首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2813篇
  免费   96篇
  国内免费   12篇
工业技术   2921篇
  2023年   20篇
  2022年   16篇
  2021年   76篇
  2020年   37篇
  2019年   29篇
  2018年   41篇
  2017年   51篇
  2016年   74篇
  2015年   39篇
  2014年   83篇
  2013年   191篇
  2012年   121篇
  2011年   178篇
  2010年   130篇
  2009年   162篇
  2008年   143篇
  2007年   131篇
  2006年   108篇
  2005年   120篇
  2004年   107篇
  2003年   95篇
  2002年   71篇
  2001年   69篇
  2000年   58篇
  1999年   69篇
  1998年   138篇
  1997年   80篇
  1996年   70篇
  1995年   57篇
  1994年   55篇
  1993年   46篇
  1992年   17篇
  1991年   18篇
  1990年   18篇
  1989年   18篇
  1988年   14篇
  1987年   9篇
  1986年   15篇
  1985年   9篇
  1984年   19篇
  1983年   11篇
  1982年   13篇
  1981年   8篇
  1980年   6篇
  1979年   7篇
  1978年   7篇
  1977年   15篇
  1976年   13篇
  1975年   10篇
  1973年   9篇
排序方式: 共有2921条查询结果,搜索用时 31 毫秒
81.
82.
Search of discrete spaces is important in combinatorial optimization. Such problems arise in artificial intelligence, computer vision, operations research, and other areas. For realistic problems, the search spaces to be processed are usually huge, necessitating long computation times, pruning heuristics, or massively parallel processing. We present an algorithm that reduces the computation time for graph matching by employing both branch-and-bound pruning of the search tree and massively-parallel search of the as-yet-unpruned portions of the space. Most research on parallel search has assumed that a multiple-instruction-stream/multiple-data-stream (MIMD) parallel computer is available. Since massively parallel stream (SIMD) computers are much less expensive than MIMD systems with equal numbers of processors, the question arises as to whether SIMD systems can efficiently handle state-space search problems. We demonstrate that the answer is yes, and in particular, that graph matching has a natural and efficient implementation on SIMD machines  相似文献   
83.
We report the two- and three-dimensional quantum lattice-gas automata simulation for one-particle electronic wave propagation in nanostructures. The transmission coefficient of the electronic wave through the two-dimensional quantum point contact is investigated taking account of the surface roughness of the confinement wall. It is demonstrated that the electron transmission is significantly affected by the surface roughness pattern even if the same roughness parameter is assumed. We also perform the three-dimensional simulation, and the wave propagation in the structure like an ultrathin-body MOSFET is visualized.  相似文献   
84.
The study investigates the performance of two-bed, silica gel-water adsorption refrigeration cycle with mass recovery process. The cycle with mass recovery can be driven by the relatively low temperature heat source. In an adsorption refrigeration cycle, the pressures in adsorber and desorber are different. The chiller with mass recovery process utilizes the pressure difference to enhance the refrigerant mass circulation. Cooling capacity and coefficient of performance (COP) were calculated by cycle simulation computer program to analyze the influences of operating conditions. The mass recovery cycle was compared with conventional cycle such as the single stage adsorption cycle in terms of cooling capacity and COP. The results show that the cooling capacity of mass recovery cycle is superior to that of conventional cycle and the mass recovery process is more effective for low regenerating temperature.  相似文献   
85.
86.
87.
Abstract— A novel preparation method for dichroic dye‐doped polymer‐dispersed liquid crystals has been developed. This was achieved by creating a porous polymer matrix first by washing out the liquid crystal from a polymer‐dispersed liquid crystal (PDLC), which is then refilled with dye‐doped liquid crystal. Optimizing the liquid crystal used in the refilling results in decreased turn‐on voltage and faster response time. Poster‐standard reflectivity and newspaper‐standard contrast was demonstrated with a 3.8‐in. QVGA reflective TFT display with a drive voltage of 10 V.  相似文献   
88.
Micro-scale textures may be engineered into surfaces for lubrication performance improvement. It is expected that a carefully chosen texture helps retain lubricant and enhances the hydrodynamic effect at the interface. The concept of model-based virtual texturing enables textured surfaces to be generated and “tested” through numerical simulations. This paper reports virtual texturing and simulation of a group of textured surfaces in a lubricated concentrated contact. The focus of the study is on the selection of texture distribution patterns based on their lubrication performance. Patterns of fishbone, sinusoidal, triangular, and honeycomb distributions have been investigated. The effects of texture direction, orientation angle, feature continuity, and aspect ratio are also studied. The results indicate that, for the given material and geometry system under the given conditions in the present work, the textures generating the strongest hydrodynamic lifting are short grooves with a small aspect ratio and sinusoidal waves of a small wavelength/amplitude ratio propagating in the motion direction.  相似文献   
89.
Gamma-ray emission probabilities of 241, 243Am and 239Np have been precisely measured with gamma- and alpha-ray spectroscopic methods. The activities of the samples were determined by measuring alpha particles using a Si semiconductor detector. Gamma rays emitted from the samples were measured with a planar type High-Purity Germanium (HPGe) detector. An efficiency curve of the HPGe detector was derived with uncertainties from 0.7% to 2.5% by combining measured efficiencies and Monte Carlo simulation. The gamma-ray emission probabilities for the major gamma rays of these nuclides were determined with uncertainties less than 1.2%.  相似文献   
90.
It has been reported that an anisotropic magnetic field could produce the three-dimensional alignment of fine single-crystal particles with the orthorhombic crystal structure.However,the three-dimensional alignment was achieved only in suspensions.Fabrication of bulk"single"materials that have the three-dimensional alignment of grains has been desired.This study proposes a procedure for the fabrication,which consists of slip casting under an oscillating magnetic field and sintering.Optimization of casting and sintering conditions achieved the three-dimensionally aligned bulkβ-FeSi2.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号