全文获取类型
收费全文 | 5783篇 |
免费 | 715篇 |
国内免费 | 641篇 |
专业分类
电工技术 | 356篇 |
综合类 | 489篇 |
化学工业 | 63篇 |
金属工艺 | 12篇 |
机械仪表 | 123篇 |
建筑科学 | 231篇 |
矿业工程 | 36篇 |
能源动力 | 33篇 |
轻工业 | 76篇 |
水利工程 | 45篇 |
石油天然气 | 18篇 |
武器工业 | 13篇 |
无线电 | 1057篇 |
一般工业技术 | 833篇 |
冶金工业 | 380篇 |
原子能技术 | 10篇 |
自动化技术 | 3364篇 |
出版年
2024年 | 65篇 |
2023年 | 152篇 |
2022年 | 242篇 |
2021年 | 263篇 |
2020年 | 296篇 |
2019年 | 291篇 |
2018年 | 291篇 |
2017年 | 317篇 |
2016年 | 268篇 |
2015年 | 275篇 |
2014年 | 395篇 |
2013年 | 384篇 |
2012年 | 456篇 |
2011年 | 417篇 |
2010年 | 288篇 |
2009年 | 288篇 |
2008年 | 324篇 |
2007年 | 309篇 |
2006年 | 252篇 |
2005年 | 250篇 |
2004年 | 230篇 |
2003年 | 221篇 |
2002年 | 163篇 |
2001年 | 129篇 |
2000年 | 85篇 |
1999年 | 58篇 |
1998年 | 45篇 |
1997年 | 52篇 |
1996年 | 37篇 |
1995年 | 56篇 |
1994年 | 40篇 |
1993年 | 34篇 |
1992年 | 22篇 |
1991年 | 18篇 |
1990年 | 17篇 |
1989年 | 9篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1963年 | 4篇 |
1961年 | 9篇 |
1955年 | 3篇 |
排序方式: 共有7139条查询结果,搜索用时 15 毫秒
61.
Kim-Choy Chung 《Behaviour & Information Technology》2014,33(7):743-756
This study investigates perceived risk and trust in relationship to the Diffusion of Innovation Theory [Rogers, E.M., 1962. Diffusion of innovations. Glencoe, IL: The Free Press; 1983. Diffusion of innovations. 3rd ed. New York: The Free Press] from a cultural perspective to understand the determinants of behavioural intent to adopt mobile commerce among the Y Generation in Kazakhstan. Surveys from 345 university-level students and subsequent structural equation modelling revealed perceived risk, trustworthiness and Rogers’ five innovation characteristics are important determinants. Perceived risk and trustworthiness are important determinants because of the high uncertainty avoidance characteristics of the Kazakh society. This study advances theory regarding culture- and generation-based characteristics to transition economies by verifying theoretical proposition regarding the behavioural intent towards mobile commerce adoption, resulting in a greater understanding of mobile commerce adoption among the Y Generation in transition economies. Marketing implications are discussed. 相似文献
62.
Recently, several restaurants have launched mobile technology-based self-services by replacing their printed menus with iPads. To assess the perceived value of the iPad menu from the customers’ perspective, this study proposed and tested a new research model which includes both functional and emotional aspects of customers’ attitudes. The aim was based on the supposition that an overall value judgement in regard to using the iPad menu to promote dining experience will influence customers’ behavioural intention to patronise restaurants that use the new technology; 332 usable data gathered from cyberspace were tested against the research model. The results demonstrated the importance of perceived value. All functional factors (i.e. perceived control, perceived usefulness and perceived ease of use) and emotional factors (i.e. perceived enjoyment and perceived novelty) were significantly affecting perceived value. For managers interested in investing in these mobile self-service technologies, the findings provided them with sound advice based on empirical research. 相似文献
63.
Examining the role of perceived value in virtual communities continuance: its antecedents and the influence of experience 总被引:1,自引:0,他引:1
Chun-Ming Chang Cheng-Se Hsu Hsiang-Lan Cheng 《Behaviour & Information Technology》2014,33(5):502-521
Although perceived value has long been recognised as an influential means of affecting continuance intention in information systems (IS), little attention has been devoted to explore its antecedents, which constitutes an important research issue. This study, building on prior literature on continued usage in IS as well as the resource-based view, proposed a model to address this gap. Our model suggests that perceived value, a major driving force for members’ satisfaction and continuance intention, is affected by four kinds of resources embedded in virtual communities, which are relationship resources, technology infrastructure, knowledge resources and human resources. To provide additional insights on the pivotal role of perceived value, we also postulate that experience moderates the link between perceived value and its antecedents. Data collected from 235 members of a professional virtual community provide strong support for the research model. It was found that perceived value exerts a great effect on both satisfaction and continuance intention. In addition, when different levels of experience are taken into consideration, relationship resources, knowledge resources and human resources were found to be more salient to high-experience members, whereas technology infrastructure was found to be more salient to low-experience members. Finally, this study discusses the implications of these findings and offers direction for future research. 相似文献
64.
