全文获取类型
收费全文 | 4870篇 |
免费 | 290篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 35篇 |
综合类 | 5篇 |
化学工业 | 1042篇 |
金属工艺 | 101篇 |
机械仪表 | 102篇 |
建筑科学 | 243篇 |
矿业工程 | 8篇 |
能源动力 | 150篇 |
轻工业 | 462篇 |
水利工程 | 47篇 |
石油天然气 | 21篇 |
武器工业 | 2篇 |
无线电 | 427篇 |
一般工业技术 | 925篇 |
冶金工业 | 830篇 |
原子能技术 | 28篇 |
自动化技术 | 743篇 |
出版年
2024年 | 6篇 |
2023年 | 42篇 |
2022年 | 82篇 |
2021年 | 137篇 |
2020年 | 95篇 |
2019年 | 110篇 |
2018年 | 142篇 |
2017年 | 128篇 |
2016年 | 161篇 |
2015年 | 122篇 |
2014年 | 159篇 |
2013年 | 276篇 |
2012年 | 274篇 |
2011年 | 339篇 |
2010年 | 241篇 |
2009年 | 266篇 |
2008年 | 300篇 |
2007年 | 283篇 |
2006年 | 229篇 |
2005年 | 240篇 |
2004年 | 175篇 |
2003年 | 152篇 |
2002年 | 157篇 |
2001年 | 79篇 |
2000年 | 66篇 |
1999年 | 62篇 |
1998年 | 61篇 |
1997年 | 62篇 |
1996年 | 70篇 |
1995年 | 52篇 |
1994年 | 59篇 |
1993年 | 56篇 |
1992年 | 43篇 |
1991年 | 37篇 |
1990年 | 44篇 |
1989年 | 43篇 |
1988年 | 38篇 |
1987年 | 41篇 |
1986年 | 40篇 |
1985年 | 32篇 |
1984年 | 27篇 |
1983年 | 28篇 |
1982年 | 28篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1979年 | 9篇 |
1978年 | 13篇 |
1976年 | 9篇 |
1975年 | 6篇 |
1974年 | 5篇 |
排序方式: 共有5171条查询结果,搜索用时 31 毫秒
31.
Over the years the number of Web users has increased dramatically unfortunately leading to the inherent problem of congestion. This can affect each user's surfing experience. This paper investigates download times associated with a web request, identifies where delays occur, and provides guidelines which can be followed by web developers to enable a faster and more efficient download and service for their users. We conclude that delays in Internet traffic and congestion can often be attributed to poorly developed sites (e.g. excessive image size). Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
32.
The relationship between facial expression and gaze processing was investigated with the Garner selective attention paradigm. In Experiment 1, participants performed expression judgments without interference from gaze, but expression interfered with gaze judgments. Experiment 2 replicated these results across different emotions. In both experiments, expression judgments occurred faster than gaze judgments, suggesting that expression was processed before gaze could interfere. In Experiments 3 and 4, the difficulty of the emotion discrimination was increased in two different ways. In both cases, gaze interfered with emotion judgments and vice versa. Furthermore, increasing the difficulty of the emotion discrimination resulted in gaze and expression interactions. Results indicate that expression and gaze interactions are modulated by discriminability. Whereas expression generally interferes with gaze judgments, gaze direction modulates expression processing only when facial emotion is difficult to discriminate. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
33.
Kevin Parmenter 《电子与电脑》2007,(8):26-27
近来,立法工作和广告活动都把焦点集中在能源使用的一个重要方面,也是功率电子产品能够产生积极作用的地方-即待机功耗.许多法规,比如 Blue Angel(蓝天使)和Top Runner(领跑者),都要求许多电子产品的待机功耗必须小于1w. 相似文献
34.
Kevin Burns 《Information Sciences》2006,176(11):1570-1589
Bayesian inference provides a formal framework for assessing the odds of hypotheses in light of evidence. This makes Bayesian inference applicable to a wide range of diagnostic challenges in the field of chance discovery, including the problem of disputed authorship that arises in electronic commerce, counter-terrorism and other forensic applications. For example, when two documents are so similar that one is likely to be a hoax written from the other, the question is: Which document is most likely the source and which document is most likely the hoax? Here I review a Bayesian study of disputed authorship performed by a biblical scholar, and I show that the scholar makes critical errors with respect to several issues, namely: Causal Basis, Likelihood Judgment and Conditional Dependency. The scholar’s errors are important because they have a large effect on his conclusions and because similar errors often occur when people, both experts and novices, are faced with the challenges of Bayesian inference. As a practical solution, I introduce a graphical system designed to help prevent the observed errors. I discuss how this decision support system applies more generally to any problem of Bayesian inference, and how it differs from the graphical models of Bayesian Networks. 相似文献
35.
