全文获取类型
收费全文 | 33988篇 |
免费 | 3212篇 |
国内免费 | 1602篇 |
专业分类
电工技术 | 5056篇 |
技术理论 | 2篇 |
综合类 | 2290篇 |
化学工业 | 1403篇 |
金属工艺 | 1284篇 |
机械仪表 | 3526篇 |
建筑科学 | 3965篇 |
矿业工程 | 2697篇 |
能源动力 | 894篇 |
轻工业 | 748篇 |
水利工程 | 3102篇 |
石油天然气 | 936篇 |
武器工业 | 155篇 |
无线电 | 2878篇 |
一般工业技术 | 1724篇 |
冶金工业 | 759篇 |
原子能技术 | 497篇 |
自动化技术 | 6886篇 |
出版年
2024年 | 126篇 |
2023年 | 423篇 |
2022年 | 909篇 |
2021年 | 1140篇 |
2020年 | 1171篇 |
2019年 | 782篇 |
2018年 | 777篇 |
2017年 | 1048篇 |
2016年 | 1301篇 |
2015年 | 1539篇 |
2014年 | 2680篇 |
2013年 | 2353篇 |
2012年 | 3276篇 |
2011年 | 3212篇 |
2010年 | 2077篇 |
2009年 | 1991篇 |
2008年 | 1804篇 |
2007年 | 2079篇 |
2006年 | 1866篇 |
2005年 | 1637篇 |
2004年 | 1440篇 |
2003年 | 1162篇 |
2002年 | 900篇 |
2001年 | 677篇 |
2000年 | 549篇 |
1999年 | 412篇 |
1998年 | 338篇 |
1997年 | 277篇 |
1996年 | 213篇 |
1995年 | 168篇 |
1994年 | 125篇 |
1993年 | 71篇 |
1992年 | 50篇 |
1991年 | 47篇 |
1990年 | 32篇 |
1989年 | 32篇 |
1988年 | 23篇 |
1987年 | 6篇 |
1986年 | 13篇 |
1985年 | 14篇 |
1984年 | 9篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1963年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
以网络技术和信息技术为依托,建立职业安全健康动态监控信息系统,进行职业安全健康管理的监控和预警,提高安全管理的现代化水平。 相似文献
22.
智能型MNS低压开关柜 总被引:1,自引:0,他引:1
MNS智能低压开关柜是ABB公司的新一代产品。除具有设计灵活、结构紧凑和免维护等特点外,安全可靠性是其最突出的优点,包括抗故障电弧、可靠的绝缘分隔及接插性能、可靠的抽屉单元和温升限制。采用和智能化电动机控制中心INSUM及配电智能化控制和能量管理系统ESD2000的完美结合,开发了了基于现场总线的智能化的系统解决方案。 相似文献
23.
Shane Y. Hong 《Journal of Intelligent Manufacturing》1993,4(3):233-241
One major bottleneck in the automation of the drilling process by robots in the aerospace industry is drill condition monitoring. This paper describes a system approach to solve this problem through the advancement of new machine design, sensor instrumentation, metal-cutting research, and intelligent software development. All drill failures can be detected and distinguished: chisel edge wear, flank wear, crater wear, margin wear, corner wear, breakage, asymmetry, lip height difference, and chipping at lips. However, in the real manufacturing environment, different workpiece materials, drill size, drill geometry, drill material, cutting speed, feed rate, etc. will change the criteria for judging the drill condition. The knowledge base used for diagnosing the drill failures requires a huge data bank and prior exhaustive testing. A self-learning scheme is therefore introduced to the machine in order to acquire the threshold history needed for automatic diagnosis by using the same new tool under the same drilling conditions. 相似文献
24.
海洋是个特殊的环境,为许多光纤传感器提供了一个极好的应用领域。对于海洋这个特殊的“敌对”环境,光纤传感器将面临许多挑战。 本文着重介绍应用于海水温度、浊度、盐份浓度、浮游生物和溶解物光吸收量以及环境湿度等海洋环境参数监测的光纤传感器的原理、结构和特性,展望光纤传感器在海洋环境监测方面的美好前景。 相似文献
25.
