全文获取类型
收费全文 | 12585篇 |
免费 | 696篇 |
国内免费 | 606篇 |
专业分类
电工技术 | 904篇 |
技术理论 | 1篇 |
综合类 | 962篇 |
化学工业 | 1042篇 |
金属工艺 | 347篇 |
机械仪表 | 964篇 |
建筑科学 | 797篇 |
矿业工程 | 309篇 |
能源动力 | 1069篇 |
轻工业 | 204篇 |
水利工程 | 187篇 |
石油天然气 | 205篇 |
武器工业 | 109篇 |
无线电 | 1192篇 |
一般工业技术 | 1116篇 |
冶金工业 | 277篇 |
原子能技术 | 71篇 |
自动化技术 | 4131篇 |
出版年
2024年 | 20篇 |
2023年 | 133篇 |
2022年 | 182篇 |
2021年 | 269篇 |
2020年 | 253篇 |
2019年 | 260篇 |
2018年 | 226篇 |
2017年 | 303篇 |
2016年 | 368篇 |
2015年 | 390篇 |
2014年 | 687篇 |
2013年 | 630篇 |
2012年 | 676篇 |
2011年 | 976篇 |
2010年 | 710篇 |
2009年 | 858篇 |
2008年 | 893篇 |
2007年 | 1025篇 |
2006年 | 897篇 |
2005年 | 752篇 |
2004年 | 633篇 |
2003年 | 607篇 |
2002年 | 465篇 |
2001年 | 343篇 |
2000年 | 288篇 |
1999年 | 215篇 |
1998年 | 174篇 |
1997年 | 132篇 |
1996年 | 118篇 |
1995年 | 105篇 |
1994年 | 85篇 |
1993年 | 51篇 |
1992年 | 44篇 |
1991年 | 32篇 |
1990年 | 25篇 |
1989年 | 13篇 |
1988年 | 15篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1977年 | 3篇 |
1974年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
介绍前向人工神经网络模型,并与传统的统计学线性模型进行比较。为了适应时间序列变量的特点,对逆传播模型进行了改进,并对太阳黑子活动的观察值这一典型的时间序列进行了分析,并检验了模型的预测能力,取得了较好的结果 相似文献
93.
94.
The proposed mode of consideration of the steel-concrete interaction (Part I) is applied to real-life engineering structures. Two structures recently investigated numerically at Vienna University of Technology are considered: (1) the reinforced concrete (RC) cooling tower III Ptolema?s SES (Greece) and (2) a part of the shotcrete tunnel lining installed at the Lainzer tunnel (Austria). In both examples, the uniaxial fracture criterion used in Part I is replaced by the maximum stress (Rankine) criterion. Together with the Drucker-Prager criterion, which is used for the simulation of compressive failure of concrete/shotcrete, it defines the space of admissible stress states in the framework of multisurface plasticity. For the simulation of early-age fracture of shotcrete, consideration of the steel-concrete interaction presented in Part I of this paper is extended towards young shotcrete. Similar to the benchmark problem investigated in Part I of this paper, several analyses with different degrees of consideration of the steel-concrete interaction are performed. The obtained results give insight into the influence of the steel-concrete interaction on the load-carrying behavior of the investigated structures. 相似文献
95.
现有的Web容器多采用线程池体系结构,而Web容器所支撑的动态Web组件在执行过程中可能需要获取多种共享资源,由共享资源并发量限制导致的线程阻塞可能会严重影响性能。提出了一种资源敏感的Web容器体系结构ROSA(resource-oriented staged architecture)。当某些共享资源达到饱和时,若Web容器接到对需要这些资源的Web组件的请求,ROSA会暂缓为这些请求提供服务以减少线程阻塞。基于排队Petri网,建立了ROSA结构和线程池结构的性能模型,通过模型仿真和负载实验验证了ROSA体系结构的性能优势。 相似文献
96.
多Agent系统中,Agent间通过形成联盟达到提高任务求解能力,获取更多收益的目的。主要关注联盟模型的改进和联盟形成阶段的改进,基于ARG(agent,role,group)元模型和学习机制提出了一种采用角色和学习机制的新联盟模型CLAR(coalition model based on learnin gagent and role);在采用合同网协议的CLAR联盟模型中提出了两阶段联盟形成机制;通过捕食者问题实验验证了角色和学习机制的作用,以及两阶段联盟形成机制在减少通讯代价上的作用。 相似文献
97.
98.
设计了适合衢州职业技术学院固定资产日常管理工作的资产管理系统.对该系统作了需求分析和详细设计,采用了ASP.NET框架技术和SQL Server后台数据库相结合的设计方法.系统基本实现了资产的登记、审核、查询、变更、统计、打印报表、上报数据等功能,有效地解决了资产管理工作的数据混乱、不准确、处理流程不规范等问题,有效地提高了管理人员的工作效率. 相似文献
99.
Communication infrastructures designed for mixed-critical MPSoCs must provide isolation of traffic, hard real-time guarantees, and fault-tolerance. In previous work, we proposed the combination of protection-switching with a hybrid Time-Division-Multiplexed (TDM) and packet-switched Network-on-Chip (NoC) to achieve all three goals. In this paper, we present an FPGA implementation of such a NoC with all its features. We give synthesis results for the hybrid NoC, including the network interface, and show that our router uses over 32% fewer LUTs and registers than a competitive state-of-the-art router for mixed-critical MPSoC. We then explore different channel and task mapping strategies for critical applications which use protection switching and evaluate the effect these mappings have on the best-effort (BE) traffic in the system. Results show, that spreading out the critical traffic rather than naively dividing the system in critical and non-critical application domains is advantageous or even necessary in many cases and can allow for up to 13% more BE traffic. We give a comprehensive trade-off analysis of three protection switching schemes—1:n, 1:1, and 1+1—and show that 1+1 protection has less than half the worst case latency for critical traffic that 1:n and 1:1 protection have. At the same time, 1+1 protection, on average, only causes a 1.18% earlier saturation rate for BE traffic, which we consider to be affordable. We conclude that 1+1 protection is ideally suited for use in mixed-critical systems with high safety requirements. 相似文献
100.
Simulation is capable to cope with the uncertain and dynamic nature of industrial value chains. However, in-depth system expertise is inevitable for mapping objects and constraints from the real world to a virtual model. This knowledge-intensity leads to long development times of respective projects, which contradicts the need for timely decision support. Since more and more companies use industrial knowledge graphs and ontologies to foster their knowledge management, this paper proposes a framework on how to efficiently derive a simulation model from such semantic knowledge bases. As part of the approach, a novel Simulation Ontology provides a standardized meta-model for hybrid simulations. Its instantiation enables the user to come up with a fully parameterized formal simulation model. Newly developed Mapping Rules facilitate this process by providing guidance on how to turn knowledge from existing ontologies, which describe the system to be simulated, into instances of the Simulation Ontology. The framework is completed by a parsing procedure for an automated transformation of this conceptual model into an executable one. This novel modeling approach makes model development more efficient by reducing its complexity. It is validated in a use case implementation from semiconductor manufacturing, where cross-domain knowledge was required in order to model and simulate the impacts of the COVID-19 pandemic on a global supply chain network. 相似文献