全文获取类型
收费全文 | 319357篇 |
免费 | 31489篇 |
国内免费 | 21832篇 |
专业分类
电工技术 | 47747篇 |
技术理论 | 31篇 |
综合类 | 36026篇 |
化学工业 | 15449篇 |
金属工艺 | 11042篇 |
机械仪表 | 23609篇 |
建筑科学 | 25476篇 |
矿业工程 | 11728篇 |
能源动力 | 10813篇 |
轻工业 | 6158篇 |
水利工程 | 8945篇 |
石油天然气 | 10979篇 |
武器工业 | 4621篇 |
无线电 | 40581篇 |
一般工业技术 | 15888篇 |
冶金工业 | 9156篇 |
原子能技术 | 2643篇 |
自动化技术 | 91786篇 |
出版年
2024年 | 1562篇 |
2023年 | 4075篇 |
2022年 | 8041篇 |
2021年 | 9383篇 |
2020年 | 9912篇 |
2019年 | 7064篇 |
2018年 | 6236篇 |
2017年 | 8225篇 |
2016年 | 9410篇 |
2015年 | 10919篇 |
2014年 | 20492篇 |
2013年 | 17377篇 |
2012年 | 23745篇 |
2011年 | 25088篇 |
2010年 | 19192篇 |
2009年 | 19498篇 |
2008年 | 19766篇 |
2007年 | 24348篇 |
2006年 | 21549篇 |
2005年 | 19298篇 |
2004年 | 15918篇 |
2003年 | 14327篇 |
2002年 | 11098篇 |
2001年 | 9389篇 |
2000年 | 7685篇 |
1999年 | 6168篇 |
1998年 | 4589篇 |
1997年 | 3762篇 |
1996年 | 3275篇 |
1995年 | 2706篇 |
1994年 | 2194篇 |
1993年 | 1455篇 |
1992年 | 1203篇 |
1991年 | 861篇 |
1990年 | 661篇 |
1989年 | 567篇 |
1988年 | 387篇 |
1987年 | 216篇 |
1986年 | 146篇 |
1985年 | 150篇 |
1984年 | 121篇 |
1983年 | 112篇 |
1982年 | 96篇 |
1981年 | 76篇 |
1980年 | 54篇 |
1979年 | 56篇 |
1978年 | 36篇 |
1977年 | 29篇 |
1976年 | 23篇 |
1959年 | 31篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
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
72.
An intertwined supply network (ISN) is an entirety of interconnected supply chains (SC) which, in their integrity secure the provision of society and markets with goods and services. The ISNs are open systems with structural dynamics since the firms may exhibit multiple behaviours by changing the buyer-supplier roles in interconnected or even competing SCs. From the positions of resilience, the ISNs as a whole provide services to society (e.g. food service, mobility service or communication service) which are required to ensure a long-term survival. The analysis of survivability at the level of ISN requires a consideration at a large scale as resilience of individual SCs. The recent example of coronavirus COVID-19 outbreak clearly shows the necessity of this new perspective. Our study introduces a new angle in SC resilience research when a resistance to extraordinary disruptions needs to be considered at the scale of viability. We elaborate on the integrity of the ISN and viability. The contribution of our position study lies in a conceptualisation of a novel decision-making environment of ISN viability. We illustrate the viability formation through a dynamic game-theoretic modelling of a biological system that resembles the ISN. We discuss some future research areas. 相似文献
73.
针对铜冶炼工艺的特点,从门架式堆取料机对前后工序衔接、结构、原理出发,介绍了其在熔炼炉系统和吹炼炉系统中的应用情况。经过试生产期的生产实践证明,门架式堆取料机具有场地利用率高、取料量大,自动化程度高和安全环保等优点。 相似文献
74.
为了提升高校实验数据处理水平,高校实验室的相关建设工作已经步入正轨,但层出不穷的信息安全问题也向高校实验室计算机网络维护工作提出了新的挑战。文章从现阶段高校实验室计算机网络的相关建设工作出发,简要论述引发网络故障的具体原因,并对其诊断技术进行探讨。 相似文献
75.
