全文获取类型
收费全文 | 253篇 |
免费 | 8篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 51篇 |
金属工艺 | 4篇 |
机械仪表 | 12篇 |
建筑科学 | 3篇 |
能源动力 | 13篇 |
轻工业 | 6篇 |
水利工程 | 1篇 |
无线电 | 68篇 |
一般工业技术 | 77篇 |
冶金工业 | 3篇 |
原子能技术 | 3篇 |
自动化技术 | 29篇 |
出版年
2024年 | 2篇 |
2023年 | 5篇 |
2022年 | 13篇 |
2021年 | 17篇 |
2020年 | 16篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 14篇 |
2016年 | 8篇 |
2015年 | 4篇 |
2014年 | 13篇 |
2013年 | 13篇 |
2012年 | 13篇 |
2011年 | 17篇 |
2010年 | 15篇 |
2009年 | 16篇 |
2008年 | 16篇 |
2007年 | 5篇 |
2006年 | 4篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 8篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有273条查询结果,搜索用时 15 毫秒
171.
Including internals in bubble columns is known to enhance the gas holdup. In this paper, a method to achieve this objective substantially has been proposed via the use of vibrating helical spring internals. Experimental observations on effect of vibrating internals such as vibrating helical springs on gas holdup in bubble columns are presented. Effects of superficial gas velocity, H/D ratio (height of the static liquid to column diameter ratio), volume fraction of helical springs, and thickness of the helical spring wires on hydrodynamics parameters are studied. Increase in gas holdup up to 135% is observed by using vibrating helical spring internals in bubble columns compared to bubble columns without internals. This method offers a simple, cost‐effective, and easy way to enhance gas holdup even at high gas fluxes. It has been reported that this enhancement stems from the fact that the vibrating springs breakup the gas into fine bubbles, which effectively reduces their rise velocity and enhances their average residence time in the liquid column. 相似文献
172.
173.
The localised corrosion resistance of 316L SS metallic implant due to H2SO4 treatment is being studied through electrochemical studies involving cyclic polarisation experiments and impedance studies. The efficiency of hydroxyapatite (HAP) coatings on H2SO4 treated 316L SS is also been investigated through electrochemical studies and the dissolution characteristics of the coatings. The study reveal that 15% H2SO4 treatment was found to be efficient in the corrosion resistance of 316L SS and dissolution of alloy is considerably reduced in the hydroxyapatite coatings on 15% H2SO4 treated 316L SS. 相似文献
174.
Shanmugam Punitha Kuppuswamy Guru Prasad Pushparaj Kishore Arumugam Balamurugan Sundaramurthy Anandhakumar Sivalingam Yuvaraj 《Journal of Materials Science: Materials in Electronics》2022,33(12):9483-9489
Journal of Materials Science: Materials in Electronics - Herein, we report CeO2 nanoparticles (CeO2 NPs) based extended gate field effect transistor for glucose detection with high sensitivity and... 相似文献
175.
Silicon - In this paper, a novel two-dimensional analytical model for threshold voltage on Dual Material Surrounding Gate Junctionless MOSFET is proposed. The analytical study is aimed at... 相似文献
176.
Kampara Roopa Kishore Deenadhayalan Balamurugan Beri Gopalakrishnan Jeyaprakash 《Journal of Porous Materials》2022,29(3):729-743
Journal of Porous Materials - In this work, Polyvinyl alcohol (PVA) based ZnO nanofibers were deposited by the electrospinning method. ZnO nanofibers obtained through this method have an average... 相似文献
177.
An analytical model for surrounding gate metal–oxide–semiconductor field effect transistors(MOSFETs)considering quantum effects is presented.To achieve this goal,we have used a variational approach for solving the Poisson and Schrodinger equations.This model is developed to provide an analytical expression for the inversionchargedistributionfunctionforallregionsofthedeviceoperation.Thisexpressionisusedtocalculatethe other important parameters like the inversion charge centroid,threshold voltage and inversion charge density.The calculated expressions for the above parameters are simple and accurate.The validity of this model was checked for the devices with different device dimensions and bias voltages.The calculated results are compared with the simulation results and they show good agreement. 相似文献
178.
