全文获取类型
收费全文 | 21968篇 |
免费 | 903篇 |
国内免费 | 1165篇 |
专业分类
电工技术 | 549篇 |
技术理论 | 1篇 |
综合类 | 912篇 |
化学工业 | 284篇 |
金属工艺 | 378篇 |
机械仪表 | 1354篇 |
建筑科学 | 573篇 |
矿业工程 | 337篇 |
能源动力 | 308篇 |
轻工业 | 158篇 |
水利工程 | 82篇 |
石油天然气 | 189篇 |
武器工业 | 212篇 |
无线电 | 2443篇 |
一般工业技术 | 781篇 |
冶金工业 | 312篇 |
原子能技术 | 264篇 |
自动化技术 | 14899篇 |
出版年
2024年 | 27篇 |
2023年 | 162篇 |
2022年 | 225篇 |
2021年 | 312篇 |
2020年 | 327篇 |
2019年 | 220篇 |
2018年 | 282篇 |
2017年 | 413篇 |
2016年 | 506篇 |
2015年 | 504篇 |
2014年 | 1195篇 |
2013年 | 982篇 |
2012年 | 1194篇 |
2011年 | 1738篇 |
2010年 | 1126篇 |
2009年 | 1133篇 |
2008年 | 1353篇 |
2007年 | 1737篇 |
2006年 | 1628篇 |
2005年 | 1638篇 |
2004年 | 1374篇 |
2003年 | 1314篇 |
2002年 | 988篇 |
2001年 | 717篇 |
2000年 | 566篇 |
1999年 | 437篇 |
1998年 | 335篇 |
1997年 | 240篇 |
1996年 | 237篇 |
1995年 | 212篇 |
1994年 | 153篇 |
1993年 | 121篇 |
1992年 | 72篇 |
1991年 | 58篇 |
1990年 | 54篇 |
1989年 | 50篇 |
1988年 | 45篇 |
1987年 | 37篇 |
1986年 | 36篇 |
1985年 | 43篇 |
1984年 | 38篇 |
1983年 | 36篇 |
1982年 | 24篇 |
1981年 | 26篇 |
1980年 | 17篇 |
1979年 | 13篇 |
1978年 | 17篇 |
1977年 | 16篇 |
1976年 | 31篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
In the Internet of Things (IoT), a huge amount of valuable data is generated by various IoT applications. As the IoT technologies become more complex, the attack methods are more diversified and can cause serious damages. Thus, establishing a secure IoT network based on user trust evaluation to defend against security threats and ensure the reliability of data source of collected data have become urgent issues, in this paper, a Data Fusion and transfer learning empowered granular Trust Evaluation mechanism (DFTE) is proposed to address the above challenges. Specifically, to meet the granularity demands of trust evaluation, time–space empowered fine/coarse grained trust evaluation models are built utilizing deep transfer learning algorithms based on data fusion. Moreover, to prevent privacy leakage and task sabotage, a dynamic reward and punishment mechanism is developed to encourage honest users by dynamically adjusting the scale of reward or punishment and accurately evaluating users’ trusts. The extensive experiments show that: (i) the proposed DFTE achieves high accuracy of trust evaluation under different granular demands through efficient data fusion; (ii) DFTE performs excellently in participation rate and data reliability. 相似文献
2.
The ability to detect gun and gun held in hand or other body parts is a typical human skill. The same problem presents an imperative task for computer vision system. Automatic observer independent detection of hand held gun or gun held in the other body part, whether it is visible or concealed, provides enhance security in vulnerable places and initiates appropriate action there. Compare to the automatic object detection systems, automatic detection of gun has very few successful attempts. In the present scope of this paper, we present an extensive survey on automatic detection of gun and define a taxonomy for this particular detection system. We also describe the inherent difficulties related with this problem. In this survey of published papers, we examine different approaches used in state-of-the-art attempts and compare performances of these approaches. Finally, this paper concludes pointing to the possible research gaps in related fields. 相似文献
3.
Smartphones are being used and relied on by people more than ever before. The open connectivity brings with it great convenience and leads to a variety of risks that cannot be overlooked. Smartphone vendors, security policy designers, and security application providers have put a variety of practical efforts to secure smartphones, and researchers have conducted extensive research on threat sources, security techniques, and user security behaviors. Regrettably, smartphone users do not pay enough attention to mobile security, making many efforts futile. This study identifies this gap between technology affordance and user requirements, and attempts to investigate the asymmetric perceptions toward security features between developers and users, between users and users, as well as between different security features. These asymmetric perceptions include perceptions of quality, perceptions of importance, and perceptions of satisfaction. After scoping the range of smartphone security features, this study conducts an improved Kano-based method and exhaustively analyzes the 245 collected samples using correspondence analysis and importance satisfaction analysis. The 14 security features of the smartphone are divided into four Kano quality types and the perceived quality differences between developers and users are compared. Correspondence analysis is utilized to capture the relationship between the perceived importance of security features across different groups of respondents, and results of importance-satisfaction analysis provide the basis for the developmental path and resource reallocation strategy of security features. This article offers new insights for researchers as well as practitioners of smartphone security. 相似文献
4.
