全文获取类型
收费全文 | 517篇 |
免费 | 12篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 17篇 |
化学工业 | 128篇 |
金属工艺 | 4篇 |
机械仪表 | 4篇 |
建筑科学 | 26篇 |
矿业工程 | 5篇 |
能源动力 | 18篇 |
轻工业 | 64篇 |
水利工程 | 2篇 |
无线电 | 62篇 |
一般工业技术 | 55篇 |
冶金工业 | 44篇 |
原子能技术 | 5篇 |
自动化技术 | 99篇 |
出版年
2024年 | 5篇 |
2023年 | 2篇 |
2022年 | 11篇 |
2021年 | 10篇 |
2020年 | 6篇 |
2019年 | 10篇 |
2018年 | 13篇 |
2017年 | 12篇 |
2016年 | 16篇 |
2015年 | 13篇 |
2014年 | 11篇 |
2013年 | 23篇 |
2012年 | 21篇 |
2011年 | 27篇 |
2010年 | 23篇 |
2009年 | 33篇 |
2008年 | 37篇 |
2007年 | 19篇 |
2006年 | 22篇 |
2005年 | 22篇 |
2004年 | 21篇 |
2003年 | 17篇 |
2002年 | 30篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 11篇 |
1998年 | 16篇 |
1997年 | 19篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 10篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1975年 | 1篇 |
1970年 | 1篇 |
1966年 | 1篇 |
1964年 | 3篇 |
1963年 | 2篇 |
排序方式: 共有533条查询结果,搜索用时 15 毫秒
81.
Natural Computing - Sending signals through DNA-based structures is one of the methods used to enhance the capabilities of DNA self-assembly systems. Signal Tile Assembly Models at temperature one,... 相似文献
82.
Kari Rappa Jacob Samargia Mazhar Sher Javier S. Pino Harold F. Rodriguez Waseem Asghar 《Microfluidics and nanofluidics》2018,22(9):100
Quite puzzling issue in biology is how sperm cells are selected naturally where human sperm has to maintain a correct swimming behavior during the various stages of reproduction process. In nature, sperm has to compete a long journey from cervix to oocyte to stand a chance for fertilization. Although various guidance mechanisms such as chemical and thermal gradients are proposed previously, these mechanisms may only be relevant as sperm reaches very close to the oocyte. Rheotaxis, a phenomenon where sperm cells swim against the flow direction, is possibly the long-range sperm guidance mechanism for successful fertilization. A little is known quantitatively about how flow shear effects may help guide human sperm cells over long distances. Here, we have developed microfluidic devices to quantitatively investigate sperm rheotaxis at various physiological flow conditions. We observed that at certain flow rates sperm actively orient and swim against the flow. Sperm that exhibit positive rheotaxis show better motility and velocity than the control (no-flow condition), however, rheotaxis does not select sperm based on hyaluronic acid (HA) binding potential and morphology. Morphology and HA binding potential may not be a significant factor in sperm transport in natural sperm selection. 相似文献
83.
Shailesh Singh Chouhan Kari Halonen 《Analog Integrated Circuits and Signal Processing》2017,92(3):343-353
This work presents a two-stage voltage multiplier (VM) useful in RF energy harvesting based applications. The proposed circuit is based on the conventional differential drive rectifier, in which the input RF signal has been level shifted using a simple arrangement. This signal is then used to drive the next stage, which has been formed by using gate cross-coupled transistors. As a result, the load driving capability of the proposed architecture increases. The load in this work has been emulated in terms of a parallel RC circuit. The architecture has been implemented using standard 0.18 \(\mu\)m CMOS technology. The measurements of the two-stage conventional VM (CVM) and proposed VM circuits were performed at ISM frequencies 13.56, 433, 915 MHz and 2.4 GHz for R\(_L\) of values 1, 5, 10, 3 and 100 K\(\Omega\) with a fixed value of C\(_L\) equal to 20 pF. The performance evaluation has been done in terms of the power conversion efficiency (PCE) and average output DC voltage. The measured results show an improvement in PCE of 5% (minimum) for 13.56, 433 and 915 MHz frequencies, and up to 2% improvement for a frequency value of 2.4 GHz at the targeted load condition of 5 K\(\Omega ||\)20 pF, when compared with the measured results of the CVM circuit. 相似文献
84.
Underground space in land-use planning 总被引:3,自引:0,他引:3
Kimmo Rnk Jouko Ritola Kari Rauhala 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》1998,13(1):39
In 1988, the Finnish Ministry of the Environment appointed a committee to review existing planning systems for underground construction. In its report in spring 1990, the committee concluded that current legislation and planning procedures were unsatisfactory. In response, a study on “Underground Space in the Planning and Land Use” was launched in June 1994, and was completed in summer 1996. The study formed part of Finland's Rock Engineering 2000 programme. The study reviewed the present situation in underground planning; examined current uses of underground facilities; created a basic method for the classifying the building potential of rock areas, identified the various methods currently available for assessing the environmental impacts of underground construction on the basis of the legislation in force (EIA); to developed methods for assessing the costs to the urban community of underground space, particularly in comparison with equivalent costs of space aboveground; and drafted a proposal concerning planning of different level and permit procedures for underground space. This paper discusses each aspect of the study. 相似文献
85.
Harri Pellikka Esa Tiiliharju Kari Halonen 《Analog Integrated Circuits and Signal Processing》2007,50(1):21-27
In this paper a 0.4 μm complementary SiGe process is used to fabricate up-conversion mixers for base-station applications.
