全文获取类型
收费全文 | 1880篇 |
免费 | 37篇 |
国内免费 | 22篇 |
专业分类
电工技术 | 10篇 |
综合类 | 29篇 |
化学工业 | 673篇 |
金属工艺 | 142篇 |
机械仪表 | 95篇 |
建筑科学 | 26篇 |
矿业工程 | 31篇 |
能源动力 | 315篇 |
轻工业 | 132篇 |
水利工程 | 7篇 |
石油天然气 | 13篇 |
武器工业 | 2篇 |
无线电 | 71篇 |
一般工业技术 | 281篇 |
冶金工业 | 68篇 |
原子能技术 | 14篇 |
自动化技术 | 30篇 |
出版年
2023年 | 15篇 |
2022年 | 27篇 |
2021年 | 29篇 |
2020年 | 35篇 |
2019年 | 34篇 |
2018年 | 35篇 |
2017年 | 54篇 |
2016年 | 46篇 |
2015年 | 58篇 |
2014年 | 114篇 |
2013年 | 226篇 |
2012年 | 72篇 |
2011年 | 133篇 |
2010年 | 117篇 |
2009年 | 105篇 |
2008年 | 80篇 |
2007年 | 101篇 |
2006年 | 105篇 |
2005年 | 81篇 |
2004年 | 76篇 |
2003年 | 60篇 |
2002年 | 64篇 |
2001年 | 43篇 |
2000年 | 37篇 |
1999年 | 49篇 |
1998年 | 18篇 |
1997年 | 24篇 |
1996年 | 23篇 |
1995年 | 18篇 |
1994年 | 15篇 |
1993年 | 12篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有1939条查询结果,搜索用时 15 毫秒
101.
102.
V.M. Nikale 《Solar Energy》2011,85(7):1336-1342
The n-CdIn2Se4/p-CdTe heterojunction solar cells have been fabricated by deposition of n-CdIn2Se4 thin films using spray pyrolysis on to p-CdTe. Current density-voltage and capacitance-voltage measurements were performed to determine the electrical properties of the structures. The capacitance-voltage behavior indicates an abrupt interface. The junction quality factor (n), series and shunt resistance (Rs and Rsh), fill factor (FF) and efficiency (η) for the cell have been estimated. The device exhibit maximum fill factor (FF), power conversion efficiency (η) of about 0.55% and 0.67%. 相似文献
103.
In this work we derive the fundamental equations for conditional moment closure (CMC) modelling of individual phases set in a two-phase flow. The derivation is based on the instantaneous transport equations for the single phase that involve a level set/indicator function technique for accounting for interfaces. Special emphasis is put on spray combustion with the CMC equations formulated for the gas phase. The CMC equations are to be viewed as an adjunct to existing methods for the modelling of the dynamics of sprays: they provide a refinement of the modelling of chemical reactions in the gas phase. The resulting CMC equations differ significantly from those already in use in the literature. They contain, of course, unclosed terms that need to be modelled. Investigation of the unclosed terms associated with evaporation at the droplet surface is well beyond the capabilities of laboratory measurement or direct numerical simulation. It is proposed that modelling of these terms be based on the well-established ‘laws’ of similarity between heat and mass transfer: an example is detailed for one example of the general modelling of the spray dynamics. Other unclosed terms are important throughout the gas phase. Models used for these terms in single-phase flows are reviewed and it is proposed that any modifications needed for these models be investigated by DNS of suitable model problems having good resolution of the flow and mixing in the inter-droplet space. It is proposed that a spray analogue of the scalar mixing layer that has been widely studied in single-phase flows be used as the model problem for such DNS studies and also for LES and RANS modelling. 相似文献
104.
M. Abdul Mujeebu M.Z. Abdullah M.Z. Abu Bakar A.A. Mohamad M.K. Abdullah 《Progress in Energy and Combustion Science》2009
Utilization of a porous medium for combustion of liquid fuels is proved to be a promising approach for future applications. The porous medium burner for liquid fuels is more advantageous than the conventional open spray flame burner for several reasons; these include enhanced evaporation of droplet spray owing to regenerative combustion characteristics, low emission of pollutants, high combustion intensity with moderate turn-down ratio and compactness. This article provides a comprehensive picture of the global scenario of research and developments in combustion of liquid fuels within a porous medium that enable a researcher to determine the direction of further investigation. Accordingly, a glossary of the important terminology, the modeling approach, advances in numerical and experimental works and applications are included. The papers published in standard journals are reviewed and summarized with relevant comments and suggestions for future work. 相似文献
105.
