were calculated by five color depth formulas. Then, trend analysis and mathematical modeling methods were used to achieve the connection between the color depth and the notations of Natural Color System basing on color depth theories. Results show that, in Natural Color System, the color samples with the same distance to pure white do not have equal depth; but the color samples with the same nuance (equal blackness, whiteness and chromaticness) have broadly equal color depth, and their average coefficient values are lower than that of Society of Dyers and Colourists Standard Depths. Besides, regressive formulas were built, with which the color depths of any chips in Natural Color System can be calculated broadly by their notation. 相似文献