The usefulness of Software Architecture (SA) documentation depends on how well its Architectural Knowledge (AK) can be retrieved by the stakeholders in a software project. Recent findings show that the use of ontology-based SA documentation is promising. However, different roles in software development have different needs for AK, and building an ontology to suit these needs is challenging. In this paper we describe an approach to build an ontology for SA documentation. This approach involves the use of typical questions for eliciting and constructing an ontology. We outline eight contextual factors, which influence the successful construction of an ontology, especially in complex software projects with diverse AK users. We tested our ‘typical question’ approach in a case study and report how it can be used for acquiring and modeling AK needs. 相似文献
65.
Kaiyu Zhao Matthew O. Ward Elke A. Rundensteiner Huong N. Higgins 《Computer Graphics Forum》2014,33(3):331-340
Linear models are commonly used to identify trends in data. While it is an easy task to build linear models using pre‐selected variables, it is challenging to select the best variables from a large number of alternatives. Most metrics for selecting variables are global in nature, and thus not useful for identifying local patterns. In this work, we present an integrated framework with visual representations that allows the user to incrementally build and verify models in three model spaces that support local pattern discovery and summarization: model complementarity, model diversity, and model representivity. Visual representations are designed and implemented for each of the model spaces. Our visualizations enable the discovery of complementary variables, i.e., those that perform well in modeling different subsets of data points. They also support the isolation of local models based on a diversity measure. Furthermore, the system integrates a hierarchical representation to identify the outlier local trends and the local trends that share similar directions in the model space. A case study on financial risk analysis is discussed, followed by a user study. 相似文献
66.
S. Chaturvedi C. Dunne Z. Ashktorab R. Zachariah B. Shneiderman 《Computer Graphics Forum》2014,33(8):52-68
An important part of network analysis is understanding community structures like topological clusters and attribute‐based groups. Standard approaches for showing communities using colour, shape, rectangular bounding boxes, convex hulls or force‐directed layout algorithms remain valuable, however our Group‐in‐a‐Box meta‐layouts add a fresh strategy for presenting community membership, internal structure and inter‐cluster relationships. This paper extends the basic Group‐in‐a‐Box meta‐layout, which uses a Treemap substrate of rectangular regions whose size is proportional to community size. When there are numerous inter‐community relationships, the proposed extensions help users view them more clearly: (1) the Croissant–Doughnut meta‐layout applies empirically determined rules for box arrangement to improve space utilization while still showing inter‐community relationships, and (2) the Force‐Directed layout arranges community boxes based on their aggregate ties at the cost of additional space. Our free and open source reference implementation in NodeXL includes heuristics to choose what we have found to be the preferable Group‐in‐a‐Box meta‐layout to show networks with varying numbers or sizes of communities. Case study examples, a pilot comparative user preference study (nine participants), and a readability measure‐based evaluation of 309 Twitter networks demonstrate the utility of the proposed meta‐layouts. 相似文献
67.
Nicholas Taylor Jennifer Jenson Suzanne de Castell Barry Dilouya 《Journal of Computer-Mediated Communication》2014,19(4):763-779
As research on virtual worlds gains increasing attention in educational, commercial, and military domains, a consideration of how player populations are ‘reassembled’ through social scientific data is a timely matter for communication scholars. This paper describes a large‐scale study of virtual worlds in which participants were recruited at public gaming events, as opposed to through online means, and explores the dynamic relationships between players and contexts of play that this approach makes visible. Challenging conventional approaches to quantitatively driven virtual worlds research, which categorizes players based on their involvement in an online game at a particular point in time, this account demonstrates how players' networked gaming activities are contingent on who they are playing with, where, and when. 相似文献
68.
随着社会生产力的不断发展,越来越多的企业认识到了财务工作的重要性。企业要利用现代高效的运作方式来开发和管理组织中最重要、最昂贵的资源,实现财务管理的精细化、自动化,提高财务资源的利用率,促进企业的发展。 相似文献
69.
当前,电力用户终端管理中出现的问题越来越多,已经影响到供电企业的发展和社会的和谐。如何解决这些问题并建立有效的电力终端管理机制,是目前电力企业面临的首要问题。 相似文献
70.
时延作为无线网络的最基本的性能之一,对网络信息分发、路由协议设计、节点部署等都具有重要意义。与传统的无线网络不同,认知无线电网络的频谱资源具有动态变化性,该特性会对网络时延产生极大的影响。因此,如何对动态频谱环境下的大规模认知无线电网络进行时延分析,是一项很具挑战性的课题。为此,首先对动态频谱环境进行建模,将认知用户的频谱接入过程建模为一个连续时间的马尔可夫链,并建立认知用户的生存函数来量化授权用户活动以及信道数量对频谱环境的影响;其次,将上述模型与首次通过渗流理论结合起来,研究了大规模认知无线电网络时延的伸缩规律,并获取了更为精确的时延与距离比的上限值。理论分析及仿真结果表明,动态频谱环境与密度一样会对时延产生极大影响。研究结论对认知无线电网络的设计具有重要的指导意义。 相似文献