全文获取类型
收费全文 | 5060篇 |
免费 | 106篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 258篇 |
综合类 | 15篇 |
化学工业 | 939篇 |
金属工艺 | 97篇 |
机械仪表 | 86篇 |
建筑科学 | 81篇 |
矿业工程 | 6篇 |
能源动力 | 134篇 |
轻工业 | 295篇 |
水利工程 | 22篇 |
石油天然气 | 30篇 |
武器工业 | 6篇 |
无线电 | 587篇 |
一般工业技术 | 819篇 |
冶金工业 | 1335篇 |
原子能技术 | 135篇 |
自动化技术 | 334篇 |
出版年
2023年 | 23篇 |
2022年 | 76篇 |
2021年 | 91篇 |
2020年 | 39篇 |
2019年 | 54篇 |
2018年 | 49篇 |
2017年 | 41篇 |
2016年 | 83篇 |
2015年 | 52篇 |
2014年 | 106篇 |
2013年 | 209篇 |
2012年 | 138篇 |
2011年 | 197篇 |
2010年 | 144篇 |
2009年 | 172篇 |
2008年 | 161篇 |
2007年 | 134篇 |
2006年 | 142篇 |
2005年 | 110篇 |
2004年 | 122篇 |
2003年 | 123篇 |
2002年 | 114篇 |
2001年 | 133篇 |
2000年 | 102篇 |
1999年 | 137篇 |
1998年 | 557篇 |
1997年 | 343篇 |
1996年 | 251篇 |
1995年 | 132篇 |
1994年 | 149篇 |
1993年 | 118篇 |
1992年 | 66篇 |
1991年 | 59篇 |
1990年 | 63篇 |
1989年 | 54篇 |
1988年 | 58篇 |
1987年 | 53篇 |
1986年 | 49篇 |
1985年 | 48篇 |
1984年 | 41篇 |
1983年 | 44篇 |
1982年 | 46篇 |
1981年 | 47篇 |
1980年 | 25篇 |
1979年 | 30篇 |
1978年 | 22篇 |
1977年 | 29篇 |
1976年 | 53篇 |
1973年 | 15篇 |
1972年 | 13篇 |
排序方式: 共有5179条查询结果,搜索用时 15 毫秒
31.
Takahashi T. Sekiguchi T. Takemura R. Narui S. Fujisawa H. Miyatake S. Morino M. Arai K. Yamada S. Shukuri S. Nakamura M. Tadaki Y. Kajigaya K. Kimura K. Itoh K. 《Solid-State Circuits, IEEE Journal of》2001,36(11):1721-1727
A multigigabit DRAM technology was developed that features a low-noise 6F2 open-bitline cell with fully utilized edge arrays, distributed overdriven sensing for operation below 1 V, and a highly reliable post-packaging repair scheme using a stacked-flash fuse. This technology, which can be used to fabricate a 0,13-μm 180-mm2 1-Gb DRAM assembled in a 400-mil package, was verified using a 57.6-mm2, 200-MHz array-cycle, 256-Mb test chip with 0.109-μm2 cells 相似文献
32.
Liang Y Nakamura S Cui L Johkura K Ogiwara N Sasaki K 《Journal of electron microscopy》2004,53(1):93-97
Three-dimensional microlocalization of adhesion molecules, i.e. ICAM-1 (intercellular adhesion molecule), VCAM-1 (vascular adhesion molecule), LFA-1 (lymphocyte function-associated antigen), Mac-1 (macrophage differentiation antigen) and VLA-4 (very late activation antigen), expressed on type-A synoviocyte (macrophage-like cell) and type-B synoviocyte (fibroblast-like cell), were detected by immuno-scanning electron microscopy (SEM) to investigate the immunoreactive microenvironment of the superficial synovial intima in lipopolysaccharide (LPS)-induced arthritis of the mouse knee. Type-B synoviocytes extended rich slender processes from the periphery and constructed a cytoplasmic network, to which ICAM-1 was restricted. VCAM-1 was expressed only in the LPS-stimulated group and was relatively limited to the microvilli of type-B synoviocytes. Type-A synoviocytes were located randomly among the network with a smoother surface and expressed Mac-1 and LFA-1, which were counter-receptors for ICAM-1, and VLA-4 for VCAM-1 on the microvilli or lamellipodia. Three-dimensional microlocalization of adhesion molecules suggests that the network constructed by cytoplasmic processes and microvilli of type-B synoviocytes forms the pathway for the migration or the foothold for the fixation of type-A synoviocytes and takes part in forming an immunoreactive environment in the articular cavity. 相似文献
33.
Lithium Phenolate Complexes with a Pyridine‐Containing Polymer for Solution‐Processable Electron Injection Layers in PLEDs 下载免费PDF全文
Takayuki Chiba Yong‐Jin Pu Shogo Takahashi Hisahiro Sasabe Junji Kido 《Advanced functional materials》2014,24(38):6038-6045
A series of (vinylphenyl)pyridine‐based polymer binders, PVPh2Py, PVPh3Py, and PVPh4Py, are designed and synthesized and it is found that mixtures of Liq and the polymers exhibit superior electron injection characteristics as ultrathin (1.6 nm) electron injection layer (EIL) films. They are comparable to those of EILs composed only of Liq. The addition of the polymers does not deteriorate the performance of Liq EILs. Additionally, when the EIL thickness is increased from 1.6 nm to 16 nm, the driving voltages increase and the external quantum efficiencies decrease. The increase in the voltage and decrease in the EQE are suppressed in the device with mixed EILs compared to those observed for the device composed of 100 wt% Liq. Furthermore, the position of the nitrogen in the pyridine ring is considered to influence the electron transport properties of the EILs. The mixing PVPh4Py with Liq improves the driving voltage of the fabricated devices, even with a thick mixed EIL. This reduced dependence of the performance of EILs on their thickness will be advantageous for the coating of large areas using solution processes. 相似文献
34.
