全文获取类型
收费全文 | 79649篇 |
免费 | 4212篇 |
国内免费 | 2818篇 |
专业分类
电工技术 | 7237篇 |
技术理论 | 27篇 |
综合类 | 9392篇 |
化学工业 | 3303篇 |
金属工艺 | 907篇 |
机械仪表 | 3099篇 |
建筑科学 | 14703篇 |
矿业工程 | 3899篇 |
能源动力 | 2597篇 |
轻工业 | 2198篇 |
水利工程 | 4750篇 |
石油天然气 | 2547篇 |
武器工业 | 313篇 |
无线电 | 5881篇 |
一般工业技术 | 3821篇 |
冶金工业 | 5543篇 |
原子能技术 | 473篇 |
自动化技术 | 15989篇 |
出版年
2024年 | 137篇 |
2023年 | 518篇 |
2022年 | 1101篇 |
2021年 | 1517篇 |
2020年 | 1733篇 |
2019年 | 1209篇 |
2018年 | 1104篇 |
2017年 | 1488篇 |
2016年 | 1905篇 |
2015年 | 2139篇 |
2014年 | 6334篇 |
2013年 | 5111篇 |
2012年 | 5726篇 |
2011年 | 6098篇 |
2010年 | 4745篇 |
2009年 | 5050篇 |
2008年 | 5016篇 |
2007年 | 6104篇 |
2006年 | 5350篇 |
2005年 | 4592篇 |
2004年 | 3979篇 |
2003年 | 3553篇 |
2002年 | 2875篇 |
2001年 | 2084篇 |
2000年 | 1705篇 |
1999年 | 1289篇 |
1998年 | 868篇 |
1997年 | 669篇 |
1996年 | 537篇 |
1995年 | 437篇 |
1994年 | 330篇 |
1993年 | 242篇 |
1992年 | 171篇 |
1991年 | 146篇 |
1990年 | 93篇 |
1989年 | 111篇 |
1988年 | 87篇 |
1987年 | 40篇 |
1986年 | 74篇 |
1985年 | 77篇 |
1984年 | 76篇 |
1983年 | 83篇 |
1982年 | 25篇 |
1981年 | 21篇 |
1980年 | 11篇 |
1979年 | 17篇 |
1977年 | 14篇 |
1975年 | 7篇 |
1961年 | 8篇 |
1959年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Minhong Wang Huaiqing Wang Doug Vogel Kuldeep Kumar Dickson K.W. Chiu 《Engineering Applications of Artificial Intelligence》2009,22(7):1046-1055
Modern businesses are facing the challenge of effectively coordinating their supply chains from upstream to downstream services. It is a complex problem to search, schedule, and coordinate a set of services from a large number of service resources under various constraints and uncertainties. Existing approaches to this problem have relied on complete information regarding service requirements and resources, without adequately addressing the dynamics and uncertainties of the environments. The real-world situations are complicated as a result of ambiguity in the requirements of the services, the uncertainty of solutions from service providers, and the interdependencies among the services to be composed. This paper investigates the complexity of supply chain formation and proposes an agent-mediated coordination approach. Each agent works as a broker for each service type, dedicated to selecting solutions for each service as well as interacting with other agents in refining the decision making to achieve compatibility among the solutions. The coordination among agents concerns decision making at strategic, tactical, and operational level. At the strategic level, agents communicate and negotiate for supply chain formation; at the tactical level, argumentation is used by agents to communicate and understand the preferences and constraints of each other; at the operational level, different strategies are used for selecting the preferences. Based on this approach, a prototype has been implemented with simulated experiments highlighting the effectiveness of the approach. 相似文献
102.
Small scale-incidents such as car crashes or fires occur with high frequency and in sum involve more people and consume more money than large and infrequent incidents. Therefore, the support of small-scale incident management is of high importance.Microblogs are an important source of information to support incident management as important situational information is shared, both by citizens and official sources. While microblogs are already used to address large-scale incidents detecting small-scale incident-related information was not satisfyingly possible so far.In this paper we investigate small-scale incident reporting behavior with microblogs. Based on our findings, we present an easily extensible rapid prototyping framework for information extraction of incident-related tweets. The framework enables the precise identification and extraction of information relevant for emergency management. We evaluate the rapid prototyping capabilities and usefulness of the framework by implementing the multi-label classification of tweets related to small-scale incidents. An evaluation shows that our approach is applicable for detecting multiple labels with an match rate of 84.35%. 相似文献
103.
