全文获取类型
收费全文 | 6121篇 |
免费 | 424篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 88篇 |
综合类 | 11篇 |
化学工业 | 1748篇 |
金属工艺 | 189篇 |
机械仪表 | 156篇 |
建筑科学 | 186篇 |
矿业工程 | 27篇 |
能源动力 | 247篇 |
轻工业 | 1011篇 |
水利工程 | 35篇 |
石油天然气 | 22篇 |
武器工业 | 1篇 |
无线电 | 301篇 |
一般工业技术 | 1279篇 |
冶金工业 | 263篇 |
原子能技术 | 19篇 |
自动化技术 | 974篇 |
出版年
2023年 | 60篇 |
2022年 | 189篇 |
2021年 | 347篇 |
2020年 | 195篇 |
2019年 | 231篇 |
2018年 | 337篇 |
2017年 | 314篇 |
2016年 | 373篇 |
2015年 | 291篇 |
2014年 | 389篇 |
2013年 | 604篇 |
2012年 | 368篇 |
2011年 | 341篇 |
2010年 | 293篇 |
2009年 | 322篇 |
2008年 | 273篇 |
2007年 | 202篇 |
2006年 | 150篇 |
2005年 | 96篇 |
2004年 | 106篇 |
2003年 | 97篇 |
2002年 | 80篇 |
2001年 | 41篇 |
2000年 | 53篇 |
1999年 | 41篇 |
1998年 | 62篇 |
1997年 | 64篇 |
1996年 | 27篇 |
1995年 | 42篇 |
1994年 | 32篇 |
1993年 | 25篇 |
1992年 | 16篇 |
1991年 | 18篇 |
1990年 | 27篇 |
1989年 | 19篇 |
1988年 | 15篇 |
1987年 | 19篇 |
1986年 | 16篇 |
1985年 | 31篇 |
1984年 | 36篇 |
1983年 | 43篇 |
1982年 | 38篇 |
1981年 | 29篇 |
1980年 | 31篇 |
1979年 | 25篇 |
1978年 | 11篇 |
1977年 | 23篇 |
1976年 | 31篇 |
1975年 | 13篇 |
1973年 | 15篇 |
排序方式: 共有6557条查询结果,搜索用时 15 毫秒
61.
62.
In this paper a discrete approach to analog modeling is presented. It is a functional-level, piecewise-linear (PWL) technique implemented in the VHDL environment. Since the models are based on some explicit formulas, fully behavioral architectural bodies have been proposed for them. Their most distinguishing features are discussed in detail. The models of practical circuits are illustrated with simulation results. 相似文献
63.
In recent years there has been a fast grow of various electronic services.Each service requires specif-ic credentials for authenticating and authorizing user ac-cess or specific subset of user's personal information for transactions the service offers.Such a situation causes problems with remembering multiple,service-specific authentication data,with controlling user's personal data spread across different services-problems with managing user's identities.This paper is an overview on Identity Management(IdM... 相似文献
64.
Detection of Carbon Dioxide in Air Using Difference-Frequency Generation Based Infrared Spectrometer
Weidong Chen Gaël Mouret Jean Burie Daniel Boucher 《Journal of Infrared, Millimeter and Terahertz Waves》1998,19(3):409-417
Spectroscopic detection of carbon dioxide (CO2) in ambient air was performed using a continuous-wave mid-infrared spectrometer based on difference-frequency generation in an AgGaS2 crystal. Significant improvement in nonlinear optical frequency conversion efficiency was achieved by Gaussian beam optical design consideration. CO2 concentration was determined from direct-absorption spectral measurement. 相似文献
65.
66.
