全文获取类型
收费全文 | 1394篇 |
免费 | 57篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 9篇 |
综合类 | 1篇 |
化学工业 | 393篇 |
金属工艺 | 54篇 |
机械仪表 | 28篇 |
建筑科学 | 26篇 |
矿业工程 | 1篇 |
能源动力 | 75篇 |
轻工业 | 60篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 166篇 |
一般工业技术 | 365篇 |
冶金工业 | 107篇 |
原子能技术 | 14篇 |
自动化技术 | 157篇 |
出版年
2023年 | 23篇 |
2022年 | 17篇 |
2021年 | 32篇 |
2020年 | 24篇 |
2019年 | 21篇 |
2018年 | 41篇 |
2017年 | 32篇 |
2016年 | 37篇 |
2015年 | 27篇 |
2014年 | 68篇 |
2013年 | 85篇 |
2012年 | 72篇 |
2011年 | 76篇 |
2010年 | 52篇 |
2009年 | 62篇 |
2008年 | 64篇 |
2007年 | 46篇 |
2006年 | 45篇 |
2005年 | 39篇 |
2004年 | 27篇 |
2003年 | 39篇 |
2002年 | 31篇 |
2001年 | 28篇 |
2000年 | 29篇 |
1999年 | 32篇 |
1998年 | 36篇 |
1997年 | 25篇 |
1996年 | 21篇 |
1995年 | 28篇 |
1994年 | 19篇 |
1993年 | 18篇 |
1992年 | 19篇 |
1991年 | 23篇 |
1990年 | 14篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1987年 | 13篇 |
1986年 | 13篇 |
1985年 | 18篇 |
1984年 | 18篇 |
1983年 | 12篇 |
1982年 | 11篇 |
1981年 | 14篇 |
1980年 | 11篇 |
1979年 | 14篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1976年 | 12篇 |
1975年 | 9篇 |
1971年 | 6篇 |
排序方式: 共有1458条查询结果,搜索用时 15 毫秒
91.
High Mn is added in line pipe steels to strengthen them. Also, Mn lowers the phase transformation temperature, which is an
advantage because it lowers the rolling temperature for grain size control. However, Mn retards the kinetics of precipitation
of NbC in thermo-mechanical processing in Nb microalloying steels. In high-grade line pipe steels, the control of strain accumulation
behavior is the key to the control of grain size. Strain accumulation can only be obtained when static recrystallization between
passes could be suppressed. The effect of NbC precipitates on suppressing recrystallization has been widely investigated,
mostly focusing on the Zener pinning of NbC on grain boundaries. However, it is applicable in large strain and long inter-pass
time. In short inter-pass time, such as strip mill rolling, recrystallization behavior is controlled by the complicated interaction
of precipitation with recovery and recrystallization. In this paper, the effect of Mn on strain accumulation during multi-pass
strip mill rolling based on the interaction of precipitates with the activation energy of grain boundary migration and recovery,
and the thermodynamics and kinetics of recrystallization are discussed systematically. 相似文献
92.
Jerusha A. Hema Rajkumari Malaka Narayanan P. Muthukumarasamy Akilandeswari Sambandam Subakanmani Subramanian Murugan Sevanan 《IET nanobiotechnology / IET》2016,10(5):288
The biosynthesis of silver nanoparticles (AgNPs) has been proved to be a cost effective and environmental friendly approach toward chemical and physical methods. In the present study, biosynthesis of AgNPs was carried out using aqueous extract of Zea mays (Zm) husk. The initial colour change from golden yellow to orange was observed between 410 and 450 nm which confirmed the synthesis of AgNPs. Also, dynamic light scattering‐particle size analysis confirmed the average size to be 113 nm and zeta potential value of −28 kV. The morphology of synthesised Zm AgNPs displayed flower‐shaped structure, X‐ray diffraction pattern revealed the strongest peaks at 2θ = 38.6° and 64° which proved that the nanoparticle has the face centred crystalline structure. The Fourier transform infrared spectroscopy results showed strong absorption bands at 1394.53, 2980.02 and 2980.02 cm−1 due to the presence of alkynes, carboxylic acids, alcoholic and phenolic groups. The maximum zone of inhibition was observed against Salmonella typhi (22 mm) and Candida albicans (18 mm). The synthesised nanoparticles exhibited more free radical scavenging activity than the aqueous plant extract. This is the first report on the synthesis of AgNP from Zm husk, delivers the efficient and stable Zm AgNPs through simple feasible approach toward green biotechnology.Inspec keywords: silver, nanoparticles, nanofabrication, light scattering, particle size, X‐ray diffraction, crystal structure, Fourier transform infrared spectra, absorption coefficients, free radicalsOther keywords: green synthesis, silver nanoparticles, biosynthesis, environmental friendly approach, aqueous extract, Zea mays husk, colour change, golden yellow, dynamic light scattering‐particle size analysis, average size, zeta potential value, flower‐shaped structure, X‐ray diffraction pattern, face centred crystalline structure, Fourier transform infrared spectroscopy, absorption bands, alkynes, carboxylic acids, alcoholic groups, phenolic groups, Salmonella typhi, Candida albicans, free radical scavenging activity, aqueous plant extraction, green biotechnology, size 113 nm, wavelength 410 nm to 450 nm 相似文献
93.
