全文获取类型
收费全文 | 39935篇 |
免费 | 4072篇 |
国内免费 | 3124篇 |
专业分类
电工技术 | 539篇 |
技术理论 | 1篇 |
综合类 | 3493篇 |
化学工业 | 8124篇 |
金属工艺 | 819篇 |
机械仪表 | 331篇 |
建筑科学 | 9766篇 |
矿业工程 | 1237篇 |
能源动力 | 791篇 |
轻工业 | 12539篇 |
水利工程 | 3247篇 |
石油天然气 | 990篇 |
武器工业 | 38篇 |
无线电 | 472篇 |
一般工业技术 | 1706篇 |
冶金工业 | 1227篇 |
原子能技术 | 382篇 |
自动化技术 | 1429篇 |
出版年
2024年 | 278篇 |
2023年 | 765篇 |
2022年 | 1482篇 |
2021年 | 1785篇 |
2020年 | 1657篇 |
2019年 | 1535篇 |
2018年 | 1485篇 |
2017年 | 1670篇 |
2016年 | 1761篇 |
2015年 | 1678篇 |
2014年 | 2529篇 |
2013年 | 2607篇 |
2012年 | 2967篇 |
2011年 | 3153篇 |
2010年 | 2324篇 |
2009年 | 2282篇 |
2008年 | 2000篇 |
2007年 | 2534篇 |
2006年 | 2175篇 |
2005年 | 1869篇 |
2004年 | 1561篇 |
2003年 | 1279篇 |
2002年 | 993篇 |
2001年 | 798篇 |
2000年 | 700篇 |
1999年 | 557篇 |
1998年 | 445篇 |
1997年 | 361篇 |
1996年 | 303篇 |
1995年 | 277篇 |
1994年 | 235篇 |
1993年 | 163篇 |
1992年 | 159篇 |
1991年 | 114篇 |
1990年 | 109篇 |
1989年 | 83篇 |
1988年 | 74篇 |
1987年 | 64篇 |
1986年 | 60篇 |
1985年 | 34篇 |
1984年 | 40篇 |
1983年 | 21篇 |
1982年 | 18篇 |
1981年 | 12篇 |
1980年 | 29篇 |
1979年 | 38篇 |
1959年 | 9篇 |
1958年 | 5篇 |
1956年 | 5篇 |
1951年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Matej Perše Author Vitae Matej Kristan Author Vitae Author Vitae Gašper Muši? Author Vitae Author Vitae Stanislav Kova?i? Author Vitae 《Pattern recognition》2010,43(4):1491-1501
This paper presents the use of place/transition petri nets (PNs) for the recognition and evaluation of complex multi-agent activities. The PNs were built automatically from the activity templates that are routinely used by experts to encode domain-specific knowledge. The PNs were built in such a way that they encoded the complex temporal relations between the individual activity actions. We extended the original PN formalism to handle the propagation of evidence using net tokens. The evaluation of the spatial and temporal properties of the actions was carried out using trajectory-based action detectors and probabilistic models of the action durations. The presented approach was evaluated using several examples of real basketball activities. The obtained experimental results suggest that this approach can be used to determine the type of activity that a team has performed as well as the stage at which the activity ended. 相似文献
92.
93.
赵馨瑜 《数码设计:surface》2010,(3):187-188
设计是创意产业,同时也是理性的、有据可循的。通过特定的方式寻找设计的创意点,有助于设计师诞生更多的优秀的设计作品。本文通过使用者的行为分析、多功能产品、特殊人群、情感化设计等方面,结合具体的设计案例,分析这些优秀设计创意点的产生,总结出寻找有效设计创意点的方法。 相似文献
94.
车载环境下基于样本熵的语音端点检测方法 总被引:1,自引:0,他引:1
在语音处理中一个关键性问题是如何准确找到语音的起止位置,目前提出许多的语音端点检测算法不能得到理想的检测结果.由于样本熵是近似熵的改进算法,提出车载环境下基于样本熵的语音端点检测方法.并采用模糊C均值聚类算法和贝叶斯信息判决算法进行样本熵特征门限估计,以及使用双门限法进行语音端点检测.在TIMIT连续语音库上的实验表明,车载噪声环境下,样本熵法和近似熵法的检测正确率均远高于谱熵法和能量谱熵法,而样本熵法相对于近似熵法具有更好的检测效果,特别是当信噪比小于等于OdB时,样本熵法的检测性能优于近似熵法近10%.因此,样本熵法在车栽智能语音领域具有很好的应用前景,能够为车载导航提供准确的语音端点检测技术. 相似文献
95.