The effect of fatty acid structure of polyethyleneimine (PEI)-fatty acid complex, which was designed as a polymer dispersant for multi-component non-aqueous slurries, on the overall processing chain of Si3N4 ceramics involving slurry stabilization, spray drying, compaction, and liquid sintering was investigated using PEI-oleic acid (PEI-OA) and PEI-isostearic (PEI-ISA) complexes. Si3N4-Y2O3-Al2O3-AlN-TiO2/toluene slurries were selected as a real model for Si3N4-based multicomponent slurries. It was observed that both PEI-OA and PEI-ISA can stabilize Si3N4-Y2O3-Al2O3-AlN-TiO2/toluene slurries; however, the PEI-ISA system tended to have slightly higher slurry viscosity, which was suspected to be due to the interactions between protruded PEI segments among short ISA chains. The spray-dried granules from PEI-ISA-stabilized slurry were observed to have filled structures with higher surface roughness whereas those prepared from PEI-OA-stabilized slurry were observed to have hollow-structured granules. The granules prepared from PEI-OA slurry had improved flow and compaction properties with higher relative density of green compacts compared with those prepared from PEI-ISA-stabilized slurry, whereas the relative density and microstructural homogeneity of S3N4 ceramics sintered at 1600?°C for 2?h were observed to be higher for the PEI-ISA system. It is suspected that PEI-OA effectively improved the dispersion stability of multicomponent slurries and flow/compaction properties of granules; however, the inhomogeneous microstructures of green compacts induced by the hollow-structured granules had an adverse effect on the sintering of Si3N4 ceramics. 相似文献
106.
This paper presents studies carried out on tin-doped indium sulfide films prepared using Chemical Spray Pyrolysis (CSP) technique. Effect of both in-situ and ex-situ doping were analyzed. Ex-situ doping was done by thermal diffusion, which was realized by annealing Sn/In2S3 bilayer films. In-situ doping was accomplished by introducing Sn into the spray solution by using SnCl4·5H2O. Interestingly, it was noted that by ex-situ doping, conductivity of the sample enhanced considerably without affecting any of the physical properties such as crystallinity or band gap. Analysis also showed that higher percentage of doping resulted in samples with low crystallinity and negative photosensitivity. In-situ doping resulted in amorphous films. In contrast to ex-situ doping, ‘in- situ doping’ resulted in widening of optical band gap through oxygen incorporation; also it gave highly photosensitive films. 相似文献
107.
108.
超临界CO2在涂料及喷涂工艺中的应用 总被引:2,自引:0,他引:2
林春绵 《浙江工业大学学报》1995,23(3):242-247
从超临界流体的溶剂性能出发,阐述了超临界CO2在涂料及喷工艺中的应用前景,详细了超临界喷雾涂料的组成、相行为、雾化机理、喷涂工艺条件及特征。 相似文献
109.
Development of an extended release oral dosage form for nifedipine using the non-uniform drug distribution matrix method was conducted. The process conducted in a fluid bed processing unit was optimized by controlling the concentration gradient of nifedipine in the coating solution and the spray rate applied to the non-pareil beads. The concentration of nifedipine in the coating was controlled by instantaneous dilutions of coating solution with polymer dispersion transported from another reservoir into the coating solution at a controlled rate. The USP dissolution method equipped with paddles at 100 rpm in 0.1 N hydrochloric acid solution maintained at 37°C was used for the evaluation of release rate characteristics. Results indicated that (1) an increase in the ethyl cellulose content in the coated beads decreased the nifedipine release rate, (2) incorporation of water-soluble sucrose into the formulation increased the release rate of nifedipine, and (3) adjustment of the spray coating solution and the transport rate of polymer dispersion could achieve a dosage form with a zero-order release rate. Since zero-order release rate and constant plasma concentration were achieved in this study using the non-uniform drug distribution technique, further studies to determine in vivo/in vitro correlation with various non-uniform drug distribution dosage forms will be conducted. 相似文献
110.
CuxS(x=1,2)纳米薄膜的异步脉冲超声喷雾热解法制备 总被引:1,自引:0,他引:1
采用改进的异步脉冲超声喷雾热解技术在玻璃衬底上成功地制备了CuxS(x =1,2 )纳米薄膜 .研究发现 ,所制备的CuxS薄膜为多晶态 ;薄膜的晶相结构依赖于CuCl2 ·2H2 O和硫脲的摩尔比及衬底温度 .XRD和XPS分析表明 :样品为纯CuxS(CuS ,Cu2 S) ,拉曼谱研究表明其峰位分别在 472cm- 1 (Cu2 S)和 474cm- 1 (CuS)处 . 相似文献