Heitham Wady Hari K. K. Subramanian 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(20):2689-2700
The nanoscale features of DNA have made it a useful molecule for bottom‐up construction of nanomaterials, for example, two‐ and three‐dimensional lattices, nanomachines, and nanodevices. One of the emerging applications of such DNA‐based nanostructures is in chemical and biological sensing, where they have proven to be cost‐effective, sensitive and have shown promise as point‐of‐care diagnostic tools. DNA is an ideal molecule for sensing not only because of its specificity but also because it is robust and can function under a broad range of biologically relevant temperatures and conditions. DNA nanostructure‐based sensors provide biocompatibility and highly specific detection based on the molecular recognition properties of DNA. They can be used for the detection of single nucleotide polymorphism and to sense pH both in solution and in cells. They have also been used to detect clinically relevant tumor biomarkers. In this review, recent advances in DNA‐based biosensors for pH, nucleic acids, tumor biomarkers and cancer cell detection are introduced. Some challenges that lie ahead for such biosensors to effectively compete with established technologies are also discussed. 相似文献
94.
The Capacitated Arc Routing Problem (CARP) stands among the hardest combinatorial problems to solve or to find high quality solutions. This becomes even more true when dealing with large instances. This paper investigates methods to improve on lower and upper bounds of instances on graphs with over 200 vertices and 300 edges, dimensions that, today, can be considered of large scale. On the lower bound side, we propose to explore the speed of a dual ascent heuristic to generate capacity cuts. These cuts are next improved with a new exact separation enchained to the linear program resolution that follows the dual heuristic. On the upper bound, we implement a modified Iterated Local Search procedure to Capacitated Vehicle Routing Problem (CVRP) instances obtained by applying a transformation from the CARP original instances. Computational experiments were carried out on the set of large instances generated by Brandão and Eglese and also on the regular size sets. The experiments on the latter allow for evaluating the quality of the proposed solution approaches, while those on the former present improved lower and upper bounds for all instances of the corresponding set. 相似文献
95.
Subramanian Palaniappan Yu-Tsern Chang Chung-Ming Liu Paramasivam Manisankar 《Materials Chemistry and Physics》2011
A facile and sustainable mechanochemical route for the synthesis of undoped polydiphenylamine (PDPA) and inorganic acid doped nanostructures are reported. Field emission scanning electron microscopic (FESEM) images highlighted the formation of distinctly different nanostructures for each of the inorganic acid doped PDPA. Elemental analysis carried out for the polymers revealed the presence of more repeating units in their backbone. The X-ray diffraction (XRD) results of the as-prepared PDPA nanostructures indicated the high degree of crystallinity ever reported for PDPA. Spectroscopic profile of the polymers showed that the prepared PDPA is in a doped conducting form. Electrochemical studies performed for the polymeric particles ascertained the redox behaviour and the good electrochemical activity of obtained PDPA samples. The probable mechanistic aspect behind the formation of PDPA nanostructures through this simple and efficient route is discussed. 相似文献
96.
