全文获取类型
收费全文 | 1190篇 |
免费 | 73篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 298篇 |
金属工艺 | 20篇 |
机械仪表 | 16篇 |
建筑科学 | 12篇 |
能源动力 | 42篇 |
轻工业 | 298篇 |
水利工程 | 5篇 |
石油天然气 | 2篇 |
无线电 | 123篇 |
一般工业技术 | 209篇 |
冶金工业 | 95篇 |
原子能技术 | 3篇 |
自动化技术 | 138篇 |
出版年
2024年 | 9篇 |
2023年 | 26篇 |
2022年 | 85篇 |
2021年 | 94篇 |
2020年 | 78篇 |
2019年 | 83篇 |
2018年 | 91篇 |
2017年 | 62篇 |
2016年 | 52篇 |
2015年 | 54篇 |
2014年 | 60篇 |
2013年 | 79篇 |
2012年 | 46篇 |
2011年 | 48篇 |
2010年 | 43篇 |
2009年 | 35篇 |
2008年 | 36篇 |
2007年 | 31篇 |
2006年 | 22篇 |
2005年 | 11篇 |
2004年 | 14篇 |
2003年 | 8篇 |
2002年 | 10篇 |
2001年 | 5篇 |
2000年 | 16篇 |
1999年 | 10篇 |
1998年 | 31篇 |
1997年 | 25篇 |
1996年 | 12篇 |
1995年 | 8篇 |
1994年 | 14篇 |
1993年 | 11篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1982年 | 2篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1271条查询结果,搜索用时 15 毫秒
101.
This paper proposes a novel secondary frequency regulation technique for an uncertain islanded micro grid (MG). The major motivation of the work is to integrate the intrinsic robustness of the sliding mode control scheme with the disturbance observer to estimate and alleviate the unknown mismatched uncertainties caused by renewable resources and load variations. To this end, a dynamical sliding manifold is first utilized and then a control law is derived with Lyapunov's method which stabilizes the MG dynamics. Moreover, in order to ensure faster time domain responses of the closed‐loop system, we employ a power rate reaching law in our proposed control design. Thereafter, the performances of the introduced control strategy are tested on an islanded MG using MATLAB/Simulink, and robustness analysis is also carried out by considering five different case studies. Further, in contrast to the existing approaches such as robust H ∞ and robust PID control, the proposed strategy renders appealing time domain characteristics such as settling time, peak overshoot, and integral absolute frequency error. 相似文献
102.
Universal Access in the Information Society - The number of Web sites is growing exponentially and so are the people who are accessing them on mobile devices including people with special... 相似文献
103.
Ammar Amran Manmeet Kaur Mahinderjit Singh 《Information Security Journal: A Global Perspective》2018,27(2):119-131
Security warning is a form of computer dialog communication used to inform the users on the risks of allowing random applications to run on a computer system. Accordingly, it is specifically designed to impersonate a legitimate security alerting function (e.g., notify, warn, and advice) to a user about the consequence effect of an action. However, most of the computer users tend to ignore those security warnings conveying the same message over and over again. This eventually leads to habituation. Considering the fact that there is a significant lack of focus paid to address this issue, the main objective of this article is to describe and summarize the related studies on users’ habituation to the security warnings. This article presents a systematic literature review to explore the current key issues, challenges, and the possible solutions related to habituation effects in security warnings. It is expected that this article could contribute to a more complete understanding of the habituation effects in security warnings and eventually bring benefits to the research communities or general publics. 相似文献
104.
Thermal decomposition of cobalt tris(malonato)ferrate(III)trihydrate precursor, Co3[Fe(CH2C2O4)3]·3H2O has been investigated from ambient temperature to 600 °C in static air atmosphere using various physico-chemical techniques, i.e. TG–DTG–DSC, XRD, Mössbauer and IR spectroscopic techniques. The precursor undergoes dehydration and decomposition simultaneously to yield cobalt malonate and iron(II) malonate intermediates at 205 °C. At higher temperature (325 °C) these intermediate species undergo exothermic decomposition to yield CoO and α-Fe2O3, respectively. Finally cobalt ferrite, CoFe2O4, has been obtained as a result of solid–solid reaction between Fe2O3 and CoO at a temperature (380 °C) much lower than that of ceramic method. SEM analysis of the final thermolysis product reveals the formation of monodisperse cobalt ferrite nano-particles with an average particle size of 45 nm. Magnetic studies show that these particles have a saturation magnetization of 3095 G and Curie temperature of 504 °C. Lower magnitude of these parameters as compared to the bulk values is attributed to the smaller particle size. 相似文献
105.
