全文获取类型
收费全文 | 397篇 |
免费 | 30篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 89篇 |
金属工艺 | 34篇 |
机械仪表 | 9篇 |
建筑科学 | 5篇 |
矿业工程 | 4篇 |
能源动力 | 19篇 |
轻工业 | 10篇 |
石油天然气 | 3篇 |
无线电 | 46篇 |
一般工业技术 | 124篇 |
冶金工业 | 12篇 |
自动化技术 | 66篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 8篇 |
2021年 | 25篇 |
2020年 | 16篇 |
2019年 | 17篇 |
2018年 | 24篇 |
2017年 | 17篇 |
2016年 | 24篇 |
2015年 | 13篇 |
2014年 | 22篇 |
2013年 | 34篇 |
2012年 | 29篇 |
2011年 | 36篇 |
2010年 | 20篇 |
2009年 | 26篇 |
2008年 | 30篇 |
2007年 | 13篇 |
2006年 | 18篇 |
2005年 | 14篇 |
2004年 | 10篇 |
2003年 | 5篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有427条查询结果,搜索用时 797 毫秒
1.
Wireless Personal Communications - Today’s world has a keen interest in systems which are battery-less and can harvest energy from their surroundings. There is an increased demand for... 相似文献
2.
Lokesh Kulhari Kanad Ray Ankit Paptan Nikhil Suri Pramod K Khanna 《International Journal of Applied Ceramic Technology》2020,17(3):1430-1439
Low temperature co-fired ceramic (LTCC) micro-hotplates show wide applications in gas sensors and micro-fluidic devices. It is easily structured in three-dimensional structures. This paper presents the low power consumption micro-hotplates which were developed with PTC (positive temperature coefficient) temperature sensor and inter-digitated electrodes. The paper presents two different structures for micro-hotplate with platinum as a heating element. The PTC temperature sensor using two different materials viz. PdAg and platinum paste are developed with micro-hotplates. The simulation has been achieved through COMSOL for LTCC and alumina micro-hotplates. The temperature variation with power consumption has been measured for the developed LTCC micro-hotplates. The change in resistance of PTC temperature sensors was measured with micro-hotplate temperature. The aim of this study was to place a temperature sensor with the gas sensor module to measure and control the temperature of micro-hotplate. A SnO2 sensing layer is coated on LTCC micro-hotplate using screen printing and characterized for the sensing of carbon monoxide gas (CO). This study will be beneficial for designing hotplates based on LTCC technology with low power consumption and better stability of temperature for gas-sensing applications. 相似文献
3.
4.
Quaternary ammonium salts of sulfonated polystyrene (SPS) were used as compatibilizers for melt intercalation of PS and pristine Na-montmorillonite. Tetra-octyl ammonium SPS and tetra-decyl ammonium SPS ionomeric compatibilizers produced significant exfoliation and a homogeneous dispersion of the polymer-clay nanocomposites. Wide angle X-ray diffraction and transmission electron microscopy were primarily used to characterize the morphology of the nanocomposites. Image analysis was used to measure the percentage exfoliation. Exfoliation increased with the increasing length of the alkyl chain of the ammonium counter-ion of the SPS ionomer. The nanocomposites containing ionomers exhibited higher storage moduli compared to nanocomposites without the compatibilizer. 相似文献
5.
Esterification of acrylic acid with methanol by reactive chromatography: Experiments and simulations
The esterification of acrylic acid with methanol using Amberlyst 15 as a stationary phase has been investigated using a chromatographic reactor. Several experimental runs at various operating conditions have been conducted on a batch column. A classical reactive chromatography model including lumped kinetics, a linear driving force transport model and a heterogeneous kinetic model for the catalytic reaction has been developed. The additional dispersion of concentration fronts due to density gradient effects has been accounted for in the model. The model parameters have been determined in a fast and reliable way by directly fitting the batch column experiments. In general, a good agreement between experimental and calculated results is obtained. The evaluation of the covariance of the fitted model parameters reveals important insights about the system behavior.Based on the detailed batch column model, a complete model of a simulated-moving-bed reactor has been implemented and its optimal point of operation for the synthesis of methyl acrylate from acrylic acid has been determined. Particularly when considering the low-operating temperature, we can regard this process as a possible competition for current technologies. 相似文献
6.
