全文获取类型
收费全文 | 1839篇 |
免费 | 87篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 16篇 |
综合类 | 1篇 |
化学工业 | 308篇 |
金属工艺 | 112篇 |
机械仪表 | 38篇 |
建筑科学 | 37篇 |
矿业工程 | 2篇 |
能源动力 | 103篇 |
轻工业 | 109篇 |
水利工程 | 5篇 |
石油天然气 | 3篇 |
无线电 | 203篇 |
一般工业技术 | 468篇 |
冶金工业 | 144篇 |
原子能技术 | 22篇 |
自动化技术 | 359篇 |
出版年
2024年 | 7篇 |
2023年 | 32篇 |
2022年 | 60篇 |
2021年 | 56篇 |
2020年 | 50篇 |
2019年 | 68篇 |
2018年 | 84篇 |
2017年 | 75篇 |
2016年 | 84篇 |
2015年 | 56篇 |
2014年 | 68篇 |
2013年 | 142篇 |
2012年 | 105篇 |
2011年 | 117篇 |
2010年 | 89篇 |
2009年 | 96篇 |
2008年 | 94篇 |
2007年 | 84篇 |
2006年 | 60篇 |
2005年 | 54篇 |
2004年 | 47篇 |
2003年 | 34篇 |
2002年 | 35篇 |
2001年 | 25篇 |
2000年 | 21篇 |
1999年 | 20篇 |
1998年 | 19篇 |
1997年 | 28篇 |
1996年 | 16篇 |
1995年 | 21篇 |
1994年 | 22篇 |
1993年 | 19篇 |
1992年 | 15篇 |
1991年 | 16篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 16篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 16篇 |
1983年 | 6篇 |
1982年 | 12篇 |
1981年 | 2篇 |
1979年 | 4篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 5篇 |
1972年 | 2篇 |
1971年 | 4篇 |
排序方式: 共有1930条查询结果,搜索用时 15 毫秒
61.
Ponnachanna C Srinivasa Nuggenahalli S Susheelamma R Ravi Rudrapatnam N Tharanathan 《Journal of the science of food and agriculture》2004,84(8):818-824
Mango (Mangifera indica) cv ‘Alphonso’ fruits, harvested 40–50 days after flowering, were stored at 27 ± 1 °C and 65% RH under three conditions of packaging: (1) perforated plastic boxes, (2) wax lined cartons sealed with low‐density polyethylene (LDPE) film, and (3) wax lined cartons sealed with chitosan films. The weight loss, firmness, Hunter colour values and acidity were determined periodically during storage. Sensory analysis was carried out to determine colour, firmness, flavour qualities and also defective spots. Principal component analysis (PCA) of the results indicated that fruits stored in perforated plastic boxes and LDPE film‐sealed cartons differed significantly with respect to mango flavour, firmness and development of defective spots, while those in chitosan film sealed cartons retained the desirable qualities for a longer period (up to 20 days) without developing defective spots. The higher level of carbon dioxide and lower level of oxygen, or lower rate of oxygen transmission, associated with chitosan films delay ripening, and the higher water vapour transmission rate minimizes the rate of transpiration and prevents condensation of water droplets on the film. This helps in establishing equilibrium moisture content of mangoes in the cartons, which, in turn, extends the shelf life of fruits for a longer period. Copyright © 2004 Society of Chemical Industry 相似文献
62.
A non‐linear optimization procedure is established to determine the elastic modulus of slender, soft materials using beams with unknown initial curvature in the presence of large rotations. Specifically, the deflection of clamped‐free beams under self‐weight – measured at different orientations with respect to gravity – is used to determine the modulus of elasticity and the intrinsic curvature in the unloaded state. The approach is validated with experiments on a number of different materials – steel, polyetherimide, rubber and pig skin. Because the loading is limited to self‐weight, the strain levels attained in these tests are small enough to assume a linear elastic material behaviour. This non‐destructive methodology is also applicable to engineered tissues and extremely delicate materials in order to obtain a quick estimate of the material's elastic modulus. 相似文献
63.
A surface functionalized gas sensing material convincingly giving enhanced response to ethanol is demonstrated by SnO2 activated ZnO. Zinc oxide was synthesized by a chemical route, deposited on an alumina substrate and activated by tin dioxide obtained by on-site oxidation of tin chloride. The XRD study of samples confirmed wurtzite hexagonal structure of zinc oxide and FESEM investigation revealed that surface of activated ZnO microrods was covered by nanoparticles of tin dioxide. Sensing response of sensing elements activated with different concentrations of tin chloride solution has been investigated. It was found that response to ethanol vapor significantly enhanced (eight times) by surface activation with tin dioxide, which optimized at a concentration of 3 wt.%. 相似文献
64.
