全文获取类型
收费全文 | 809篇 |
免费 | 60篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 3篇 |
综合类 | 4篇 |
化学工业 | 163篇 |
金属工艺 | 16篇 |
机械仪表 | 7篇 |
建筑科学 | 43篇 |
矿业工程 | 3篇 |
能源动力 | 20篇 |
轻工业 | 73篇 |
水利工程 | 4篇 |
武器工业 | 1篇 |
无线电 | 86篇 |
一般工业技术 | 167篇 |
冶金工业 | 75篇 |
原子能技术 | 9篇 |
自动化技术 | 197篇 |
出版年
2024年 | 4篇 |
2023年 | 15篇 |
2022年 | 18篇 |
2021年 | 27篇 |
2020年 | 20篇 |
2019年 | 34篇 |
2018年 | 33篇 |
2017年 | 21篇 |
2016年 | 42篇 |
2015年 | 33篇 |
2014年 | 41篇 |
2013年 | 47篇 |
2012年 | 47篇 |
2011年 | 70篇 |
2010年 | 43篇 |
2009年 | 43篇 |
2008年 | 55篇 |
2007年 | 45篇 |
2006年 | 43篇 |
2005年 | 22篇 |
2004年 | 18篇 |
2003年 | 13篇 |
2002年 | 25篇 |
2001年 | 9篇 |
2000年 | 8篇 |
1999年 | 9篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 1篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有871条查询结果,搜索用时 15 毫秒
21.
We extracted a collection of eye movement signals employed for almost two decades in clinical otoneurological tests at a balance laboratory. During those years we designed and programmed signal analysis methods to analyse their features in detail and to compute medically important attributes. In the present study, using such attributes and their results computed we classified test cases into groups of healthy subjects and patients with multilayer perceptron neural networks. Classification succeeded in total accuracies from 60% to 90% depending on the type of eye movements, which were saccades, nystagmus, sinusoidal movements and vestibulo-ocular reflex stimulated in two different ways; these are the chief eye movement tests applied in otoneurology. 相似文献
22.
Heikki Ailisto Lauri Pohjanheimo Pasi Välkkynen Esko Strömmer Timo Tuomisto Ilkka Korhonen 《Personal and Ubiquitous Computing》2006,10(6):333-344
The prevalent visions of ambient intelligence emphasise natural interaction between user and functions and services embedded in the environment or available through mobile devices. In these scenarios the physical and virtual worlds seamlessly gear into each other, making crossing the border between these worlds natural or even invisible to the user. The bottleneck in reaching these scenarios appear in the natural mapping between the physical objects and their virtual counterparts. The emergence of local connectivity in mobile devices opens possibilities for implementing novel user interface paradigms to enhance this mapping. We present physical selection paradigm for implementing an intuitive human technology interaction for mobile devices. In order to demonstrate the feasibility of the paradigm we implemented two experimental set-ups using commercially available smart phones with IrDA connectivity. The experiments involved selecting a website by physically pointing at its symbol and making a phone call by pointing at an icon representing the person to be called. In tentative user experiments the physical selection method was more time-efficient and it was perceived more positively by the users than a conventional method.
相似文献
Heikki AilistoEmail: |
23.
24.
The phrase business cycle is usually used for short term fluctuations in macroeconomic time series. In this paper we focus
on the estimation of business cycles in a bivariate manner by fitting two series simultaneously. The underlying model is thereby
nonparametric in that no functional form is prespecified but smoothness of the functions are assumed. The functions are then
estimated using penalized spline estimation. The bivariate approach will allow to compare business cycles, check and compare
phase lengths and visualize this in forms of loops in a bivariate way. Moreover, the focus is on separation of long and short
phase fluctuation, where only the latter is the classical business cycle while the first is better known as Friedman or Goodwin
cycle, respectively. Again, we use nonparametric models and fit the functional shape with penalized splines. For the separation
of long and short phase components we employ an Akaike criterion. 相似文献
25.
