全文获取类型
收费全文 | 1275篇 |
免费 | 65篇 |
专业分类
电工技术 | 19篇 |
化学工业 | 365篇 |
金属工艺 | 24篇 |
机械仪表 | 30篇 |
建筑科学 | 53篇 |
矿业工程 | 2篇 |
能源动力 | 20篇 |
轻工业 | 70篇 |
水利工程 | 20篇 |
石油天然气 | 6篇 |
无线电 | 77篇 |
一般工业技术 | 163篇 |
冶金工业 | 350篇 |
原子能技术 | 6篇 |
自动化技术 | 135篇 |
出版年
2023年 | 9篇 |
2022年 | 10篇 |
2021年 | 23篇 |
2020年 | 10篇 |
2019年 | 17篇 |
2018年 | 24篇 |
2017年 | 23篇 |
2016年 | 34篇 |
2015年 | 12篇 |
2014年 | 30篇 |
2013年 | 45篇 |
2012年 | 42篇 |
2011年 | 60篇 |
2010年 | 48篇 |
2009年 | 60篇 |
2008年 | 77篇 |
2007年 | 49篇 |
2006年 | 63篇 |
2005年 | 52篇 |
2004年 | 45篇 |
2003年 | 27篇 |
2002年 | 35篇 |
2001年 | 41篇 |
2000年 | 32篇 |
1999年 | 22篇 |
1998年 | 49篇 |
1997年 | 36篇 |
1996年 | 30篇 |
1995年 | 22篇 |
1994年 | 27篇 |
1993年 | 29篇 |
1992年 | 9篇 |
1991年 | 13篇 |
1990年 | 15篇 |
1989年 | 17篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 14篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1983年 | 13篇 |
1982年 | 8篇 |
1981年 | 12篇 |
1980年 | 15篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 14篇 |
1975年 | 17篇 |
1974年 | 11篇 |
排序方式: 共有1340条查询结果,搜索用时 15 毫秒
1.
A silver palladium (Ag/Pd) alloy powder is used as an example material to illustrate potential applications of electrophoretic deposition (EPD) in electronics manufacturing, in particular the forming of multilayer devices. The dispersion and deposition of the Ag/Pd powder in acetic acid is characterized. It is found that deposition can be explained by the direct action of electrostatic force on individual particles. Depositions of this Ag/Pd powder are then used to demonstrate: forming of a continuous layer on a rigid substrate; forming of continuous layers in laminated and sintered BaTiO3 multilayers; and incorporation of patterned depositions into a multilayer by either overcasting the patterned deposition with a particulate slip to form a multicomponent tape, or direct lamination of the patterned deposition to a low temperature co-fired ceramic (LTCC) tape. It is shown that electrically conducting layers can be formed at an average thickness of only two times the diameter of the starting powder. Continuous conductor lines thirty times the average diameter of the starting powder were formed. 相似文献
2.
S. Mardnio P. Lucena Randall Q. Snurr Clio L. Cavalcante Jr. 《Microporous and mesoporous materials》2008,111(1-3):89-96
The adsorption of xylene isomers in AlPO4-11 (AEL network) was investigated using biased grand canonical Monte Carlo (GCMC) simulations. Preferential o-xylene adsorption was predicted by the simulations, in agreement with previously reported experimental data. In AlPO4-11 the selective adsorption behavior comes from the smaller length of the o-xylene molecule along the crystallographic c-axis compared to p-xylene. This is in contrast to AlPO4-5 and AlPO4-8, where the ortho-selectivity is caused by the characteristic face-to-face positioning of o-xylene. Energy minimization studies were also performed in a flexible AlPO4-11 lattice to study the structural changes upon xylene adsorption. The energy minimization study showed that the AlPO4-11 crystal distorts upon p- and o-xylene adsorption. The distortion mechanism is related to the strong interaction between xylene methyl groups and the sieve oxygen atoms in the O3 position in the wide region of the pore. 相似文献
3.
4.
Randall Billi; Moss Helen E.; Rodd Jennifer M.; Greer Mike; Tyler Lorraine K. 《Canadian Metallurgical Quarterly》2004,30(2):393
Patients with category-specific deficits have motivated a range of hypotheses about the structure of the conceptual system. One class of models claims that apparent category dissociations emerge from the internal structure of concepts rather than fractionation of the system into separate substores. This account claims that distinctive properties of concepts in the living domain are vulnerable because of their weak correlation with other features. Given the assumption that mutual activation among correlated properties produces faster activation in the normal system, the authors predicted a disadvantage for the distinctive features of living things for unimpaired adults. Results of a speeded feature verification study supported this prediction, as did a computational simulation in which networks mapped from orthography to semantics. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
South Africa’s Reconstruction and Development Programme set ambitious goals for providing basic services to all, including housing and electrification. More efficient use of energy has the potential to socially and politically support these goals, particularly when it is targeted at low-income communities lacking adequate energy services. This paper examines the economics of energy efficiency for the urban poor from the perspective of society, utilities and poor consumers, using five example programmes. While the five energy efficiency programmes generally have significant economic and environmental benefits from a social perspective, they may not be as attractive to utilities and consumers. Also examined are the policy options for overcoming the significant barriers to energy efficiency, and ways government can bridge the gap between what is good for society and what is good for the electricity industry. 相似文献
6.
