全文获取类型
收费全文 | 31193篇 |
免费 | 1858篇 |
国内免费 | 1627篇 |
专业分类
电工技术 | 2157篇 |
综合类 | 2606篇 |
化学工业 | 1933篇 |
金属工艺 | 1435篇 |
机械仪表 | 3234篇 |
建筑科学 | 1305篇 |
矿业工程 | 583篇 |
能源动力 | 1080篇 |
轻工业 | 405篇 |
水利工程 | 443篇 |
石油天然气 | 400篇 |
武器工业 | 272篇 |
无线电 | 2097篇 |
一般工业技术 | 2874篇 |
冶金工业 | 638篇 |
原子能技术 | 177篇 |
自动化技术 | 13039篇 |
出版年
2024年 | 76篇 |
2023年 | 304篇 |
2022年 | 474篇 |
2021年 | 587篇 |
2020年 | 664篇 |
2019年 | 701篇 |
2018年 | 630篇 |
2017年 | 847篇 |
2016年 | 912篇 |
2015年 | 1120篇 |
2014年 | 1612篇 |
2013年 | 2080篇 |
2012年 | 1709篇 |
2011年 | 2119篇 |
2010年 | 1541篇 |
2009年 | 1787篇 |
2008年 | 1886篇 |
2007年 | 2035篇 |
2006年 | 1815篇 |
2005年 | 1712篇 |
2004年 | 1402篇 |
2003年 | 1255篇 |
2002年 | 1076篇 |
2001年 | 852篇 |
2000年 | 785篇 |
1999年 | 703篇 |
1998年 | 604篇 |
1997年 | 547篇 |
1996年 | 464篇 |
1995年 | 371篇 |
1994年 | 373篇 |
1993年 | 292篇 |
1992年 | 248篇 |
1991年 | 194篇 |
1990年 | 148篇 |
1989年 | 137篇 |
1988年 | 127篇 |
1987年 | 66篇 |
1986年 | 68篇 |
1985年 | 46篇 |
1984年 | 64篇 |
1983年 | 41篇 |
1982年 | 44篇 |
1981年 | 26篇 |
1980年 | 23篇 |
1979年 | 31篇 |
1978年 | 12篇 |
1977年 | 23篇 |
1976年 | 14篇 |
1975年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
31.
This paper presents a class of dual–primal proximal point algorithms (PPAs) for extended convex programming with linear constraints. By choosing appropriate proximal regularization matrices, the application of the general PPA to the equivalent variational inequality of the extended convex programming with linear constraints can result in easy proximal subproblems. In theory, the sequence generated by the general PPA may fail to converge since the proximal regularization matrix is asymmetric sometimes. So we construct descent directions derived from the solution obtained by the general PPA. Different step lengths and descent directions are chosen with the negligible additional computational load. The global convergence of the new algorithms is proved easily based on the fact that the sequences generated are Fejér monotone. Furthermore, we provide a simple proof for the O(1/t) convergence rate of these algorithms. 相似文献
32.
The evolutionary design can produce fast and efficient implementations of digital circuits. It is shown in this paper how evolved circuits, optimized for the latency and area, can increase the throughput of a manually designed classifier of application protocols. The classifier is intended for high speed networks operating at 100 Gbps. Because a very low latency is the main design constraint, the classifier is constructed as a combinational circuit in a field programmable gate array (FPGA). The classification is performed using the first packet carrying the application payload. The improvements in latency (and area) obtained by Cartesian genetic programming are validated using a professional FPGA design tool. The quality of classification is evaluated by means of real network data. All results are compared with commonly used classifiers based on regular expressions describing application protocols. 相似文献
33.
董智勇 《电子制作.电脑维护与应用》2015,(4):136-137
C语言程序设计是一门重要的课程,却难学难教。教学方法优化十分必要。教学方法优化应从激发学生兴趣入手,采用循序渐进的方式,着重培养学生举一反三的编程能力,引导学生写出高质量的程序,并丰富考核方式。 相似文献
34.
