全文获取类型
收费全文 | 14758篇 |
免费 | 1301篇 |
国内免费 | 719篇 |
专业分类
电工技术 | 838篇 |
综合类 | 1191篇 |
化学工业 | 2397篇 |
金属工艺 | 636篇 |
机械仪表 | 741篇 |
建筑科学 | 1072篇 |
矿业工程 | 373篇 |
能源动力 | 358篇 |
轻工业 | 1536篇 |
水利工程 | 271篇 |
石油天然气 | 642篇 |
武器工业 | 90篇 |
无线电 | 1429篇 |
一般工业技术 | 1436篇 |
冶金工业 | 1774篇 |
原子能技术 | 233篇 |
自动化技术 | 1761篇 |
出版年
2024年 | 61篇 |
2023年 | 256篇 |
2022年 | 457篇 |
2021年 | 561篇 |
2020年 | 455篇 |
2019年 | 346篇 |
2018年 | 379篇 |
2017年 | 435篇 |
2016年 | 357篇 |
2015年 | 541篇 |
2014年 | 736篇 |
2013年 | 844篇 |
2012年 | 897篇 |
2011年 | 1013篇 |
2010年 | 917篇 |
2009年 | 912篇 |
2008年 | 863篇 |
2007年 | 815篇 |
2006年 | 825篇 |
2005年 | 764篇 |
2004年 | 518篇 |
2003年 | 351篇 |
2002年 | 423篇 |
2001年 | 349篇 |
2000年 | 317篇 |
1999年 | 263篇 |
1998年 | 549篇 |
1997年 | 367篇 |
1996年 | 235篇 |
1995年 | 181篇 |
1994年 | 142篇 |
1993年 | 132篇 |
1992年 | 55篇 |
1991年 | 54篇 |
1990年 | 45篇 |
1989年 | 40篇 |
1988年 | 31篇 |
1987年 | 20篇 |
1986年 | 32篇 |
1985年 | 12篇 |
1984年 | 9篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 24篇 |
1979年 | 4篇 |
1977年 | 33篇 |
1976年 | 114篇 |
1974年 | 4篇 |
1955年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
161.
针对物联网系统中信息交互的实时性和系统自治特性,提出一种基于Internet和嵌入式设备构建物联网的技术;通过基于客户/服务器的体系结构和面向连接的设备实时在线技术实现信息交互的实时性,进一步通过一种服务器地址自动迁移技术实现基于Inter-net的嵌入式设备物联网的系统自治特性;通过多台嵌入式设备组网进行实际测试验证,系统满足良好的扩展性和设备即插即用特性,设备间数据通信相应时间低于1s,具有良好的实时性,可广泛应用于嵌入式设备的互联互通。 相似文献
162.
本文提出了一种多功能网络监控与防御系统。文中根据网络自身的结构,从骨干层、汇聚层、接入层三个层次分析,采用三层设计模式,它们相互独立又相互协作,共同构成高性能、多层次、多功能综合解决方案。形成深度防御体系,最大限度地保护企业和组织的网络安全。 相似文献
163.
结合资源保障系统的特点,讨论了GIS技术在应急资源保障系统中的应用,包括系统的体系结构、功能模块划分以及采用的关键技术,并设计了基于GIS技术的应急资源保障系统,提高了最近资源查找的准确性和效率.当突发事件发生后,能够快速分析应急物资的分布、数量,并且能够实时监控应急资源的生产,调度状态,提高政府部门及其他专业部门处理应急突发事件的能力,为应急领域的指挥调度工作提供了决策的依据. 相似文献
164.
We present a new intuitive UI, which we call cross‐boundary brushes, for interactive mesh decomposition. The user roughly draws one or more strokes across a desired cut and our system automatically returns a best cut running through all the strokes. By the different natures of part components (i.e., semantic parts) and patch components (i.e., flatter surface patches) in general models, we design two corresponding brushes: part‐brush and patch‐brush. These two types of brushes share a common user interface, enabling easy switch between them. The part‐brush executes a cut along an isoline of a harmonic field driven by the user‐specified strokes. We show that the inherent smoothness of the harmonic field together with a carefully designed isoline selection scheme lead to segmentation results that are insensitive to noise, pose, tessellation and variation in user's strokes. Our patch‐brush uses a novel facet‐based surface metric that alleviates sensitivity to noise and fine details common in region‐growing algorithms. Extensive experimental results demonstrate that our cutting tools can produce user‐desired segmentations for a wide variety of models even with single strokes. We also show that our tools outperform the state‐of‐art interactive segmentation tools in terms of ease of use and segmentation quality. 相似文献
165.
