全文获取类型
收费全文 | 2259篇 |
免费 | 63篇 |
专业分类
电工技术 | 7篇 |
综合类 | 1篇 |
化学工业 | 193篇 |
金属工艺 | 10篇 |
机械仪表 | 11篇 |
建筑科学 | 13篇 |
能源动力 | 30篇 |
轻工业 | 132篇 |
水利工程 | 2篇 |
石油天然气 | 10篇 |
无线电 | 50篇 |
一般工业技术 | 103篇 |
冶金工业 | 1628篇 |
原子能技术 | 3篇 |
自动化技术 | 129篇 |
出版年
2023年 | 6篇 |
2022年 | 14篇 |
2021年 | 22篇 |
2020年 | 20篇 |
2019年 | 28篇 |
2018年 | 24篇 |
2017年 | 26篇 |
2016年 | 26篇 |
2015年 | 26篇 |
2014年 | 25篇 |
2013年 | 47篇 |
2012年 | 39篇 |
2011年 | 55篇 |
2010年 | 29篇 |
2009年 | 33篇 |
2008年 | 33篇 |
2007年 | 39篇 |
2006年 | 27篇 |
2005年 | 18篇 |
2004年 | 19篇 |
2003年 | 18篇 |
2002年 | 22篇 |
2001年 | 18篇 |
2000年 | 16篇 |
1999年 | 47篇 |
1998年 | 492篇 |
1997年 | 297篇 |
1996年 | 191篇 |
1995年 | 117篇 |
1994年 | 78篇 |
1993年 | 120篇 |
1992年 | 14篇 |
1991年 | 19篇 |
1990年 | 14篇 |
1989年 | 22篇 |
1988年 | 31篇 |
1987年 | 24篇 |
1986年 | 31篇 |
1985年 | 19篇 |
1982年 | 10篇 |
1981年 | 11篇 |
1980年 | 14篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 40篇 |
1976年 | 87篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1966年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有2322条查询结果,搜索用时 15 毫秒
121.
This papers presents a sliding mode controller based on a first-order-plus-dead-time model of the process for controlling open-loop unstable systems. The proposed controller has a simple and fixed structure with a set of tuning equations as a function of the desired performance. Both linear and nonlinear models were used to study the controller performance by computer simulations. 相似文献
122.
123.
124.
125.
María?Luz?Pérez-Rea Fernando?Rojas Victor?M.?CastanoEmail author 《Materials Research Innovations》2003,7(6):341-352
One of the most important structural parameters involved in the characterization of the void space of soils is the pore size distribution. In this work, a nitrogen adsorption method is presented as an alternative to determine the mesopore contribution of slit-shaped pores to the abovementioned parameter in montmorillonite-containing soils. The mesopore size structural parameter obtained via this sorption method is related to montmorillonite d001 interlayer distances proceeding from either X-ray or electron diffraction analysis, if only by assuming during sorption analysis that mesopores resident inside clay grains adopt slit-shaped geometries. Mineralogical analysis and determination of some important geotechnical properties of these montmorillonite-containing soils complement the preceding sorption and structural studies. 相似文献
126.
A. Guillén I. Rojas J. González H. Pomares L. J. Herrera 《Neural Processing Letters》2000,12(3):307-308
Volume Contents
Contents, Volume 12, 2000 相似文献127.
Cristian R. Rojas Author Vitae Author Vitae Graham C. Goodwin Author Vitae Author Vitae 《Automatica》2007,43(6):993-1008
This paper develops the idea of min-max robust experiment design for dynamic system identification. The idea of min-max experiment design has been explored in the statistics literature. However, the technique is virtually unknown by the engineering community and, accordingly, there has been little prior work on examining its properties when applied to dynamic system identification. This paper initiates an exploration of these ideas. The paper considers linear systems with energy (or power) bounded inputs. We assume that the parameters lie in a given compact set and optimise the worst case over this set. We also provide a detailed analysis of the solution for an illustrative one parameter example and propose a convex optimisation algorithm that can be applied more generally to a discretised approximation to the design problem. We also examine the role played by different design criteria and present a simulation example illustrating the merits of the proposed approach. 相似文献
128.
K. Bobzin F. Ernst R. Nickel J. Rösing Dipl.‐Ing. Y. Rojas 《Materialwissenschaft und Werkstofftechnik》2007,38(7):533-537
Wear Protection of Titanium using Surface Brazing Titanium and titanium alloys possess high specific strengths up to a temperature of about 600 °C in addition to an extraordinary corrosion resistance [1]. The low wear resistance constitutes a crucial impediment for a much broader use. Titanium materials are especially susceptible to friction fatigue and erosion. Coating techniques have to be developed in order to counteract this technical constraint. Surface brazing presents a promising approach. Hard metals mixed with brazing filler metals on a silver and titanium basis were brazed in a vacuum furnace and subsequently characterized. Wear resistance was quantified and optimized using ball on disc measurements. 相似文献
129.
R. Gutiérrez Fuentes J. F. Sánchez Ramírez J. L. Jiménez Pérez J. A. Pescador Rojas E. Ramón-Gallegos A. Cruz-Orea 《International Journal of Thermophysics》2007,28(3):1048-1055
Nanoparticles appear to be ideally suited for applications in targeted thermal effects in medical therapies and photothermally
activated drug delivery; all depend critically on the thermal transport between the nanoparticles and the surrounding liquid.
In this work thermal lens spectroscopy (TLS) was used to determine the thermal diffusivity of protoporphyrin IX (PpIX) solutions
mixed with gold metallic nanoparticles. PpIX disodium salt (DS) was used in a HCl solution at 25%. Fluids containing gold
(Au) nanoparticles at different concentrations were prepared and added to the PpIX solutions. For each solution, UV–Vis spectroscopy
was used to obtain the optical absorption spectrum, and transmission electron microscopy (TEM) was used to obtain the gold
nanoparticle size. From the TLS signal intensity, it was possible to determine the characteristic time constant of the transient
thermal by fitting the theoretical expression to the experimental data. From this characteristic time, the thermal diffusivity
was obtained for each solution. The results show that the thermal diffusivity of PpIX mixed with gold nanoparticles increases
with an increase of the nanoparticle metallic concentration. 相似文献
130.
O. Rojas F. Rembold J. Delincé O. Léo 《International journal of remote sensing》2013,34(12):3249-3265
Rainfall estimates derived from satellite imagery and global circulation models are frequently used for vegetation monitoring in many areas of Africa because of the shortage of observed rainfall data and the sparse network of meteorological stations. At the same time, this scarce density of rain gauge stations makes the calibration and validation of the modelled data nearly impossible. In this study we propose a methodology for a rapid quality assessment of rainfall estimates that is based on the well-known relationship between rainfall and the Normalized Difference Vegetation Index (NDVI). The results clearly confirm that the NDVI can be used as an indicator of the quality of rainfall estimates at the continental/regional scale and allow a rapid detection of major over- and underestimations of the two rainfall datasets examined for the African continent. 相似文献