全文获取类型
收费全文 | 285篇 |
免费 | 9篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 50篇 |
金属工艺 | 4篇 |
机械仪表 | 3篇 |
建筑科学 | 12篇 |
矿业工程 | 3篇 |
能源动力 | 23篇 |
轻工业 | 16篇 |
水利工程 | 3篇 |
无线电 | 34篇 |
一般工业技术 | 35篇 |
冶金工业 | 81篇 |
自动化技术 | 26篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 7篇 |
2016年 | 5篇 |
2015年 | 6篇 |
2014年 | 10篇 |
2013年 | 17篇 |
2012年 | 9篇 |
2011年 | 16篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 6篇 |
2007年 | 8篇 |
2006年 | 2篇 |
2005年 | 11篇 |
2004年 | 7篇 |
2003年 | 8篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 7篇 |
1998年 | 22篇 |
1997年 | 15篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 5篇 |
1991年 | 2篇 |
1990年 | 7篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1972年 | 3篇 |
1969年 | 1篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1949年 | 1篇 |
1943年 | 1篇 |
排序方式: 共有294条查询结果,搜索用时 15 毫秒
41.
Principles of cylindrical concentrators for solar energy 总被引:1,自引:0,他引:1
42.
A simple test procedure to differentiate between sources of pregelatinized starch NF has been developed. The procedure is based on the swelling characteristics of the materials. Three pregelatinized starch NF products were distinguished by observing their sedimentation volumes. Microscopic differences in the particle morphology of each starch product were also observed. The study indicates that sedimentation testing can be used as an addition to the current compendial identity tests for pregelatinized starch NF. 相似文献
43.
This paper presents initial information on the development and validation of three team task analysis scales. These scales were designed to quantitatively assess the extent to which a group of tasks or a job is team based. During a 2-week period, 52 male students working in 4-person teams were trained to perform a complex highly interdependent computer-simulated combat mission consisting of both individual- and team-based tasks. Our results indicated that the scales demonstrated high levels of interrater agreement. In addition, the scales differentiated between tasks that were predetermined to be individual versus team based. Finally, the results indicated that job-level ratings of team workflow were more strongly related to team performance than were aggregated task-level ratings of team-relatedness or team workflow. These results suggest that the scales presented here are an effective means of quantifying the extent to which tasks or jobs are team based. A research and practical implication of our findings is that the team task analysis scales could serve as criterion measures in the evaluation of team training interventions or predictors of team performance. 相似文献
44.
Ravishankar Sathyamurthy Abd Elnaby Kabeel El‐Sayed El‐Agouz DSilva Rufus Hitesh Panchal Thirugnanasambantham Arunkumar Athikesavan Muthu Manokar David Gnanaraj Prince Winston 《国际能源研究杂志》2019,43(8):3295-3305
This work aims at augmenting the amount of potable water using MgO and TiO2 in stepped solar still. Experiments were carried out for the climatic conditions of Chennai, India, with two different concentrations of nanofluids inside a stepped basin under three different cases. Results show that there is an improvement in yield of fresh water from stepped solar still by 33.18% and 41.05% using 0.1% and 0.2% volume concentration of TiO2 nanofluid, respectively, whereas the freshwater yield from stepped still with MgO nanofluids improved by 51.7% and 61.89%. Furthermore, the economic analysis revealed that the cost of potable water from the modified solar still reduced from 0.029 to 0.016 $/kg. Similarly, the useful annual energy, yearly cost per kilogram, and annual cost per kilowatt hour are significantly profitable with the use of MgO nanofluid in the stepped basin and found as 512.46 kWh, 0.025 $/kg, and 0.026 $/kWh, respectively. It is also found that the cost of potable water from the modified still significantly increases as the amount of fresh water produced is decreased with increased fabrication cost of the solar still. 相似文献
45.
