全文获取类型
收费全文 | 31543篇 |
免费 | 3130篇 |
国内免费 | 1550篇 |
学科分类
工业技术 | 36223篇 |
出版年
2024年 | 75篇 |
2023年 | 391篇 |
2022年 | 869篇 |
2021年 | 1068篇 |
2020年 | 1102篇 |
2019年 | 742篇 |
2018年 | 718篇 |
2017年 | 990篇 |
2016年 | 1230篇 |
2015年 | 1465篇 |
2014年 | 2575篇 |
2013年 | 2207篇 |
2012年 | 3172篇 |
2011年 | 3044篇 |
2010年 | 1988篇 |
2009年 | 1911篇 |
2008年 | 1721篇 |
2007年 | 1931篇 |
2006年 | 1706篇 |
2005年 | 1513篇 |
2004年 | 1308篇 |
2003年 | 1047篇 |
2002年 | 803篇 |
2001年 | 586篇 |
2000年 | 489篇 |
1999年 | 356篇 |
1998年 | 272篇 |
1997年 | 223篇 |
1996年 | 176篇 |
1995年 | 138篇 |
1994年 | 102篇 |
1993年 | 62篇 |
1992年 | 40篇 |
1991年 | 42篇 |
1990年 | 27篇 |
1989年 | 29篇 |
1988年 | 21篇 |
1987年 | 6篇 |
1986年 | 13篇 |
1985年 | 10篇 |
1984年 | 7篇 |
1983年 | 11篇 |
1982年 | 10篇 |
1981年 | 8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 234 毫秒
101.
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
102.
When describing scenes, speakers gaze at objects while preparing their names (Z. M. Griffin & K. Bock, 2000). In this study, the authors investigated whether gazes to referents occurred in the absence of a correspondence between visual features and word meaning. Speakers gazed significantly longer at objects before intentionally labeling them inaccurately with the names of similar things (e.g., calling a horse a dog) than when labeling them accurately. This held for grammatical subjects and objects as well as agents and patients. Moreover, the time spent gazing at a referent before labeling it with a novel word or accurate name was similar and decreased as speakers gained experience using the novel word. These results suggest that visual attention in speaking may be directed toward referents in the absence of any association between their visual forms and the words used to talk about them. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
103.
104.
105.
水轮机组状态监测与故障诊断系统,在水轮发电机组及电力系统中有着举足轻重的地位,提高水轮机组状态监测与故障诊断系统的准确性和及时性,对电力系统的安全运行具有重大意义。作者采用一种改进的BP网络算法,用于水轮机组状态监测与故障诊断系统中,试验表明,此方法改善了传统BP网络容易陷入局部最小点、网络收敛速度慢等不利因素,提高了水轮机组状态监测与故障诊断的准确性。 相似文献
106.
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
107.
混凝土大坝的变形,尤其是坝基和拱座的变形,是衡量工程安全与否的一个重要指标。变形自动监测仪器与人工测读的仪器相比,具有精度高、时间快的优点。本文参考国外资料,提出测斜仪、钻孔变位计、垂线自动监测仪等三种国内外正在试用的电子仪器。将有助于提高并改善大坝设计的经济性和安全性。 相似文献
108.
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
109.
110.
运用监控系统增强矿井防灾能力 总被引:1,自引:0,他引:1
瓦斯监测系统是煤矿瓦斯管理的重要手段。同时也可用于防治矿井胶带运输系统外因火灾,从而大大提高矿井的防灾抗灾水平。 相似文献