全文获取类型
收费全文 | 1332篇 |
免费 | 84篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 26篇 |
综合类 | 2篇 |
化学工业 | 282篇 |
金属工艺 | 31篇 |
机械仪表 | 43篇 |
建筑科学 | 32篇 |
能源动力 | 87篇 |
轻工业 | 95篇 |
水利工程 | 10篇 |
石油天然气 | 28篇 |
无线电 | 120篇 |
一般工业技术 | 351篇 |
冶金工业 | 130篇 |
原子能技术 | 10篇 |
自动化技术 | 175篇 |
出版年
2024年 | 4篇 |
2023年 | 25篇 |
2022年 | 30篇 |
2021年 | 64篇 |
2020年 | 62篇 |
2019年 | 59篇 |
2018年 | 65篇 |
2017年 | 68篇 |
2016年 | 83篇 |
2015年 | 48篇 |
2014年 | 72篇 |
2013年 | 110篇 |
2012年 | 89篇 |
2011年 | 83篇 |
2010年 | 52篇 |
2009年 | 55篇 |
2008年 | 44篇 |
2007年 | 39篇 |
2006年 | 28篇 |
2005年 | 30篇 |
2004年 | 16篇 |
2003年 | 20篇 |
2002年 | 30篇 |
2001年 | 15篇 |
2000年 | 11篇 |
1999年 | 20篇 |
1998年 | 30篇 |
1997年 | 13篇 |
1996年 | 26篇 |
1995年 | 18篇 |
1994年 | 18篇 |
1993年 | 16篇 |
1992年 | 7篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有1422条查询结果,搜索用时 15 毫秒
131.
Bishnu Prasad De R. Kar D. Mandal S. P. Ghoshal 《International Journal of Numerical Modelling》2016,29(5):873-896
This paper presents an efficient approach for the optimal designs of two analog circuits, namely complementary metal oxide semiconductor) two‐stage comparator with p‐channel metal oxide semiconductor input driver and n‐channel input and folded‐cascode operational amplifier using a recently proposed meta‐heuristic‐based optimization algorithm named as colliding bodies optimization (CBO). It is a multi‐agent algorithm that does not depend upon any internal control parameter, making the algorithm extremely simple. The main objective of this paper is to optimize the metal oxide semiconductor (MOS) transistors' sizes using CBO in order to reduce the areas occupied by the circuits and to get better performance parameters of the circuits. Simulation Program with Integrated Circuit Emphasis simulation has been carried out by using the optimal values of MOS transistors' sizes and other design parameters to validate that CBO‐based design is satisfying the desired specifications. Simulation results demonstrate that the design specifications are closely met and the required functionalities are achieved. The simulation results also confirm that the CBO‐based approach is superior to the other algorithms in terms of MOS area and performance parameters like gain, power dissipation, etc., for the examples considered. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
132.
This article presents a methodology that provides a method for design optimization of steel truss structures based on a refined big bang–big crunch (BB-BC) algorithm. It is shown that a standard formulation of the BB-BC algorithm occasionally falls short of producing acceptable solutions to problems from discrete size optimum design of steel trusses. A reformulation of the algorithm is proposed and implemented for design optimization of various discrete truss structures according to American Institute of Steel Construction Allowable Stress Design (AISC-ASD) specifications. Furthermore, the performance of the proposed BB-BC algorithm is compared to its standard version as well as other well-known metaheuristic techniques. The numerical results confirm the efficiency of the proposed algorithm in practical design optimization of truss structures. 相似文献
133.
K. Ashok G. K. Mandal D. Bandyopadhyay 《Transactions of the Indian Institute of Metals》2015,68(1):9-18
Deoxidation of liquid steel involves consumption of high energy materials like ferro alloys and generation of deoxidation products which could be entrapped into liquid steel as non-metallic inclusions. The present investigation is focused on deoxidation of liquid steel, considering mainly aluminium and silicon as deoxidizer. A simple and realistic mathematical model of deoxidation of liquid steel has been developed based on the thermodynamic principles and material balance approach for day to day industrial practice. One of the main aims of the theoretical study was to predict the amount of deoxidizers required for a given steel composition. A methodology has also been developed to predict the stability of different oxides expected to be present in liquid steel after deoxidation. Model predictions have been compared with the industrial data as well as results obtained from commercial thermodynamic software package FactSage 6.4, simulated under identical conditions. Model predictions are in reasonable agreement with the ferro alloy consumption in industrial steelmaking processes. 相似文献
134.
T. Saud D.P. SinghT.K. Mandal Ranu GadiH. Pathak M. SaxenaS.K. Sharma R. GautamA. Mukherjee R.P. Bhatnagar 《Biomass & bioenergy》2011,35(2):932-941
Biomass is widely used as energy source in rural households in India. Biomass samples and socio-economic data have been collected at district level in the rural areas of Indo-Gangetic plain (IGP), India to determine the emissions of trace gases and aerosols from domestic fuels. Dung cake, fuelwood and crop residue are main sources of energy in rural areas of the IGP. Dung cake is the major domestic fuel (80-90%) in the rural areas of Delhi, Punjab, Haryana, Uttar Pradesh, Bihar and West Bengal, whereas, 99% of rural households in Uttarakhand use wood as the main energy source. Using crop production data and usage of crop residues as energy, new consumption values have been estimated (21.13 Mt). Present information on the domestic fuel usage would be helpful in determining budgets estimates of trace gases and aerosols for India. 相似文献
135.
