首页 | 本学科首页   官方微博 | 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   25908篇
  免费   889篇
  国内免费   524篇
电工技术   771篇
技术理论   4篇
综合类   1457篇
化学工业   1455篇
金属工艺   944篇
机械仪表   2897篇
建筑科学   5465篇
矿业工程   420篇
能源动力   731篇
轻工业   990篇
水利工程   356篇
石油天然气   554篇
武器工业   127篇
无线电   1830篇
一般工业技术   1955篇
冶金工业   897篇
原子能技术   288篇
自动化技术   6180篇
  2024年   52篇
  2023年   200篇
  2022年   287篇
  2021年   417篇
  2020年   472篇
  2019年   335篇
  2018年   342篇
  2017年   368篇
  2016年   629篇
  2015年   675篇
  2014年   1400篇
  2013年   1396篇
  2012年   1596篇
  2011年   1896篇
  2010年   1442篇
  2009年   1494篇
  2008年   1278篇
  2007年   1647篇
  2006年   1609篇
  2005年   1488篇
  2004年   1314篇
  2003年   1245篇
  2002年   1021篇
  2001年   782篇
  2000年   708篇
  1999年   653篇
  1998年   498篇
  1997年   411篇
  1996年   330篇
  1995年   279篇
  1994年   213篇
  1993年   170篇
  1992年   134篇
  1991年   101篇
  1990年   83篇
  1989年   59篇
  1988年   51篇
  1987年   35篇
  1986年   26篇
  1985年   31篇
  1984年   38篇
  1983年   21篇
  1982年   16篇
  1981年   10篇
  1980年   8篇
  1979年   5篇
  1978年   5篇
  1976年   8篇
  1964年   6篇
  1960年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
In this paper, we investigate how adaptive operator selection techniques are able to efficiently manage the balance between exploration and exploitation in an evolutionary algorithm, when solving combinatorial optimization problems. We introduce new high level reactive search strategies based on a generic algorithm's controller that is able to schedule the basic variation operators of the evolutionary algorithm, according to the observed state of the search. Our experiments on SAT instances show that reactive search strategies improve the performance of the solving algorithm.  相似文献   
2.
In architectural design, surface shapes are commonly subject to geometric constraints imposed by material, fabrication or assembly. Rationalization algorithms can convert a freeform design into a form feasible for production, but often require design modifications that might not comply with the design intent. In addition, they only offer limited support for exploring alternative feasible shapes, due to the high complexity of the optimization algorithm.We address these shortcomings and present a computational framework for interactive shape exploration of discrete geometric structures in the context of freeform architectural design. Our method is formulated as a mesh optimization subject to shape constraints. Our formulation can enforce soft constraints and hard constraints at the same time, and handles equality constraints and inequality constraints in a unified way. We propose a novel numerical solver that splits the optimization into a sequence of simple subproblems that can be solved efficiently and accurately.Based on this algorithm, we develop a system that allows the user to explore designs satisfying geometric constraints. Our system offers full control over the exploration process, by providing direct access to the specification of the design space. At the same time, the complexity of the underlying optimization is hidden from the user, who communicates with the system through intuitive interfaces.  相似文献   
3.
This paper is the second one of the two papers entitled “Weighted Superposition Attraction (WSA) Algorithm”, which is about the performance evaluation of the WSA algorithm in solving the constrained global optimization problems. For this purpose, the well-known mechanical design optimization problems, design of a tension/compression coil spring, design of a pressure vessel, design of a welded beam and design of a speed reducer, are selected as test problems. Since all these problems were formulated as constrained global optimization problems, WSA algorithm requires a constraint handling method for tackling them. For this purpose we have selected 6 formerly developed constraint handling methods for adapting into WSA algorithm and analyze the effect of the used constraint handling method on the performance of the WSA algorithm. In other words, we have the aim of producing concluding remarks over the performance and robustness of the WSA algorithm through a set of computational study in solving the constrained global optimization problems. Computational study indicates the robustness and the effectiveness of the WSA in terms of obtained results, reached level of convergence and the capability of coping with the problems of premature convergence, trapping in a local optima and stagnation.  相似文献   
4.
5.
Numerous design choices need to be made at several levels when designing high-tech products: technology, processes, architecture, components, materials… and these choices need to be made in relation to the product life cycle with the corresponding experts for each stage of the life cycle. At the same time, to ensure product sustainability, a specific focus on the future potential environmental impacts is highly recommended. In this research, an agile model is proposed to help designers make decisions while monitoring environmental performance indicators of high-tech solutions. The concept of Critical Product Life Cycle Parameters had to be introduced to facilitate the eco-design of the final product. The approach is illustrated by the Electric Vehicle Li-Ion Batteries case study.  相似文献   
6.
《工程(英文)》2019,5(4):637-645
The rapid development of information and communication technologies (ICTs) and cyber–physical systems (CPSs) has paved the way for the increasing popularity of smart products. Context-awareness is an important facet of product smartness. Unlike artifacts, various bio-systems are naturally characterized by their extraordinary context-awareness. Biologically inspired design (BID) is one of the most commonly employed design strategies. However, few studies have examined the BID of context-aware smart products to date. This paper presents a structured design framework to support the BID of context-aware smart products. The meaning of context-awareness is defined from the perspective of product design. The framework is developed based on the theoretical foundations of the situated function–behavior–structure ontology. A structured design process is prescribed to leverage various biological inspirations in order to support different conceptual design activities, such as problem formulation, structure reformulation, behavior reformulation, and function reformulation. Some existing design methods and emerging design tools are incorporated into the framework. A case study is presented to showcase how this framework can be followed to redesign a robot vacuum cleaner and make it more context-aware.  相似文献   
7.
An engineered variant of the yeast Pichia pastoris was used to produce the potential malaria vaccine D1M1. This paper describes the implementation of an expanded bed adsorption chromatography step into a sequential cultivation process of the yeast in order to link protein expression, cell release, and product capture of the secreted protein in a fully automated plant. The process is operated with a semi-continuous strategy for an integrated production. Process improvements have been achieved using design of experiments. Resulting purities of product achieved up to 87% with recoveries of 51% in a single downstream operation. Furthermore, a multivariate analysis of historical batch data was used to develop a golden batch model for process monitoring.  相似文献   
8.
文中分析了大同市水资源开发利用的状况,并对水资源承载能力的有关问题进行了讨论。  相似文献   
9.
在PTA(精对苯二甲酸)的生产过程中,工艺废气经尾气膨胀透平机降压后进入RTO蓄热式焚烧炉将有毒有害的有机物焚烧分解后排入大气,为了达到粉尘的排放标准(小于120mg/m~3),在焚烧炉之后加上这台高温烟气除尘器,废气经除尘后达到了排放标准,而且最大程度地减少了热量损失,实践证明此项改造是成功的。文章探讨如何进行高温烟气除尘器的设计,并介绍了高温多管陶瓷旋风烟气除尘器的结构。  相似文献   
10.
加氢反应器制造技术的新进展   总被引:2,自引:1,他引:1  
随着加氢装置的大型化,对加氢反应器的设计、主体材质的选用及制造均提出了新的、更高的要求。文章较全面地介绍了国内外加氢反应器的设计准则、主体材质(抗氢钢)和制造技术等方面的新进展。  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