全文获取类型
收费全文 | 650篇 |
免费 | 28篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 181篇 |
金属工艺 | 16篇 |
机械仪表 | 14篇 |
建筑科学 | 18篇 |
矿业工程 | 1篇 |
能源动力 | 48篇 |
轻工业 | 57篇 |
水利工程 | 5篇 |
无线电 | 63篇 |
一般工业技术 | 148篇 |
冶金工业 | 19篇 |
原子能技术 | 2篇 |
自动化技术 | 102篇 |
出版年
2024年 | 1篇 |
2023年 | 17篇 |
2022年 | 36篇 |
2021年 | 43篇 |
2020年 | 45篇 |
2019年 | 25篇 |
2018年 | 34篇 |
2017年 | 39篇 |
2016年 | 28篇 |
2015年 | 17篇 |
2014年 | 29篇 |
2013年 | 52篇 |
2012年 | 28篇 |
2011年 | 31篇 |
2010年 | 28篇 |
2009年 | 41篇 |
2008年 | 27篇 |
2007年 | 24篇 |
2006年 | 16篇 |
2005年 | 6篇 |
2004年 | 8篇 |
2003年 | 6篇 |
2002年 | 10篇 |
2001年 | 3篇 |
2000年 | 9篇 |
1999年 | 9篇 |
1998年 | 8篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有682条查询结果,搜索用时 15 毫秒
51.
52.
In this article, we report the preparation of conducting natural rubber (NR) with polyaniline (Pani). NR was made into a conductive material by the compounding of NR with Pani in powder form. NR latex was made into a conductive material by the in situ polymerization of aniline in the presence of NR latex. Different compositions of Pani–NR semi‐interpenetrating networks were prepared, and the dielectric properties of all of the samples were determined in microwave frequencies. The cavity perturbation technique was used for this study. A HP8510 vector network analyzer with a rectangular cavity resonator was used for this study. S bands 2–4 GHz in frequency were used. Thermal studies were also carried out with thermogravimetric analysis and differential scanning calorimetry. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2682–2686, 2007 相似文献
53.
A numerical investigation has been conducted to explore the steady nonlinear low Prandtl number flow/thermal transition in a differentially heated cubic cavity. For small values of Rayleigh number (Ra), it is observed that initially there was only one symmetric steady-state solution. When the Ra was amplified, the system bifurcates from one fixed-point solution to the two stationary solutions, namely, Mode I and Mode II pitchfork bifurcations. This is due to the symmetric nature existing along the vertical and diagonal planes. The flow structure in the present nonlinear system consists of a pair of asymmetric counter-rotating helical cells in a double helix structure, foliated with invariant helically symmetric surfaces containing the fibre-like fluid particle orbits. Also the evolution of different symmetry-breaking orientations on the transverse and diagonal planes of the cavity was noticed. In the Mode I orientation a symmetric vortex coreline was observed. However, in the Mode II orientation a pair of anti-symmetric vortex corelines was observed. Detailed topological study was made based on the rule of Hunt and the structural stability criteria. Also the simulated results were corroborated with numerical evidence. The existence of the critical Ra values was ascertained with the aid of the predicted L2-error norms, thermal/flow iso-contours and streamlines. The route of Mode I orientation was made of the alternate symmetric and asymmetric flows as Ra was augmented. 相似文献
54.
The spectral distribution of photoconductivity in poly(6-tert-butyl-3-methyl-3,4-dihydro-2H-1,3-benzoxazine) was studied in the sandwich configuration with indium tin oxide and silver electrodes. The photocurrent was found to originate mainly from the bulk dissociation of excitons with lesser contribution from electrode-mediated exciton dissociation. The molecule was fluorescent, but in the presence of the electron acceptor molecule 2,4,6-trinitrophenol (TNP), the intensity was reduced. The reduction in fluorescence intensity corresponded to an increase in photocurrent. The molecule showed photoconductivity in the visible without any sensitizers, which makes it suitable for stable photorefractive composites. 相似文献
55.