F. Aiello F.L. Bellifemine G. Fortino S. Galzarano R. Gravina 《Engineering Applications of Artificial Intelligence》2011,24(7):1147-1161
Nowadays wireless body sensor networks (WBSNs) have great potential to enable a broad variety of assisted living applications such as human biophysical/biochemical control and activity monitoring for health care, e-fitness, emergency detection, emotional recognition for social networking, security, and highly interactive games. It is therefore important to define design methodologies and programming frameworks which enable rapid prototyping of WBSN applications. Several effective application development frameworks have been already proposed for WBSNs designed for TinyOS-based sensor platforms, e.g. CodeBlue, SPINE, and Titan. In this paper we present an application of MAPS, an agent framework for wireless sensor networks based on the Java-programmable Sun SPOT sensor platform, for the development of a real-time WBSN-based system for human activity monitoring. The agent-oriented programming abstractions provided by MAPS allow effective and rapid prototyping of the sensor-side software. In particular, the architecture of the developed system is a typical star-based WBSN composed of a coordinator node and two sensor nodes located respectively on the waist and the thigh of the monitored assisted living. The coordinator relies on a JADE-based enhancement of the SPINE coordinator and allows configuring sensors, receiving their data, and recognizing pre-defined human activities. On the other hand, each sensor node runs a MAPS-based agent that performs sensing of the 3-axial accelerometer sensor, computation of significant features on the acquired data, feature aggregation and transmission to the coordinator. The experimentation phase of the prototype, which allows evaluating the obtainable monitoring performances and activity recognition accuracy, is described. Moreover, a comparison of the monitoring system based on MAPS, AFME and SPINE in terms of programming effectiveness and system performances is discussed. 相似文献
96.
In this paper we study the single machine common due date assignment and scheduling problem with the possibility to perform a rate-modifying activity (RMA) for changing the processing times of the jobs following this activity. The objective is to minimize the total weighted sum of earliness, tardiness and due date costs. Placing the RMA to some position in the schedule can decrease the objective function value. Several properties of the problem are considered which in some cases can reduce the complexity of the solution algorithm. 相似文献
97.
Using online simulation in Holonic manufacturing systems 总被引:1,自引:1,他引:0
Olivier Cardin Pierre Castagna 《Engineering Applications of Artificial Intelligence》2009,22(7):1025-1033
This paper deals with the use of online simulation on Holonic manufacturing systems. Concepts needed for the use of online simulation in a classical hierarchical system were already defined, the observer being the central one. The behavior's differences between both classes of systems are studied to determine the best way to adapt these concepts to this new environment. In the product resource order staff approach (PROSA) reference architecture, staff holons were chosen to welcome the simulation models and the observer. An application on an industrial sized Holonic manufacturing system is described to demonstrate the validity of the approach. 相似文献
98.
99.
Twenty-seven subjects completed 2-min typing tasks using four typing styles: right-hand holding/typing (S-thumb) and two-hand typing at three heights (B-low, B-mid and B-high). The styles had significant effects on typing performance, neck and elbow flexion and muscle activities of the right trapezius and several muscles of the right upper limb (p < 0.0001 by repeated-measure analysis of variance). The subjects typed the fewest words (error-adjusted characters per minute: 78) with the S-thumb style. S-thumb style resulted in similar flexion angles of the neck, elbow and wrist, but significantly increased muscle activities in all tested muscles compared with the B-mid style. Holding the phone high or low reduced the flexion angles of the neck and right elbow compared with the B-mid style, but the former styles increased the muscle activity of the right trapezius. Right-hand holding/typing was not a preferable posture due to high muscle activities and slow typing speed.
Practitioner Summary: Right-hand holding/typing was not favoured, due to increased muscle activities and slower typing speed. Holding the phone high or low reduced the flexion angles of the neck and right elbow, but the former styles increased the muscle activity of the right trapezius compared with holding the phone at chest level. 相似文献
100.
Research suggests that cell phone use is related to sedentary behavior, that cell phone use during exercise reduces intensity, and that high frequency cell phone users are less fit than other users. Thus, cell phone use appears connected to health and fitness behaviors and should be better understood within this context. The present study investigated the sedentary nature of cell phone use, and examined the likelihood of cellphone use interfering with exercise behavior.DesignA validated survey was administered to a random sample of students from a public US university (N = 226).ResultsMean self-reported cell phone use was 380 min day−1, 87% reported cell phone use primarily occurs while sitting, and 70% of use was for leisure. Cell phone use was positively related to sedentary behavior (β = 0.30, p < 0.001). It was not related to physical activity. However, the likelihood of cell phone use during moderate (p = 0.006) and mild (p < 0.001) intensity exercise increased as cell phone use increased.ConclusionLike other screens (e.g., TVs), cell phone use appears to be a sedentary leisure behavior. Furthermore, high frequency use increases the likelihood that it will occur during exercise, likely lowering exercise intensity. 相似文献