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81.
Priyanka Shailesh N. Sharma Samsher Salam Mushahid Husain Mohan Lal 《Solar Energy Materials & Solar Cells》2007,91(15-16):1510-1514
In this work, porous silicon (PS) films were prepared by anodization on polished substrates of (1 0 0) Si for a fixed current density (Id)20 mA cm−2 and for a fixed anodization time of 30 min using different screen-printed (SP) back contacts, namely Ag and Al. The properties of PS formed using Ag as the back contact were found to be superior compared to the corresponding film using Al as the back contact. The PS formed with Ag-back contact exhibits higher porosity, negligible photoluminescence (PL) decay, better adherence to the substrate and smooth surface morphology compared to that formed with Al as the back contact for the same current density and time of anodization. Fourier transform infrared (FTIR) studies indicated significant presence of Si–O related features at 1050–1150 cm−1 for PS films formed with Al as back contact, which could be responsible for traps and interface (PS–Si) defect densities as compared to corresponding PS films with Ag as the back contact. Measurements of capacitance–voltage (C–V) and current–voltage (I–V) were used for the investigation of the electrical properties of PS films with different back contacts. The frequency-dependent C–V characteristics were analysed to understand the effects of interface states and traps on the properties of PS films. The results have been analysed in terms of eutectic temperature and back surface field (BSF) across the metal–silicon interface. 相似文献
82.
Eichhornia spp. biomass was collected from Chandola Lake, Ahmedabad, Gujarat, India. Point of zero charge of the biomass was pH 7.3. Flask study showed pH 5 and 2–3 h contact time as optimum conditions for copper sorption with 67.25% copper removal. At the end of 24 h of contact time, copper removal reached to 85.0%, from 100 ppm copper containing solution. Copper loading capacity of the biomass ranged between 9.9 and 28.5 mg g?1 of biomass. To understand the interaction among pH, temperature, presence of nickel and zinc in the system, 24 factorial experiment was performed. Under the experimental conditions pH and interactions between pH–nickel, temperature–pH and temperature–pH–nickel–zinc were found to be significant with 60–74.7% copper removal. Langmuir isotherm was better fit as compared to Freundlich isotherm and pseudo-second order equation gave R2 of 0.999 for biosorption kinetic of Eichhornia biomass. Reactor study showed 90% overall copper removal from 24 L of copper containing waste studied and sulphate-reducing bacteria played a significant role. SEMquant element analysis showed increase from 41.66% to 53.93%, 1.02–19.73% and 0.0–12.39% of chloride, aluminium and copper respectively in the loaded biomass as compare to unexposed biomass. 相似文献
83.
84.
Shailesh Vidhate Lucia Innocentini‐Mei Nandika Anne D'Souza 《Polymer Engineering and Science》2012,52(6):1367-1374
In this work, nanocomposites of poly(hydroxybutyrate‐co‐hydroxyvalerate) PHBV and multiwalled carbon nanotubes (MWNT) were prepared by melt blending. Mechanical, thermal, morphological, and electrical properties of the prepared PHBV/MWNT nanocomposites were investigated. Differential scanning calorimetry (DSC) and X‐ray diffraction (XRD) results showed MWNT effectively enhanced the crystallization and nucleation of PHBV. Dynamic thermo‐mechanical and static uniaxial mechanical tensile and compressive properties were increased by the addition of MWNT. MWNT observed in the nanocomposites using transmission electron microscopy (TEM) showed dimensions similar to separated nanotubes inferring a good dispersion. The presence of nanotubes in close vicinity with each other formed an interconnecting network that led to the formation of electrically conductive nanocomposites. The electrical resistance of the nanocomposites was reduced with the addition of MWNT. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers 相似文献
85.
Badarinath KV Kharol SK Kaskaoutis DG Kambezidis HD 《The Science of the total environment》2007,384(1-3):316-332
According to the Earth Observatory dust outbreaks are considered as natural hazards, which affect the ecosystems and human life. The main objective of this study is to assess and monitor the movement of aerosols and pollutants from local or other sources, both natural and anthropogenic, using a combination of ground-based monitoring and satellite data. The turbid and polluted atmosphere in the densely-populated area of Hyderabad, India is further degradated from dust outbreaks originated from Thar desert. A dust event occurred during 10th to 11th April 2006 in the northwest region of India; its plume substantially spreaded across the downwind direction affecting the study region. Using both irradiance measurements and satellite data this dust event is investigated. The analysis shows a significant change in Aerosol Optical Depth (AOD), Aerosol Index (AI) and aerosol-particle size during the dust event. The Aerosol Optical Depth in the dusty day is about 0.2 higher than the previous non-dusty days, while the Angstr?m exponent rapidly decreases when the dust plume affected the study area. The surface PM concentrations show enhanced values during the dusty day directly influenced by the dust deposition. There is also a remarkable decrease in ground-reaching global radiation, UV erythemal (UV(ery)) and other irradiance components. The analysis suggested that the use of the diffuse-to-direct-beam ratio is the most appropriate parameter for the dust monitoring since its values at the longer wavelengths are not affected by the solar zenith angle. 相似文献
86.
