全文获取类型
收费全文 | 61篇 |
免费 | 3篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 29篇 |
机械仪表 | 3篇 |
能源动力 | 4篇 |
轻工业 | 2篇 |
无线电 | 4篇 |
一般工业技术 | 12篇 |
原子能技术 | 2篇 |
自动化技术 | 1篇 |
出版年
2021年 | 2篇 |
2020年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 9篇 |
2012年 | 3篇 |
2011年 | 7篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2006年 | 3篇 |
2005年 | 5篇 |
2003年 | 4篇 |
2002年 | 1篇 |
1999年 | 2篇 |
1990年 | 1篇 |
1980年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有64条查询结果,搜索用时 15 毫秒
1.
Florina D. Cojocaru Vera Balan Constantin-Edi Tanase Ionel Marcel Popa Maria Butnaru Ovidiu Bredetean Mihai Mares Valentin Nastasa Sorin Pasca Liliana Verestiuc 《Ceramics International》2021,47(8):11209-11219
Fine-tuning of the scaffolds structural features for bone tissue engineering can be an efficient approach to regulate the specific response of the osteoblasts. Here, we loaded magnetic nanoparticles aka superparamagnetic iron oxide nanoparticles (SPIONs) into 3D composite scaffolds based on biological macromolecules (chitosan, collagen, hyaluronic acid) and calcium phosphates for potential applications in bone regeneration, using a biomimetic approach. We assessed the effects of organic (chitosan/collagen/hyaluronic acid) and inorganic (calcium phosphates, SPIONs) phase over the final features of the magnetic scaffolds (MS). Mechanical properties, magnetic susceptibility and biological fluids retention are strongly dependent on the final composition of MS and within the recommended range for application in bone regeneration. The MS architecture/pore size can be made bespoken through changes of the final organic/inorganic ratio. The scaffolds undertake mild degradation as the presence of inorganic components hinders the enzyme catalytic activity. In vitro studies indicated that osteoblasts (SaOS-2) on MS9 had similar cell behaviour activity in comparison with the TCP control. In vivo data showed an evident development of integration and resorption of the MS composites with low inflammation activity. Current findings suggest that the combination of SPIONs into 3D composite scaffolds can be a promising toolkit for bone regeneration. 相似文献
2.
3.
Abstract
The electrical conductivity of barium and lead perovskites used as catalysts for the total oxidation of methane, has been measured under nitrogen, methane–nitrogen mixture, air and methane–air mixture (reaction mixture) at the catalytic reaction temperature. The two compounds appeared to be p-type semiconductors under air with positive holes as the main charge carriers but became n-type when contacted with methane–nitrogen mixture. Their conductivities differ by 1.5 orders of magnitude as n-type semiconductors and by three orders of magnitude when being p-type semiconductors. These results explained the difference in the catalytic activity encountered on the two solids. The alkane activation was proposed to be related in both cases to the p-type semiconducting properties of the solids, likely through hydrogen abstraction by a surface O− species, forming a CH3• radical. The overall reaction mechanism on both perovskites can be assimilated to a Mars and van Krevelen mechanism. 相似文献4.
Gerlinde Rusu Nicolas Joly Geza Bandur Ionel Manoviciu Patrick Martin Lucian Rusnac 《Journal of Polymer Research》2011,18(6):2495-2504
New inulin-based materials were obtained by graft-copolymerization of inulin (poly-β(1 → 2)-fructoside) with 2-ethyl-hexyl
acrylate. Inulin mixed esters were first synthesized by acylation using methacryloyl and palmitoyl chlorides. Further, these
esters were copolymerized with 2-ethyl-hexyl acrylate in order to obtain bio-based crosslinked materials that could be used
as commodity plastics and that would have biodegradable properties. The obtained products were characterized using FT-IR and
1H NMR spectroscopies, thermogravimetry; differential scanning calorimetry, and activation energy for the degradation processes
(using Kissinger method) was calculated. These biomaterials were also subjected to density measurement, tensile and torsion
tests to evaluate their mechanical properties. 相似文献
5.
Loan Silaghi-Dumitrescu Attila Kun Ionel Haiduc 《Fullerenes, Nanotubes and Carbon Nanostructures》1999,7(5):841-854
AMI molecular orbital calculations with full geometry optimisation of 4/6, 5/5 and 4/5/6 isomers of E20 (E=Si, Ge) show a clear preference of germanium to be accommodated in four membered rings and to achieve coordination numbers greater than 3 (V A). as a consequence, unlike C20 or Si20, the dodecahedral form of Ge20 was not localised on the potential surface, instead an opened structure derived from an octagermaprismane (IV B) can be predicted. Notable kinetic stabilisation in the (SiR)20 systems is suggested by the HOMO-LUMO differences. 相似文献
6.
