全文获取类型
收费全文 | 257篇 |
免费 | 18篇 |
国内免费 | 5篇 |
学科分类
工业技术 | 280篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 8篇 |
2020年 | 7篇 |
2019年 | 13篇 |
2018年 | 22篇 |
2017年 | 15篇 |
2016年 | 20篇 |
2015年 | 9篇 |
2014年 | 12篇 |
2013年 | 26篇 |
2012年 | 12篇 |
2011年 | 16篇 |
2010年 | 15篇 |
2009年 | 19篇 |
2008年 | 14篇 |
2007年 | 8篇 |
2006年 | 4篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2000年 | 1篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
排序方式: 共有280条查询结果,搜索用时 0 毫秒
1.
Sarband Ebrahim Mokallaf Araghinejad Shahab Attari Jalal 《Water Resources Management》2020,34(2):447-462
Water Resources Management - In water resource management, assessing water resource allocation scenarios (WRASs) is an important multi-attribute decision making (MADM) problem. It involves... 相似文献
2.
Tsung-Liang Wu Chaw-Wu Tseng Chen-Chi Lin Shahab Hatam-Tabrizi I. Y. Shen 《Microsystem Technologies》2010,16(1-2):9-17
This paper is to study how stray magnetic forces encountered in a long seeking process affect position errors of a hard disk drive after it finishes the seek and settles. The study consists of three parts: analysis of stray magnetic forces, numerical modeling, and analysis of numerical results. In the analysis of stray magnetic forces, we lump the stray magnetic forces into three components D1, D2 and D4. Specifically, D1 is a pair of stray magnetic forces in the plane of the voice coil. The two forces act on the two equal legs of the voice coil. In addition, the two forces point to and away from the pivot center, respectively. D2 is a pair of stray magnetic forces out of the plane of the voice coil. The two forces are equal in magnitudes but opposite in directions. The two force components also act on the two equal legs of the voice coil. D4 is identical to D2, except that the two force components in D4 act in the same direction. In the numerical study, we adopt a numerical model that includes a spinning spindle motor, a spinning disk pack with multiple disks, a stationary base plate with a top cover, and a slewing head-stack assembly. Moreover, multiple bearings are present in the model to connect the multiple components. In particular, fluid-dynamic bearings connect the rotating spindle and disk pack with the base plate, pivot bearings connect the base plate with the head-stack assembly, and air bearings connect the spinning disk pack with head sliders located at the tip of the slewing head-stack assembly. Also, the numerical model assumes that the head-stack assembly seeks according to a user-specified seeking profile. Numerical simulations show two major conclusions. First, stray magnetic force component D1 does not lead to significant position errors when the head-stack assembly settles. Stray magnetic force components D2 and D4, however, can affect the position errors by significantly exciting torsion and bending modes of the head-stack assembly. Second, a flex cable can significantly increase position errors below 1 kHz during settling. 相似文献
3.
Tumuluru Jaya Shankar Shahab Sokhansanj Sukumar Bandyopadhyay A. S. Bawa 《Food and Bioprocess Technology》2010,3(4):498-510
In the present study, response surface method (RSM) and genetic algorithm (GA) were used to study the effects of process variables like screw speed, rpm (x 1), L/D ratio (x 2), barrel temperature (°C; x 3), and feed mix moisture content (%; x 4), on flow rate of biomass during single-screw extrusion cooking. A second-order regression equation was developed for flow rate in terms of the process variables. The significance of the process variables based on Pareto chart indicated that screw speed and feed mix moisture content had the most influence followed by L/D ratio and barrel temperature on the flow rate. RSM analysis indicated that a screw speed?>?80 rpm, L/D ratio?>?12, barrel temperature?>?80 °C, and feed mix moisture content?>?20% resulted in maximum flow rate. Increase in screw speed and L/D ratio increased the drag flow and also the path of traverse of the feed mix inside the extruder resulting in more shear. The presence of lipids of about 35% in the biomass feed mix might have induced a lubrication effect and has significantly influenced the flow rate. The second-order regression equations were further used as the objective function for optimization using genetic algorithm. A population of 100 and iterations of 100 have successfully led to convergence the optimum. The maximum and minimum flow rates obtained using GA were 13.19?×?10?7 m3/s (x 1?=?139.08 rpm, x 2?=?15.90, x 3?=?99.56 °C, and x 4?=?59.72%) and 0.53?×?10?7 m3/s (x 1?=?59.65 rpm, x 2?=?11.93, x 3?=?68.98 °C, and x 4?=?20.04%). 相似文献
4.