Ratnaparkhi Girish S.; Awasthi Satish Kumar; Rani P.; Balaram P.; Varadarajan R. 《Protein engineering, design & selection : PEDS》2000,13(10):697-702
The S proteinS peptide interaction is a model systemto study binding thermodynamics in proteins. We substitutedalanine at position 4 in S peptide by 相似文献
56.
Using the basic equations of heat conducting micropolar fluid, heat transfer through a channel of porous walls has been studied. The temperature distribution is obtained for different values of suction parameter , convective parameter and micropolar parameter . 相似文献
57.
Amutha Rani Devaraj Chris R. Cheeseman Aldo R. Boccaccini David Deegan 《International Journal of Applied Ceramic Technology》2010,7(6):925-934
Air pollution control (APC) residues produced from cleaning gas emissions at energy from waste (EfW) plants processing municipal solid waste are a problematic hazardous waste. In this research they have been treated using DC plasma technology and this produces an inert glass. Glass-ceramic tiles were prepared by powder pressing and sintering fritted APC residue-derived glass. Tile samples prepared with high levels of plasma treated APC residue glass had comparable physical properties to commercially available ceramics such as porcelain and monoporosa, with high bulk density (2.4 g/cm3), low water absorption (<6%) and high flexural strength (∼60 MPa). 相似文献
58.
Tanja Zseby Joachim Fabini Dipika Rani 《e & i Elektrotechnik und Informationstechnik》2014,131(1):8-13
Synchronized phasor measurements provide the basis for fine-grained wide area power quality monitoring in electric grids. Time-synchronized phasor measurement units (PMUs) are deployed at different locations in the grid and report 10–60 measurements/second to energy management systems or other applications. For control applications it is crucial to receive measurement data as soon as possible after a state change in order to trigger corrective actions in time to prevent incidents in the grid. In this paper we analyze characteristics of synchrophasor M2M communication for different network technologies, including VDSL, HSPA and LTE networks. We briefly review synchrophasor communication approaches and real-time demands. We then emulate PMU traffic and perform measurements on different networks. We show how the underlying technology influences one-way delay patterns for synchrophasor communication, which has direct implication on the achievable real-time properties. 相似文献
59.
T. Prathap Kumar K. N. Prasanna Rani M. Mallikarjun V. V. Basava Rao 《Chemical Engineering Communications》2013,200(4):572-589
Levulinic acid, a carboxylic acid containing a ketone structure, can be used as an acidulant in foods and beverages. Reactive extraction is a promising alternative for the recovery of carboxylic acids from aqueous streams. The design of an amine extraction process requires kinetic data for the acid-amine + solvent system used. In this study, equilibrium and kinetic data on the extraction of levulinic acid from aqueous solutions using tri-n-octylamine (TOA) in 1-octanol have been determined. The mass transfer coefficients of levulinic acid, TOA, and 2:1 levulinic acid-amine complex in 1-octanol were calculated from the acetic acid mass transfer coefficient, which was determined by measuring its fluxes of simple diffusion from kerosene to water. Based on the Hatta number and the criterion given by Doraiswamy and Sharma, the reaction regime has been found to be instantaneous reaction regime occurring at the interface on the organic phase side. An extraction model comprising equilibrium complexation constant w.r.t 2:1 levulinic acid-TOA complex formation, KE2i (14.794 (m3 kmol?1)2), and complex mass transfer coefficient, kB2A (2.193 × 10?6 m s?1), has been developed. 相似文献
60.
The oxidation of alcohols to carbonyls was investigated by an efficient catalyst system comprising of Fe(III)–Schiff base–triphenylphosphine complex. The complex chloroN-(2-mercaptophenyl)salicylideneiminebis(triphenylphosphine)iron(III) showed higher activity for oxidation of various alcohols under relatively mild conditions. 相似文献