全文获取类型
收费全文 | 42644篇 |
免费 | 4291篇 |
国内免费 | 3021篇 |
专业分类
电工技术 | 2432篇 |
技术理论 | 1篇 |
综合类 | 4294篇 |
化学工业 | 6285篇 |
金属工艺 | 3113篇 |
机械仪表 | 1807篇 |
建筑科学 | 3069篇 |
矿业工程 | 1938篇 |
能源动力 | 1807篇 |
轻工业 | 3353篇 |
水利工程 | 1208篇 |
石油天然气 | 2483篇 |
武器工业 | 582篇 |
无线电 | 4359篇 |
一般工业技术 | 4489篇 |
冶金工业 | 3128篇 |
原子能技术 | 1018篇 |
自动化技术 | 4590篇 |
出版年
2024年 | 176篇 |
2023年 | 562篇 |
2022年 | 1122篇 |
2021年 | 1355篇 |
2020年 | 1559篇 |
2019年 | 1292篇 |
2018年 | 1307篇 |
2017年 | 1666篇 |
2016年 | 1790篇 |
2015年 | 1822篇 |
2014年 | 2767篇 |
2013年 | 2960篇 |
2012年 | 3312篇 |
2011年 | 3359篇 |
2010年 | 2543篇 |
2009年 | 2469篇 |
2008年 | 2248篇 |
2007年 | 2745篇 |
2006年 | 2281篇 |
2005年 | 1980篇 |
2004年 | 1696篇 |
2003年 | 1460篇 |
2002年 | 1223篇 |
2001年 | 1049篇 |
2000年 | 884篇 |
1999年 | 724篇 |
1998年 | 622篇 |
1997年 | 523篇 |
1996年 | 486篇 |
1995年 | 407篇 |
1994年 | 304篇 |
1993年 | 231篇 |
1992年 | 221篇 |
1991年 | 167篇 |
1990年 | 148篇 |
1989年 | 101篇 |
1988年 | 75篇 |
1987年 | 45篇 |
1986年 | 44篇 |
1985年 | 37篇 |
1984年 | 31篇 |
1983年 | 17篇 |
1982年 | 17篇 |
1981年 | 13篇 |
1980年 | 16篇 |
1975年 | 10篇 |
1959年 | 11篇 |
1956年 | 6篇 |
1955年 | 12篇 |
1954年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
91.
Effect of additives on formation of natural gas hydrate 总被引:1,自引:0,他引:1
The formation of natural gas hydrate (NGH) is studied in this work. Kinetics data of hydrate formation with no agitation were collected at various concentrations of the aqueous solutions with different additives such as alkylpolyglucside, sodium dodecyl benzene sulfonate and potassium oxalate monohydrate. Various kinds of additive increased the formation rates of NGH and its storage capacity and reduced the induction time of NGH formation. Moreover, the storage capacity, the induction time and the hydrate formation rate were influenced by the concentration of the aqueous solution. 相似文献
92.
93.
94.
《Computer Speech and Language》2014,28(2):420-433
Automatic detection of a user's interest in spoken dialog plays an important role in many applications, such as tutoring systems and customer service systems. In this study, we propose a decision-level fusion approach using acoustic and lexical information to accurately sense a user's interest at the utterance level. Our system consists of three parts: acoustic/prosodic model, lexical model, and a model that combines their decisions for the final output. We use two different regression algorithms to complement each other for the acoustic model. For lexical information, in addition to the bag-of-words model, we propose new features including a level-of-interest value for each word, length information using the number of words, estimated speaking rate, silence in the utterance, and similarity with other utterances. We also investigate the effectiveness of using more automatic speech recognition (ASR) hypotheses (n-best lists) to extract lexical features. The outputs from the acoustic and lexical models are combined at the decision level. Our experiments show that combining acoustic evidence with lexical information improves level-of-interest detection performance, even when lexical features are extracted from ASR output with high word error rate. 相似文献
95.
