全文获取类型
收费全文 | 6978篇 |
免费 | 338篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 77篇 |
综合类 | 10篇 |
化学工业 | 1345篇 |
金属工艺 | 110篇 |
机械仪表 | 140篇 |
建筑科学 | 263篇 |
矿业工程 | 19篇 |
能源动力 | 109篇 |
轻工业 | 656篇 |
水利工程 | 47篇 |
石油天然气 | 5篇 |
无线电 | 592篇 |
一般工业技术 | 1180篇 |
冶金工业 | 1692篇 |
原子能技术 | 38篇 |
自动化技术 | 1041篇 |
出版年
2023年 | 42篇 |
2022年 | 48篇 |
2021年 | 121篇 |
2020年 | 97篇 |
2019年 | 90篇 |
2018年 | 199篇 |
2017年 | 201篇 |
2016年 | 206篇 |
2015年 | 170篇 |
2014年 | 195篇 |
2013年 | 443篇 |
2012年 | 383篇 |
2011年 | 387篇 |
2010年 | 287篇 |
2009年 | 267篇 |
2008年 | 341篇 |
2007年 | 262篇 |
2006年 | 250篇 |
2005年 | 229篇 |
2004年 | 174篇 |
2003年 | 171篇 |
2002年 | 137篇 |
2001年 | 99篇 |
2000年 | 115篇 |
1999年 | 114篇 |
1998年 | 534篇 |
1997年 | 303篇 |
1996年 | 221篇 |
1995年 | 126篇 |
1994年 | 120篇 |
1993年 | 126篇 |
1992年 | 41篇 |
1991年 | 53篇 |
1990年 | 33篇 |
1989年 | 43篇 |
1988年 | 46篇 |
1987年 | 42篇 |
1986年 | 40篇 |
1985年 | 48篇 |
1984年 | 35篇 |
1983年 | 35篇 |
1982年 | 43篇 |
1981年 | 49篇 |
1980年 | 30篇 |
1979年 | 29篇 |
1978年 | 29篇 |
1977年 | 54篇 |
1976年 | 60篇 |
1975年 | 28篇 |
1973年 | 24篇 |
排序方式: 共有7324条查询结果,搜索用时 15 毫秒
1.
2.
In this paper, a new inverse identification method of constitutive parameters is developed from full kinematic and thermal field measurements. It consists in reconstructing the heat source field from two different approaches by using the heat diffusion equation. The first one requires the temperature field measurement and the value of the thermophysical parameters. The second one is based on the kinematic field measurement and the choice of a thermo-hyperelastic model that contains the parameters to be identified. The identification is carried out at the local scale, ie, at any point of the heat source field, without using the boundary conditions. In the present work, the method is applied to the challenging case of hyperelasticity from a heterogeneous test. Due to large deformations undergone by the rubber specimen tested, a motion compensation technique is developed to plot the kinematic and the thermal fields at the same points before reconstructing the heterogeneous heat source field. In the present case, the constitutive parameter of the Neo-Hookean model has been identified, and its distribution has been characterized with respect to the strain state at the surface of a cross-shaped specimen. 相似文献
3.
4.
Laura Menini Corrado Possieri Antonio Tornambè 《International Journal of Adaptive Control and Signal Processing》2015,29(12):1578-1590
The main goal of this paper is to design a compensator able to restore the nominal behavior of a planar system, which is rendered chaotic by an unmeasurable sinusoidal disturbance input. To reach such a goal, some instruments, taken from algebraic geometry, are used to estimate the unmeasurable disturbance from the time derivatives of the output of the system and of the control input. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
5.
Previous experimental results indicate that the humidification conditions at the anode have an impact on the liquid water distribution in the cathode gas diffusion layer. Numerical simulations are developed to reproduce and analyze this effect. Results consistent with the experimental results are first obtained by playing with the partition coefficients of an advanced pore network model computing the liquid water formation and transfer in the cathode gas diffusion layer (GDL) for a large range of operating conditions. Then, a model for the full anode – cathode assembly is developed by combining the pore network model of the cathode GDL and a 1D model describing the heat and water transfer in the various components of the anode-cathode assembly. This enables one to generalize the dry – wet regime diagram introduced in a previous work by incorporating the effect of the humidity condition at the anode. 相似文献
6.