Yasin Kanbur Mihai Irimia-Vladu Eric D. Głowacki Gundula Voss Melanie Baumgartner Günther Schwabegger Lucia Leonat Mujeeb Ullah Hizir Sarica Sule Erten-Ela Reinhard Schwödiauer Helmut Sitter Zuhal Küçükyavuz Siegfried Bauer Niyazi Serdar Sariciftci 《Organic Electronics》2012,13(5):919-924
We report on the fabrication and performance of vacuum-processed organic field effect transistors utilizing evaporated low-density polyethylene (LD-PE) as a dielectric layer. With C60 as the organic semiconductor, we demonstrate low operating voltage transistors with field effect mobilities in excess of 4 cm2/Vs. Devices with pentacene showed a mobility of 0.16 cm2/Vs. Devices using tyrian Purple as semiconductor show low-voltage ambipolar operation with equal electron and hole mobilities of ~0.3 cm2/Vs. These devices demonstrate low hysteresis and operational stability over at least several months. Grazing-angle infrared spectroscopy of evaporated thin films shows that the structure of the polyethylene is similar to solution-cast films. We report also on the morphological and dielectric properties of these films. Our experiments demonstrate that polyethylene is a stable dielectric supporting both hole and electron channels. 相似文献
67.
Wireless Personal Communications - For robust monitoring, control and proper energy management of renewable energy sources (RES), wireless sensing networks (WSNs) are proved to be a vital solution.... 相似文献
68.
Lopes da Silva FH Blanes W Kalitzin SN Parra J Suffczynski P Velis DN 《IEEE transactions on bio-medical engineering》2003,50(5):540-548
In this overview, we consider epilepsies as dynamical diseases of brain systems since they are manifestations of the property of neuronal networks to display multistable dynamics. To illustrate this concept we may assume that at least two states of the epileptic brain are possible: the interictal state characterized by a normal, apparently random, steady-state electroencephalography (EEG) ongoing activity, and the ictal state, that is characterized by paroxysmal occurrence of synchronous oscillations and is generally called, in neurology, a seizure. The transition between these two states can either occur: 1) as a continuous sequence of phases, like in some cases of mesial temporal lobe epilepsy (MTLE); or 2) as a sudden leap, like in most cases of absence seizures. In the mathematical terminology of nonlinear systems, we can say that in the first case the system's attractor gradually deforms from an interictal to an ictal attractor. The causes for such a deformation can be either endogenous or external. In this type of ictal transition, the seizure possibly may be anticipated in its early, preclinical phases. In the second case, where a sharp critical transition takes place, we can assume that the system has at least two simultaneous interictal and ictal attractors all the time. To which attractor the trajectories converge, depends on the initial conditions and the system's parameters. An essential question in this scenario is how the transition between the normal ongoing and the seizure activity takes place. Such a transition can occur either due to the influence of external or endogenous factors or due to a random perturbation and, thus, it will be unpredictable. These dynamical changes may not be detectable from the analysis of the ongoing EEG, but they may be observable only by measuring the system's response to externally administered stimuli. In the special cases of reflex epilepsy, the leap between the normal ongoing attractor and the ictal attractor is caused by a well-defined external perturbation. Examples from these different scenarios are presented and discussed. 相似文献
69.
Multidimensional Systems and Signal Processing - The paper is devoted to the development of the octonion Fourier transform (OFT) theory initiated in 2011 in articles by Hahn and Snopek. It is also... 相似文献
70.
Assembly and Characterizations of Bifunctional Fluorescent and Magnetic Microneedles With One Decade Length Tunability 下载免费PDF全文
Jean‐Baptiste Lugagne Gwennhaël Brackx Emek Seyrek Sophie Nowak Yann Sivry Leticia Vitorazi Jean‐François Berret Pascal Hersen Gaëlle Charron 《Advanced functional materials》2017,27(31)
This report presents the fabrication of bifunctional magnetic and fluorescent microneedles (µNDs) made of a ternary mixture of magnetic nanoparticles (NPs), quantum dots (QDs), and polyelectrolyte. The assembly relies on the electrostatic complexation of negatively charged NPs with positively charged polymer strands and is controlled by the charge ratio between the nanoparticle building blocks and the polymer mortar. The resulting 1D objects can be actuated using an external magnetic field and can be imaged using fluorescence microscopy, thanks to the fluorescent and superparamagnetic properties inherited from their NP constituents. Using a combination of core and surface characterizations and a state‐of‐the‐art image analysis algorithm, the dependence of the brightness and length on the ternary composition is thoroughly investigated. In particular, statistics on hundreds of µNDs with a range of compositions show that the µNDs have a log‐lormal length distribution and that their mean length can be robustly tuned in the 5–50 µm range to match the relevant length scales of various applications in micromixing, bioassays or biomechanics. 相似文献