S. Swathi R. Yuvakkumar G. Ravi E. Sunil Babu Dhayalan Velauthapillai Sulaiman Ali Alharbi 《Ceramics International》2021,47(5):6521-6527
Photoelectrochemical (PEC) water splitting is beneficial and has received attractive attention due to a greater potential to generate hydrogen and oxygen from water by using plentiful solar light to solve the problem of energy crisis. Various active semiconductor materials are used in PEC water splitting applications. Nevertheless, in past decades, most of the researchers suggested that titanium oxide (TiO2) is the best photoanode for this type of applications. Now, Zinc oxide (ZnO) is considered a perfect substitution to TiO2 due to its comparable energy band structure and superior photogenerated electron transfer rate. In this study, bare and phosphorous-doped ZnO nanorods were successfully developed on fluorine-doped tin oxide-coated glass (FTO) substrate by chemical vapor deposition. X-ray diffraction (XRD) pattern authenticated hexagonal structure formation with strong diffraction peak of (101), which showed that ZnO nanorods were perfectly developed along c axis. The optical and morphological properties were analyzed by UV–Vis and scanning electron microscopy images. The energy-dispersive X-ray spectra demonstrated that doping agent phosphorous was present in ZnO nanorods. The PEC properties of the developed ZnO nanorods were further investigated and obtained results suggested that a small amount of phosphorous-doped ZnO nanorods enhances their PEC performance. 相似文献
65.
66.
67.
Mayur Sutaria Vinesh H. GadaAtul Sharma B. Ravi 《Journal of Materials Processing Technology》2012,212(6):1236-1249
The aim of the present work is to compute feed-paths and hot-spots by combining level-set-method based sharp interface and feed-path model. The model is based on the solution of energy and level-set equations in solid and liquid, with Stefan condition on the interface. The energy and level-set equation are discretized using finite-volume and finite-difference method, respectively. Feed-path is computed by tracking mass-less particles along the liquid-solid interface during solidification using combined Eulerian-Lagrangian framework. The proposed model is benchmarked on six test cases, where temperature contours and solidification time are compared with a finite-element-method based commercial software. The capability to predict the temporal evolution of interface and to identify multiple hot-spots is validated with an industrial aluminum-alloy lug casting. The numerical as well as experimental validations demonstrate the effectiveness of level-set-method for feed-path calculation. 相似文献
68.
Tailoring the luminescence and photocatalytic activity of KMn4(PO4)3 by Anions (N3‐ and S2‐) doping
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
69.
Madhava Naidu Madineni Sheema Faiza Ragu Sai Surekha Ramasamy Ravi Manisha Guha 《Food science and biotechnology》2012,21(3):747-752
Starch isolated from maranta (Maranta arundinacea) tuber and studied for its various physicochemical characteristics. The amylose content of the starch was 24.8%. SEM showed that the granules were small indented and spherical. Maranta starch granule size has a range of 2.92–6.42 μm, (mean of 4.84 μm), length/degree of 1.20, and roundness of 0.73. Maranta starch has a gelatinization temperature of 74.8°C, peak viscosity of 498 BU, and cold paste viscosity of 669 BU. It also possessed higher freeze-thaw stability. Dynamic rheological properties of maranta starch, measured using parallel plate geometry showed increased storage modulus (G’) values, while loss modulus (G″) values were decreased with increasing frequency values (0–100 Hz). The low gelatinization temperature and high freeze thaw stability of starch indicates its potential for application as a thickener in food industries. 相似文献
70.
Polymer blend of composition 80 wt% polyamide 66/20 wt% polytetraflurotheylene (PA66/PTFE) was selected as a matrix and reinforced with different weight percentage of short glass fibers (SGF). These composites were prepared by melt mix method using twin screw extruder followed by injection molding. The tribological behaviors were tested by using pin on disc machine by varying the different experimental parameters. The friction and wear mechanisms were studied as a function of sliding velocity, sliding load, and distance. The effect of fiber loading lowered the wear volume loss of SGF filled PA66/PTFE blend. The least frictional coefficient of 0.24 was obtained for 20 wt% of SGF in the blend. However, the wear resistance was not apparently improved by SGF loading in the experimental range for comparison with unfilled PA66/PTFE blend. The worn surfaces of specimen were examined by scanning electron microscopy photographs. The observations revealed that the frictional behavior was a function of development and formation of transfer film. Matrix wear and fiber wear were the result of frictional mechanism. The critical wear volume of PA66/PTFE/SGF composites was the contribution of both matrix and fiber wear. The abrasive nature of SGF was also one of the important factor for frictional behavior. 相似文献