全文获取类型
收费全文 | 2545篇 |
免费 | 50篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 159篇 |
综合类 | 2篇 |
化学工业 | 523篇 |
金属工艺 | 79篇 |
机械仪表 | 29篇 |
建筑科学 | 34篇 |
能源动力 | 74篇 |
轻工业 | 166篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 252篇 |
一般工业技术 | 336篇 |
冶金工业 | 769篇 |
原子能技术 | 52篇 |
自动化技术 | 123篇 |
出版年
2023年 | 10篇 |
2022年 | 21篇 |
2021年 | 34篇 |
2020年 | 19篇 |
2019年 | 8篇 |
2018年 | 24篇 |
2017年 | 30篇 |
2016年 | 46篇 |
2015年 | 19篇 |
2014年 | 48篇 |
2013年 | 91篇 |
2012年 | 59篇 |
2011年 | 88篇 |
2010年 | 58篇 |
2009年 | 89篇 |
2008年 | 89篇 |
2007年 | 72篇 |
2006年 | 74篇 |
2005年 | 70篇 |
2004年 | 56篇 |
2003年 | 57篇 |
2002年 | 65篇 |
2001年 | 43篇 |
2000年 | 42篇 |
1999年 | 69篇 |
1998年 | 305篇 |
1997年 | 203篇 |
1996年 | 130篇 |
1995年 | 67篇 |
1994年 | 72篇 |
1993年 | 82篇 |
1992年 | 42篇 |
1991年 | 39篇 |
1990年 | 30篇 |
1989年 | 31篇 |
1988年 | 23篇 |
1987年 | 23篇 |
1986年 | 19篇 |
1985年 | 26篇 |
1984年 | 17篇 |
1983年 | 20篇 |
1982年 | 18篇 |
1981年 | 17篇 |
1980年 | 15篇 |
1979年 | 13篇 |
1978年 | 18篇 |
1977年 | 21篇 |
1976年 | 37篇 |
1974年 | 8篇 |
1969年 | 8篇 |
排序方式: 共有2600条查询结果,搜索用时 15 毫秒
81.
82.
Shaoying Lu Michailova A. Saucerman J. Yuhui Cheng Zeyun Yu Kaiser T. Li W. Bank R. Holst M. Mccammon J. Hayashi T. Hoshijima M. Arzberger P. McCulloch A. 《IEEE engineering in medicine and biology magazine》2009,28(2):46-57
This paper indicates that in ventricular myocytes when the SR (sarcoplasmic reticulum) is pharmacologically inhibited, the intracellular Ca2+concentration rapidly increases during Ca2+ entrance (0-70 ms), whereas the decay of Ca2+ is slow; in the absence of fluorescent dye, large Ca2+ concentration gradients might develop near the cell membrane; intracellular Ca2+ distribution is tightly regulated by the localization of Ca2+transporter proteins along the sarcolemma and strongly relays on the presence of mobile and stationary Ca2+ buffers. These studies also imply that in ventricular cells with intact and functional SR, the Ca2+ signal most likely would spread faster along the t-tubular system, surface membrane than to the cell interior and that in the absence of Ca2+ dye high Ca2+ gradients under the surface membrane and more uniform Ca2+ distribution in the cell interior might be expected. 相似文献
83.
84.
V.Yu. Osipov A.I. Shames T. Enoki K. Takai M. Endo T. Hayashi Y. Kaburagi A.Ya. Vul' 《Diamond and Related Materials》2009,18(2-3):220-223
Prolonged (up to 2 h) heat treatment at 1600 °C of nanodiamond particles (5 nm) leads to their conversion to the mixture of quasi-spherical carbon onions and multi-shell polyhedral nanographites. Structural and magnetic properties of two (A and B) series of nanographite samples obtained at various annealing intervals were studied. XRD data show that both multi-shell nanographite samples have practically the same crystalline structures. HRTEM evidences that the most of particles obtained by short time (7 min) annealing have a spherical like shape whereas the long time (~ 2 h) annealing leads to the majority of particles having a polyhedral shape with a hollow inside. Electronic and magnetic properties of these nanocarbons were investigated by magnetic susceptibility and EPR. Annealing results in entire transformation of the EPR signal of nanodiamond to new EPR signals of various line shapes and widths. These signals are extremely sensitive to ambient oxygen. Concentrations for all EPR active spins vary from ~ 1 × 1019 spins/g (7 min) to ~ 2 × 1019 spins/g (2 h). Temperature dependences of EPR spectra' parameters were obtained for vacuum-processed samples within the range 4?600 K. Intensity vs. T plots may be well-fitted by the combination of Curie–Weiss and temperature-independent Pauli susceptibility contributions. The latter one increases on heat treatment. Significant extension of electron spin-lattice relaxation time on decreasing temperature was found. 相似文献
85.