Carbon supported bimetallic Ru‐Co catalysts for H2 production through NaBH4 and NH3BH3 hydrolysis
下载免费PDF全文
![点击此处可从《国际能源研究杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This work investigates the effect of the addition of small amounts of Ru (0.5‐1 wt%) to carbon supported Co (10 wt%) catalysts towards both NaBH4 and NH3BH3 hydrolysis for H2 production. In the sodium borohydride hydrolysis, the activity of Ru‐Co/carbon catalysts was sensibly higher than the sum of the activities of corresponding monometallic samples, whereas for the ammonia borane hydrolysis, the positive effect of Ru‐Co systems with regard to catalytic activity was less evident. The performances of Ru‐Co bimetallic catalysts correlated with the occurrence of an interaction between Ru and Co species resulting in the formation of smaller ruthenium and cobalt oxide particles with a more homogeneous dispersion on the carbon support. It was proposed that Ru°, formed during the reduction step of the Ru‐Co catalysts, favors the H2 activation, thus enhancing the reduction degree of the cobalt precursor and the number of Co nucleation centers. A subsequent reduction of cobalt and ruthenium species also occurs in the hydride reaction medium, and therefore the state of the catalyst before the catalytic experiment determines the state of the active phase formed in situ. The different relative reactivity of the Ru and Co active species towards the two investigated reactions accounted for the different behavior towards NaBH4 and NH3BH3 hydrolysis. 相似文献
7.
Graded evolution of anisotropic microstructure during sintering from crystal-oriented powder compact
Shoko Baba Alexandre Maître Nicolas Pradeilles Guy Antou Nobuo Saito Satoshi Tanaka 《International Journal of Applied Ceramic Technology》2020,17(2):677-684
Anisotropic sintering, including shrinkage and grain growth, was examined for c-axis-oriented (Sr,Ca)2NaNb5O15 (SCNN) ceramics, which were prepared by colloidal processing under a magnetic field. In the c-axis-oriented SCNN powder compact, shrinkage and grain growth along the c-axis were higher than those along the a-axis. The anisotropic microstructural development was clearly associated with anisotropic sintering shrinkage. X-ray diffraction, scanning electron microscopy, and energy back scattering diffraction showed that the grain growth of oriented particles by including random grains contribute to the development of the oriented microstructure. Finally, the highly crystal-oriented SCNN ceramics with a densified microstructure were obtained through anisotropic sintering. These results clearly showed the potential to develop a well-defined anisotropic microstructure during sintering by designing and controlling the particle packing structure in a powder compact. 相似文献
8.
Jean-Fran?ois Blais Nathalie Meunier Guy Mercier Patrick Drogui Rajeshwar Dayal Tyagi 《Canadian Metallurgical Quarterly》2004,130(5):516-525
This research is related to a preindustrial pilot scale study of the performance of the simultaneous sewage sludge digestion and metal leaching (SSDML) process for decontamination and stabilization of sewage sludge. Ten batch tests were carried out in two 4?m3 bioreactors under various conditions of operation. Results indicated that the addition of 1.0 to 1.5?g?S0/L, which is the equivalent of approximately 30 to 50?kg?S0 per tons dry sludge, is sufficient to obtain conditions of acidity (pH<2.5) and oxido-reduction potential greater than 500 mV necessary for an effective solubilization of toxic metals. The final average of metal solubilization in the output sludge during the SSDML process varied in the following ranges: 25–78% Cd, 9–32% Cr, 48–100% Cu, 77–99% Mn, 15–53% Ni, 12–47% Pb, and 66–100% Zn. The N, P, and K contents were also preserved in the decontaminated sludge. Moreover, the use of low concentrations of elemental sulfur makes it possible to obtain decontaminated sludge with a low total sulfur content (1.4–1.5% S) compatible with agricultural use. The suspended solids removal calculated for the SSDML process was slightly lower, (2.5±0.4)% volatile suspended solids per day, than those reached using standard aerobic digestion. Finally, the SSDML process was found to be effective in removing bad odors and in the destruction (99–100%) of indicator bacteria. 相似文献
9.
10.
A Newman-Tancredi V Audinot C Chaput L Verrièle MJ Millan 《Canadian Metallurgical Quarterly》1997,282(1):181-191
Great progress has been made in the last 10 years in the understanding of the various types of viral hepatitis, and new viruses, concepts, therapies, preventive measures, and control strategies have been recognized. Even more agents, vaccines, and drugs will be discovered or developed in the future, and pediatricians increasingly will be expected to provide guidance to patients and to the community on the importance and use of these new tools. 相似文献