全文获取类型
收费全文 | 37059篇 |
免费 | 4031篇 |
国内免费 | 2585篇 |
专业分类
电工技术 | 1755篇 |
技术理论 | 5篇 |
综合类 | 2824篇 |
化学工业 | 1569篇 |
金属工艺 | 1293篇 |
机械仪表 | 3971篇 |
建筑科学 | 1389篇 |
矿业工程 | 551篇 |
能源动力 | 636篇 |
轻工业 | 890篇 |
水利工程 | 535篇 |
石油天然气 | 670篇 |
武器工业 | 367篇 |
无线电 | 5066篇 |
一般工业技术 | 3793篇 |
冶金工业 | 1112篇 |
原子能技术 | 529篇 |
自动化技术 | 16720篇 |
出版年
2024年 | 110篇 |
2023年 | 501篇 |
2022年 | 864篇 |
2021年 | 949篇 |
2020年 | 1013篇 |
2019年 | 808篇 |
2018年 | 843篇 |
2017年 | 1197篇 |
2016年 | 1362篇 |
2015年 | 1474篇 |
2014年 | 2278篇 |
2013年 | 2168篇 |
2012年 | 2386篇 |
2011年 | 3018篇 |
2010年 | 2141篇 |
2009年 | 2110篇 |
2008年 | 2192篇 |
2007年 | 2470篇 |
2006年 | 2095篇 |
2005年 | 1765篇 |
2004年 | 1563篇 |
2003年 | 1533篇 |
2002年 | 1224篇 |
2001年 | 1002篇 |
2000年 | 919篇 |
1999年 | 863篇 |
1998年 | 899篇 |
1997年 | 691篇 |
1996年 | 574篇 |
1995年 | 460篇 |
1994年 | 359篇 |
1993年 | 315篇 |
1992年 | 272篇 |
1991年 | 208篇 |
1990年 | 171篇 |
1989年 | 127篇 |
1988年 | 150篇 |
1987年 | 60篇 |
1986年 | 86篇 |
1985年 | 108篇 |
1984年 | 82篇 |
1983年 | 57篇 |
1982年 | 32篇 |
1981年 | 32篇 |
1980年 | 15篇 |
1979年 | 20篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1974年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
李凯花 《石油化工管理干部学院学报》2003,(4):19-21
推进施工企业党组织的建设必须与时俱进,坚持一岗双责、两个融合、三个同步、四个同时,创新工作思路、工作机制、工作方法和工作方式。把贯彻落实“三个代表”重要思想,作为检验工作成效的根本标准。 相似文献
52.
T.L. Phillips 《Polymer》2005,46(24):11035-11050
Results are presented from atomistic molecular dynamics simulations of the mobile pseudo-hexagonal phase of polyethylene, which occurs under conditions of elevated pressure and temperature. Three different types of model are considered, all of which employ periodic boundary conditions. The first model consists of n-alkane sequences (48×-C24H48-) that are bonded across the simulation box boundaries to produce chains that are effectively infinite in extent. On heating, at high pressure, this system displays a rotator phase, in which the chains retain an all-trans conformation, and rotate as semi-rigid units. A second model, consisting of finite n-alkanes (48×C24H50) displays the same behaviour at low temperatures, but at high temperature and pressure forms a conformationally disordered rotator phase, characterised by a large proportion of gauche defects and a significant lattice expansion. The final model considered contains long n-alkanes (24×C102H206) which contain jog defects and each pass twice through the simulation box. This model forms a conformationally disordered rotator phase at high temperature and ambient pressure. The behaviour of the three models, in terms of the variations in chain conformation and rotational and translational dynamics, are compared. The conformationally disordered phases provide useful representations of the experimentally observed mobile phase. 相似文献
53.