Xiujun Gong Kensuke Nakamura Hua Yu Kei Yura Nobuhiro Go 《IEEE transactions on information technology in biomedicine》2007,11(4):428-434
The emerging grid computing technologies enable bioinformatics scientists to conduct their researches in a virtual laboratory, in which they share public databases, computational tools as well as their analysis workflows. However, the development of grid applications is still a nightmare for general bioinformatics scientists, due to the lack of grid programming environments, standards and high-level services. Here, we present a system, which we named Bioinformatics: Ask Any Questions (BAAQ), to automate this development procedure as much as possible. BAAQ allows scientists to store and manage remote biological data and programs, to build analysis workflows that integrate these resources seamlessly, and to discover knowledge from available resources. This paper addresses two issues in building grid applications in bioinformatics: how to smoothly compose an analysis workflow using heterogeneous resources and how to efficiently discover and re-use available resources in the grid community. Correspondingly an intelligent grid programming environment and an active solution recommendation service are proposed. Finally, we present a case study applying BAAQ to a bioinformatics problem. 相似文献
35.
Tomioka T. Nakamura M.S. Furuyama H. Onomura M. Ohshima S. 《Electronics letters》1992,28(19):1788-1790
A new heterodyne receiver is demonstrated. The local laser diode (LD) was built-in and no fibre was used between the parts. The number of optical parts and assembly processes was reduced, and a better performance was achieved because there was no polarisation fluctuation of the local light. The effect of a mismatch in the beam profile is discussed.<> 相似文献
36.
A sample preparation machine introduces a variety of techniques for low-damage sample preparation, especially for the physical analysis of chip size packages (CSPs) and the flip-chip. The techniques are not only useful for CSPs and the flip-chip, but also for a variety of single components. Sample preparation time is greatly reduced. 相似文献
37.
Temperature dependence of the gain in erbium-doped fibers 总被引:6,自引:0,他引:6
The temperature dependence of the gain in erbium-doped fibers between -20 and +85°C is discussed. The characteristics of three types of erbium-doped fibers with different erbium concentrations and glass compositions are investigated. The gain decreased with increasing temperature at the rate of -0.07 dB/°C when pumped at 1.48 μm. The change in the gain was small when pumped at 0.98 μm. By measuring the change in the absorption and fluorescence spectra with temperature, it is deduced that the change in the gain is mainly due to the change in the saturated population inversion 相似文献
38.
Shigeyuki Nakamura Yoshihisa Mori Ken’ichi Takarabe 《Journal of Electronic Materials》2014,43(6):2174-2178
High-performance Mg2Si thermoelectric devices have been obtained by spark plasma sintering of high-purity, pre-synthesized, all-molten Mg2Si powder. We studied the effects of source powder particle size on thermoelectric performance. To improve the performance, further investigation of the microstructure of the devices is needed. In this work we studied the microstructure of grain boundaries and interfaces between electrodes and Mg2Si sintered bodies to increase understanding of Mg2Si thermoelectric devices. 相似文献
39.
Y. Matsuzawa K. Ueki M. Yoshida N. Tamaoki T. Nakamura H. Sakai M. Abe 《Advanced functional materials》2007,17(9)
An illustration of the phototriggered organization and dispersion of tri‐peptide‐substituted azobenzene derivatives, as reported on p. 1507 by Yoko Matsuzawa and co‐workers. The tri‐peptide units form a beta‐sheet structure through hydrogen bonding to assemble a fibrous network system. Cis–trans photoisomerization of the azobenzene moiety leads to a large polarity change of the component molecule to break and re‐form hydrogen bonds between the tri‐peptide units. Assembled systems consisting of an azobenzene moiety as the photofunctional component and valyl units as the network backbone are investigated. The molecular ordering of these assemblies is examined by spectroscopy and theoretical calculations. The number of valyl units greatly influences the molecular order in the organized systems. Only N‐(L ‐valyl‐L ‐valyl‐L ‐valyl)azobenzene‐4‐carboxamide ( 3 ) forms a complete β‐sheet structure in this artificial assembly. Upon photoirradiation, the azobenzene moieties isomerize completely, revealing the reversibility in the structural organization through the flexibility of the β‐sheet network in this system. 相似文献
40.
Zhaoyang Liu Xiao-Feng Wang Zhongqiang Wang Haruhiko Ojima Ziruo Hong Wenjing Tian Junji Kido 《Organic Electronics》2013,14(9):2210-2215
We demonstrated the use of an asymmetrical donor–acceptor-type indoline dye—D131, developed for dye-sensitized solar cells, as an electron donor and fullerene C70 as an electron acceptor for thermal co-evaporated bulk-heterojunction organic solar cells (OSCs). In spite of the presence of intermolecular hydrogen bonds among D131 molecules, they can be thermally evaporated in high vacuum at a relatively low temperature of 220 °C. The blend ratio and thickness of the active layer of D131/C70 blend films in OSCs were optimized to achieve a maximum power-conversion efficiency of 4.5% with a short-circuit current of 9.1 mA cm?2, an open-circuit voltage of 0.89 V, and a fill factor of 0.56 under AM 1.5G solar illumination (100 mW cm?2), which is the best value reported so far for OSCs based on indoline-based donor materials. 相似文献