Michael P. Canares 《Information Technology for Development》2016,22(3):121-138
This research joins the growing body of literature that advocates for the use of information and communication technology (ICT) in local governance more particularly in public financial management. Using a case study in Bohol, a province in the Philippines, this paper discusses the impact of ICT on local revenue generation by analyzing both quantitative and qualitative data from 15 municipalities which used e-taxation. This paper argues that the use of ICT can make possible more transparent and accountable revenue generation systems to benefit both government and taxpayers. However, these results are differentiated depending on the level of political leadership, the nature of articulation of the demand for ICT use, the ratio of benefit against cost, and the availability of technical skills and resources at the sub-national level. It is within this context that an eco-system analysis is argued to be useful in analyzing how ICT can be adopted, scaled, and used by sub-national governments to achieve better governance. 相似文献
104.
ARP预算管理信息系统应用探索 总被引:1,自引:1,他引:0
随着国家建设和信息产业的不断发展,研究所在发展的同时业务范围也在逐步扩张和多元化,如何在这一过程中实现合理、高效的预算管理和监控,成为研究所预算管理的核心.本项目基于ARP综合财务和科研项目系统,根据研究所以课题为成本中心的核算体制模式,建立ARP预算管理系统,关联科研项目预算与实际支出,通过课题预算录入、报销预算控制及实时预算查询等业务流程,实现事前预算编制、事中预算控制和事后预算分析的预算管理模式,为研究所管理者和科研人员提供预算执行情况、收支明细查询等综合信息服务. 相似文献
105.
无线传感器网络的应用日益广泛但安全性问题越发突出,由于其计算能力、存储能力和通信能力有限,一直被认为不适合使用公钥密码学方案。然而近年来不需要认证中心的IBE算法的研究成果表明,IBE方案非常适合无线传感器网络。本文提出一种高效的IBE方案,并做了算法介绍,同时在无线传感器网络中提出相应的密钥分配、认证、管理以及更新的应用方案。与现有其他算法相比,新方案具有系统参数短、安全性高等特点。 相似文献
106.
A new approach is introduced for turbidite modeling, leveraging the potential of computational fluid dynamics methods to simulate the flow processes that led to turbidite formation. The practical use of numerical flow simulation for the purpose of turbidite modeling so far is hindered by the need to specify parameters and initial flow conditions that are a priori unknown. The present study proposes a method to determine optimal simulation parameters via an automated optimization process. An iterative procedure matches deposit predictions from successive flow simulations against available localized reference data, as in practice may be obtained from well logs, and aims at convergence towards the best-fit scenario. The final result is a prediction of the entire deposit thickness and local grain size distribution. The optimization strategy is based on a derivative-free, surrogate-based technique. Direct numerical simulations are performed to compute the flow dynamics. A proof of concept is successfully conducted for the simple test case of a two-dimensional lock-exchange turbidity current. The optimization approach is demonstrated to accurately retrieve the initial conditions used in a reference calculation. 相似文献
107.
Jianping PengAuthor Vitae 《Decision Support Systems》2011,51(1):88-98
This paper explores the impacts of essential elements of management on IT application maturity (ITAM). A game theoretical model is established to show that a firm's IT application maturity should match with its essential elements of management. In order to further validate the analytical result, a data set with 137 firms was collected via a survey instrument. Using reliability and factor analysis on the dataset, a four-dimension measurement construct of IT application maturity is proposed together with a three-dimension measurement construct of essential elements of management. Empirical analysis is then conducted to address research questions on the impacts of essential elements of management on IT application maturity. It is found that while a firm's strategic cooperation capability has no significant effect on IT application maturity, its internal coordination capability positively influences all four dimensions of IT application maturity. For the firm's execution capability, although it shows no significant effect on the overall IT application maturity, it does positively affect the technology and man-machine synergy dimensions of IT application maturity. The findings of this study offer practical guidance for organizations to better align their IT application maturity with essential elements of management. 相似文献
108.
针对电力系统经济负荷分配问题,提出一种有效的差分蜂群算法.受差分进化算法的启发,该算法基于差分进化操作改进了雇佣蜂的搜索方式,提高了探索能力和收敛速度.此外,提出一种有效的修复机制以保证新个体的可行性.该算法在带有阀点效应和多燃料特征的典型电力系统经济负荷分配问题上进行了测试.仿真结果验证了所提算法的有效性. 相似文献
109.
介绍了一个面向中小型企业的产品数据管理系统SMPDM。它是一个建立在PDM基本框架之上,集产品结构与配置管理、图档管理、工艺卡片管理及编码管理为一体的实用系统。它实施简单,见效快,是管理中小型企业产品数据的良好工具。 相似文献
110.
This paper develops a framework for the consideration of internal markets as an alternative to information systems (IS) outsourcing. It is based on an assessment of the pros and cons of both outsourcing and of insourcing based on the internal markets approach. It is formulated in terms of the operational, tactical, and strategic impacts of the choice among the alternatives. The framework, and the propositions that are developed from it, should be useful both for researchers, who can use it for developing testable research hypotheses, and for practitioners, who may use it as a basis for developing a comprehensive set of criteria for the evaluation of these sourcing options. 相似文献