Corner detection is a low-level feature detection operator that is of great use in image processing applications, for example, optical flow and structure from motion by image correspondence. The detection of corners is a computationally intensive operation. Past implementations of corner detection techniques have been restricted to software. In this paper we propose an efficient very large-scale integration (VLSI) architecture for detection of corners in images. The corner detection technique is based on the half-edge concept and the first directional derivative of Gaussian. Apart from the location of the corner points, the algorithm also computes the corner orientation and the corner angle and outputs the edge map of the image. The symmetrical properties of the masks are utilized to reduce the number of convolutions effectively, from eight to two. Therefore, the number of multiplications required per pixel is reduced from 1800 to 392. Thus, the proposed architecture yields a speed-up factor of 4.6 over conventional convolution architectures. The architecture uses the principles of pipelining and parallelism and can be implemented in VLSI. 相似文献
54.
Molecular dynamics simulations are used to investigate polymer networks made by either end-linking or randomly crosslinking a melt of linear precursor chains. The resulting network structures are very different, since end-linking leads to nearly ideal monodisperse networks, while random crosslinking leads to polydisperse networks, characterized by an exponential strand length distribution. Networks with average strand length 20 and 100 were generated. These networks were used to study the effects of disorder in the network connectivity on observables averaged either over the entire network or selected sub-structures. Heterogeneities in the randomly crosslinked networks cause significant differences in the localization of monomers, however, neither the localization of crosslinks nor the microscopic strain response are significantly affected. Compared to end-linked networks, randomly crosslinked networks have a slightly increased tube diameter, and as a result a slightly decreased shear modulus, but otherwise identical stress-strain behavior. For the investigated systems, we conclude that the microscopic strain response, tube diameter, and stress-strain relation are all insensitive to the heterogeneities due to the linking process by which the network were made. 相似文献
55.
56.
A constant trend towards more compact mechanical systems with higher power densities and increased thermo-mechanical loads emphasises the importance of the development of new design approaches and novel tribological systems. Ignoring this may cause a significant slow down in technological and industrial development. Tribotronics or active tribology based on adaptive performance is thought of as being critical in the implementation of smart machine concepts. Recognition of the importance of tribotronics, or active control of system loss outputs, such as those through friction and wear will have significant beneficial economic consequences as a result of the associated accelerated rate of technological progress. These smart tribotronic systems can be embedded in a great variety of machines and mechanisms. If this integration is made at the design stage, products that are more flexible, efficient and reliable can be produced. The concept of tribotronics is presented and discussed in this paper. Some illustrative examples that show the feasibility of an “active” approach are given. In addition, various possibilities already reported in literature are discussed. 相似文献
57.
Matthias Zobel Joachim Denzler Benno Heigl Elmar Nöth Dietrich Paulus Jochen Schmidt Georg Stemmer 《Machine Vision and Applications》2003,14(1):26-34
Abstract. This contribution introduces MOBSY, a fully integrated, autonomous mobile service robot system. It acts as an automatic dialogue-based
receptionist for visitors to our institute. MOBSY incorporates many techniques from different research areas into one working
stand-alone system. The techniques involved range from computer vision over speech understanding to classical robotics.
Along with the two main aspects of vision and speech, we also focus on the integration aspect, both on the methodological
and on the technical level. We describe the task and the techniques involved. Finally, we discuss the experiences that we
gained with MOBSY during a live performance at our institute. 相似文献
58.
介绍了补偿中子测井仪刻度的基本原理及在Windows98平台下利用Borland C Builder5.0^[1]编程环境开发的中子测井仪刻度管理软件,实现了对中子测井仪的刻度管理,列举了应用实例。 相似文献
59.
提出了基于压电技术的微操作系统的自动标定方法,采用混合式步进电机直接驱动的宏动平台,实现系统大行程宏动定位,安装在宏动平台上的压电陶瓷驱动的微动平台和精密光栅,实现亚微米级的分辨率和定位精度,通过以上两部分实现定位机构的全闭环反馈控制,采用显微视觉反馈获取微动台操作器在图像中的位置信息进行标定。实验结果表明:系统的动态和稳定性能良好,自动标定运算速度快,运行速度达到11 frame/s,实现了对系统的精确标定,标定精度达到0.1μm。 相似文献
60.
介绍了现在制造业中面临的问题,通过对问题的分析,提出了发展先进制造前沿技术的见解和在我国发展先进制造技术的途径,同时展望了先进制造技术的发展前景。 相似文献