Organosilane self-assembled monolayers (SAMs) have been applied to resist materials for nanolithography based on scanning probe microscopy. An organosilane SAM was prepared on Si substrates from a precursor, that is octadecyltrimethoxysilane. Using an atomic force microscope with a conductive probe, current was injected from the probe into the SAM-covered Si substrate so that the SAM was locally degraded at the probe-contacting point. Nanoscale patterns drawn on the SAM was clearly imaged by lateral force microscopy. The patterning could be conducted in air while, in vacuum at the order of 10(-6) Torr, no detectable patterns were fabricated. The presence of adsorbed water at the probe/sample junction was confirmed to be crucial for the patterning of the SAM/Si. Its mechanism was, thus, ascribed to electrochemical reactions of both the SAM and Si with adsorbed water. 相似文献
86.
Honda Y Kitaoka M Sakka K Ohmiya K Hayashi K 《Journal of Bioscience and Bioengineering》2002,93(3):313-317
The kinetic parameters of Cex, a family 10 xylanase from Cellulomonas fimi, were determined at various pH levels using soluble birchwood xylan (BWX) as a natural polymeric substrate along with three other synthetic aryl-beta-D-xylobioside substrates. Using BWX, a high level of substrate inhibition was observed which increased with decreasing pH. In contrast, typical Michaelis-Menten-type profiles were obtained using the three aryl-beta-D-xylobiosides as substrates. The k(cat) values determined using o-nitrophenyl-beta-D-xylobioside did not change as the pH increased, whereas the k(cat) values obtained with BWX, phenyl-beta-D-xylobioside and p-nitrophenyl-beta-D-xylobioside decreased, suggesting that the presence of an ortho nitro group affects the activity displayed by Cex. These differences were not observed with XynB from Clostridium stercorarium F9, a member of the same family of xylanases as Cex. These results indicate that a careful evaluation is required when employing substituted aryl-beta-D-xylobiosides in the characterization of xylanases. 相似文献
87.
Learning theoretic aspects of mathematics and logic have been studied by many authors. They study how mathematical and logical objects are algorithmically “learned” (inferred) from finite data. Although they study mathematical objects, the objective of the studies is learning. In this paper, a mathematics whose foundation itself is learning theoretic will be introduced. It is called Limit-Computable Mathematics. It was originally introduced as a means for “Proof Animation”, which is expected to make interactive formal proof development easier. Although the original objective was not learning theoretic at all, learning theory is indispensable for our research. It suggests that logic and learning theory are related in a still unknown but deep new way. 相似文献
88.
V. N. Manuilov T. Idehara M. Kamada T. Hayashi La Agusu T. Kanemaki K. Yatsui Wiehua Jiang 《Journal of Infrared, Millimeter and Terahertz Waves》2006,27(3):343-353
High power Large Orbit Gyrotron (LOG) [1] is now under development at FIR FU. First version of this device was recently manufactured and then assembled with power supply ETIGO-IV [2]. Results of preliminary tests of electron-optic system are presented. The conditions when stable flat form of current pulse realized are discussed. Analytical estimations of cathode-anode distance to achieve small influence of cathode plasma during high voltage (HV) pulse are performed. Two new electron gun versions with decreased influence of the cathode plasma on its impedance and pulse form are suggested and optimized. New optimal magnetic field distributions are found. First gun has quiasi-flat cathode configuration near the anode diaphragm and provides operating current about 60 A. Second one uses blade cathode with operating current about 30 A. Beam quality for both guns is suitable for LOG operation. 相似文献
89.
Shinsuke Hara Hiroyuki Yomo Petar Popovski Kazunori Hayashi 《Wireless Personal Communications》2006,37(3-4):233-241
This paper discusses what a new paradigm can be in wireless communication systems of the twenty-first century. First, it suggests two directions for the new paradigm; one is “micro- and nano-device communication system” which is the projected scenario considering that the entities in source and destination have been shrinking throughout the history of wireless communication systems. The second direction is “networked robot system”, which emerges as a natural extension of mobile ad hoc networking where the networking is closely related to motion control of robots. Secondly, it shows two interesting research topics, “the new communication protocol design” and “signal processing”, respectively, that arise in the wake of the fusion between the two directions in the novel communication paradigm. Finally, it considers a new science of wireless communications in the twenty-first century.