High purity multi-walled carbon nanotubes were synthesized from aromatic hydrocarbons (benzene, toluene, xylene and trimethyl benzene) using ferrocene as the source of Fe catalyst. Screening studies of aromatic feeds at 675 °C, residence time of 14 s and Fe/C atom ratio of 1.07%, resulted in feedstock carbon conversion of 20-31%, CNT yield of 19.8-30.5%, and catalyst yield of 5.3-8.3 (g CNT/g catalyst). While the quality of the CNTs as determined by TGA, SEM, TEM and Raman spectroscopy, were high and comparable for different feedstocks; their carbon conversion, CNT yield and catalyst yield differed noticeably. A process optimization study for toluene feed showed that carbon conversion of more than 39%, CNT yield of 38.7% and catalyst yield of 18.3 can be achieved at temperature of 800 °C, Fe/C atom ratio of 0.47%, and residence time of 10-20 s. 相似文献
7.
Low temperature steam reforming of ethanol in the temperature range of 200–360°C was studied to maximize the production of H2. The optimum reaction conditions in presence of a suitable catalyst can produce mainly the desired products H2 and CO2. Cu/Al2O3 catalysts with six different concentrations ranging from 0 to 10 wt.% Mn, were prepared, characterized and studied for the ethanol-steam reforming reaction. Maximum ethanol conversion of 60.7% and hydrogen yield of 3.74 (mol H2 / mol ethanol converted) were observed at 360°C for catalyst with 2.5 wt.% Mn loading. 相似文献
8.
Chinmoy Saha Siva Ponnupandian Francis R. Costa Gert Heinrich Nikhil K. Singha 《Polymer Engineering and Science》2021,61(12):3163-3169
This investigation reports the synthesis of a new class of polyurethane (PU) based on bis(hydroxyalkyl) polydimethylsiloxane (PDMS) as diol and isophorone diisocyanate as diisocyanate followed by the preparation of PU/layered double hydroxide (PU/LDH) nanocomposite via ex-situ technique. Nuclear magnetic resonance and Fourier-transform infrared spectroscopy studies confirm the formation of PU and incorporation of PDMS into the PU backbone. Thermogravimetry analysis revealed that thermal stability of the composite improves significantly with incorporation of LDH into the PU matrix. This may be accredited to the barrier effect rendered by the LDH layers. Differential scanning calorimetry study reveals that with the incorporation of LDH, glass transition temperature (Tg) of the composite increases for an optimum level of loading beyond which it remains constant. 相似文献
9.
Marriwala Nikhil Punj Himanshu Panda Sunita Kaur Inderjeet Rathore Deepak 《Wireless Personal Communications》2022,124(1):119-145
Wireless Personal Communications - This is the era of Intelligent Cognitive Radio Network (CRN) technology that provides the available spectrum with efficient utilization. Cognitive Radio (CR)... 相似文献
10.
Ritika Puri Mohit Mahajan Nikhil Shri Sahajpal Harjeet Singh Harmanpreet Singh 《Drug development and industrial pharmacy》2016,42(7):1032-1041
Context: Docosahexanoic acid (DHA) is an essential omega-3 fatty acid for normal brain development and its use has increased considerably in recent years.Objective: The aim of this study is to develop and evaluate self-nanoemulsifying drug delivery systems (SNEDDS) of DHA for improved palatability, dispersibility and bioavailability.Methods: The SNEDDS were prepared and evaluated for miscibility, employing different combinations of olive oil and soyabean oil as oil phase, Span 80, Span 20, soya phosphatidylcholine, Labrafil M 1944 CS as surfactants while Tween 80, PEG 400, Cremophor RH40 and propylene glycol as cosurfactants. Thermodynamically stable SNEDDS were characterized for dispersibility, self-emulsification time, droplet size, zeta potential along with sensory analysis. The optimized formulation was subjected to ex vivo and in vivo evaluation such as intestinal permeability, memory performance test, brain concentration and histopathology studies.Results: The optimized SNEDDS formulation showed emulsification time of 27?±?4.7?s with droplet size of 17.6?±?3.5?nm and zeta potential of??37.6?±?0.5?mV. Intestinal absorption study depicted 18.3%, 21.5%, 41.5%, 98.7% absorption of DHA with SNEDDS-based formulation in comparison to 8.2%, 15.1%, 28.8%, 46.1% absorption of DHA with oil-based marketed formulation after 0.5, 1, 2 and 4?h. DHA concentration in brain homogenate was found to be increased to 2.6-fold in comparison to DHA-marketed formulation. This could be ascribed to enhanced dispersibility and bioavailability of DHA from nanosized formulation.Conclusion: The developed formulation led to enhanced dispersibility and bioavailability of DHA due to the formation of nanodroplets. 相似文献