全文获取类型
收费全文 | 673篇 |
免费 | 54篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 7篇 |
综合类 | 1篇 |
化学工业 | 255篇 |
金属工艺 | 50篇 |
机械仪表 | 26篇 |
建筑科学 | 16篇 |
能源动力 | 52篇 |
轻工业 | 69篇 |
水利工程 | 7篇 |
石油天然气 | 3篇 |
无线电 | 37篇 |
一般工业技术 | 113篇 |
冶金工业 | 27篇 |
原子能技术 | 3篇 |
自动化技术 | 62篇 |
出版年
2024年 | 1篇 |
2023年 | 12篇 |
2022年 | 31篇 |
2021年 | 42篇 |
2020年 | 26篇 |
2019年 | 31篇 |
2018年 | 32篇 |
2017年 | 42篇 |
2016年 | 37篇 |
2015年 | 23篇 |
2014年 | 20篇 |
2013年 | 59篇 |
2012年 | 34篇 |
2011年 | 51篇 |
2010年 | 32篇 |
2009年 | 37篇 |
2008年 | 39篇 |
2007年 | 32篇 |
2006年 | 23篇 |
2005年 | 16篇 |
2004年 | 10篇 |
2003年 | 4篇 |
2002年 | 11篇 |
2001年 | 6篇 |
2000年 | 1篇 |
1999年 | 8篇 |
1998年 | 12篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 3篇 |
1992年 | 8篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1980年 | 1篇 |
1978年 | 3篇 |
排序方式: 共有728条查询结果,搜索用时 15 毫秒
61.
Answering queries in disjunctive logic programming requires the use of ancestry-resolution. The resulting complication makes it difficult to implement a Prolog-type query answering procedure for disjunctive logic programs. However, SLO-resolution provides a mechanism which is similar to SLD-resolution and hence offers a solution to this problem. The Warren Abstract Machine has been a very effective model for implementing Prolog. In this paper, we extend the WAM model of Prolog and adapt it for DISLOG — a language for disjunctive logic programming. We describe the extensions and additional instructions needed to make WAM viable for modeling and executing DISLOG. The extension is made in such a way that the original architecture is not disturbed and a Prolog program will execute as efficiently as it does in the original WAM.This work was done while the author was at the University of Kentucky. 相似文献
62.
Yusuf Yagci Yusuf Z. Menceloglu Bahattin M. Baysal Atilla Gungor 《Polymer Bulletin》1989,21(3):259-263
Summary Acrylonitrile was polymerized by an insertion process on being added to solutions containing the adduct of the reaction of tetrakis(dimethylamino) titanium (T4) and azobisisobutyronitrile (AIBN). The obtained azo-linked polyacrylonitrile has appropriate initiating functionality for a subsequent vinyl polymerization. 相似文献
63.
Sulfur release and capture behavior of lignites with highly combustible sulfur-contents were investigated by extending a previously-developed comprehensive model to incorporate sulfur retention. The predictive performance of the model was tested by comparing the model predictions with on-line concentration measurements of O2, CO2, CO and SO2. Favorable comparisons are obtained between the predicted and measured concentrations of gaseous species along the combustor. Results show that freeboard sulfur-capture is enhanced significantly with recycling of elutriated sorbent particles as the sulfur release to the freeboard is significant for fuels rich in combustible sulfur. 相似文献
64.
Effects of UV stabilised polyethylene (UV+PE), IR absorbers polyethylene (IR+PE), double layers of polyethylene (D-Poly) and single layer of polyethylene (PE), as greenhouse covers, on aubergine growth, productivity and energy requirement were investigated in a late autumn season (2001). The late and final yields of plants grown in D-Poly houses were higher than those grown in UV+PE, IR+PE and PE. Light transmission was the highest in PE, intermediate in UV+PE and IR+PE, and the lowest in D-Poly houses. Relative humidity was the highest in D-Poly, intermediate in IR+PE and UV+PE, and the lowest in PE houses. The plants in D-Poly houses grew and developed faster (more leaves and flowers) than those in IR+PE, UV+PE and PE houses. Plant growth and development in UV+PE and IR+PE houses was similar. Economic analyses showed that aubergine production was economically viable in D-Poly, UV+PE and IR+PE houses. For aubergine production in climatic conditions similar to Black Sea Region, the D-Poly greenhouse is strongly recommended, because there was a higher productivity and a lower heating requirement in comparison to UV+PE, IR+PE and PE houses. 相似文献
65.