87.
Beena K. Vaghasiya Shailesh P. Satasia Rahul P. Thummar Ronak D. Kamani Jemin R. Avalani Nirav H. Sapariya 《Journal of Sulfur Chemistry》2018,39(5):507-515
An efficient and simple method is reported for the cyanation on arylboronic acid using various simple/indole thiocyanates using a new IL-PdCl4 catalyst. The cascade process involves a coupling reaction without any additive to give a wide range of cyanide derivatives. Cyanation on various arylboronic acids underwent smoothly affording the corresponding arylnitriles in good to high yields. 相似文献
88.
Plasma Spraying of Lanthanum Chromite Films for Solid Oxide Fuel Cell Interconnection Application 总被引:2,自引:0,他引:2
Lewis J. H. Kuo Shailesh D. Vora Subhash C. Singhal 《Journal of the American Ceramic Society》1997,80(3):589-593
This paper discusses a novel plasma-spraying process for depositing dense LaCrO3 -based interconnection for solid oxide fuel cells (SOFCs). Calcium aluminate was mixed with LaCrO3 in a slurry containing PVA binder and spray dried to form free-flowing agglomerates. These free-flowing agglomerates were plasma sprayed onto a porous substrate of doped LaMnO3 and then heat-treated to form a gas-tight and electrically conducting interconnection. Samples of the plasma-sprayed interconnection were characterized for morphology, phase constituents, and coefficient of thermal expansion, as well as electrical resistivity and oxygen nonstoichiometry at 1000°C in the P O2 range from 1 to} 1× 10-16 atm. The calcium aluminate additive was found to facilitate densification of the interconnection, most likely through the formation of low-temperature melting phase(s) in the system Ca–Cr–Al–O. A SOFC with such a plasma-sprayed interconnection was fabricated and electrically tested. This cell exhibited good electrical performance, and the interconnection was stable under fuel cell operation conditions. 相似文献
89.
Shailesh Singh Chouhan Kari Halonen 《Analog Integrated Circuits and Signal Processing》2014,80(3):399-406
In this work we are proposing the all MOST based reference voltage generating circuit, which utilizes the classical principle of addition of two voltages with opposite temperature coefficients. The targeted application of the proposed circuit is a low-dropout regulator which is used in a RF energy harvesting system. The proposed voltage reference circuit is implemented using a standard 0.18 μm CMOS technology. It generates the average reference voltage of 543.658 mV with an average temperature coefficient of 17.43 ppm/°C in the temperature range of ?40 to +85 °C, for the operating supply voltage ranging from 1.25 to 2 V. The maximum power consumption of the proposed architecture is ≈1.5 μW, including power dissipation in bias circuitry and the reference voltage generating core at 2 V supply voltage. The averaged measured line regulation is 1.642 mV/V. The measured power-supply rejection ratio without any filtering capacitor at 100 Hz and 1 MHz are ?62.24 and ?18.94 dB, respectively. Additionally, the measured noise density without any filtering capacitor at 10 Hz and 100 KHz is 20.54 and \(0.30\,\upmu \hbox {V}/\sqrt{\hbox{Hz}}\) , respectively. The proposed circuit has silicon area of ≈0.007 mm2. 相似文献
90.
Longzhou Ma Keh-Minn Chang Sarwan K. Mannan Shailesh J. Patel 《Metallurgical and Materials Transactions A》2002,33(11):3465-3478
The effect of isothermal exposure on the elevated-temperature, time-dependent fatigue-crack propagation (FCP) in INCONEL Alloy
783 is investigated. Commercially produced Alloy 783 was annealed and aged following the standard heat-treatment procedure.
One set of specimens was then isothermally exposed at 500 °C for 3000 hours. All specimens were subjected to FCP tests with
various hold-time periods and sustained-loading crack-growth tests at 538 °C and 650 °C in a laboratory-air environment. Without
a hold time, the as-produced and isothermally exposed materials had comparable FCP rates at both test temperatures. With hold
times of 100 and 300 seconds, the as-produced and isothermally exposed specimens had comparable FCP rates at 538 °C. Hold-time
testing of the as-produced material at 650 °C showed abnormal time-dependent FCP and sustained-loading crack-growth retardation.
However, hold-time testing of isothermally exposed material at 650 °C showed the steady sustained-loading crack growth and
fully time-dependent FCP typically observed in many superalloys. Comparison with Alloy 718 data from the literature shows
that FCP rates of as-produced Alloy 718 and isothermally exposed Alloy 783 are comparable at 650 °C. A fully time-dependent
FCP model based on the damage-zone concept and a thermal-activation equation is proposed to characterize the FCP behaviors. 相似文献