全文获取类型
收费全文 | 12816篇 |
免费 | 685篇 |
国内免费 | 42篇 |
专业分类
电工技术 | 171篇 |
综合类 | 15篇 |
化学工业 | 2686篇 |
金属工艺 | 450篇 |
机械仪表 | 939篇 |
建筑科学 | 230篇 |
矿业工程 | 3篇 |
能源动力 | 440篇 |
轻工业 | 1099篇 |
水利工程 | 83篇 |
石油天然气 | 13篇 |
无线电 | 2347篇 |
一般工业技术 | 2751篇 |
冶金工业 | 707篇 |
原子能技术 | 167篇 |
自动化技术 | 1442篇 |
出版年
2024年 | 13篇 |
2023年 | 163篇 |
2022年 | 231篇 |
2021年 | 439篇 |
2020年 | 282篇 |
2019年 | 326篇 |
2018年 | 367篇 |
2017年 | 420篇 |
2016年 | 457篇 |
2015年 | 379篇 |
2014年 | 554篇 |
2013年 | 825篇 |
2012年 | 836篇 |
2011年 | 1015篇 |
2010年 | 738篇 |
2009年 | 781篇 |
2008年 | 724篇 |
2007年 | 570篇 |
2006年 | 495篇 |
2005年 | 447篇 |
2004年 | 416篇 |
2003年 | 368篇 |
2002年 | 384篇 |
2001年 | 292篇 |
2000年 | 261篇 |
1999年 | 244篇 |
1998年 | 363篇 |
1997年 | 237篇 |
1996年 | 179篇 |
1995年 | 123篇 |
1994年 | 111篇 |
1993年 | 91篇 |
1992年 | 65篇 |
1991年 | 56篇 |
1990年 | 50篇 |
1989年 | 57篇 |
1988年 | 30篇 |
1987年 | 39篇 |
1986年 | 18篇 |
1985年 | 30篇 |
1984年 | 16篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1973年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Myung Hyun Lee Hyoung-Ki Choi Kiwan Bang Seokwon 《International Journal of Control, Automation and Systems》2010,8(3):667-676
The odometry information used in mobile robot localization can contain a significant number of errors when robot experiences
slippage. To offset the presence of these errors, the use of a low-cost gyroscope in conjunction with Kalman filtering methods
has been considered by many researchers. However, results from conventional Kalman filtering methods that use a gyroscope
with odometry can unfeasible because the parameters are estimated regardless of the physical constraints of the robot. In
this paper, a novel constrained Kalman filtering method is proposed that estimates the parameters under the physical constraints
using a general constrained optimization technique. The state observability is improved by additional state variables and
the accuracy is also improved through the use of a nonapproximated Kalman filter design. Experimental results show that the
proposed method effectively offsets the localization error while yielding feasible parameter estimation. 相似文献
102.
Driving characteristics of the electrowetting-on-dielectric device using atomic-layer-deposited aluminum oxide as the dielectric 总被引:2,自引:1,他引:1
Jong-hyeon Chang Dae Young Choi Seungoh Han James Jungho Pak 《Microfluidics and nanofluidics》2010,8(2):269-273
Electrowetting on dielectric (EWOD) is useful in manipulating droplets for digital (droplet-based) microfluidics, but its high driving voltage over several tens of volts has been a barrier to overcome. This article presents the characteristics of EWOD device with aluminum oxide (Al2O3, ε r ≈ 10) deposited by atomic layer deposition (ALD), for the first time as the high-k dielectric for lowering the EWOD driving voltage substantially. The EWOD device of the single-plate configuration was fabricated by several steps for the control electrode array of 1 mm × 1 mm squares with 50 μm space, the dielectric layer of 1,270 Å thick ALD Al2O3, the reference electrode of 20 μm wide line electrode, and the hydrophobic surface treatment by Teflon-AF coating, respectively. We observed the movement of a 2 μl water droplet in an air environment, applying a voltage between one of the control electrodes and the reference electrode in contact with the droplet. The droplet velocity exponentially depending on the applied voltage below 15 V was obtained. The measured threshold voltage to move the droplet was as low as 3 V which is the lowest voltage reported so far in the EWOD researches. This result opens a possibility of manipulating droplets, without any surfactant or oil treatment, at only a few volts by EWOD using ALD Al2O3 as the dielectric. 相似文献
103.
Hyung-Il Choi Yongbin Lee Dong-Hoon Choi Joo-Sung Maeng 《Structural and Multidisciplinary Optimization》2010,40(1-6):537-548
This study presents design optimization of a viscous micropump with two rotating cylinders. The desired performance of the pump is to maximize the pumping efficiency while satisfying the constraints on flow rate and geometry. As a preliminary step, the effects of geometric configurations on the pumping performance are investigated by carrying out parametric studies using an unstructured grid Navier–Stokes method. Next, an optimization problem is formulated to determine the design variable values which maximize the pumping efficiency subject to the constraints. Then, a computational procedure, combining the analysis method with a sequential metamodel-based optimization method, is established to solve the optimization problem formulated. Finally, this procedure is applied to the optimization of ten design cases with varying flow rates specified. The optimization results demonstrate the effectiveness of the design optimization method presented in this study by showing that the efficiencies of the optimally designed micropumps are enhanced without any constraint violations. 相似文献
104.
