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排序方式: 共有189条查询结果,搜索用时 15 毫秒
181.
    
In this article, a hybrid metaheuristic method for solving the open shop scheduling problem (OSSP) is proposed. The optimization criterion is the minimization of makespan and the solution method consists of four components: a randomized initial population generation, a heuristic solution included in the initial population acquired by a Nawaz-Enscore-Ham (NEH)-based heuristic for the flow shop scheduling problem, and two interconnected metaheuristic algorithms: a variable neighborhood search and a genetic algorithm. To our knowledge, this is the first hybrid application of genetic algorithm (GA) and variable neighborhood search (VNS) for the open shop scheduling problem. Computational experiments on benchmark data sets demonstrate that the proposed hybrid metaheuristic reaches a high quality solution in short computational times. Moreover, 12 new hard, large-scale open shop benchmark instances are proposed that simulate realistic industrial cases.  相似文献   
182.
This study aims to investigate the thermal conductivity and the linear coefficient of thermal expansion for short fibre reinforced composites. The study combines numerical and statistical analyses in order to primarily examine the representative size and the effective properties of the volume element. Effects of various micromechanical parameters, such as fibre’s aspect ratio and fibre’s orientation, on the minimum representative size are discussed. The numerically acquired effective properties, obtained for the representative size, are presented and compared with analytical models.  相似文献   
183.
In theory, it can be established that nonlinear control laws for linear or nonlinear plants can be used to meet strict performance requirements. The success of these control designs in practical situations will very much depend on whether they can still meet the expected performance characteristics in the presence of inevitable modeling errors. In this paper, we develop necessary and sufficient conditions for a general class of nonlinear control laws in the presence of high-frequency unmodeled dynamics, under which global signal boundedness or asymptotic stability is guaranteed. We show that a wide class of nonlinear control laws does not satisfy these conditions and therefore does not guarantee global stability in the presence of high-frequency unmodeled dynamics  相似文献   
184.
    
Pure tetraesters of erythritol with C10, C12, C14, C16, C18 saturated, and C18:1 unsaturated (oleoyl) fatty acyl chains have been prepared for the first time and characterized using the acylating systems fatty acid/N,N′‐dicyclohexylcarbodiimide/4‐dimethylaminopyridine (DMAP), fatty acid anhydride/DMAP, fatty acyl chloride/pyridine, and fatty acyl chloride/boron trifluoride etherate. For the first three systems the yields were in the range of 80–90% while the fatty acyl chloride/pyridine system has the advantage of lower cost. The fatty acyl chloride/boron trifluoride etherate system gave lower (ca 70%) yields of the tetraesters. The tetraesters of erythritol may have applications analogues to those of triglycerides. In addition, new applications can be envisaged for these compounds, as a result of their differences in physical, chemical, and biochemical properties compared to triglycerides. Practical applications: The tetraesters of erythritol with saturated fatty acyl chains may have applications analogous to those of saturated triglycerides. However, tetraesters with unsaturated fatty acid chains may have greater prospects of having industrial uses after doing chemistry on the carbon–carbon double bonds.  相似文献   
185.
The characteristics of the front and back channels of 1-μm-long SIMOX MOSFETs were measured before and after various types of periods of hot-electron stress, and a comparison between the induced degradations was made. The back channel degrades much more severely than the front channel for both partially depleted and fully depleted devices. Fully depleted MOSFETs (140-nm-thick) are favorably contrasted with partially depleted ones (300-nm-thick) as to their vulnerability to hot-carrier-induced damage. Although defects are always located at and/or near the interface of the stressed channel, they may influence the properties of the opposite channel (via interface coupling) in fully depleted MOSFETs  相似文献   
186.
The dynamic transconductance technique of MOSFET interface characterization is adapted to fully depleted silicon-on-insulator (SOI) transistors and is used to measure the interface-state density energy profiles in several SIMOX (separation by implanted oxygen) transistors. By making measurements first with the current flowing through the channel under measurement and then through the opposite channel, much of the energy gap (from accumulation to well into weak inversion) can be probed. Remarkably high sensitivity is achieved by utilizing the imaginary part of the dynamic transconductance. Measured interface trap densities were in the region of ~1010-1011 eV-1-cm-2  相似文献   
187.
Photo-injection was used to study the charge trapping properties of high-temperature oxidation (HITOX) SIMOX buried oxides (BOX), provided by two independent vendors. After electron injection, from a 5 eV mercury light source, the electron trapping per area for both HITOX material sources was found to be larger than their respective standard (control) separation by implantation of oxygen (SIMOX) structures. This increase has been attributed to the HITOX's process influence on the formation of the HITOX/BOX oxide  相似文献   
188.
An increasing number of studies have profiled gene expressions in tumor specimens using distinct microarray platforms and analysis techniques. One challenging task is to develop robust statistical models in order to integrate multi-platform findings. We compare some methodologies on the field with respect to estrogen receptor (ER) status, and focus on a unified-among-platforms scale implemented by Shen et al. in 2004, which is based on a Bayesian mixture model. Under this scale, we study the ER intensity similarities between four breast cancer datasets derived from various platforms. We evaluate our results with an independent dataset in terms of ER sample classification, given the derived gene ER signatures of the integrated data. We found that integrated multi-platform gene signatures and fold-change variability similarities between different platform measurements can assist the statistical analysis of independent microarray datasets in terms of ER classification.  相似文献   
189.
    
Evacuation leaders and/or equipment provide route and exit information for people and guide them to the expected destinations, which could make crowd evacuation more efficient in case of emergency. The purpose of this paper is to provide an overview of recent advances in guided crowd evacuation. Different guided crowd evacuation approaches are classified according to guidance approaches and technologies. A comprehensive analysis and comparison of crowd evacuation with static signage, dynamic signage, trained leader, mobile devices, mobile robot and wireless sensor networks are presented based on a single guidance mode perspective. In addition, the different evacuation guidance systems that use high-tech means such as advanced intelligent monitoring techniques, AI techniques, computer technology and intelligent inducing algorithms are reviewed from a system’s perspective. Future researches in the area of crowd evacuation are also discussed.   相似文献   
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