An organic-inorganic heterojunction based on a BODIPY dyes has been produced by forming dye thin film on n-Si. The electrical parameters of the structure have been investigated by current-voltage (I-V) and capacitance-voltage (C-V) measurements. The ideality factor, the barrier height and the series resistance values of the diode have been calculated as 2.43, 0.84 eV, and about 1.3 kΩ, respectively. The diode behaves as a non-ideal diode because of the series resistance and interface layer. The barrier height value obtained from I-V measurement has been compared with one from C-V measurement. Moreover, it has been seen that the diode is highly sensitive to the light and the reverse bias current increases about 1 × 104 times at −1 V under 100 mW/cm2 and AM1.5 illumination condition. The short photocurrent density (Jsc) and the open circuit voltage (Voc), the fill factor (FF) and power conversion efficiency (η) have been determined as 3.78 mA/cm2, 327 mV, 0.28 and 0.48 %, respectively. 相似文献
66.
67.
Virtual CNC system. Part II. High speed contouring application 总被引:4,自引:1,他引:3
Kaan Erkorkmaz Chi-Ho Yeung Yusuf Altintas 《International Journal of Machine Tools and Manufacture》2006,46(10):1124-1138
This paper presents a trajectory planning strategy for maintaining the tool positioning accuracy in high speed cornering applications. A 3D contour error estimation algorithm is presented for determining the geometric deviation from arbitrarily shaped toolpaths. Two spline fitting strategies are developed for smoothening sharp corners. The under-corner approach reduces the toolpath length, and therefore the cornering time. This technique yields successful results when used with a high bandwidth servo controller (such as sliding mode control), capable of accurately tracking the commanded toolpath. The over-corner approach is based on stretching out the sharp corner with a smooth curve, which counteracts the ‘undercut’ caused by the large phase lag in low bandwidth servo controllers (such as P–PI control). The cornering feedrate is adjusted in the Virtual CNC platform, developed in the first part of this article, to ensure that contour error violation does not occur. The achieved cornering accuracy is verified in experiments, which are in close agreement with predictions obtained with the Virtual CNC. 相似文献
68.
Synthesis, characterization and electrochromic properties of a conducting copolymer of pyrrole functionalized polystyrene with pyrrole 总被引:2,自引:0,他引:2
A well-defined polystyrene (PSt) based polymer containing at one end-chain 3,5-dibromobenzene moiety, prepared by atom transfer radical polymerization (ATRP), was modified in two reaction steps. First one constitutes a Suzuki coupling reaction between aromatic dibromine functional polymer and 3-aminophenylboronic acid, when a diamino-containing intermediate was obtained. The second step is a condensation reaction between the diamino functional polystyrene and 2-pyrrole aldehyde. Thus, a polymer containing a conjugated sequence having pyrollyl groups at the extremities was synthesized. The presence of oxidable pyrrole groups in the structure of the polymer permitted further electropolymerization. The structures of intermediate polymers were analyzed by spectral methods (1H NMR, FTIR). Electrochemical copolymerization of pyrrole functionalized polymer (PStPy) with pyrrole was carried out in acetonitrile (ACN)-tetrabutylammonium tetrafluoroborate (TBAFB) solvent electrolyte couple. Characterization of the resulting copolymer were performed via Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), spectroelectrochemical analysis, and kinetic study. Spectroelectrochemical analysis show that the copolymer of PStPy with Py has an electronic band gap (due to π-π* transition) of 2.4 eV at 393 nm, with a yellow color in the fully reduced form and a blue color in the fully oxidized form. Via kinetic studies, the optical contrast %ΔT was found to be 20% for P(PStPy-co-Py). Results showed that the time required to reach 95% of the ultimate T was 1.7 s for the P(PStPy-co-Py). 相似文献
69.
Redox polymerization of methylmethacrylate (MMA) using Ce(IV) with poly(oxyethylene) having azo and hydroxy functions was carried out to yield methylmethacrylate-ethylene glycol block copolymers with labile azo linkages in the main chain. These prepolymers were used to initiate the radical polymerization of styrene through the thermal decomposition of the azo group, resulting in the formation of multiblock copolymers. Successful blocking has been confirmed by fractional precipitation, a strong change in the molecular weight distribution and spectral measurements. 相似文献
70.
Mahshid?DehghanEmail author Nawal?Al Hamad AfzalHussein?Yusufali Fathimunissa?Nusrath Salim?Yusuf Anwar?T?Merchant 《Nutrition journal》2005,4(1):18