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   9135篇
  免费   444篇
  国内免费   472篇
电工技术   510篇
技术理论   2篇
综合类   674篇
化学工业   1146篇
金属工艺   199篇
机械仪表   724篇
建筑科学   1497篇
矿业工程   704篇
能源动力   170篇
轻工业   106篇
水利工程   250篇
石油天然气   331篇
武器工业   45篇
无线电   281篇
一般工业技术   823篇
冶金工业   433篇
原子能技术   941篇
自动化技术   1215篇
  2024年   18篇
  2023年   70篇
  2022年   183篇
  2021年   230篇
  2020年   201篇
  2019年   270篇
  2018年   181篇
  2017年   215篇
  2016年   239篇
  2015年   238篇
  2014年   575篇
  2013年   612篇
  2012年   662篇
  2011年   784篇
  2010年   610篇
  2009年   510篇
  2008年   460篇
  2007年   536篇
  2006年   522篇
  2005年   448篇
  2004年   386篇
  2003年   380篇
  2002年   286篇
  2001年   242篇
  2000年   221篇
  1999年   192篇
  1998年   163篇
  1997年   122篇
  1996年   99篇
  1995年   67篇
  1994年   57篇
  1993年   47篇
  1992年   39篇
  1991年   24篇
  1990年   14篇
  1989年   12篇
  1988年   10篇
  1987年   3篇
  1986年   7篇
  1985年   14篇
  1984年   11篇
  1983年   15篇
  1982年   7篇
  1981年   19篇
  1980年   12篇
  1979年   5篇
  1978年   6篇
  1959年   14篇
  1955年   2篇
  1954年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
本文讲述了在公共卫生信息平台项目的开发过程中采用软件工程化方法和技术进行平台的开发。分析了软件工程化开发现状及需求,探讨了软件工程化目标和软件工程化技术路线,并给出了软件工程化开发步骤。  相似文献   
92.
Solving engineering design and resources optimization via multiobjective evolutionary algorithms (MOEAs) has attracted much attention in the last few years. In this paper, an efficient multiobjective differential evolution algorithm is presented for engineering design. Our proposed approach adopts the orthogonal design method with quantization technique to generate the initial archive and evolutionary population. An archive (or secondary population) is employed to keep the nondominated solutions found and it is updated by a new relaxed form of Pareto dominance, called Pareto-adaptive ϵ-dominance (paϵ-dominance), at each generation. In addition, in order to guarantee to be the best performance produced, we propose a new hybrid selection mechanism to allow the archive solutions to take part in the generating process. To handle the constraints, a new constraint-handling method is employed, which does not need any parameters to be tuned for constraint handling. The proposed approach is tested on seven benchmark constrained problems to illustrate the capabilities of the algorithm in handling mathematically complex problems. Furthermore, four well-studied engineering design optimization problems are solved to illustrate the efficiency and applicability of the algorithm for multiobjective design optimization. Compared with Nondominated Sorting Genetic Algorithm II, one of the best MOEAs available at present, the results demonstrate that our approach is found to be statistically competitive. Moreover, the proposed approach is very efficient and is capable of yielding a wide spread of solutions with good coverage and convergence to true Pareto-optimal fronts.  相似文献   
93.
基于项目驱动模式下的“软件工程”教学改革   总被引:5,自引:3,他引:2  
本文介绍了我院针对软件工程传统教学模式的弊端,以项目为驱动,结合案例教学、团队合作等教学方法,使学生能够系统地掌握软件开发的过程、方法和工具,从而具备计算机软件系统开发和维护的能力,为学生将来的工作打下坚实的基础。  相似文献   
94.
首先对国内外软件开发理论的应用现状作了比较,然后重点分析软件系统开发流程,综合分析比较软件开发流程的各个阶段.  相似文献   
95.
Work carried out by European Associations on Safety and Environment inside the EC Fusion Technology Programme and by NET has been concentrated on safety-related guidance and on safety assessment of the NET Predesign. Emphasis has been put on analysis of accident sequences of regulatory concern up to worst case accidents, including quantification of consequences to components, systems, and plant, and of doses to the public. Probabilistic safety studies for the most important systems and broadly for the entire plant have been performed to supplement the calculated accidental doses by expectation values for their occurrence rate, and to check the relevance of the reference accident sequences selected initially by judgment. Waste masses per year of operation and for decommissioning have been quantified. For two countries and according to the practices and regulations of these countries, volumes of radioactive waste packaged for final disposal have been determined.Presented at the IAEA Technical Committee Meeting on Developments in Fusion Safety, Toronto, June 7–11, 1993.  相似文献   
96.