Woo Y. Lee † F Kevin M. Cooley† Christopher C. Berndt ‡ Debra L. Joslin † David P. Stinton † 《Journal of the American Ceramic Society》1996,79(10):2759-2762
The potential application of Ca05Sr05Zr4P6O24 (CS50) as a corrosion-resistant coating material for Si-based ceramics and as a thermal barrier coating material for Ni-based superalloys was explored. A ∼200 (xm thick CS50 coating was prepared by air plasma spray with commercially available powder. A Nicalon/SiC ceramic matrix composite and a Ni-based superalloy coated with a ∼200 (xm thick metallic bond coat layer were used as substrate materials. Both the powder and coating contained ZrP2O7 as an impurity phase, and the coating was highly porous as-deposited. The coating deposited on the Nicalon/SiC substrate was chemically stable upon exposure to air and Na2SO4/O2 atmospheres at 1000°C for 100 h. In contrast, the coating sprayed onto the superalloy substrate significantly reacted with the bond coat surface after similar oxidation in air. 相似文献
36.
A multiparameter wearable physiologic monitoring system for space and terrestrial applications. 总被引:4,自引:0,他引:4
Carsten W Mundt Kevin N Montgomery Usen E Udoh Valerie N Barker Guillaume C Thonier Arnaud M Tellier Robert D Ricks Robert B Darling Yvonne D Cagle Nathalie A Cabrol Stephen J Ruoss Judith L Swain John W Hines Gregory T A Kovacs 《IEEE transactions on information technology in biomedicine》2005,9(3):382-391
A novel, unobtrusive and wearable, multiparameter ambulatory physiologic monitoring system for space and terrestrial applications, termed LifeGuard, is presented. The core element is a wearable monitor, the crew physiologic observation device (CPOD), that provides the capability to continuously record two standard electrocardiogram leads, respiration rate via impedance plethysmography, heart rate, hemoglobin oxygen saturation, ambient or body temperature, three axes of acceleration, and blood pressure. These parameters can be digitally recorded with high fidelity over a 9-h period with precise time stamps and user-defined event markers. Data can be continuously streamed to a base station using a built-in Bluetooth RF link or stored in 32 MB of on-board flash memory and downloaded to a personal computer using a serial port. The device is powered by two AAA batteries. The design, laboratory, and field testing of the wearable monitors are described. 相似文献
37.
The use and impacts of accelerated weathering of limestone (AWL; reaction: CO2+H2O+CaCO3→Ca2++2(HCO3−) is explored as a CO2 capture and sequestration method. It is shown that significant limestone resources are relatively close to a majority of CO2-emitting power plants along the coastal US, a favored siting location for AWL. Waste fines, representing more than 20% of current US crushed limestone production (>109 tonnes/yr), could provide an inexpensive or free source of AWL carbonate. With limestone transportation then as the dominant cost variable, CO2 mitigation costs of $3-$4/tonne appear to be possible in certain locations. Perhaps 10–20% of US point–source CO2 emissions could be mitigated in this fashion. It is experimentally shown that CO2 sequestration rates of 10−6 to 10−5 moles/sec per m2 of limestone surface area are achievable, with reaction densities on the order of 10−2 tonnes CO2 m−3day−1, highly dependent on limestone particle size, solution turbulence and flow, and CO2 concentration. Modeling shows that AWL would allow carbon storage in the ocean with significantly reduced impacts to seawater pH relative to direct CO2 disposal into the atmosphere or sea. The addition of AWL-derived alkalinity to the ocean may itself be beneficial for marine biota. 相似文献
38.
This work presents a method based on Computer Aided Design or CAD for facilitating the synthesis of Revolute–Revolute (R–R) dyads with adjustable moving pivots. The CAD-based method presented in this work ensures that all prescribed rigid-body parameters used to synthesize the R–R dyad satisfy particular kinematic requirements of an R–R dyad. Through the application of this CAD method, five of the six general R–R dyad constraint equations are satisfied and therefore not essential for the synthesis of the R–R dyad. By reducing the number of dyad design constraints from six to one, the user can synthesize R–R links with adjustable moving pivots for multi-phase motion and path generation applications. The example included demonstrates the use of the CAD method in the synthesis of an RRSS path generator with adjustable moving pivots. 相似文献
39.
Kenneth W. Young Kevin J. Whittle 《Journal of the science of food and agriculture》1985,36(5):383-392
Hunter L, a and b values are used to order fish mince colour according to species or processing parameters. Mince colour difference (ΔE) or statistical examination of L, a and b values are used to establish a 3-dimensional plot to illustrate colour differences between samples. 相似文献
40.
Kevin R. Boyle Martijn Udink Anton de Graauw Leo P. Ligthart 《Antennas and Propagation, IEEE Transactions on》2007,55(2):373-382
A dual-fed, self-diplexing planar inverted F antenna and an associated RF front-end are described. It is shown that co-design of the antenna and front-end can be used to double the operational bandwidth, without significant size or performance penalties. Indeed, the use of two feeds allows the antenna to be self-diplexing, which results in improved overall efficiency 相似文献