Oladapo A. Afolabi Mobolaji E. Aluko Gino C. Wang Winston A. Anderson Folahan O. Ayorinde 《Journal of the American Oil Chemists' Society》1989,66(7):983-985
This paper examines the synthesis of a toughened elastomer fromVernonia galamensis seed oil by reacting vernonia oil with vernonia oil-derived suberic acid (octanedioic acid), and cross-linking the pre-polymer
in the immediate presence of cross-linked polystyrene preparedin situ. The paper also demonstrates that the progress of reaction can be followed by monitoring the generation of hydroxyl groups
using infrared spectroscopy. Analysis of some crystalline material on the cooler parts of the reaction vessels revealed the
presence of component fatty acids of vernonia oil. Transmission electron microscopy characterization of the synthesized toughened
elastomer suggests that vernonia oil-suberic acid polyester and polystyrene polymer are interpenetrating. 相似文献
46.
Formation process of core‐shell microparticles by solute migration during drying of homogenous composite droplets 下载免费PDF全文
Nan Fu Winston Duo Wu Zhangxiong Wu Fei Tzhung Moo Meng Wai Woo Cordelia Selomulya Xiao Dong Chen 《American Institute of Chemical Engineers》2017,63(8):3297-3310
Particle formation process during spray drying profoundly impacts particle morphology and microstructure. This study experimentally investigated the formation of core‐shell‐structured microparticles by one‐step drying of composite droplets made of Eudragit® RS (a polycationic acrylic polymer in nanoparticle form) and silica sol. The formation of an incipient surface shell was monitored using single droplet drying technique, and the freshly formed shell was recovered for subsequent analyses. Adding silica to RS precursor increased the shell formation time and altered the properties of the incipient shell from water‐dispersible to nondispersible. The incipient shell formed from RS/silica droplets with mass ratios of 1.5%:1.5% and 0.5%:2.5% showed ingredient segregation with a preferential accumulation of RS, similar to the shell region of dried microparticles. After shell formation, excess silica sol in the liquid phase could flow inward, producing a dense core. This mobility‐governed solute migration would be useful for constructing core‐shell microparticles using other precursor systems. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3297–3310, 2017 相似文献
47.
Pierre‐Marie Nigay Ange Nzihou Claire E. White Winston O. Soboyejo 《Journal of the American Ceramic Society》2017,100(10):4748-4759
In this paper, the structure‐property relationships of a clay ceramic with organic additives (biomass and biochar) are investigated to develop an alternative material for thermal energy storage. The firing transformations were elucidated using X‐ray pair distribution function analysis, differential scanning calorimetry, and scanning electron microscopy. It was found that the biomass increased the porosity, which resulted in a decrease of the specific heat capacity. On the other hand, the biochar remained in the clay ceramic without any interaction with the clay matrix up to 950°C. The specific heat capacity of the clay ceramic increased from 1.20 to 1.49 kJ/kg·K for a 30 wt% addition of biochar. The clay ceramic with a 30 wt% addition of biochar also conserved a high flexural strength of 11.1 MPa compared to that of the clay ceramic without organic additives (i.e., 18.9 MPa). Furthermore, the flexural strength only decreased by 23% after 100 thermal cycles. The crack growth associated with the thermal fatigue was limited by crack bridging and crack trapping. Hence, the current results suggest that clay/biochar ceramics can be as efficient as molten salts in thermal energy storage with the added benefit of an ease of use in the physical form of bricks. 相似文献
48.