An integrated approach to measure the cost efficiency of the postal network of Universal Service Provider is proposed. An integrated approach enables the measurement of cost efficiency for delivery and non-delivery postal network units. The proposed approach is verified and tested on the postal network of the selected provider and the results were derived by using Data Envelopment Analysis (DEA). The results show that the main sources of inefficiency are inadequate allocation of resources relative to the network units. In addition, the study indicates that economies of scale have a positive impact on the efficiency of postal network units. 相似文献
5.
This article presents a new method for pairing devices securely. The commitment-based authentication uses a fuzzy secret that the devices only know approximately. Its novel feature is time-based opening of commitments in a single round. We also introduce a new source for the fuzzy secret: synchronized drawing with two fingers of the same hand on two touch screens or surfaces. The drawings are encoded as strings and compared with an edit-distance metric. A prototype implementation of this surprisingly simple and natural pairing mechanism shows that it accurately differentiates between true positives and man-in-the-middle attackers. 相似文献
6.
随着社会的不断发展,矿产资源为我国带来了巨大的经济效益,并在社会经济发展中占有重要的地位。但在矿山资源开发的过程中,威胁人身安全的事故经常发生。因此,本文对探矿工程安全措施进行了研究和分析。 相似文献
7.
Communication between organizations is formalized as process choreographies in daily business. While the correct ordering of exchanged messages can be modeled and enacted with current choreography techniques, no approach exists to describe and automate the exchange of data between processes in a choreography using messages. This paper describes an entirely model-driven approach for BPMN introducing a few concepts that suffice to model data retrieval, data transformation, message exchange, and correlation – four aspects of data exchange. For automation, this work utilizes a recent concept to enact data dependencies in internal processes. We present a modeling guideline to derive local process models from a given choreography; their operational semantics allows to correctly enact the entire choreography from the derived models only including the exchange of data. Targeting on successful interactions, we discuss means to ensure correct process choreography modeling. Finally, we implemented our approach by extending the camunda BPM platform with our approach and show its feasibility by realizing all service interaction patterns using only model-based concepts. 相似文献
8.
Fault detection, isolation and optimal control have long been applied to industry. These techniques have proven various successful theoretical results and industrial applications. Fault diagnosis is considered as the merge of fault detection (that indicates if there is a fault) and fault isolation (that determines where the fault is), and it has important effects on the operation of complex dynamical systems specific to modern industry applications such as industrial electronics, business management systems, energy, and public sectors. Since the resources are always limited in real-world industrial applications, the solutions to optimally use them under various constraints are of high actuality. In this context, the optimal tuning of linear and nonlinear controllers is a systematic way to meet the performance specifications expressed as optimization problems that target the minimization of integral- or sum-type objective functions, where the tuning parameters of the controllers are the vector variables of the objective functions. The nature-inspired optimization algorithms give efficient solutions to such optimization problems. This paper presents an overview on recent developments in machine learning, data mining and evolving soft computing techniques for fault diagnosis and on nature-inspired optimal control. The generic theory is discussed along with illustrative industrial process applications that include a real liquid level control application, wind turbines and a nonlinear servo system. New research challenges with strong industrial impact are highlighted. 相似文献
9.
The study examined a decision tree analysis using social big data to conduct the prediction model on types of risk factors related to cyberbullying in Korea. The study conducted an analysis of 103,212 buzzes that had noted causes of cyberbullying and data were collected from 227 online channels, such as news websites, blogs, online groups, social network services, and online bulletin boards. Using opinion-mining method and decision tree analysis, the types of cyberbullying were sorted using SPSS 25.0. The results indicated that the total rate of types of cyberbullying in Korea was 44%, which consisted of 32.3% victims, 6.4% perpetrators, and 5.3% bystanders. According to the results, the impulse factor was also the greatest influence on the prediction of the risk factors and the propensity for dominance factor was the second greatest factor predicting the types of risk factors. In particular, the impulse factor had the most significant effect on bystanders, and the propensity for dominance factor was also significant in influencing online perpetrators. It is necessary to develop a program to diminish the impulses that were initiated by bystanders as well as victims and perpetrators because many of those bystanders have tended to aggravate impulsive cyberbullying behaviors. 相似文献
10.
《International Journal of Hydrogen Energy》2021,46(59):30267-30287
This work aims to improve the existing monitoring systems MS for two grid-connected PV stations GCPVS of URERMS ADRAR, to eliminate its limitations. This improvement consists of developing an MS which is used for two PV stations with different configurations. This MS contains new LabVIEW-based monitoring software for visualizing real-time measured data and evaluating GCPVS performance. In addition, it illustrates the 2D and 3D real-time relationships of PV system parameters, which allow us to understand the dynamic behavior of PV system components. This developed monitoring software synchronizes also the various data acquisition units DAU of GCPVS, allowing simultaneous data access.To perform a reliable performance analysis and a comparative study of different GCPVS based on accurate measurements, the sensor's calibration is performed with its DAU. The MS autonomy is ensured by integrating developed PV-UPS. A graphical user interface is provided for the evaluation of PV-UPS performance. 相似文献