Vo-Gia Loc Ig Mo Koo Duc Trong Tran Sangdoek Park Hyungpil Moon Hyouk Ryeol ChoiAuthor vitae 《Robotics and Autonomous Systems》2011,59(12):1036-1048
This paper presents a study on improving the traversability of a quadruped walking robot in 3D rough terrains. The key idea is to exploit body movement of the robot. The position and orientation of the robot are systematically adjusted and the possibility of finding a valid foothold for the next swing is maximized, which makes the robot have more chances to overcome the rough terrains. In addition, a foothold search algorithm that provides the valid foothold while maintaining a high traversability of the robot, is investigated and a gait selection algorithm is developed to help the robot avoid deadlock situations. To explain the algorithms, new concepts such as reachable area, stable area, potential search direction, and complementary kinematic margin are introduced, and the effectiveness of the algorithms is validated via simulations and experiments. 相似文献
105.
As μ-TAS (micro total analysis system) is developed with enhancement of MEMS technology, the growth of medical and biological research areas increases rapidly. The study on LOC (lab on a chip), which is one of the μ-TAS and has the functions of mixing and analyzing with a tiny amount of sample and reagent on one chip, is actively progressed. LOC is composed of the microfluidic components such as micromixers and micropumps. Because the flow on the microfluidic system is generally laminar, it is very difficult to mix and feed fluidic reagents efficiently. This paper presents the design and the fabrication of the MHD micropump with mixing function, in which the fluids are simultaneously mixed and pumped by coupling between Lorentz force and the moving force of an electric charge in the electric field. The advanced model was determined through the commercial CFD program after several models were modified. The numerical results have been compared with the experimental results. This study shows the proposed micropump can be made through simple fabrication procedure and has the low energy consumption. 相似文献
106.
Autonomous topological modeling of a home environment and topological localization using a sonar grid map 总被引:1,自引:0,他引:1
This paper presents a method of autonomous topological modeling and localization in a home environment using only low-cost
sonar sensors. The topological model is extracted from a grid map using cell decomposition and normalized graph cut. The autonomous
topological modeling involves the incremental extraction of a subregion without predefining the number of subregions. A method
of topological localization based on this topological model is proposed wherein a current local grid map is compared with
the original grid map. The localization is accomplished by obtaining a node probability from a relative motion model and rotational
invariant grid-map matching. The proposed method extracts a well-structured topological model of the environment, and the
localization provides reliable node probability even when presented with sparse and uncertain sonar data. Experimental results
demonstrate the performance of the proposed topological modeling and localization in a real home environment. 相似文献
107.
This paper describes the design and fabrication of a MEMS guide plate, which was used for a vertical probe card to test a
wafer level packaged die wafer. The size of the fabricated MEMS guide plate was 10.6 × 10.6 cm. The MEMS guide plate consisted
of 8,192 holes to insert pogo pins, and four holes for bolting between the guide plate and the housing. To insert pogo pins
easily, an inclined plane was defined at the back of each hole. Pitch and diameter of the hole were 650 and 260 μm, respectively.
In order to define inserting holes and inclined planes at an exact position, silicon MEMS technology was used such as anisotropic
etching, deep reactive etching and more. Silicon was used as the material of the guide plate to reduce alignment mismatch
between the pogo pins and solder bumps during a high temperature testing. A combined probe card with the fabricated MEMS guide
plate showed good x–y alignment and planarity errors within ±9 and ±10 μm at room temperature, respectively. In addition, x–y alignment and planarity are ±20 and ±16 μm at 125°C, respectively. The proposed MEMS guide plate can be applied to a vertical
probe card for burn-in testing of a wafer level packaged die wafer because the thermal expansion coefficient of the MEMS guide
plate and die wafer is same. 相似文献
108.
109.
Yong Suk Choi 《Knowledge》2011,24(8):1139-1150
Recently, due to the widespread on-line availability of syntactically annotated text corpora, some automated tools for searching in such text corpora have gained great attention. Generally, those conventional corpus search tools use a decomposition-matching-merging method based on relational predicates for matching a tree pattern query to the desired parts of text corpora. Thus, their query formulation and expressivity are often complicated due to poorly understood query formalisms, and their searching tasks may require a big computational overhead due to a large number of repeated trials of matching tree patterns. To overcome these difficulties, we present TPEMatcher, a tool for searching in parsed text corpora. TPEMatcher provides not only an efficient way of query formulation and searching but also a good query expressivity based on concise syntax and semantics of tree pattern query. We also demonstrate that TPEMatcher can be effectively used for a text mining in practice with its useful interface providing in-depth details of search results. 相似文献
110.
Surface texture is one of the important properties for the human to identify objects by touch. Effective reconstructions of
textures are necessary for realistic interactions between the human and environment via human–computer interfaces. This paper
presents a systematic approach for sensing and reconstructing periodic surface textures. Three significant issues are discussed:
a pen-type texture sensor that measures the spatial information based on the measurements of contact forces; an algorithm
for the reconstruction of periodic textures based on the obtained spatial information; and the method of incremental scanning
to identify the polar spectrum of a surface by limited number of scans. The concept of polar spectrum is introduced to describe
the spatial properties of the surface, that is, the relation between spatial frequencies and the direction of measurement.
The pattern of polar spectrum is used to facilitate surface reconstructions. Experimental results based on the spatial information
obtained with a laser displacement sensor and the pen-type texture sensor demonstrate the effectiveness of the proposed methods
for the measurement and reconstruction of periodic textures. 相似文献