Magnetic nanofluid actuation by rotating magnetic fields was proposed as a high‐performance tool for liquid mixing with enhanced micromixing features. A comparative study was conducted to evaluate the mixing index in T‐type mixers of magnetic and nonmagnetic fluids subject to static (SMF), oscillating (OMF), and rotating (RMF) magnetic fields. RMF excitation unveiled superior mixing indices with strong dependences to magnetic field frequency and content of magnetic nanoparticles. The impact of magnetic field types on micromixing was further examined at low and moderate Re numbers using the Villermaux–Dushman reaction and IEM micromixing model. The IEM‐inferred micromixing times were remarkably shorter by nearly four orders of magnitude in comparison with OMF and SMF excitations, and without magnetic field. The proposed mixing strategy is foreseen to complement innovative microfluidic devices with valuable mixing tools and methods for the diagnosis of the coupling between transport and intrinsic kinetics. © 2016 American Institute of Chemical Engineers AIChE J, 63: 337–346, 2017 相似文献
5.
Fereydoon Aflaki Vanik Ghoulipour Nader Saemian Shahab Sheibani 《Food Analytical Methods》2014,7(3):713-720
A rapid, sensitive, and reproducible high-performance liquid chromatographic procedure for the determination of nine biogenic amines in non-alcoholic beers was developed by an optimized benzoylation procedure. A Plackett–Burman factorial design was used in order to screen the statistically significant variables. The significant factors of biogenic amine benzoylation, reagent volume and pH, were optimized by a complete factorial response surface design, and optimal reaction conditions were generated. The optimized method showed good linearity (correlation coefficients > 0.997) and good recoveries (from 88.6 to 104.7 %). The repeatability and reproducibility of method were >3.9 and >4.6 %, respectively. Moreover, the detection limits of biogenic amines were calculated between 0.05 and 0.15 μg/ml in wine samples. The optimized method has been applied to the determination of biogenic amine contents of non-alcoholic beers consumed in Iran. Their values ranged from 0 to 2.56 mg/l, no significant differences (p?>?0.05) were observed between the analyzed samples, and none of these samples surpass the toxic levels reported in the literature. 相似文献
6.
Abolghasem Nourmohammadi Saeid Jalali Asadabadi Mohammad Hasan Yousefi Majid Ghasemzadeh 《Nanoscale research letters》2012,7(1):689
The photoluminescence emission of nanoporous anodic aluminum oxide films formed in phosphoric acid is studied in order to explore their defect-based subband electronic structure. Different excitation wavelengths are used to identify most of the details of the subband states. The films are produced under different anodizing conditions to optimize their emission in the visible range. Scanning electron microscopy investigations confirm pore formation in the produced layers. Gaussian analysis of the emission data indicates that subband states change with anodizing parameters, and various point defects can be formed both in the bulk and on the surface of these nanoporous layers during anodizing. 相似文献
7.
8.
R. Mirzaeifar H. Bahai S. Shahab 《International journal for numerical methods in engineering》2008,75(12):1492-1510
In this paper, a new method for computing eigenvalue and eigenvector derivatives of asymmetric non‐conservative systems with distinct eigenvalues is presented. Several approaches have been proposed for eigenderivative analysis of systems with asymmetric and non‐positive‐definite mass, damping and stiffness matrices. The proposed formulation that is developed by combining the modal and algebraic methods neither have the complications of modal methods in calculating the complex left and right eigenvector derivatives nor suffer from numerical instability problems usually associated with algebraic methods. The method is applied to a functionally graded material (FGM) plate actively controlled by piezoelectric sensor/actuators. In this system, the feedback signal applied to each actuator patch is implemented as a function of the electric potential in its corresponding sensor patch. The use of this closed‐loop controlling system leads to a non‐self‐adjoint system with complex eigenvalues and eigenvectors. A finite element model is developed for static and dynamic analysis of closed‐loop controlled FGM plate. The first‐ and second‐order approximations of Taylor expansion are used to estimate the corresponding changes in the plate modal properties due to change in design parameters (the displacement feedback gains and the piezoelectric layer thickness in each S/A pair). Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
9.
10.