全文获取类型
收费全文 | 38614篇 |
免费 | 4427篇 |
国内免费 | 2247篇 |
专业分类
电工技术 | 6532篇 |
技术理论 | 4篇 |
综合类 | 4311篇 |
化学工业 | 1662篇 |
金属工艺 | 1098篇 |
机械仪表 | 3341篇 |
建筑科学 | 5116篇 |
矿业工程 | 1180篇 |
能源动力 | 1040篇 |
轻工业 | 659篇 |
水利工程 | 1182篇 |
石油天然气 | 1055篇 |
武器工业 | 680篇 |
无线电 | 5477篇 |
一般工业技术 | 3194篇 |
冶金工业 | 1071篇 |
原子能技术 | 345篇 |
自动化技术 | 7341篇 |
出版年
2024年 | 215篇 |
2023年 | 547篇 |
2022年 | 1101篇 |
2021年 | 1280篇 |
2020年 | 1507篇 |
2019年 | 1187篇 |
2018年 | 962篇 |
2017年 | 1379篇 |
2016年 | 1569篇 |
2015年 | 1606篇 |
2014年 | 3131篇 |
2013年 | 2484篇 |
2012年 | 3283篇 |
2011年 | 3461篇 |
2010年 | 2461篇 |
2009年 | 2542篇 |
2008年 | 2258篇 |
2007年 | 2620篇 |
2006年 | 2168篇 |
2005年 | 1870篇 |
2004年 | 1517篇 |
2003年 | 1312篇 |
2002年 | 1055篇 |
2001年 | 877篇 |
2000年 | 620篇 |
1999年 | 504篇 |
1998年 | 345篇 |
1997年 | 317篇 |
1996年 | 240篇 |
1995年 | 203篇 |
1994年 | 140篇 |
1993年 | 110篇 |
1992年 | 107篇 |
1991年 | 68篇 |
1990年 | 56篇 |
1989年 | 57篇 |
1988年 | 46篇 |
1987年 | 13篇 |
1986年 | 6篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 12篇 |
1975年 | 2篇 |
1965年 | 1篇 |
1960年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
杨桂华 《石油化工管理干部学院学报》2002,(4):46-48
介绍一种在企业管理干部培训实施中的四步操作模式。通过对该模式整体思路和四个步骤操作要点的阐释,说明在对企业管理干部的培训实施过程中如何将学员的学习特征与现代培训理念、培训元素进行有机的结合,使培训效果真正落实到提高学员的能力上,以使其工作得到改善。 相似文献
12.
The cost of maintaining a software system over a long period of time far exceeds its initial development cost. Much of the maintenance cost is attributed to the time required by new developers to understand legacy systems. High-level structural information helps maintainers navigate through the numerous low-level components and relations present in the source code. Modularization tools can be used to produce subsystem decompositions from the source code but do not typically produce high-level architectural relations between the newly found subsystems. Controlling subsystem interactions is one important way in which the overall complexity of software maintenance can be reduced.We have developed a tool, called ARIS (Architecture Relation Inference System), that enables software engineers to define rules and relations for regulating subsystem interactions. These rules and relations are called Interconnection Styles and are definedusing a visual notation. The style definition is used by our tool to infer subsystem-level relations in designs being reverse engineered from source code.In this paper we describe our tool and its underlying techniques and algorithms. Using a case study, we describe how ARIS is used to reverse engineer high-level structural information from a real application. 相似文献
13.
14.
Ali J. Koshkouei 《International Journal of Adaptive Control and Signal Processing》2008,22(9):859-874
Passivity with sliding mode control for a class of nonlinear systems with and without unknown parameters is considered in this paper. In fact, a method for deriving a nonlinear system with external disturbances to a passive system is considered. Then a passive sliding mode control is designed corresponding to a given storage function. The passivity property guarantees the system stability while sliding mode control techniques assures the robustness of the proposed controller. When the system includes unknown parameters, an appropriate updated law is obtained so that the new transformed system is passive. The passivation property of linear systems with sliding mode is also analysed. The linear and nonlinear theories are applied to a simple pendulum model and the gravity‐flow/pipeline system, respectively. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
15.
对智能电动机控制器的情况作了介绍,结合工作实践提出了维护要点和建议,并对该控制器的参数设置进行了说明,这对使用该设备的工业企业有一定的指导意义。 相似文献
16.
17.
Sangkwon Jeong 《低温学》2004,44(4):241-248
This paper describes transient numerical modeling for thermal characteristic of vapor-cooled current leads under pulse operation. The transient thermal analysis considers the temperature difference between a helium gas flow and a copper lead with temperature dependent properties of helium gas, copper and stainless steel. The numerical analysis was validated by an experiment with commercially available 100 A vapor-cooled current leads. A proper overloading factor calculation and the effect of intermediate cooling are presented for the current leads under pulse operation, which can significantly reduce heat input to a cryostat. 相似文献
18.
通过对黑岱沟露天煤矿运输设备出动率调查,初步分析了目前主要运输设备的现状以及存在问题的原因和影响因素,就加大预防性维修的比重,实行全面的预防性维修制度提出了一些看法。 相似文献
19.
Y. MURAKAMI K. TAKAHASHI R. KUSUMOTO 《Fatigue & Fracture of Engineering Materials & Structures》2003,26(6):523-531
ABSTRACT The fatigue crack growth behaviour of 0.47% carbon steel was studied under mode II and III loadings. Mode II fatigue crack growth tests were carried out using specially designed double cantilever (DC) type specimens in order to measure the mode II threshold stress intensity factor range, ΔKIIth. The relationship ΔKIIth > ΔKIth caused crack branching from mode II to I after a crack reached the mode II threshold. Torsion fatigue tests on circumferentially cracked specimens were carried out to study the mechanisms of both mode III crack growth and of the formation of the factory‐roof crack surface morphology. A change in microstructure occurred at a crack tip during crack growth in both mode II and mode III shear cracks. It is presumed that the crack growth mechanisms in mode II and in mode III are essentially the same. Detailed fractographic investigation showed that factory‐roofs were formed by crack branching into mode I. Crack branching started from small semi‐elliptical cracks nucleated by shear at the tip of the original circumferential crack. 相似文献
20.
基于SDL的通信软件维护模型SMM 总被引:1,自引:0,他引:1
软件维护是软件生存周期的一个重要且花费很大的阶段,维护工作的自动化是软件行业十分迫切的需要。本文提出了一个基于ITU-TSDL语言的通信软件维护模型SMM。在此模型中,软件维护被分成三个部分:建立面向维护的数据库,制定维护规范和基于功能转换的自动维护。该模型将有助于软件维护支撑环境的建立 相似文献