全文获取类型
收费全文 | 134篇 |
免费 | 11篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 3篇 |
综合类 | 1篇 |
化学工业 | 38篇 |
金属工艺 | 8篇 |
机械仪表 | 4篇 |
建筑科学 | 5篇 |
能源动力 | 5篇 |
轻工业 | 21篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
无线电 | 12篇 |
一般工业技术 | 17篇 |
冶金工业 | 7篇 |
原子能技术 | 3篇 |
自动化技术 | 20篇 |
出版年
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 14篇 |
2020年 | 6篇 |
2019年 | 15篇 |
2018年 | 15篇 |
2017年 | 8篇 |
2016年 | 8篇 |
2015年 | 10篇 |
2014年 | 12篇 |
2013年 | 12篇 |
2012年 | 9篇 |
2011年 | 11篇 |
2010年 | 3篇 |
2009年 | 7篇 |
2008年 | 2篇 |
2007年 | 5篇 |
2006年 | 1篇 |
2004年 | 1篇 |
排序方式: 共有149条查询结果,搜索用时 0 毫秒
11.
The shear stress distribution in circular channels was modeled in this study using gene expression programming (GEP). 173 sets of reliable data were collected under four flow conditions for use in the training and testing stages. The effect of input variables on GEP modeling was studied and 15 different GEP models with individual, binary, ternary, and quaternary input combinations were investigated. The sensitivity analysis results demonstrate that dimensionless parameter y/P, where y is the transverse coordinate, and P is the wetted perimeter, is the most influential parameter with regard to the shear stress distribution in circular channels. GEP model 10, with the parameter y/P and Reynolds number (Re) as inputs, outperformed the other GEP models, with a coefficient of determination of 0.7814 for the testing data set. An equation was derived from the best GEP model and its results were compared with an artificial neural network (ANN) model and an equation based on the Shannon entropy proposed by other researchers. The GEP model, with an average RMSE of 0.0301, exhibits superior performance over the Shannon entropy-based equation, with an average RMSE of 0.1049, and the ANN model, with an average RMSE of 0.2815 for all flow depths. 相似文献
12.
Low-velocity impact tests are performed on fiberglass/AZ31B-H24 magnesium fiber-metal laminates (FMLs) with various configurations in order to gain a better understanding of the effect of an impactor's features on the response of this type of FML. For that, impactors with two different shapes (hemispherical and sharp-edged) and sizes are used to impact the specimens. The impact response data, such as the deformation of the contact location and energy absorption, is obtained directly during the impact tests through the impact equipment, while mechanical sectioning was carried out to establish the extent of delaminated area and post-impact residual deformation. While the sharp-edged impactor caused the development of cracks on the metal constituent, and delamination within the specimens, the hemispherical ones imposed more influence over the residual deformation. Noticeable differences are observed in response of FML specimens made with two and three layers of magnesium, especially with respect to the energy absorption capacity. Moreover, finite-element analysis, as a major part of this study, has been employed to simulate the low-velocity impact response of FML specimens. The behavior of specimens has been simulated using the commercial finite-element code ABAQUS. The results imply that there is a good agreement between the experimental and numerical results. 相似文献
13.
14.
Water Resources Management - Sustainable utilization of water resources requires preventive measures that must be taken to promote optimal use of water resources together with consideration of... 相似文献
15.
Mostafa Niazi Effat Alizadeh Amir Zarebkohan Khaled Seidi Mohammad Hosein Ayoubi-Joshaghani Mehdi Azizi Hamed Dadashi Hossein Mahmudi Tahereh Javaheri Mehdi Jaymand Michael R. Hamblin Rana Jahanban-Esfahlan Zohreh Amoozgar 《Advanced functional materials》2021,31(41):2104123
Advanced forms of hydrogels have many inherently desirable properties and can be designed with different structures and functions. In particular, bioresponsive multifunctional hydrogels can carry out sophisticated biological functions. These include in situ single-cell approaches, capturing, analysis, and release of living cells, biomimetics of cell, tissue, and tumor-specific niches. They can allow in vivo cell manipulation and act as novel drug delivery systems, allowing diagnostic, therapeutic, vaccination, and immunotherapy methods. In the present review of multitasking hydrogels, new approaches and devices classified into point-of-care testing (POCT), microarrays, single-cell/rare cell approaches, artificial membranes, biomimetic modeling systems, nanodoctors, and microneedle patches are summarized. The potentials and application of each format are critically discussed, and some limitations are highlighted. Finally, how hydrogels can enable an “all-in-one platform” to play a key role in cancer therapy, regenerative medicine, and the treatment of inflammatory, degenerative, genetic, and metabolic diseases is being looked forward to. 相似文献
16.
