全文获取类型
收费全文 | 485篇 |
免费 | 17篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 72篇 |
综合类 | 21篇 |
化学工业 | 56篇 |
金属工艺 | 13篇 |
机械仪表 | 8篇 |
建筑科学 | 31篇 |
矿业工程 | 1篇 |
能源动力 | 20篇 |
轻工业 | 97篇 |
水利工程 | 8篇 |
石油天然气 | 6篇 |
武器工业 | 3篇 |
无线电 | 34篇 |
一般工业技术 | 24篇 |
冶金工业 | 5篇 |
原子能技术 | 4篇 |
自动化技术 | 105篇 |
出版年
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 18篇 |
2013年 | 16篇 |
2012年 | 20篇 |
2011年 | 39篇 |
2010年 | 13篇 |
2009年 | 41篇 |
2008年 | 32篇 |
2007年 | 42篇 |
2006年 | 32篇 |
2005年 | 23篇 |
2004年 | 14篇 |
2003年 | 22篇 |
2002年 | 42篇 |
2001年 | 41篇 |
2000年 | 32篇 |
1999年 | 39篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有508条查询结果,搜索用时 15 毫秒
11.
Novel synthetic strategy toward shape memory polyurethanes with a well-defined switching temperature
Shape memory polyurethanes (SMPUs) have been synthesised via a novel synthetic methodology, resulting in an improvement of the phase separation in the multi-block structure of the polyurethane and in its shape memory properties. ABA block copolymers based on semi-crystalline poly(-caprolactone) and amorphous poly(propylene oxide) (PPO) were used as precursor for the SMPUs. For their synthesis, poly(-caprolactone) diols have been converted into isocyanate end-capped prepolymers by using a mixture of 3(4) isocyanato-1-methyl-cyclohexylisocyanate isomers, after which a coupling with low-Tg poly(propylene oxide) oligomers is done. The shape memory polymers are obtained by reaction of the ABA block copolymers with hexamethylenediisocyanate and 1,4-butanediol as chain extender. Using this new strategy, a flexible segment (PPO) was introduced between the hard and the switching segments of the SMPU. For comparison, SMPUs without flexible segment have also been prepared with the conventional synthetic route. DSC, isostrain experiments and cyclic shape memory tests revealed narrower switching temperatures for the SMPUs including a flexible segment. 相似文献
12.
13.
Philippe Rodriguez Valrie Meille Stphanie Pallier Mohamad Ali Al Sawah 《Applied Catalysis A: General》2009,360(2):1225
Different types of aqueous TiO2–P25 suspensions were prepared and their properties, including rheological behaviour and zeta potential, were studied. Then, TiO2 suspensions were used to elaborate TiO2 coatings on various substrates (cordierite monolith, stainless steel plates and -SiC foam) using a dip-coating method. The relationship between the suspension stability and the coating adhesion has been considered. The structural and morphological characterisation of TiO2 coatings has been performed using scanning electron microscopy, X-ray diffraction and other methods. Finally, the photocatalytic properties of the materials have been determined by studying the photooxidation of aqueous ammonia. 相似文献
14.
Vimal Kumar Burhanuddin Faizee Monisha Mridha K.D.P. Nigam 《Chemical Engineering and Processing: Process Intensification》2008,47(12):2287-2295
In the present study a tube-in-tube helically coiled (TTHC) heat exchanger has been numerically modeled for fluid flow and heat transfer characteristics for different fluid flow rates in the inner as well as outer tube. The three-dimensional governing equations for mass, momentum and heat transfer have been solved using a control volume finite difference method (CVFDM). The renormalization group (RNG) k– model is used to model the turbulent flow and heat transfer in the TTHC heat exchanger. The fluid considered in the inner tube is compressed air at higher pressure and cooling water in the outer tube at ambient conditions. The inner tube pressure is varied from 10 to 30 bars. The Reynolds numbers for the inner tube ranged from 20,000 to 70,000. The mass flow rate in the outer tube is varied from 200 to 600 kg/h. The outer tube is fitted with semicircular plates to support the inner tube and also to provide high turbulence in the annulus region. The overall heat transfer coefficients are calculated for both parallel and counter flow configurations. The Nusselt number and friction factor values in the inner and outer tubes are compared with the experimental data reported in the literature. New empirical correlations are developed for hydrodynamic and heat-transfer predictions in the outer tube of the TTHC. 相似文献
15.