A current feedback mixer, and a mixer with a folded input, were designed in order to test benefits obtainable from the use
of equally fast PNP- and NPN-transistors. The target was to improve linearity and to increase output compression point (
) of the mixers. A +5 dBm output compression point @2 GHz was measured while drawing 43 mA from 5 V voltage supply.
Harri Pellikka was born in Espoo, Finland, in 1980. He received the M.Sc. degree in electronics and electrical engineering from Helsinki
University of Technology in 2005. He has been with Helsinki University of Technology Electronic Circuit Design Laboratory
since 2003, where he works as research engineer. His research interests include the design of integrated circuits for telecommunication
applications.
Esa Tiiliharju was born in Rovaniemi, Finland, in 1966. He received the M.Sc. degree in information technology in 1995, and the Lic.Tech
degree in electrical engineering in 1998, both from Helsinki University of Technology, Finland. He has joined the Microelectronics
Laboratory in University of Turku in 2006. His research interests include the design of integrated circuits for telecommunication
applications.
Kari A. I. Halonen was born in Helsinki, Finland, on May 23, 1958. He received the M.Sc. degree in electrical engineering from Helsinki University
of Technology, Finland, in 1982, and the Ph.D. degree in electrical engineering from the Katholieke Universiteit Leuven, in
Heverlee, Belgium, in 1987.
Since 1988 he has been with the Electronic Circuit Design Laboratory, Helsinki University of Technology. From 1993 he has
been an associate professor, and since 1997 a full professor at the Faculty of Electrical Engineering and Telecommunications.
He became the Head of Electronic Circuit Design Laboratory year 1998. From 1997 to 1999 he was an associate editor of IEEE
Transactions on Circuits and Systems I. He has been a guest editor for IEEE Journal of Solid-State Circuits and the Technical
Program Committee Chairman for European Solid-State Circuits Conference year 2000. He has been awarded the Beatrice Winner
Award in ISSCC’02 Conference year 2002.
He specializes in CMOS and BiCMOS analog integrated circuits, particularly for telecommunication applications. He is author
or co-author over a hundred and fifty international and national conference and journal publications on analog integrated
circuits. He has several patents on analog integrated circuits. 相似文献
86.
Fenton's process was used in oxidative degradation of ethylediaminetetraacetic acid (EDTA) and novel complexing agents, namely BCA5 and BCA6, in distilled water and spiked samples of integrated pulp and paper mill waste water and ECF-pulp bleaching effluent. In waste water, over 90% of EDTA was degraded within 3 min when temperature was 60 degrees C, pH 4, and molecular ratio of H2O2:Fe2+:EDTA was 70:2:1 (0.26 mM EDTA) or higher. In spiked ECF bleaching effluent up to 42% of EDTA was degraded in similar reaction conditions, still higher than published results indicate biological waste water treatment of pulp and paper mill waste water being capable of. In pH 3, EDTA proved readily degradable by Fenton's process in otherwise similar conditions. According to these results, Fenton's process could be used as a pre-treatment method for EDTA-containing bleaching effluents prior to the biological waste water treatment. In addition, BCA5 and BCA6 proved their superiority in terms of degradability also by Fenton's process in both pH 3 and 4. 相似文献
87.
Susanne Siebentritt Philipp Walk Ulrich Fiedeler Iver Lauermann Kari Rahne Martha Ch. Lux‐Steiner Thomas P. Niesen Franz Karg 《Progress in Photovoltaics: Research and Applications》2004,12(5):333-338
ZnSe prepared by metal organic chemical vapor deposition is used as a buffer layer in Cu(In,Ga)(S,Se)2 solar cells without any utilization of wet chemistry. Cell efficiencies are as good as cells with the conventional CdS buffer. Stability of unencapsulated cells under damp heat conditions is somewhat lower for the alternative buffer. The first stages of photoassisted growth are studied. X‐ray photoemission spectroscopy shows that a continuous layer is formed. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
88.
Isoamylase hydrolysates of wet‐ (WC) and dry‐cationised (DC) waxy maize starch were fractionated by ion‐exchange chromatography on CM‐Sepharose into an unbound and four bound fractions. The amount of bound dextrins was higher in the WC than in the DC sample. The fractions were characterised by gel‐permeation chromatography and proton‐NMR spectroscopy. The unbound fraction from the WC sample consisted mainly of linear chains formed from amylopectin. The dextrins in the bound fractions contained increased amounts, from 1.2—7.9, of cationic substituents per molecule and the degree of polymerisation increased with the density of substituents. Dextrins weakly bound to CM‐Sepharose had a linear structure, whereas more tightly bound fractions were mixtures of linear and branched dextrins. In the latter, the debranching was incomplete because of sterical hindrance by substituents at or close to the branch points. Most of the dextrins were partly hydrolysed by β‐amylase, but the more highly substituted fractions possessed also a population of β‐amylase resistant dextrins, suggesting substituents at the non‐reducing ends. 相似文献
89.
90.
Macroporous, monosized poly(meta‐divinylbenzene) and poly(para‐divinylbenzene) beads have been prepared by the two‐step activated swelling method with toluene or 2‐ethylhexanoic acid as pore‐forming agents. The type of divinylbenzene isomer as well as the type of porogen has a large effect on both physical and chemical properties of the monodisperse beads. Large pores are obtained with 2‐ethylhexanoic acid as porogen while beads prepared in the presence of toluene consist of only small pores and exhibit a shrinking behavior upon drying. The beads have considerable amounts of residual vinyl groups at the end of polymerization, as determined by bromination and Fourier transform IR analysis. The morphology and texture of the particles have been investigated by scanning electron microscopy and atomic force microscopy. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 152–169, 2000 相似文献