电刷摩擦系数测量   总被引:1,自引:0,他引:1  
本文介绍电刷摩擦系数的测量装置-电刷试验转台。由正压力给定系统测量电刷的正压力,力矩反馈系统测量摩擦力对旋转中心产生的转矩,游标尺测量电刷至旋转中心距离,从而得出摩擦力。摩擦力除以正压力即摩擦系数。文中给出二个测量系统之测试结果。  相似文献   
97.
产教融合作为地方应用型高校培养工程创新人才的有效途径日益得到重视。在实施产教融合过程中,由于学校和企业利益着眼点、管理体制的差异,导致产业企业在应用型人才工程实践能力、工程创新能力培养过程中的参与深度不足、效果不佳的问题。针对上述不足,本文以江苏省地方应用型高校—南京工程学院的电气类产教融合模式探索为例,通过建立互利共赢的多元协同育人机制,实施匹配工程场景项目化教学改革,施行全程贯穿的工程创新训练,以期提升产教融合的育人效果,为产教深度融合提供借鉴。  相似文献   
98.
针对自制炸药爆炸事故造成人员伤亡、财产损失巨大,社会影响恶劣的情况,采用红外光谱法(IR)和拉曼光谱法(Raman)等快速检验技术对爆炸现场的遗留物、残留物和抛散物等进行检验、初步定性和来源推断。通过一起自制炸药爆炸事故的现场勘查和物证临场快速检验,实现了对自制炸药主要组分的快速推断和爆炸现场重建,并对爆炸事故原因进行了分析判定,可为同类爆炸事故现场快速勘验和原因分析提供借鉴,对提升爆炸事故现场勘查效率,实现爆炸事故原因快速认定具有重要的应用价值,并对查清犯罪事实,打击犯罪和维护社会稳定有着重要的作用。  相似文献   
99.
Sustainable hydrogen production via photocatalytic, electrocatalytic, and synergetic photoelectrocatalytic processes has been regarded as an effective strategy to address both energy and environmental crises. Due to their unique structures and properties, emerging ultrathin two-dimensional (2D) materials can bring about promising opportunities to realize high-efficiency hydrogen evolution. This review presents a critical appraisal of advantages and advancements for ultrathin 2D materials in catalytic hydrogen evolution, with an emphasis on structure–activity relationship. Furthermore, strategies for tailoring the microstructure, electronic structure, and local atomic arrangement, so as to further boost the hydrogen evolution activity, are discussed. Finally, we also present the existing challenges and future research directions regarding this promising field.  相似文献   
100.
Manufacturing ultralight and mechanical reliable materials has been a long-time challenge. Ceramic-based mechanical metamaterials provide significant opportunities to reverse their brittle nature and unstable mechanical properties and have great potential as strong, ultralight, and ultrastiff materials. However, the failure of ceramics nanolattice and degradation of strength/modulus with decreasing density are caused by buckling of the struts and failure of the nodes within the nanolattices, especially during cyclic loading. Here, we explore a new class of 3D ceramic-based metamaterials with a high strength–density ratio, stiffness, recoverability, cyclability, and optimal scaling factor. Deformation mode of the fabricated nanolattices has been engineered through the unique material design and architecture tailoring. Bending-dominated hollow nanolattice (B-H-Lattice) structure is employed to take advantages of its flexibility, while a few nanometers of carbonized mussel-inspired bio-polymer (C-PDA) is coherently deposited on ceramics’ nanolayer to enable non-buckling struts and bendable nodes during deformation, resulting in reliable mechanical properties and outperforming the current bending-dominated lattices (B-Lattices) and carbon-based cellulose materials. Meanwhile, the structure has comparable stiffness to stretching-dominated lattices (S-Lattices) while with better cyclability and reliability. The B-H-Lattices exhibit high specific stiffness (>106?Pa·kg?1·m?3), low-density (~30?kg/m3), buckling-free recovery at 55% strain, and stable cyclic loading behavior under up to 15% strain. As one of the B-Lattices, the modulus scaling factor reaches 1.27, which is lowest among current B-Lattices. This study suggests that non-buckling behavior and reliable nodes are the key factors that contribute to the outstanding mechanical performance of nanolattice materials. A new concept of engineering the internal deformation behavior of mechanical metamaterial is provided to optimize their mechanical properties in real service conditions.  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