Zohreh Roustaie 《International Journal of Electronics》2018,105(4):614-628
In this paper, a novel recessed gate metal–semiconductor field-effect transistor (RG-MESFET) is presented by modifying the depletion region and the electric field. The proposed structure improves the breakdown voltage, drain current and high frequency characteristics by embedding a lateral insulator region between drain and gate while is placed laterally into the metal gate and a silicon well exactly under the insulator region. We called this new structure as modified recess gate MESFET (MRG-MESFET). The radio frequency and direct current (DC) characteristics of the proposed structure is studied using numerical simulations and compared with a conventional MESFET (C-MESFET). The breakdown voltage, drain current DC transconductance and maximum power density of the proposed structure increase by 27%, 16.5%, 15% and 48%, respectively, relative to the C-MESFET. Also, the gate-source capacitance and the minimum noise figure of the proposed structure improve relative to the C-MESFET. The proposed structure can be used for high breakdown voltage, high saturation drain current, high DC transconductance, high power, high frequency, and low noise applications. 相似文献
17.
Philippe Perret Zohreh Khani Thierry Brousse Daniel Bélanger Daniel Guay 《Electrochimica acta》2011,56(24):8122
A new hybrid electrochemical capacitor based on an activated carbon negative electrode, lead dioxide thin film and nanowire array positive electrode with an electrolyte made of a lead salt dissolved in methanesulfonic acid was investigated. It is shown that the maximum energy density and specific capacity of the C/PbO2 nanowire system increase during the first 50 cycles before reaching their maximum values, which are 29 Wh kg−1 and 34 F g−1, respectively, at a current density of 10 mA cm−2 and a depth of discharge (positive active electrode material) of 3.8%, that corresponds to a 22C rate. This is 7–8 times higher than the corresponding maximum values reached with a C/PbO2 thin film cell operated in the same conditions. After an initial activation period, the performances of the C/PbO2 nanowire system stay constant and do not show any sign of degradation during more than 5000 cycles. For comparison, the C/PbO2 thin film system exhibits a 50% decrease of its performances in similar conditions. 相似文献
18.
Azim Ziyaei Halimehjani M. Ali Alaei Farzaneh Soleymani Movahed Negin Jomeh Mohammad R. Saidi 《Journal of Sulfur Chemistry》2016,37(5):529-536
An effective approach for the synthesis of 2-(alkylthio)thiazol-4(5H)-ones from alkyl dithiocarbamates and chloroacetyl chloride in the presence of NaHCO3 has been developed. Good to excellent yields of products, simple reaction conditions and general applicability are the most important advantages of this protocol. 相似文献
19.
Waste glass powder was used as a low cost precursor for production of colloidal nanosilica for the first time. The process includes production of wet silica gel and thermal peptization of the wet gel. Purification of the glass powder and wet gel production were initiated by acid washing. The obtained powder was reacted with sodium hydroxide to produce wet silica gel. Type of the applied acid was examined in one factor at a time route. Temperature of the alkaline step and concentrations of the applied acid and base were investigated using Taguchi design of experiments. After finding the best combination of the investigated factor levels in production of the wet gel, time of the stabilization in thermal peptization was studied. Characterizations of the wet gel and colloidal silica were performed by XRF, DLS, FESEM, TEM, FTIR and N2 sorption evaluation. Accordingly pure and stable colloidal nanosilica (98.50%) with average particle size of 21.9?nm was produced from the glass powder successfully. Specific surface area of the dried porous optimum sample was 83.63?m2/g. 相似文献
20.
Zohreh Pourhassan N. Haiyang Cui Sakshi Khosa Mehdi D. Davari Karl-Erich Jaeger Sander H. J. Smits Ulrich Schwaneberg Lutz Schmitt 《Chembiochem : a European journal of chemical biology》2022,23(6):e202100702
Type 1 secretion systems (T1SS) have a relatively simple architecture compared to other classes of secretion systems and therefore, are attractive to be optimized by protein engineering. Here, we report a KnowVolution campaign for the hemolysin (Hly) enhancer fragment, an untranslated region upstream of the hlyA gene, of the hemolysin T1SS of Escherichia coli to enhance its secretion efficiency. The best performing variant of the Hly enhancer fragment contained five nucleotide mutations at five positions (A30U, A36U, A54G, A81U, and A116U) resulted in a 2-fold increase in the secretion level of a model lipase fused to the secretion carrier HlyA1. Computational analysis suggested that altered affinity to the generated enhancer fragment towards the S1 ribosomal protein contributes to the enhanced secretion levels. Furthermore, we demonstrate that involving a native terminator region along with the generated Hly enhancer fragment increased the secretion levels of the Hly system up to 5-fold. 相似文献