76.
"如何构造高可信的软件系统"已成为学术界和工业界的研究热点.操作系统内核作为软件系统的基础组件,它的安全可靠是构造高可信软件系统的重要环节.为了确保操作系统内核的安全可靠,将形式化方法引入到操作系统内核验证中,提出了一个自动化验证操作系统内核的框架.该验证框架包括:(1)分别对C语言程序和混合语言程序(C语言和汇编语言)进行验证;(2)在混合语言程序验证中,为汇编程序建立抽象模型,并将C语言程序和抽象模型粘合形成基于C语言验证工具可接收的验证模型;(3)从规范中提取性质,基于该自动验证工具,对性质完成自动验证;(4)该框架不限于特定的硬件架构.成功地运用该验证框架对两种不同硬件平台的嵌入式实时操作系统内核μC/OS-II进行了验证.结果显示:利用该框架在对两个不同的硬件平台上内核验证时,框架的可重复利用率很高,高达到88%,虽然其抽象模型需要根据不同的硬件平台进行重构.在对基于这两种平台的操作系统内核验证中,分别发现了10~12处缺陷.其中,在ARM平台上两处与硬件相关的问题被发现.实验表明,该方法对不同硬件平台的同一个操作系统分析验证具有一定的通用性. 相似文献
77.
《Calphad》2020
This publication contains the thermodynamic results received by the drop calorimetry method. The experiments were conducted for four different cross sections, at the temperature of 1080 K. The investigated alloys were as follows: (Ga0.75Li0.25)1-xGex, (Ge0.50Li0.50)1-xGax, (Ga0.50Li0.50)1-xGex, (Ga0.25Li0.75)1-xGex. The mixing enthalpy changes measured for all four cross sections of the Ga-Ge-Li system are characterized by negative deviations from the ideal solutions. The Muggianu model with the ternary interaction parameters was applied to elaborate the experimental data of the mixing enthalpy change with the use of the optimized thermodynamic parameters of the binary systems available in the literature. 相似文献
78.
Creating an intelligent system that can accurately predict stock price in a robust way has always been a subject of great interest for many investors and financial analysts. Predicting future trends of financial markets is more remarkable these days especially after the recent global financial crisis. So traders who access to a powerful engine for extracting helpful information throw raw data can meet the success. In this paper we propose a new intelligent model in a multi-agent framework called bat-neural network multi-agent system (BNNMAS) to predict stock price. The model performs in a four layer multi-agent framework to predict eight years of DAX stock price in quarterly periods. The capability of BNNMAS is evaluated by applying both on fundamental and technical DAX stock price data and comparing the outcomes with the results of other methods such as genetic algorithm neural network (GANN) and some standard models like generalized regression neural network (GRNN), etc. The model tested for predicting DAX stock price a period of time that global financial crisis was faced to economics. The results show that BNNMAS significantly performs accurate and reliable, so it can be considered as a suitable tool for predicting stock price specially in a long term periods. 相似文献
79.
80.
现有的时态网络可视化方法大多采用等量时间片来可视化网络的演变,不利于时态模式的快速挖掘和发现。为此,根据时态网络固有的特征提出自适应时间片划分方法(Adaptive Time Slice Partition method,ATSP)。在时态网络的两种表示方式(基于事件的表示方式和基于快照的表示方式)的基础上,构建了ATSP的基础模型,同时提出了一种改进模型用来描述事件间隔时间服从长尾分布的时态网络。为了实现时间片的不等量划分,针对探索任务的不同提出了基于时态模式的ATSP规则和基于中心节点的ATSP规则,并提出了实现算法--层次划分算法(Hierarchical Partition algorithm,HP)和增量划分算法(Incremental Partition algorithm,IP)。实验结果表明,ATSP方法比传统的时间片划分方法更能准确地表示网络的时态特征,且该方法应用于可视化时,能有效归纳并展示网络的特征,明显提高了视觉分析的效率。 相似文献