The effect of temperature dependent viscosity μ(T), on steady two dimensional natural convection flow along a vertical wavy cone with uniform surface heat flux has been investigated. Viscosity is taken to be an exponential function of temperature. Using the appropriate variables the basic equations are transformed to non-dimensional boundary layer equations and then solved numerically employing implicit finite difference method. The effects of viscosity variation parameter on the velocity profile, temperature profile, velocity vector field, skin friction, average Nusselt number, streamlines and isotherm have been discussed. The results have been shown graphically by utilizing the visualizing software Techplot. 相似文献
136.
Kundu B Nandi SK Dasgupta S Datta S Mukherjee P Roy S Singh AK Mandal TK Das P Bhattacharya R Basu D 《Journal of materials science. Materials in medicine》2011,22(3):705-720
A systematic and extensive approach incorporating in vitro and in vivo experimentation to treat chronic osteomyelitis in animal model were made using antibiotic loaded special bioactive glass porous scaffolds. After thorough characterization for porosity, distribution, surface charge, a novel drug composite were infiltrated by using vacuum infiltration and freeze-drying method which was subsequently analyzed by SEM-EDAX and studied for in vitro drug elution in PBS and SBF. Osteomyelitis in rabbit was induced by inoculation of Staphylococcus aureus and optimum drug-scaffold were checked for its efficacy over control and parenteral treated animals in terms of histopathology, radiology, in vivo drug concentration in bone and serum and implant-bone interface by SEM. It was optimized that 60P samples with 60-65% porosity (bimodal distribution of macro- to micropore) with average pore size ~60 μm and higher interconnectivity, moderately high antibiotic adsorption efficiency (~49%) was ideal. Results after 42 days showed antibiotic released higher than MIC against S. aureus compared to parenteral treatment (2 injections a day for 6 weeks). In vivo drug pharmacokinetics and SEM on bone-defect interface proved superiority of CFS loaded porous bioactive glass implants over parenteral group based on infection eradication and new bone formation. 相似文献
137.
Faramarz Khoshnoudian Ali Imani Azad 《The Structural Design of Tall and Special Buildings》2011,20(8):986-1018
Torsion in base‐isolated structures using bilinear rubber isolators effected by two horizontal components of earthquake simultaneously is investigated under various principal parameters including number of storeys; ratio of uncoupled torsional frequency to lateral frequency in the superstructure; ratio of uncoupled torsional frequency to lateral frequency in the isolation system; mass eccentricity in the superstructure and isolation system; and, in addition, the direction of eccentricity. Structure was supposed a shear structure and it was modeled by using concentrated mass and springs. Isolators are modelled by using nonlinear springs considering the interaction of isolator behaviour in two directions. The effect of variation in considered parameters on the behaviour of the superstructure and isolation system is investigated under seven ground motions. It is demonstrated that the parameters affect asymmetric structure behaviour with respect to symmetric one. The results of our investigations help us to understand the asymmetric structure behaviour under bidirectional earthquake by comparing it with a symmetric one. These results demonstrate that asymmetry in the superstructure or isolation system could have a significant effect on the torsional behaviour of isolated structures. In addition, the results show that the use of rigid superstructures and calculation of dynamic torsion by multiplying eccentricity by the dynamic base shear are unacceptable assumptions. Torsional effect on the isolated structural behaviour is amplified by considering two horizontal components of earthquake and comparing them with just one horizontal component. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
138.
Nijwm Wary Pradip Mandal 《AEUE-International Journal of Electronics and Communications》2014,68(10):969-975
In this work we propose a low impedance receiver for on-chip high speed current-mode signalling over global interconnect. The receiver provides a very low input impedance even with a low quiescent power. The low input impedance helps to get high link bandwidth without any passive terminator. Moreover, the receiver has high transimpedance gain over a large bandwidth. This facilitates in reducing the signalling current by 6.7 times compared to a passive termination. A test chip has been fabricated in 0.18 μm CMOS process to test the topology with a prototype global interconnect having a length of 10 mm. Power consumption of the transceiver for a data rate of 2.5 Gbps data is 2 mW. This gives an energy efficiency of 0.8 pJ/b. 相似文献
139.
Complex formation of DNA with a number of cationic amphiphiles has been examined using fluorescence, gel electrophoresis, and chemical nuclease digestion. Here we have addressed the status of both DNA and lipid upon complexation with each other. DNA upon binding with cationic amphiphiles changes its structure in such a way that it loses the ability to intercalate and becomes resistant to nuclease digestion. Fluorescence anisotropy measurements due to 1, 6-diphenylhexatriene (DPH) doped in cationic liposomes demonstrated that upon complexation with DNA, the resulting complexes still retain lamellar organizations with modest enhancement in thermal stabilities. The lipid-DNA complexation is most effective only when the complexation was carried out at or around the phase transition temperatures of the cationic lipid employed in the complexation with DNA. The release of DNA from cationic lipid-DNA complexes could be induced by several anionic additives. Determination of fluorescence anisotropies (due to DPH) as a function of temperature clearly demonstrates that the addition of equivalent amounts of anionic amphiphile into cationic lipid-DNA complexes leads to the ion-pairing of the amphiphiles, the melting profiles of which are virtually the same as those obtained in the absence of DNA. In this process DNA gets released from its complexes with cationic lipids and regains its natural intercalation ability, movement, and staining ability on agarose gel and also the sensitivities toward nuclease digestion. This clearly suggests that combination of ion-pairing and hydrophobic interactions between cationic and anionic amphiphiles is stronger than the electrostatic forces involved in the cationic lipid-DNA complexation. It is further revealed that the DNA release by anions is most efficient from the cationic lipid-DNA complexes at or around the Tm of the cationic lipid used in DNA complexation. This explains why more effective DNA delivery is achieved with cationic lipids that bear unsaturated hydrocarbon chains than with their saturated hydrocarbon counterparts. 相似文献
140.