Perri Michael G.; McAllister David A.; Gange James J.; Jordan Randall C.; McAdoo W. George; Nezu Arthur M. 《Canadian Metallurgical Quarterly》1988,56(4):529
This study evaluated the effectiveness of four posttreatment programs designed to enhance the long-term maintenance of weight loss. Mildly and moderately obese adults (N?=?123) were randomly assigned to one of the following five conditions: (a) behavior therapy only; (b) behavior therapy plus a posttreatment therapist-contact maintenance program; (c) behavior therapy plus posttreatment therapist contact plus a social influence maintenance program; (d) behavior therapy plus posttreatment therapist contact plus an aerobic exercise maintenance program; or (e) behavior therapy plus posttreatment therapist contact plus both the aerobic exercise and social influence maintenance programs. All posttreatment programs were conducted in 26 biweekly sessions during the year following behavioral treatment for obesity. At an 18-month follow-up evaluation, all four conditions that combined behavior therapy with a posttreatment maintenance program yielded significantly greater long-term weight losses than behavior therapy alone. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
Deborah C. Blaine John D. Gurosik Seong Jin Park Randall M. German Donald F. Heaney 《Metallurgical and Materials Transactions A》2006,37(3):715-720
Sintering experiments with various molybdenum powders are rationalized using a master sintering curve concept that collapses
density, grain size, or other parameters onto a single curve. In this case, the integral work of sintering is developed and
customized for different green densities. Construction of the master sintering curve is described to show how the curve can
be normalized with respect to green density effects. Various grades of molybdenum for metal injection molding and die compaction
are included in the analysis, processed over a range of heating cycles. Die-compacted samples of varying green densities are
used to illustrate the efficacy of the new, normalized master sintering curve concept. Sintering cycle optimization is one
possible outcome from this analysis. 相似文献
8.
Wurman J. Randall M. Frush C.L. Loew E. Holloway C.L. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1994,82(12):1861-1872
A bistatic dual-Doppler network consisting of an existing single transmitting pencil-beam weather radar and a remotely located, nontransmitting, passive bistatic receiver with a low-gain antenna was constructed and tested during 1993. High-quality dual Doppler vector winds were retrieved from this system. The windfields were compared with those collected with a traditional two-transmitter dual-Doppler system. Several interesting engineering challenges relating to frequency and timing synchronization were resolved in order to retrieve successfully Doppler velocities at a remote bistatic site. Frequency synchronization was achieved by using extremely stable local oscillators, linked by both Global Positioning Satellite (GPS) signals and transmitter sidelobe coupling. Both methods provided the necessary one part in 109 coherence necessary for calculating accurate Doppler velocities. Timing/gating synchronization with submicrosecond accuracy was achieved by using local oscillators at each site linked with GPS and sidelobe coupling. The successful testing of this system demonstrates that inexpensive and practical bistatic multiple-Doppler networks can be deployed. These systems can provide three-dimensional vector winds for a number of purposes in research, aviation, media, weather prediction, education, meteorological modeling and severe weather detection 相似文献
9.
John A. Hughes Dave Randall Dan Shapiro 《Computer Supported Cooperative Work (CSCW)》1992,1(3):123-141
This paper explores the issues involved in moving from ethnographic explorations of work in context to a practical contribution to system design. It does so using the example of an interdisciplinary research project involving sociologists and computer scientists in the domain of air traffic control systems. It forms a pair with another paper (Sommerville et al., 1992) exploring these questions from the perspective of our computer science partners. We characterise ethnography as a research method, and consider the differences between undertaking it for strictly sociological or anthropological purposes by contrast with interdisciplinary and design purposes. We summarise some of our results in ethnographic explications of the work of air traffic controllers, and the sociality which it manifests. We describe the dialogues involved in rendering these observations informative for systems design, and the mutual translations implied in attempting to reconcile sociological with software engineering questions about supporting the work. We conclude by specifying some features of cooperative work which an engineering approach is in danger of overlooking; the ways, and limits, in which ethnographers can form a bridge between users and designers; and some of the conflicts of interest entrained in generating technical change.The research is funded by the UK MRC/SERC/ESRC Cognitive Science/HCI Initiative with the title Social Analysis of Control Systems for HCI Design, grant number SPG 8931598. The computer science partners are Professor Ian Sommerville, Dr Tom Rodden, Dr Pete Sawyer and Mr Richard Bentley. Thanks are due to Val King, Kjeldt Schmidt, Ian Sommerville and Tom Rodden for very helpful comments on earlier drafts of this paper. 相似文献
10.
Michael K. Cinibulk John R. Welch Randall S. Hay 《Journal of the American Ceramic Society》1996,79(9):2481-2484
A method of preparing transmission electron microscopy (TEM) specimens of coated ceramic fibers has been developed, which produces large electron transparent areas due to the minimal preferential milling of the fiber, coating, or epoxy matrix. Multiple individual fibers or tows are impregnated with a high-temperature epoxy and contained to assure a high fiber-to-epoxy volume ratio. The samples are then sectioned and mechanically thinned either parallel or normal to the fiber axes using a wedge polisher on diamond lapping films to achieve a thickness of less than 5 μ.m. The thinned sample is then ion-milled to electron transparency in less than 30 min, giving representative specimens of the coating, fiber, and coating-fiber interface. This technique is also well suited to preparing extremely flat specimens for scanning electron microscopy analysis of thin coatings. Examples of TEM sections of coated fibers prepared using this technique are presented. 相似文献