P. Kurpas A. Oster M. Weyers A. Rumberg K. Knorr W. Richter 《Journal of Electronic Materials》1997,26(10):1159-1163
Reflectance anisotropy spectroscopy (RAS) has been used to study As-by-P exchange during metalorganic vapor phase epitaxy.
The study focuses on the processes occurring during switching from GaAs to GaInP, especially the effect of purging PH3 over a GaAs surface. GaAsP/GaAs superlattices of different periodicity were grown and the P-content was determined by high-resolution
x-ray diffraction and correlated to the RAS spectra. From the temperature dependence of the P-content, an activation energy
of 0.56 eV was estimated for the incorporation mechanism. In addition to the insights into the processes at mixed group-V
heterointerfaces, our study demonstrates the reproducibility of RAS transients that thus can be used for process monitoring. 相似文献
26.
27.
Determining contributions of source-monitoring and inhibitory function to age-related forgetting has been an elusive goal for cognitive theorists. Five studies used a verbal working memory paradigm to examine mechanisms accounting for disproportionate retroactive interference (RI) experienced with adult aging. Participants distinguished studied target-word pairs from interfering pairs that were read aloud. Source-monitoring and inhibitory task components varied through manipulations of response requirements. RI effects were primarily due to source-monitoring failures rather than to inhibitory failures. Removing both source and inhibitory components eliminated age differences in RI. When source monitoring was emphasized, RI continued to be observed in all age groups but disproportionately for older adults. Process dissociation analyses of memory found recollection decreases and familiarity increases consistent with source failures. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
28.
Modeling mercury speciation is an important requirement for estimating harmful emissions from coal-fired power plants and developing strategies to reduce them. First-principle models based on chemical, kinetic, and thermodynamic aspects exist, but these are complex and difficult to develop. The use of modern data-based machine learning techniques has been recently introduced, including neural networks. Here we propose an alternative approach using abductive networks based on the group method of data handling (GMDH) algorithm, with the advantages of simplified and more automated model synthesis, automatic selection of significant inputs, and more transparent input–output model relationships. Models were developed for predicting three types of mercury speciation (elemental, oxidized, and particulate) using a small dataset containing six inputs parameters on the composition of the coal used and boiler operating conditions. Prediction performance compares favourably with neural network models developed using the same dataset, with correlation coefficients as high as 0.97 for training data. Network committees (ensembles) are proposed as a means of improving prediction accuracy, and suggestions are made for future work to further improve performance. 相似文献
29.
森林火灾是造成森林资源破坏的重大灾害之一。作者根据近年来从事森林火灾卫星监刚的实践,结合国内外有关利用气象卫星监测林火的资料,介绍了林火卫星监测的原理、方法和实用效果。 相似文献
30.
D. Clifton A. R. Mount G. M. Alder D. Jardine 《International Journal of Machine Tools and Manufacture》2002,42(11)
During the process of electrochemical machining the dependency of the inter-electrode gap with time and process parameters can be used to determine process characteristics and to define the shape of the workpiece surface relative to the tool surface. Defining process variables to map out the required gap-time function requires the use of time-consuming iterative trials. In-line monitoring of the gap would enable process control and tool to workpiece transfer characteristics to be achieved (for ideal conditions) without the requirement to generate such parameter maps. This work explores the use of ultrasound applied as a passive, non-intrusive, in-line gap measurement system for ECM. The accuracy of this technique was confirmed through correspondence between the generated gap-time and current time data and theoretical models applicable to ideal conditions. Gap measurements are also used to demonstrate and quantify the degree of departure from ideal behaviour for an In718/chloride system as the electrolyte flow rate is reduced from 16 to 4 l min−1. The monitoring of the gap size has also been shown to be effective when determining shape convergence under ideal conditions, for the example case of a 2D sinusoidal profile. 相似文献