A. Muthu Manokar M. Vimala D. Prince Winston D. R. Rajendran Ravishankar Sathyamurthy A. E. Kabeel 《亚洲传热研究》2020,49(8):4394-4409
In this paper, an experimental study of the conventional solar still (CSS), the conventional solar still with glass cooling (CSSGC), the conventional solar still with basin heating (CSSBH), and the conventional solar still with glass cooling and basin heating (CSSGCBH) was carried out on the basis of the distilled water production, the energy efficiency (EnE), the exergy efficiency (ExE), and economic analysis. The CSSGC and CSSBH contain Peltier modules for cooling the glass and heating the basin. The evaporative heat transfer coefficient for all the experimental stills was calculated. The values of daily distilled water production from the CSSGCBH, CSSBH, CSSGC, and CSS were 4.56, 3.79, 2.49, and 1.89 kg/m2, respectively. The daily distilled yield of the CSSBH and CSSGCBH were increased by 58.55% and 50.13%, respectively, as compared with the CSS. Moreover, the daily EnE and ExE of the CSSGCBH were 27.03% and 3.5%, respectively, whereas the EnE and ExE of the CSS were 10.88% and 1.3%, respectively. Furthermore, the cost of distilled water production was found to be 0.26, 0.35, 0.53, and 0.64 $/day for the CSS, CSSGC, CSSBH, and CSSGCBH, respectively, if the selling price of the distilled water was Rs10. 相似文献
49.
Alginate hydrogel as a promising scaffold for dental-derived stem cells: an in vitro study 总被引:1,自引:0,他引:1
Alireza Moshaverinia Chider Chen Kentaro Akiyama Sahar Ansari Xingtian Xu Winston W. Chee Scott R. Schricker Songtao Shi 《Journal of materials science. Materials in medicine》2012,23(12):3041-3051
The objectives of this study were to: (1) develop an injectable and biodegradable scaffold based on oxidized alginate microbeads encapsulating periodontal ligament (PDLSCs) and gingival mesenchymal stem cells (GMSCs); and (2) investigate the stem cell viability, and osteogenic differentiation of the stem cells in vitro. Stem cells were encapsulated using alginate hydrogel. The stem cell viability, proliferation and differentiation to adipogenic and osteogenic tissues were studied. To investigate the expression of both adipogenesis and ontogenesis related genes, the RNA was extracted and RT-PCR was performed. The degradation behavior of hydrogel based on oxidized sodium alginate with different degrees of oxidation was studied in PBS at 37?°C as a function of time by monitoring the changes in weight loss. The swelling kinetics of alginate hydrogel was also investigated. The results showed that alginate is a promising candidate as a non-toxic scaffold for PDLSCs and GMSCs. It also has the ability to direct the differentiation of these stem cells to osteogenic and adipogenic tissues as compared to the control group in vitro. The encapsulated stem cells remained viable in vitro and both osteo-differentiated and adipo-differentiated after 4?weeks of culturing in the induction media. It was found that the degradation profile and swelling kinetics of alginate hydrogel strongly depends on the degree of oxidation showing its tunable chemistry and degradation rate. These findings demonstrate for the first time that immobilization of PDLSCs and GMSCs in the alginate microspheres provides a promising strategy for bone tissue engineering. 相似文献
50.
Akinluwade Kunle Joseph Adelana Rasaki Adetunji Mosobalaje Adeoye Lasisi Ejibunu Umoru Adeyinka Taofeek Taiwo Peter Kalu Azeez Rommly Dayo Adeyemi Isadare Winston Wole Soboyejo Olusegun Oyeleke Adewoye 《材料科学与工程:中英文B版...》2013,(9):567-570
This study investigates the microstructure of the processed cassava leaves. Standard parts machined from low visible diffusion zone formed in low carbon steel pack cyanided using carbon steel were pack cyanided by high temperature in-situ diffusion of nascent carbon and nitrogen into austenite. Formation of a visible diffusion zone was confirmed after observation with a Reichert-Jung Polyval optical microscope coupled with Zeiss AxioCam ICc 1 camera. High magnification Scanning Electron Microscope (SEM) imaging of the visible diffusion zone was done with a CamScan Series 2 scanning electron microscope. The zone was found variable in depth as measured from a representative position. The structure of all samples consists of ferrite and pearlite as determined by optical and SEM examination. Resulting products were thus both tough and hard suitable for service environments requiring high resistance to both wear and impact failure. 相似文献