马扬 《电子制作.电脑维护与应用》2015,(11)
现代化建设事业的发展离不开计算机水平的提高。计算机编程语言作为人与机器沟通的桥梁,在计算机系统里有着非常重要的地位。本文从探讨计算机编程语言的概念出发,详细阐述了计算机编程语言所包含的内容和基本分类。接着笔者又深入分析了计算机输入设备的发展问题。最后,针对计算机编程语言和输入之间的联系问题,笔者做了观点性和理论性的论述分析。 相似文献
35.
《Advanced Engineering Informatics》2015,29(3):562-574
High-utility itemsets mining (HUIM) is a critical issue which concerns not only the occurrence frequencies of itemsets in association-rule mining (ARM), but also the factors of quantity and profit in real-life applications. Many algorithms have been developed to efficiently mine high-utility itemsets (HUIs) from a static database. Discovered HUIs may become invalid or new HUIs may arise when transactions are inserted, deleted or modified. Existing approaches are required to re-process the updated database and re-mine HUIs each time, as previously discovered HUIs are not maintained. Previously, a pre-large concept was proposed to efficiently maintain and update the discovered information in ARM, which cannot be directly applied into HUIM. In this paper, a maintenance (PRE-HUI-MOD) algorithm with transaction modification based on a new pre-large strategy is presented to efficiently maintain and update the discovered HUIs. When the transactions are consequentially modified from the original database, the discovered information is divided into three parts with nine cases. A specific procedure is then performed to maintain and update the discovered information for each case. Based on the designed PRE-HUI-MOD algorithm, it is unnecessary to rescan original database until the accumulative total utility of the modified transactions achieves the designed safety bound, which can greatly reduce the computations of multiple database scans when compared to the batch-mode approaches. 相似文献
36.
首先分析了TAPI协议的结构、通信编程原理和编程应用环境,重点介绍了TAPI协议的层次化模型结构及其模块化设计方法,该方法可以对进一步研究和开发TAPI软电话应用产品提供借鉴。 相似文献
37.
陈爱华 《计算机光盘软件与应用》2011,(13)
电信用户欠费是当今电信业者面临的日益严峻的问题,本文主要阐述如何利用电信企业拥有的数据仓库,依靠技术手段分析追踪和预防用户异常行为,达到防范电信欠费的效果。 相似文献
38.
39.
The recent evolution of wireless sensor networks have yielded a demand to improve energy-efficient scheduling algorithms and energy-efficient medium access protocols. This paper proposes an energy-efficient real-time scheduling scheme that reduces power consumption and network errors on dual channel networks. The proposed scheme is based on a dynamic modulation scaling scheme which can scale the number of bits per symbol and a switching scheme which can swap the polling schedule between channels. Built on top of EDF scheduling policy, the proposed scheme enhances the power performance without violating the constraints of real-time streams. The simulation results show that the proposed scheme enhances fault-tolerance and reduces power consumption. 相似文献
40.
K. Marti 《Computer Methods in Applied Mechanics and Engineering》2008,198(1):42-51
Problems from plastic analysis are based on the convex, linear or linearised yield/strength condition and the linear equilibrium equation for the stress (state) vector. In practice one has to take into account stochastic variations of several model parameters. Hence, in order to get robust maximum load factors, the structural analysis problem with random parameters must be replaced by an appropriate deterministic substitute problem. A direct approach is proposed based on the primary costs for missing carrying capacity and the recourse costs (e.g. costs for repair, compensation for weakness within the structure, damage, failure, etc.). Based on the mechanical survival conditions of plasticity theory, a quadratic error/loss criterion is developed. The minimum recourse costs can be determined then by solving an optimisation problem having a quadratic objective function and linear constraints. For each vector a(·) of model parameters and each design vector x, one obtains then an explicit representation of the “best” internal load distribution F∗. Moreover, also the expected recourse costs can be determined explicitly. Consequently, an explicit stochastic nonlinear program results for finding a robust maximal load factor μ∗. The analytical properties and possible solution procedures are discussed. 相似文献