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31.
Ductile failure of heterogeneous materials, such as cast aluminum alloys and discretely reinforced aluminums or DRA’s, initiates with cracking, fragmentation or interface separation of inclusions, that is followed by propagation in the matrix by a ductile mechanism of void nucleation and growth. Damage localizes in bands of intense plastic deformation between inclusions and coalesces into a macroscopic crack leading to overall failure. Ductile fracture is very sensitive to the local variations of the microstructure morphology. This is the first of a two part paper on the effect of microstructural morphology and properties on the ductile fracture in heterogeneous ductile materials. In this paper the locally enhanced Voronoi cell finite element method (LE-VCFEM) for rate-dependent porous elastic–viscoplastic materials is used to investigate the sensitivity of strain to failure to loading rates, microstructural morphology and material properties. A model is also proposed for strain to failure, incorporating the effects of important morphological parameters. 相似文献
32.
Soma Maji Amir Raza Subhani Bijay Kumar Show Joydeep Maity 《Journal of Materials Engineering and Performance》2017,26(7):3058-3070
A systematic study has been carried out to ascertain the effect of cooling rate on structure and mechanical properties of eutectoid steel subjected to a novel incomplete austenitization-based cyclic heat treatment process up to 4 cycles. Each cycle consists of a short-duration holding (6 min) at 775 °C (above A1) followed by cooling at different rates (furnace cooling, forced air cooling and ice-brine quenching). Microstructure and properties are found to be strongly dependent on cooling rate. In pearlitic transformation regime, lamellar disintegration completes in 61 h and 48 min for cyclic furnace cooling. This leads to a spheroidized structure possessing a lower hardness and strength than that obtained in as-received annealed condition. On contrary, lamellar disintegration does not occur for cyclic forced air cooling with high air flow rate (78 m3 h?1). Rather, a novel microstructure consisting of submicroscopic cementite particles in a ‘interweaved pearlite’ matrix is developed after 4 cycles. This provides an enhancement in hardness (395 HV), yield strength (473 MPa) and UTS (830 MPa) along with retention of a reasonable ductility (%Elongation = 19) as compared to as-received annealed condition (hardness = 222 HV, YS = 358 MPa, UTS = 740 MPa, %Elongation = 21). 相似文献
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1. Introduction The requirement of minimal bottom coverageand thick sidewall coverage for PVD-based films forlow via resistance and improved stress migration isnot easy to achieve with traditional depositionmethods. Modern I-PVD techniques give high bot-tom coverage, due to the ionized component of thedeposition flux. Sidewall coverage tends to be low,which is mainly due to off-normal deposition fluxand a less than unity sticking coefficient. 相似文献
36.
Binary liquid-liquid-equilibria data for several aniline-paraffin and furfural-paraffin systems have been taken. These data along with data for other aniline-hydrocarbon and furfural-hydrocarbon systems from literature have been correlated using UNIFAC model. The UNIFAC group interaction parameters have been found to have a linear temperature dependence. The CH2 groups in cyclo and non cyclo paraffins require different interaction parameters. It was also found that a scaling of the combinatorial term is necessary for higher molecular weight hydrocarbons. 相似文献
37.
Failure of a borosilicate glass as a result of repeated impact has been studied. Impact fatigue study was conducted in an
improved pendulum type repeated impact apparatus specially designed and fabricated for determining single and repeated impact
strength. For elimination of the effect of humidity, repeated impact tests were carried out under liquid nitrogen. Quasi-static
measurements were determined under four-point bending. Using a square waveform as applicable to the present impact tests and
fracture mechanics interpretation, the number of cycles to failure during impact fatigue tests were predicted from quasi-static
fatigue measurements. It has been shown that repeated impact loading has a deleterious effect on the failure cycles compared
to slow stressing. The role of an added mechanical effect during repeated impacts has been suggested in controlling the cyclic
fatigue behaviour.
Paper presented at the poster session of MRSI AGM VI, Kharagpur, 1995 相似文献
38.
Dip Majumder Jyoti Prakash Maity Min-Jen Tseng Vanita Roshan Nimje Hau-Ren Chen Chien-Cheng Chen Young-Fo Chang Tsui-Chu Yang Chen-Yen Chen 《International journal of molecular sciences》2014,15(9):16772-16786
Microbial fuel cells (MFCs) represent a novel platform for treating wastewater and at the same time generating electricity. Using Pseudomonas
putida (BCRC 1059), a wild-type bacterium, we demonstrated that the refinery wastewater could be treated and also generate electric current in an air-cathode chamber over four-batch cycles for 63 cumulative days. Our study indicated that the oil refinery wastewater containing 2213 mg/L (ppm) chemical oxygen demand (COD) could be used as a substrate for electricity generation in the reactor of the MFC. A maximum voltage of 355 mV was obtained with the highest power density of 0.005 mW/cm2 in the third cycle with a maximum current density of 0.015 mA/cm2 in regard to the external resistor of 1000 Ω. A maximum coulombic efficiency of 6 × 10−2% was obtained in the fourth cycle. The removal efficiency of the COD reached 30% as a function of time. Electron transfer mechanism was studied using cyclic voltammetry, which indicated the presence of a soluble electron shuttle in the reactor. Our study demonstrated that oil refinery wastewater could be used as a substrate for electricity generation. 相似文献
39.
Somnath Middya Animesh Layek Arka Dey Partha Pratim Ray 《材料科学技术学报》2014,30(8):770-775
In this paper,we have reported the synthesis of FeS2 of higher band gap energy(2.75 eV) by using capping reagent and its successive application in organic-inorganic based hybrid solar cells.Hydrothermal route was adopted for preparing iron pyrite(FeS2) nanoparticles with capping reagent PEG-400.The quality of synthesized FeS2 material was confirmed by X-ray diffraction,field emission scanning electron microscopy,transmission electron microscopy,Fourier transform infrared,thermogravimetric analyzer,and Raman study.The optical band gap energy and electro-chemical band gap energy of the synthesized FeS2 were investigated by UV-vis spectrophotometry and cyclic voltammetry.Finally band gap engineered FeS2 has been successfully used in conjunction with conjugated polymer MEHPPV for harvesting solar energy.The energy conversion efficiency was obtained as 0.064%with a fill-factor of 0.52. 相似文献
40.
As the energy consumption to operate a ventilation system is 25 to 50% of the total energy requirements of an underground coal mine, proper planning, redesign, implementation and maintenance are necessary to achieve energy saving in this potentially viable area. Many researchers all over the world are therefore busy with solution for optimizing the consumption of energy in ventilation system. In this paper, the energy saving possibilities is discussed from different angles and a survey of current research is presented particularly on potential for electrical energy cost saving by implementation of various new technologies/methods. Ventilation demand in coal mines may vary throughout the year and by designing/developing a good ventilation system can not only minimize the cost of energy for the fan but also try to create healthy environment in mine. A number of recent commercially available systems are also reviewed in the paper to get the proper understanding. 相似文献