Vimal Kumar Vaibhav Shirke K.D.P. Nigam 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2008,139(2):284-295
The present study deals with the numerical simulation of flow patterns and mixing behaviour in Kenics static mixer over a wide range of Reynolds number. Three different sets of Kenics mixer (aspect ratio = 1.5) comprised of 3, 9 and 25 elements each have been characterized. The Reynolds number was varied in the range of 1 to 25,000 (i.e., from laminar to turbulent flow regime). The numerical approach takes into account the aspects of the fluid flow at higher Reynolds number values including circumferential velocity profiles at different cross-sections within the Kenics mixer, which were neglected in previous studies. It was observed that cross-sectional mixing in the turbulent flow regime takes place up to 30% of each element length at element-to-element transition; beyond that velocity profiles were uniform. The experiments were also carried out to measure the circumferential and axial velocity profiles and pressure drop in three different Kenics Mixers using air as fluid. The pressure drop per unit element (ΔP/η) was found to be independent of the number of Kenics mixing elements used in the system. The total pressure drop across Kenics mixer obtained by CFD simulations were compared with the experimental pressure drop values and correlations available in the literature. The numerical results were found in good agreement with the experimental as well as the results reported in the literature. A new pressure drop correlation in the Kenics static mixer has been developed. 相似文献
16.
Constructivist Management of Knowledge,Communication and Enterprise Innovation: Lessons from Indian Experience 总被引:1,自引:1,他引:0
Prime movers of enterprise innovation are inside the organisation. The enterprise NIIT, studied in this paper, tells us how
elicitation and recognition of knowledge and its contents set an enterprise on the move. Recognised knowledge is actionable.
Each act of recognition is an addition to knowledge content, and such additions took place in NIIT through acts of communications
and self-searching. These contents form a large collage that cannot be strewn into a single novelistic episode. Perspectives
and context, motives and suggestions render to each member of the enterprise different disjoint appearances of knowledge.
There are thus many knowledge systems and multiple narrations, each with small episode-like finality. Enterprise innovation
is achieved not through any grand episodic integration of all knowledge contents, but by constructively eliciting further
new contents of knowledge, and encouraging acts of communications and discourses on this new knowledge. Constructive management
of knowledge and communication towards enterprise innovation has thus been defined. Through such constructive management,
NIIT enabled itself innovationally and empowered its members in eliciting knowledge and acting communicatively. A critical
feature of knowledge work is that it requires multidisciplinary expertise and mutual learning in order to achieve a complex
synthesis of highly specialised state-of-the-art technologies and knowledge domains. A convivial work culture and a culture
of communicative acts enable sharing of the non-informatised yet recognised contents of knowledge. 相似文献
17.
18.
Over the past few years, a number of studies have examined the impact of the Rate My Professors (RMP) website (RateMyProfessors.com) on higher education. The focal area of examination is whether students’ evaluations of their professors on RMP are valid. The current study attempts to push the RMP discussions to a deeper level through two studies. Study 1 illustrates that students rely on the valence of review information on RMP to make their course selection decisions without considering its validity. Study 2 shows that students’ decision-making process tends to be biased as a result of review information available. The results of both studies suggest it is necessary for institutions to test new teaching evaluation models online. 相似文献
19.
20.
简要介绍了组件式GIS、土地监测系统的组成架构,以及面向对象技术的特点,给出了系统的逻辑模型,并结合土地监测系统阐述了组件式GIS、OOP方法在地理信息系统中的应用及实现. 相似文献