Balamurugan Ramalingam Abdul Majeed Seayad Li Chuanzhao Marc Garland Kazuhiko Yoshinaga Manabu Wadamoto Takushi Nagata Christina L. L. Chai 《Advanced Synthesis \u0026amp; Catalysis》2010,352(13):2153-2158
Close to perfect enantioselectivity (up to 98% ee) is obtained for the formation of amino nitriles using hydrogen cyanide (HCN) as the cyanide source at room temperature for the first time. In an operationally simple process, the catalyst generated from a partially hydrolyzed titanium alkoxide (PHTA) and (S)‐N‐salicyl‐β‐amino alcohol ligand, catalyzes the cyanation of imines in a short reaction time. 相似文献
179.
Balasubramanian B Kraemer KL Valloppilly SR Ducharme S Sellmyer DJ 《Nanotechnology》2011,22(40):405605
The embedding of oxide nanoparticles in polymer matrices produces a greatly enhanced dielectric response by combining the high dielectric strength and low loss of suitable host polymers with the high electric polarizability of nanoparticles. The fabrication of oxide-polymer nanocomposites with well-controlled distributions of nanoparticles is, however, challenging due to the thermodynamic and kinetic barriers between the polymer matrix and nanoparticle fillers. In the present study, monodisperse TiO(2) nanoparticles having an average particle size of 14.4?nm and predominant rutile phase were produced using a cluster-deposition technique without high-temperature thermal annealing and subsequently coated with uniform vinylidene fluoride oligomer (VDFO) molecules using a thermal evaporation source, prior to deposition as TiO(2)-VDFO nanocomposite films on suitable substrates. The molecular coatings on TiO(2) nanoparticles serve two purposes, namely to prevent the TiO(2) nanoparticles from contacting each other and to couple the nanoparticle polarization to the matrix. Parallel-plate capacitors made of TiO(2)-VDFO nanocomposite film as the dielectric exhibit minimum dielectric dispersion and low dielectric loss. Dielectric measurements also show an enhanced effective dielectric constant in TiO(2)-VDFO nanocomposites as compared to that of pure VDFO. This study demonstrates for the first time a unique electroactive particle coating in the form of a ferroelectric VDFO that has high-temperature stability as compared to conventionally used polymers for fabricating dielectric oxide-polymer nanocomposites. 相似文献
180.
GC-MS analysis and ecotoxicological risk assessment of triclosan, carbamazepine and parabens in Indian rivers 总被引:3,自引:0,他引:3
Ramaswamy BR Shanmugam G Velu G Rengarajan B Larsson DG 《Journal of hazardous materials》2011,186(2-3):1586-1593
Pharmaceutical and personal care products are used extensively worldwide and their residues are frequently reported in aquatic environments. In this study, antiepileptic, antimicrobial and preservative compounds were analyzed in surface water and sediment from the Kaveri, Vellar and Tamiraparani rivers, and in the Pichavaram mangrove in India by gas chromatography-mass spectrometry (GC-MS). The mean concentration of carbamazepine recorded in the Kaveri River water (28.3 ng/L) was higher than in the other rivers and the mangrove. Because carbamazepine is used only in human drugs, this may reflect the relative contributions of human excretions/sewage in these rivers. The mean triclosan level in the Tamiraparani River (944 ng/L) was an order of magnitude greater than in the other water systems, and the concentrations at two of the sites reported here (3800-5160 ng/L) are, to our best knowledge, among the highest detected in surface waters. Sediment levels were, however, comparable with other sites. We conclude that industrial releases are likely major contributors of triclosan into this river system. Among parabens, ethyl paraben was predominantly observed. Hazard Quotients suggest greater environmental risks for triclosan than for carbamazepine and parabens. This is the first study on antiepileptic, antimicrobial and preservatives in rivers and mangroves from India. 相似文献