全文获取类型
收费全文 | 6884篇 |
免费 | 358篇 |
国内免费 | 23篇 |
专业分类
电工技术 | 79篇 |
技术理论 | 2篇 |
综合类 | 185篇 |
化学工业 | 121篇 |
金属工艺 | 43篇 |
机械仪表 | 103篇 |
建筑科学 | 4990篇 |
矿业工程 | 44篇 |
能源动力 | 221篇 |
轻工业 | 73篇 |
水利工程 | 146篇 |
石油天然气 | 94篇 |
武器工业 | 6篇 |
无线电 | 110篇 |
一般工业技术 | 164篇 |
冶金工业 | 161篇 |
原子能技术 | 14篇 |
自动化技术 | 709篇 |
出版年
2024年 | 3篇 |
2023年 | 59篇 |
2022年 | 98篇 |
2021年 | 137篇 |
2020年 | 176篇 |
2019年 | 104篇 |
2018年 | 129篇 |
2017年 | 105篇 |
2016年 | 228篇 |
2015年 | 233篇 |
2014年 | 432篇 |
2013年 | 426篇 |
2012年 | 453篇 |
2011年 | 500篇 |
2010年 | 424篇 |
2009年 | 520篇 |
2008年 | 394篇 |
2007年 | 480篇 |
2006年 | 460篇 |
2005年 | 354篇 |
2004年 | 301篇 |
2003年 | 209篇 |
2002年 | 219篇 |
2001年 | 152篇 |
2000年 | 165篇 |
1999年 | 130篇 |
1998年 | 106篇 |
1997年 | 58篇 |
1996年 | 49篇 |
1995年 | 34篇 |
1994年 | 17篇 |
1993年 | 14篇 |
1992年 | 16篇 |
1991年 | 9篇 |
1990年 | 5篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 2篇 |
1986年 | 13篇 |
1985年 | 16篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有7265条查询结果,搜索用时 19 毫秒
1.
The next-generation systems are expected to be largely cyber–physical systems (CPSs) that autonomously control physical processes, through sensors and actuators typically in real-time feedback and cooperative control loops distributed among physical and cyber environments. The rapid technological advancements enhance the smartness of these CPSs, pushing their boundaries of performance and efficiency by embedding new information and communication technologies. However, to what extent CPSs should be smarter so that they do not compromise safety and security of safety critical systems? is an open research question. Towards this goal, the purpose of this study is to establish a grounded theory to analyse what makes these systems smart? and eventually, how to find a balance between smartness and safety risks? In this precinct, this article aims to develop a conceptual framework, define the dimensions and derive the characteristics that make CPSs smart. The proposed approach combines an automated informetric and systematic analysis of literature pertinent to the topic of smartness across anthropology, science, engineering and technology. The analysis of a case study building and the discussions presented herein support the connection between the existing understanding of CPSs and smartness offered by the building design approach in urban environment. 相似文献
2.
Smart grid has opened up a new role of “prosumer” in an energy value network, transforming many conventional energy consumers into prosumers, who not only generate green energy but also share the surplus with utilities and other consumers. The concept of a goal-oriented prosumer community group (PCG) has emerged recently as an effective way to fulfill sustainable energy exchange. Such community-based energy sharing networks comprise multiple irreconcilable objectives such as demand constraints, cost constraints, and income maximization. In many cases, one goal may be achievable only at the expense of other goals. This necessitates the development of an effective framework to manage the multiple goals and reduce the gap with their achievement levels. Therefore, in this research paper, an effective framework is developed to negotiate among the multiple goals and thus to define optimal mutual goals for each PCG in a more sustainable manner using multiple-criteria goal programming techniques. Simulation results are presented to illustrate how the methods work in practical situations, where each of the objective measure is given a target value and the unwanted deviations from this set are minimized in an achievement function. 相似文献
3.
4.
中国未来电力需求与核能 总被引:5,自引:0,他引:5
本文介绍了我国未来电力需求和能源结构,阐述了核能是我国满足经济发达地区电力需求的合理选择,并提出了我国“九五”核电计划和中期目标,以及发展核电中面临的问题和基本对策。 相似文献
5.
DCS的现状与发展趋势 总被引:1,自引:0,他引:1
钟霖田 《自动化与仪器仪表》1994,(3):1-6
叙述DCS的进展。目前的DCS正面临来自用户需求的挑战,为保住全球市场竞争优势,制造加工行业用户需要建立集过程控制数据与商业信息于一体的CIMS。未来DCS应具备服从国际标准的开放性和互换操作性。以ISP现场总线为基础的系统结构可能成为未来的DCS。提高应用水平有助于发展未来的DCS 相似文献
6.
以衢州市花园岗中心区为例,提出城市设计要在尊重历史文化的基础上,结合自然地理条件,通过创造性的设计手段,来描绘未来城市中心区富有文化和生态内涵的全新形象。 相似文献
7.
Mohammed Saad Svetlana Cicmil Margaret Greenwood 《International Journal of Project Management》2002,20(8)
This paper attempts to broaden the analysis of the technology transfer phenomenon by refocusing research attention on the level of performance assessment of technology transfer projects. An holistic evaluation framework based on the considerations of an extended Project Life Cycle model is proposed to overcome some of the shortcomings of conventional approaches to project evaluation. This also reinforces the need for open systems thinking in assessing and managing risk of technology transfer projects. The discussion is based on two case studies which articulate the experiences with two integrated mechanisms of technology transfer used in Algeria from 1965 to 1990: turnkey and “product-in-hand”. The aim is to gain a better understanding of the processes of technology transfer and to contribute to the improvement of associated managerial practices in developing economies. 相似文献
8.
Kathryn Kromroy Kathleen Ward Paul Castillo Jennifer Juzwik 《Landscape and urban planning》2007,80(4):375-385
Urbanization was associated with loss and transformation of the oak forest in the Twin Cities (Minneapolis and St. Paul) metropolitan area (TCMA) over a recent 7-year interval. Between 1991 and 1998, urbanization increased based on several indicators: population density, area of developed land, and area of impervious surface—total impervious area and area within three classes of increasing degree of imperviousness (protected, affected, and degraded). We quantified relationships between changes in urbanization and changes in several parameters describing the oak forest at the scale of ecological subsection. Increased total and affected impervious area were strongly correlated with decreased area of oak forest when changes of the urbanization indicators and oak were expressed as percentages of the subsection area. Relationships were reversed when changes were expressed as percentages of the 1991 values. Increased population density was strongly correlated with increased loss in numbers and increased isolation of oak patches, but weakly correlated with loss of oak forest area. This is the first study to quantify relationships between changes in urbanization and changes in a specific forest cover type. Our results demonstrate complexities of urbanization impacts on a metropolitan forest resource, and highlight the importance of selected variables, spatial and temporal scales, and expressions of change when quantifying these relationships. 相似文献
9.
10.
清代皇家园林规划设计控制的量化研究——以圆明三园、清漪园为例 总被引:1,自引:0,他引:1
本文通过量化分析探索了清代皇家园林规划设计的控制规律及相关理论。 相似文献