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排序方式: 共有103条查询结果,搜索用时 31 毫秒
81.
Philip L-F. Liu Madjid Abbaspour 《International journal for numerical methods in engineering》1982,18(10):1497-1504
A hybrid integral equation method is formulated to study the diffraction of oblique waves by an infinite cylinder. The water depth and the geometry of the floating cylinder are assumed to be uniform in the y-direction (one of the horizontal axes). Numerical discretization and integrations are performed in the vertical plane. Analytical solutions are used in far fields such that radiation boundary conditions are satisfied. Numerical results are obtained for the case of wave scattering by a floating rectangular cylinder in a constant water depth. The accuracy and efficiency of present method are compared with those obtained by other numerical techniques. 相似文献
82.
A novel model to study the pull-in behavior of nonlinear electromechanically coupled systems has been developed. The proposed
model is based on the multilayered cantilever and fixed–fixed micro beam type MEMS switches. Due to the complexity of the
nonlinear beam mechanics, exact analytical solutions are not generally available; therefore, the derived nonlinear equation
has been numerically solved fully using the nonlinear finite difference method. Furthermore, the results obtained are summarized
and compared with the other existing empirical and analytical models. These results can be useful in the optimization of MEMS
switch designs or other actuators. In addition, the method developed in this paper has a good potential for analyzing other
types of complex MEMS devices.
An erratum to this article can be found at 相似文献
83.
Andreas Kohler Karim C. Abbaspour Martin Fritsch Rainer Schulin 《Canadian Metallurgical Quarterly》2001,127(6):355-362
Numerical flow models usually represent drains as a system dependent boundary condition. If soil is saturated, drains act as the Dirichlet boundary condition with pressure head set equal to zero, and if soil is unsaturated, drains act as the Neumann boundary condition with flow set equal to zero. The underlying assumption is that drains exhibit ideal behavior. In reality, however, this is generally not so, and the flow encounters additional resistances due to pipe slotting and clogging of the envelope material around the drains. To account for the resulting resistance, a Hooghoudt-type boundary condition was developed that prescribes drain flow in relation to the groundwater level at a reference position. The measured drain discharge in an old drainage system was compared with calculated discharge assuming an ideal drain. It was found that the ideal drain assumption led to large errors in simulated discharge. With a correctly formulated and calibrated Hooghoudt boundary condition, however, more accurate drain discharges were obtained. 相似文献
84.
Sara Abbaspour Amir Abbas Nourbakhsh Roozbeh Javad Kalbasi Kenneth J.D. Mackenzie 《Ceramics International》2013
Nanocomposites of Al–SBA-15 with the organic polymers poly-4-vinyl pyridine (P4VP) and polyacrylamide (PAM) were synthesized to produce SiAlON precursors containing various carbon contents. These CRN precursors, and their products after firing under N2 at 1450 °C for 3 h were investigated by XRD, SEM/EDS and surface area analysis (BET) to compare the influence of the organic polymer carbon source. The results were also compared with those from precursors containing carbon black as the carbon source. XRD and SEM/EDS analysis of the Al–SBA-15 confirmed the formation of mesoporous structures, while BET and pore size distribution measurements indicated that the entry of P4VP into the Al–SBA-15 nanocomposite precursor is significantly more efficient than that of PAM. Firing these precursors in nitrogen produced β-SiAlON and β-cristobalite. At all carbon concentrations the P4VP nanocomposite precursors formed significantly more SiAlON than those of the PAM and carbon black precursors, due to the proximity of a greater amount of the organic carbon source to the silica template in the P4VP composite, and possibly also to the lack of oxygen in the P4VP monomer, in contrast with PAM. At least twice the stoichiometric amount of carbon was required in all cases, with optimal SiAlON formation occurring in the P4VP precursor containing 6 times the stoichiometric amount of carbon. Increasing the carbon content further suppresses SiAlON formation, possibly due to the build-up of back pressure of CO by-products in the pores of the nanocomposite. 相似文献
85.
Farhad Saba Seyed Abdolkarim Sajjadi Mohsen Haddad-Sabzevar Faming Zhang 《Ceramics International》2018,44(7):7949-7954
In the present study, single-phase TiC nanotubes and nanorods were synthesized by a novel pressureless spark plasma sintering (SPS) technique using carbon nanotubes (CNTs) and titanium powders at 1050?°C for 5?min. Moreover, formation mechanism of the resultant nanomaterials was clarified in detail. X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) patterns and Raman spectroscopy were conducted to study the microstructure and nature of the produced samples. XRD patterns indicated that all powders reacted to form TiC after applying 1050?°C. In addition, according to the TGA results, a significant increment in thermal properties was achieved compared to the pristine CNTs. 相似文献
86.
87.
88.
Alizadeh Azar Mosalanezhad Fatemeh Afroozeh Abdolkarim Akbari Elnaz Buntat Zolkafle 《Microsystem Technologies》2019,25(1):115-119
Microsystem Technologies - In this study, MoS2 gas sensor based on field effect transistor has been proposed and the adsorption of NO2 molecules on the channel surface can lead to significant... 相似文献
89.
Wireless Personal Communications - Advances in directional sensors technology and impressive development of wireless sensor networks, created a new class of wireless sensor networks called... 相似文献
90.
The effects of various methods of reinforcement modification on the microstructure and mechanical properties of Al–Al2O3 nanocomposites were investigated. Alumina nanoparticles were modified by electroless deposition of Cu, Ni and Co. Subsequently, aluminium matrix nanocomposites reinforced with uncoated and coated nanoparticles were produced by the stir casting method. The results of microstructural analysis showed improved wettability of coated nanoparticles in the molten aluminium alloy. Furthermore, coated nanoparticles exhibited a more desirable interface with the matrix and were homogenously distributed within it. The mechanical properties of the nanocomposites were improving significantly when coated nanoparticles were used as reinforcements. Among the reinforcement modification methods, Ni-coating was recognised as being more effective for improving the mechanical properties of Al–Al2O3 nanocomposites. 相似文献