Austenitization process of three SG irons with varying compositions and as cast matrix microstructure has been studied at
three austenitization temperatures of 850, 900 and 950C for different time periods. Microstructure, hardness and X-ray diffraction
have been used to reveal the nature of dependence of the process on austenitization temperature, time and as cast structure.
The optimum austenitization time is maximum for ferritic and minimum for pearlitic matrix. 相似文献
106.
The optical and electrical properties of the conducting polymer poly(3-hexylthiophene) and single walled carbon nanotube (SWCNT) composites have been investigated. The composites were prepared by dispersing carbon nanotubes in the polymer matrix already dissolved in 1,2-dichlorobenzene. The optical absorption, photoluminescence (PL) and electrical conductivity of the composite was studied as a function of SWCNT concentration in the solution. The absorption coefficient of the polymer was found to be unaffected upto a SWCNT concentration 5% w/w. However a minor decrease in the absorption in visible region was observed for higher SWCNT concentrations. The intensity of PL emission from the composite was measured and was found to decrease with the increase in SWCNT concentration. For a SWCNT concentration of 30% w/w, ∼90% of the PL was quenched, indicating an ultra fast transfer of photoinduced charges from donor polymer to acceptor SWCNT. Direct current conductivity of the composite film was found to increase rapidly with the increase in SWCNT concentration and an increase of ∼5 orders of magnitude was observed for a 30% w/w concentration. The enhancement in conductivity is explained in terms of percolation theory with an estimated percolation threshold of 2% w/w. 相似文献
107.
Paramjit Kaur Divya Sareen Sandeep Kaur Kamaljit Singh 《Inorganic chemistry communications》2009,12(3):272-275
A triarylmethane dye 1 detects CN? from water and shows remarkable selectivity over other anions and dramatic color changes, in solution as well as when dyed. The pH stability of 1 in the range of 1.2–10.7 offers additional advantage in the sensing process under physiological conditions. 相似文献
108.
This review is focused on the two avenues of development that promise a major impact on future ocular drug therapeutics: bioadhesives, including hydrogels and other agents like carbopols, polyacrylic acids, chitosan, etc., and penetration enhancers, including different surfactants, calcium chelators, etc. The capacity of some polymers to adhere to the mucin coat covering the conjunctiva and the corneal surface of the eye forms the basis for ocular mucoadhesion. These systems markedly prolong the residence time of a drug in the conjunctival sac, since clearence is now controlled by the much slower rate of mucus turnover rather than the tear turnover rate. But improving the corneal drug retention alone is inadequate in bringing about a significant improvement of drug bioavailability. Another approach consists of transiently increasing the pentration characteristics of the cornea with appropriate substances, known as penetration enhancers or absorption promoters. The main aim of this article is to give an insight into the potential application of mucoadhesives and corneal penetration enhancers for the conception of innovative opthalmic delivery appraoches, to decrease the systemic side effects, and create a more focused effect, which may be achieved with lower doses of the drug. Ophthalmic formulations based on these mucoadhesives and penetration enhancers are simple to manufacture and exhibit an excellent tolerance when administered into the cornea. The use of the former considerably prolongs the corneal contact time and the use of the latter increases the rate and amount of drug transport. The various corneal epithelial barriers along with the major routes of transport of drugs are discussed. The article includes a list of the various substances in use or under investigation for the aforementioned properties, along with their mechanisms of action. A fair appraisal of the subject with regard to these two therapeutic approaches and any expected ill effects has been made. 相似文献
109.
Silicon - Hydro machinery components such as turbines, pipes, guide vanes, and pumps suffer from severe slurry erosion caused by the abrasive particles entrained in working fluid. In the current... 相似文献
110.
Mohar Satinder Singh Goyal Sonia Kaur Ranjit 《Wireless Personal Communications》2021,116(4):2835-2853
Wireless Personal Communications - For the optimal performance of wireless sensor networks in different areas of applications needs to maximize the coverage area of sensor nodes. The coverage of... 相似文献