The paper presents theoretical and experimental results on an original anthropomorphic gripping concept. Compared to the existing anthropomorphic grippers, this gripper is very simple, yet it has the advantage of high performance in terms of gripping possibilities and a very low manufacturing cost. Source of inspiration was the human hand, which is able to catch objects by only using two fingers. The analyzed anthropomorphic gripper has two fingers, with two phalanxes each, and is based on a new mechanism with articulated bars. The kinematic analysis performed on the gripping mechanism reveals the optimal displacement in the translational coupling, which was experimentally validated. The gripping possibilities were increased by attaching clamping jaws to each phalanx. The clamping jaws have been attached by means of spherical couplings, thus offering the possibility to catch objects with any type of surface. By carrying out gripping tests with different objects, we underline the importance of a safe use of the two-fingered anthropomorphic grippers in different applications. Due to the innovative mechanical structure, the gripper can insure the minimal gripping conditions, whilst the complexity of the objects that can be gripped make it suitable for the use in robots. 相似文献
7.
Raluca C. Cretu Delia M. Gligor Laura Muresan Ionel Catalin Popescu Liana M. Muresan 《Journal of Applied Electrochemistry》2006,36(12):1327-1332
Prussian Blue-modified graphite electrodes (G/PB) with electrocatalytic activity toward H2O2 reduction were obtained by PB potentiostatic electrodeposition from a mixture containing 2.5 mm FeCl3 + 2.5 mm K3[Fe(CN)6] + 0.1 m KCl + 0.1 m HCl. From cyclic voltammetric measurements, performed in KCl aqueous solutions of different concentrations (5 × 10−2–1 m), the rate constant for the heterogeneous electron transfer (k
s) was estimated by using the Laviron treatment. The highest ks value (10.7 s−1) was found for 1 m KCl solution. The differences between the electrochemical parameters of the voltammetric response, as well as the shift of the formal potential, observed in the presence of Cl− and NO3− compared to those observed in the presence of SO42− ions, points to the involvement of anions in the redox reactions of PB. The G/PB electrodes showed a good electrochemical stability proved by a low deactivation rate constant (0.8 × 10−12 mol cm2 s−1). The electrocatalytic efficiency, estimated as the ratio
, was found to be 3.6 (at an applied potential of 0 mV vs. SCE; Γ = 5 × 10−8 mol cm−2) for a H2O2 concentration of 5 mm, thus indicating G/PB electrodes as possible H2O2 sensors. 相似文献
8.
9.
Gheorghe Virgil Aldica Magdalena Lidia Ciurea Dorina Magdalena Chipara Ana Maria Lepadatu Karen Lozano Ionel Stavarache Stelian Popa Mircea Chipara 《应用聚合物科学杂志》2017,134(38)
Nanocomposites have been obtained by dispersing various amounts of vapor grown carbon nanofibers within isotactic polypropylene. Thermal investigations done by differential scanning calorimetry and dynamic mechanical analysis revealed the effect of the vapor grown carbon nanofibers on the melting, crystallization, α, and β relaxations. Direct current electrical features of these nanocomposites have been investigated and related to the thermal features of these nanocomposites. The effect of the loading with carbon nanofibers on the electrical properties of these nanocomposites is discussed within the percolation theory. The percolation threshold was estimated at about 5.5% wt carbon nanofibers. The temperature dependence of the direct current conductivity is analyzed in detail and it is concluded that the electronic hopping is the dominant transport mechanism. A transition from one‐dimensional hopping towards a three‐dimensional hopping was noticed as the concentration of carbon nanofibers was increased from 10% wt to 20% wt carbon nanofiber. The possibility of a differential negative resistivity is suggested. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45297. 相似文献
10.
Ionel D.M. Popescu M. Dellinger S.J. Miller T.J.E. Heideman R.J. McGilp M.I. 《Industry Applications, IEEE Transactions on》2006,42(3):658-667
A model of core losses, in which the hysteresis coefficients are variable with the frequency and induction (flux density) and the eddy-current and excess loss coefficients are variable only with the induction, is proposed. A procedure for identifying the model coefficients from multifrequency Epstein tests is described, and examples are provided for three typical grades of non-grain-oriented laminated steel suitable for electric motor manufacturing. Over a wide range of frequencies between 20-400 Hz and inductions from 0.05 to 2 T, the new model yielded much lower errors for the specific core losses than conventional models. The applicability of the model for electric machine analysis is also discussed, and examples from an interior permanent-magnet and an induction motor are included. 相似文献