T. Ramanathan M. A. Muthumanickam K. Subramanian 《Materials and Manufacturing Processes》2000,15(6):845-852
The influence of loading rate, span-to-thickness ratio and fiber volume fraction on composites was studied by three-point bend test on glass fiber reinforced in polyester composite laminate fabricated by compression moulding method. For lower L/h ratio, shear fracture was observed. Tensile fracture was observed for the specimen having higher L/h ratio irrespective of loading rate. Shear fracture dominates at high loading rates. This behavior was interpreted as being due to the fact that the increase in loading rate increases the brittleness of materials, subsequently increasing the defect sensitivity and leading to shear fracture. 相似文献
97.
Bjørn Winther‐Jensen Noel Clark Priya Subramanian Richard Helmer Syed Ashraf Gordon Wallace Leone Spiccia Douglas MacFarlane 《应用聚合物科学杂志》2007,104(6):3938-3947
Conducting polymers such as polypyrrole may be useful in smart packaging products, provided application methods can be developed that circumvent the insolubility and infusibility of these materials. Experiments were conducted in five research areas relevant to the application of polypyrrole to nonrigid substrates. The studies reveal that application of polypyrrole from the liquid phase, either by deposition from depleted bulk solution or inkjet printing dispersions, is unlikely to give films as regular as those produced by vapor phase polymerization. Using the latter approach, two potential methods of applying patterned polypyrrole films to nonrigid substrates were developed. The first used hypochlorite to pattern a continuous film of polypyrrole, previously applied by vapor phase polymerization. The second used inkjet printing to apply an oxidant solution, whose pH had been raised with a volatile base, to nonrigid substrates. The higher pH reduced corrosion of the print head, increasing the lifetime of printers exposed to oxidative compounds. The base was subsequently evaporated by heating, and the dried oxidant used as a template for vapor phase polymerization of polypyrrole. This method gave smooth, shiny and adherent polypyrrole films on papers and polyester transparency, with high resolution. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3938–3947, 2007 相似文献
98.
Nalini P. Subramanian Xuguang LiVijayadurda Nallathambi Swaminatha P. KumaraguruHector Colon-Mercado Gang WuJong-Won Lee Branko N. Popov 《Journal of power sources》2009
Nitrogen-modified carbon-based catalysts for oxygen reduction were synthesized by modifying carbon black with nitrogen-containing organic precursors. The electrocatalytic properties of catalysts were studied as a function of surface pre-treatments, nitrogen and oxygen concentrations, and heat-treatment temperatures. On the optimum catalyst, the onset potential for oxygen reduction is approximately 0.76 V (NHE) and the amount of hydrogen peroxide produced at 0.5 V (NHE) is approximately 3% under our experimental conditions. The characterization studies indicated that pyridinic and graphitic (quaternary) nitrogens may act as active sites of catalysts for oxygen reduction reaction. In particular, pyridinic nitrogen, which possesses one lone pair of electrons in addition to the one electron donated to the conjugated π bond, facilitates the reductive oxygen adsorption. 相似文献
99.
Investigations on nucleation thermodynamical parameters are very essential for the successful growth of good quality single
crystals from high temperature solution. A theoretical estimation of the nucleation thermodynamical parameters like interfacial
energy between the solid Nd123 and its flux BaO-CuO, metastable zone-width, Gibbs free energy, critical energy barrier for
nucleation and critical nucleation radius have been calculated from the knowledge of solubility data and by applying the classical
nucleation theory. Results are discussed to understand the growth kinetics of Nd123 crystals.
Paper presented at the 5th IUMRS ICA98, October 1998, Bangalore 相似文献
100.
G. Prathap G. Subramanian C. Ramesh Babu 《International journal for numerical methods in engineering》1987,24(4):711-724
Exactly integrated isoparametric plane stress elements behave poorly in flexure. The 4-noded element ‘locks’, with errors that progress indefinitely as element aspect ratio increases. Reduced integration of the shear strain energy eliminates this locking entirely. The 8-noded element does not lock, but improves in performance with reduced integration of shear strain energy. Both elements, with their original shape functions, show severe shear stress oscillations in flexure. In this paper we attribute these oscillations to the lack of ‘consistency’ of shear strain fields derived directly from independent field-variable interpolations. We derive error models for specific tractable examples which can confirm the accuracy of this conceptual scheme through digital computation using the finite element models. A field-consistent redistribution strategy for the shear strain field is offered as an elegant procedure to free the elements of spurious oscillations and give a ‘lock’-free performance. 相似文献