This paper establishes an axiomatic foundation and a representation theorem for the rigorous, constructive process, called sequence-based specification, of deriving precise specifications from ordinary (informal) statements of functional requirements. The representation theorem targets a special class of Mealy state machines, and algorithms are presented for converting from the set of sequences that define the specification to the equivalent Mealy machine, and vice versa. Since its inception, sequence-based specification has been effectively used in a variety of real applications, with gains reported in quality and productivity. This paper establishes the mathematical foundation independently of the process itself. 相似文献
166.
Yulei Wu Geyong Min Mohamed Ould-Khaoua Hao Yin Lan Wang 《The Journal of supercomputing》2010,51(2):115-130
The hypercube and torus are two important message-passing network architectures of high-performance multicomputers. Analytical
models of multicomputer networks under the non-bursty Poisson traffic have been widely reported. Motivated by the convincing
evidence of bursty and batch arrival nature of traffic generated by many real-world parallel applications in high-performance
computing environments, we develop a new and concise analytical model in this paper for hypercube and torus networks in the
presence of batch message arrivals modelled by the compound Poisson process with geometrically distributed batch sizes. The
average degree of virtual channel multiplexing is derived by employing a Markov chain which can capture the batch arrival
nature. An attractive advantage of the model is its constant computation complexity independent of the network size. The accuracy
of the analytical performance results is validated against those obtained from simulation experiments of an actual system. 相似文献
167.
168.
为了解决多传感器目标识别中不同等级信息源数据的融合问题,在研究DSmT证据理论的基础上,引入证据可信度矩阵.依据可信度矩阵对证据进行转化,使之可以用传统的方法进行证据融合.将这种方法应用到等级不同的多传感器目标识别中,可以解决传统证据理论只能进行相同等级传感器目标识别的难题.仿真实验表明,该方法提高了目标识别的准确性和有效性. 相似文献
169.
通过对异构网络的安全事件特点的深入分析,指出在大量不完整、模糊的安全事件中准确地定位潜在的安全威胁,对态势和威胁及其重要程度进行全面及时的评估,是当前安全管理的一个技术难题.提出一种基于时间关联窗口的安全事件模糊关联算法,在一定程度上解决安全事件的漏报与领域知识的不完备性问题,对当前的安全态势、安全威胁及其重要程度进行全面及时评估提供有力的支持. 相似文献
170.
Material procurement planning (MPP) deals with the problem that purchasing the right quantity of material from the right supplier
at the right time, a purchaser can reduce the material procurement costs via a reasonable MPP model. In order to handle the
MPP problem in a fuzzy environment, this paper presents a new class of two-stage fuzzy MPP models, in which the material demand,
the spot market material unit price and the spot market material supply quantity are assumed to be fuzzy variables with known
possibility distributions. In addition, the procurement decisions are divided into two groups. Some procurement decisions,
called first-stage decisions, must be taken before knowing the the particular values taken by the fuzzy variables; while some other decisions, called
second-stage decisions, can be taken after the realizations of the fuzzy variables are known. The objective of the proposed fuzzy MPP model is to
minimize the expected material procurement costs over the two stages. On other hand, since the fuzzy material demand, the
fuzzy spot market material unit price and the fuzzy spot market material supply quantity are usually continuous fuzzy variables
with infinite supports, the proposed MPP model belongs to an infinite-dimensional optimization problem whose objective function
cannot be computed exactly. To avoid this difficulty, we suggest an approximation approach (AA) to evaluating the objective
function, and turn the original MPP model into an approximating finite-dimensional one. To show the credibility of the AA,
the convergence about the objective function of the approximating MPP model to that of the original MPP one is discussed.
Since the exact analytical expression for the objective function in the approximating fuzzy MPP model is unavailable, and
the approximating MPP model is a mixed-integer program that is neither linear nor convex, the traditional optimization algorithms
cannot be used to solve it. Therefore, we design an AA-based particle swarm optimization to solve the approximating two-stage
fuzzy MPP model. Finally, we apply the two-stage MPP model to an actual fuel procurement problem, and demonstrate the effectiveness
of the designed algorithm via numerical experiments. 相似文献