Shinsuke Hara received the B.Eng., M.Eng. and Ph.D. degrees in communications engineering from Osaka University, Osaka, Japan, in 1985, 1987 and 1990, respectively. From April 1990 to March 1997, he was an assistant professor in the Department of Communication Engineering, School of Engineering, Osaka University, and from October 1997 to September 2005, he was an associate professor in the Department of Electronic, Information and Energy Engineering, Graduate School of Engineering, Osaka University. Since October 2005, he has been a professor in the Department of Physical Electronics and Informatics, Graduate School of Engineering, Osaka City University. In addition, from April 1995 to March 1996, he was a visiting scientist at Telecommunications and Traffic Control Systems Group, Delft University of Technology, Delft, The Netherlands. His research interests include wireless communications systems and digital signal processing.
Hiroyuki Yomo received B.S. degree in communication engineering from Department of Communication Engineering, Osaka University, Osaka, Japan, in 1997, and M.S. and Ph.D. degrees in communication engineering from Department of Electronic, Information, and Energy Engineering, Graduate School of Engineering, Osaka University, Osaka Japan, in 1999 and 2002, respectively. From April 2002 to March 2004, he was a Post-doctoral Fellow in Department of Communication Technology, Aalborg University, Denmark. From April 2004 to September 2004, he was at Internet System Laboratory, NEC Corporation, Japan. Since October 2004, he has been an Assistant Research Professor in Center for TeleInfrastructure (CTIF), Aalborg University, Denmark. His main research interests are access technologies, radio resource management, and link-layer techniques in the area of short-range communication, cellular network, cognitive radio, and sensor network.
Petar Popovski received the Dipl.-Ing. in electrical engineering and M.Sc. in communication engineering from the Faculty of Electrical Engineering, Sts. Cyril and Methodius University, Skopje, Republic of Macedonia, in 1997 and 2000, respectively. He received a Ph.D. degree from Aalborg University, Denmark, in 2004. From 1998 to 2001 he was a teaching and research assistant at the Institute of Telecommunications, Faculty of Electrical Engineering in Skopje. He is currently Assistant Professor at the Department of Communication Technology at the Aalborg University. His research interests are related to the PHY-MAC aspects of wireless protocols, wireless sensor networks, random access protocols, and network coding.
Kazunori Hayashi received the B.E., M.E. and Ph.D. degrees in communication engineering from Osaka University, Osaka, Japan, in 1997, 1999 and 2002, respectively. He spent 3 months in 2000 at Aalborg University, Denmark, as a Visiting Scholar. Since 2002, he has been with the Department of Systems Science, Graduate School of Informatics, Kyoto University. He is currently an Assistant Professor there. His research interests include digital signal processing for communications systems. 相似文献
90.
Okamura T Takeno T Dohi M Yasumasa I Hayashi T Toyoda M Noda H Fukuda S Horie N Ohsugi M 《Journal of Bioscience and Bioengineering》2000,89(5):474-478
With thrombosis a major cause of death in Japan and the Western world, thrombin-inhibitory agents that constrain the formation of fibrin are sought. We screened for basidiomycetes showing anti-thrombin activity and isolated Laetiporus sulphureus. However, it was difficult to cultivate and its form was not satisfactory. We therefore used protoplast fusion between L. sulphureus and the commonly cultivated basidiomycete Hypsizygus marmoreaus to obtain cultivable basidiomycetes that produced an anti-thrombin substance. For the protoplast fusion of L. sulphureus and H. marmoreaus, the protoplast concentration, alternating electric field intensity, dielectrophoresis duration, and field pulse intensity used were of 1 x 10(7) protoplasts/ml, 100 V/cm.1 MHz, 60 s, and 8 kV/cm, respectively. The number of regenerated colonies obtained was 4961, from which 43 strains were selected for electrophoretic analysis. Four of the fusants were found to have a band from each parent in isozyme patterns obtained using their crude extract. The fruiting bodies of the fusants were very similar to those of H. marmoreaus. Crude extract from each of the fusants and from L. sulphureus showed anti-coagulative activity in terms of the thrombin clotting time. We thus obtained improved basidiomycetes that produce an anti-thrombin substance, are easily cultivated, and whose form resembles H. marmoreaus, a commonly used culinary mushroom. 相似文献