全文获取类型
收费全文 | 427篇 |
免费 | 22篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 6篇 |
综合类 | 1篇 |
化学工业 | 93篇 |
金属工艺 | 15篇 |
机械仪表 | 12篇 |
建筑科学 | 25篇 |
矿业工程 | 1篇 |
能源动力 | 48篇 |
轻工业 | 12篇 |
水利工程 | 2篇 |
石油天然气 | 5篇 |
无线电 | 60篇 |
一般工业技术 | 82篇 |
冶金工业 | 25篇 |
原子能技术 | 4篇 |
自动化技术 | 60篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 8篇 |
2020年 | 14篇 |
2019年 | 12篇 |
2018年 | 15篇 |
2017年 | 11篇 |
2016年 | 15篇 |
2015年 | 17篇 |
2014年 | 18篇 |
2013年 | 39篇 |
2012年 | 31篇 |
2011年 | 28篇 |
2010年 | 34篇 |
2009年 | 43篇 |
2008年 | 21篇 |
2007年 | 30篇 |
2006年 | 17篇 |
2005年 | 14篇 |
2004年 | 11篇 |
2003年 | 12篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 1篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有451条查询结果,搜索用时 15 毫秒
71.
72.
Oktar FN Agathopoulos S Ozyegin LS Gunduz O Demirkol N Bozkurt Y Salman S 《Journal of materials science. Materials in medicine》2007,18(11):2137-2143
Biologically derived hydroxyapatite from calcinated (at 850 °C) bovine bones (BHA) was doped with 5 wt% and 10 wt% of SiO2, MgO, Al2O3 and ZrO2 (stabilized with 8% Y2O3). The aim was to improve the sintering ability and the mechanical properties (compression strength and hardness) of the resultant
BHA-composites. Cylindrical samples were sintered at several temperatures between 1,000 and 1,300 °C for 4 h in air. The experimental
results showed that sintering generally occurs at 1,200 °C. The BHA–MgO composites showed the best sintering performance.
In the BHA–SiO2 composites, extended formation of glassy phase occurred at 1,300 °C, resulting in structural degradation of the resultant
samples. No sound reinforcement was achieved in the case of doping with Al2O3 and zirconia probably due to the big gap between the optimum sintering temperatures of BHA and these two oxides. 相似文献
73.
Conjugated polymer-based organic solar cells 总被引:3,自引:0,他引:3
74.
Magnetic poly(styrene) particles including active groups were prepared for enzyme immobilization without any activation process. Glucoamylase, which is widely used in industry, was immobilized onto these particles. The effects of pH, buffer concentration, and temperature on immobilization were investigated; moreover, the effect of immobilization temperature on immobilized glucoamylase activity was determined for the hydrolysis of maltose. The acetate buffer with the concentration of 6 × 10−4 M at pH 4 and 20–30°C was found as the most suitable medium for the immobilization of the glucoamylase. The amount of bound protein is 8 mg/g particle with the immobilization yield of 70%. The maximum activity obtained with immobilized glucoamylase is approximately 70% of the free one. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 69–73, 1999 相似文献
75.
76.
77.
Research and development towards high efficiency plastic solar cells have been accelerating in recent years. Polymer-based bulk heterojunction solar cells are offering an attractive and inexpensive concept for large scale production by solution processing as well as advantageous flexible and aesthetic form factors. The thin film nano-morphology of bulk-heterojunction solar cells has been shown to dramatically influence the photovoltaic performance of the devices. This article reviews the different methods used to control the film nano-morphology of bulk-heterojunction solar cells focussing on the chemical additives during solution processing. All power conversion efficiency limiting mechanisms of bulk-heterojunction solar cells are discussed in detail. It is shown, how the formation of optimal percolation pathways between donor and acceptor influences the photovoltaic device performance. It is explained how the film nano-morphology relates to light absorption, free charge carrier generation as well as charge transport to the electrodes. 相似文献
78.
This paper presents a unique structural reliability estimation method incorporating structural parameter identification results based on the seismic response measurement. In the shaking table test, a three-bent concrete bridge model was shaken to different damage levels by a sequence of earthquake motions with increasing intensities. Structural parameters, stiffness and damping values of the bridge were identified under damaging seismic events based on the seismic response measurement. A methodology was developed to understand the importance of structural parameter identification in the reliability estimation. Along this line, a set of structural parameters were generated based on the Monte Carlo simulation. Each of them was assigned to the base bridge model. Then, every bridge model was analyzed using nonlinear time history analyses to obtain damage level at the specific locations. Last, reliability estimation was performed for bridges modeled with two sets of structural parameters. The first one was obtained by the nonlinear time history analysis with the Monte Carlo simulated parameters which is called nonupdated structural parameters. The second one was obtained by updating the first set in Bayesian sense based on the vibration-based identification results which is called updated structural parameters. In the scope of this paper, it was shown that residual reliability of the system estimated using the updated structural parameters is lower than the one estimated using the nonupdated structural parameters. 相似文献
79.
This study presents numerical analyses of transient temperature and thermally induced stress distributions in a stationary hollow steel disk partially heated by a moving uniform heat source from its outer surface under stagnant ambient conditions. The moving heat source applied on a certain angular segment of the processed surface rotates with a constant angular speed (ω). The peak levels of the temperature gradients and the thermal stress ratios at the heated segments do not rise very much after 2–3 cycles. When the value of ω is increased, the maximum effective thermal stress ratio can be decreased in a considerable amount. 相似文献
80.
Oil-based macroinitiator (MI) obtained from sunflower oil was styrenated using reversible addition–fragmentation chain transfer polymerization (RAFT) in the presence of phenacyl morpholine dithiocarbamate (PMDC) as chain transfer agent. The solvent effect and effect of the molar ratio of the transfer agent, PMDC, on polydispersity and molecular weight of the polymers were investigated. The obtained results showed that, 1,4-dioxane is a better solvent and 1/4 molar ratio of [MI]/[PMDC] provides relatively low polydispersities. No homopolystyrene was detected under these conditions, indicating the efficiency of PMDC in the chain transfer process. Livingness of the polymerization process was confirmed by chain extension with styrene using the preformed polymer as macrotransfer agent. The film properties of styrenated oil samples were determined according to the related standards. To improve film properties, the polymer obtained by RAFT technique was modified by reaction with MI. The resulting material gave transparent films with good film properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献