Kaupo Kukli Mikko Ritala Timo Sajavaara Timo Hnninen Markku Leskel 《Thin solid films》2006,500(1-2):322-329
Calcium oxide and calcium hafnium oxide thin films were grown by atomic layer deposition on borosilicate glass and silicon substrates in the temperature range of 205–300 °C. The calcium oxide films were grown from novel calcium cyclopentadienyl precursor and water. Calcium oxide films possessed refractive index 1.75–1.80. Calcium oxide films grown without Al2O3 capping layer occurred hygroscopic and converted to Ca(OH)2 after exposure to air. As-deposited CaO films were (200)-oriented. CaO covered with Al2O3 capping layers contained relatively low amounts of hydrogen and re-oriented into (111) direction upon annealing at 900 °C. In order to examine the application of CaO in high-permittivity dielectric layers, mixtures of Ca and Hf oxides were grown by alternate CaO and HfO2 growth cycles at 230 and 300 °C. HfCl4 was used as a hafnium precursor. When grown at 230 °C, the films were amorphous with equal amounts of Ca and Hf constituents (15 at.%). These films crystallized upon annealing at 750 °C, showing X-ray diffraction peaks characteristic of hafnium-rich phases such as Ca2Hf7O16 or Ca6Hf19O44. At 300 °C, the relative Ca content remained below 8 at.%. The crystallized phase well matched with rhombohedral Ca2Hf7O16. The dielectric films grown on Si(100) substrates possessed effective permittivity values in the range of 12.8–14.2. 相似文献
26.
Within the scope of a parameter study the influence of the mixture composition of different self-compacting concretes on the
fresh concrete properties was investigated. For this purpose the standard test methods as well as the fresh concrete rheometer
“BTRHEOM” were used. The concrete was modelled as a two-phase system, consisting of the fluid phase paste and the solid phase
aggregates. The consistency control parameters paste volume, mortar volume and the coarse aggregate volume could be transferred
into the model parameter thickness of excess paste. By means of this model parameter the characteristic values of the standard
test methods like slump flow test and V-funnel test as well as the fundamental rheological parameters yield stress and the
plastic viscosity could be described. A comparative study showed that the yield stress and the plastic viscosity of self-compacting
concrete can be estimated based on the characteristic values of the slump flow test. 相似文献
27.
28.
This work studies the effects of the drain pn capacitance grading coefficient, duty cycle and supply modulation on the operation
of class E amplifier. The class E operation analysis with a combination of nonlinear and linear output capacitances is revisited
and duty cycle is added to the equations to allow further investigations for optimum class E circuit tuning. The presented
analysis method can be used for synthesis as well, where necessary load components are calculated for a transistor with a
specific grading coefficient both in the output capacitance and in the nonlinear feedback capacitance. Further, the grading
coefficient of the nonlinear output capacitance is varied in the paper while investigating the changes in normalized peak
voltages and harmonics. Drain efficiency, supply-to-amplitude modulation (V
dd
/AM) and supply-to-phase modulation (V
dd
/PM) are studied. It is shown that by varying the device duty cycle, one can scale the optimum load and the level of peak
voltages over the switching device. Also, the choice of grading coefficient affects the drain efficiency, V
dd
/AM and V
dd
/PM behaviour of the class E amplifier. Last, a case study about increasing the efficiency of a class E amplifier with hyperabrupt
output junction capacitance is shown. 相似文献
29.
Yoonsang Park Hossein Daneshpajooh Timo Scholehwar Eberhard Hennig Kenji Uchino 《Journal of the European Ceramic Society》2021,41(12):5900-5908
The IEEE standard to determine physical parameters of piezoceramics has been utilized for decades by many researchers, yet it omits presence of important loss factors and possesses serious deficits that restrict accurate parameter determination. To resolve these issues, the partial electrode (PE) method was previously proposed, though the focus has been merely made on development of the method itself. In this study, we provide method simplification and more detailed analysis. The omission of unnecessary samples greatly boosts experiment and analysis process. To prove that the PE method is reliable, possible causes of errors were investigated; it is shown that they were either negligibly small or can be resolved with proper calibration. Furthermore, Applicability of PE method to various types of piezoceramic materials and compatibility with impedance analyzers are shown. Finally, PE method is proved to be reliable and can be alternative to IEEE Standard on Piezoelectricity. 相似文献
30.