Ahmet Kolus Philippe-Antoine Dubé Daniel Imbeau Richard Labib Denise Dubeau 《Applied ergonomics》2014
In new approaches based on adaptive neuro-fuzzy systems (ANFIS) and analytical method, heart rate (HR) measurements were used to estimate oxygen consumption (VO2). Thirty-five participants performed Meyer and Flenghi's step-test (eight of which performed regeneration release work), during which heart rate and oxygen consumption were measured. Two individualized models and a General ANFIS model that does not require individual calibration were developed. Results indicated the superior precision achieved with individualized ANFIS modelling (RMSE = 1.0 and 2.8 ml/kg min in laboratory and field, respectively). The analytical model outperformed the traditional linear calibration and Flex-HR methods with field data. The General ANFIS model's estimates of VO2 were not significantly different from actual field VO2 measurements (RMSE = 3.5 ml/kg min). With its ease of use and low implementation cost, the General ANFIS model shows potential to replace any of the traditional individualized methods for VO2 estimation from HR data collected in the field. 相似文献
96.
Evandro Eduardo Broday Antonio Augusto de Paula XavierReginaldo de Oliveira 《International Journal of Industrial Ergonomics》2014
The incorrect determination of metabolic rate can be linked to discrepancies between the model of the PMV (Predicted Mean Vote) and real thermal sensation collected in field studies. Aiming to improve the correlation of the PMV model and the real thermal sensation, this work established new values for the metabolic rate: one way being called “calculated” using Newton's Method and the other called "measured" using a metabolic analyzer. Welder's activities were evaluated, through the measurements of environmental and personal variables. New values of metabolic rate were determined for this activity. The values found for the calculated form and the measured one were, respectively, 178.63 and 145.46 W/m2, different from the range provided by the table of ISO 8996 (2004) for this activity (75–125 W/m2). In order to verify which of the values of the metabolic rate was closer to the real thermal sensation of PMV, a linear regression was made between the PMV and the real thermal sensation in three ways: S × PMVtabulated (R2 = 0.1749), S × PMVcalculated (R ² = 0.7481) and S × PMVmeasured (R2 = 0.7854). It was found that the values measured by the instrument gave a higher coefficient of determination which was chosen for the correction of the table. The correction of the table provides a value of Mpredicted, that is a value of metabolic rate that corrects the values provided by the tables of ISO 8996 (2004), by means of a correction coefficient. For the welder's activities in a metal-mechanics industry, tabulated values can be multiplied by the correction coefficient 1.4648 in order to minimize inaccuracies. The PMVpredicted, obtained through the Mpredicted, when related to the actual thermal sensation, provides a coefficient of determination of 0.7511, thereby improving the model of the PMV. 相似文献
97.
L. Rodríguez-Liñares M.J. Lado X.A. Vila A.J. Méndez P. Cuesta 《Computer methods and programs in biomedicine》2014
In this paper, the gHRV software tool is presented. It is a simple, free and portable tool developed in python for analysing heart rate variability. It includes a graphical user interface and it can import files in multiple formats, analyse time intervals in the signal, test statistical significance and export the results. 相似文献
98.
《Expert systems with applications》2014,41(13):6039-6046
Consumer complaints on online social network quickly become online groups complaints through many people’s aggregation and looking on, interaction and word-of-mouth communication. Therefore, assessing and managing online complain influence has become a new problem for enterprise to listen to and manage online group complaints. This paper analyzed the complaint information feature of consumer group on online social network, from three-dimensional perspective of complaint text’s quality, transmission timeliness and user interaction degree. We built the influence measure model of online complaint theme based on entropy weight model by monitoring and analyzing real-time the static and dynamic properties of complaint information, explored the measure method of complaint theme influence, employed empirical method to verify the validity and provided scientific decision-making tools and methods for enterprise listening to and managing online group complains. 相似文献
99.
100.