全文获取类型
收费全文 | 117篇 |
免费 | 19篇 |
国内免费 | 3篇 |
专业分类
综合类 | 1篇 |
化学工业 | 42篇 |
金属工艺 | 13篇 |
机械仪表 | 5篇 |
建筑科学 | 1篇 |
能源动力 | 4篇 |
轻工业 | 1篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 11篇 |
一般工业技术 | 33篇 |
冶金工业 | 17篇 |
原子能技术 | 1篇 |
自动化技术 | 8篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 13篇 |
2020年 | 7篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 14篇 |
2015年 | 4篇 |
2014年 | 15篇 |
2013年 | 6篇 |
2012年 | 15篇 |
2011年 | 15篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 3篇 |
2002年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有139条查询结果,搜索用时 15 毫秒
71.
ABSTRACTRecent efforts in engineering metals with high structural efficiency have resulted in developing a new category of artificial materials with heterogeneous microstructures architected across multiple scales. In this critical assessment, a relatively new concept of heterogeneous bimodal harmonic-structure (bHS) materials is introduced and analysed. It is shown that the bHS concept is applicable to a large variety of metallic materials and is most efficient in scenarios where changes in the chemical composition of materials are restricted for some reason. Basic principles, weaknesses and advantages along with present development status and perspectives are discussed. The overview of critical performance characteristics of various bHS materials is provided, and interesting directions for future research, development and applications are proposed. 相似文献
72.
Dmytro Barbash Julia E. Fulghum Jing Yang 《Drug development and industrial pharmacy》2013,39(4):480-486
A novel X-ray photoelectron spectroscopic (XPS) technique combined with principal component analysis of spectra-to-image datasets was employed to study the effects of atomization air pressure used during the coating process on film–tablet interfacial thickness. Placebo tablet cores were prepared and coated with Eudragit® RL 30 D. Atomization air pressure was varied from 10 to 20 psi, whereas all other processing parameters were held constant. Higher air pressures generally produced thinner interfaces, although the interfacial region was not uniform across the tablet surface and was dependent on the sampling location. These results demonstrate the suitability of this XPS technique to study the coating–tablet interface. Moreover, the variability in the interfacial thickness illustrates the need to further study such systems. 相似文献
73.
Dmytro Korablov Dorthe B. Ravnsbæk Voraksmy Ban Yaroslav Filinchuk Flemming Besenbacher Torben R. Jensen 《International Journal of Hydrogen Energy》2013
Systematic investigations of MBH4−VCl2, M = Li, Na, or K, 2:1 or 3:1, samples prepared by mechano-chemistry and different milling time in order to gain insight in the phase stability and search for novel borohydrides. The samples were investigated using powder X-ray diffraction and Raman spectroscopy. Subsequently, the samples were exposed to heat treatment and investigated by in-situ synchrotron radiation powder X-ray diffraction (SR-PXD). These studies reveal formation of numerous compounds during decomposition of the samples, which contrasts with previous investigations. In several cases the formed compounds were in a less well-crystalline state, which did not allow identification. One of the unidentified compounds was observed both in the LiBH4−VCl2 and NaBH4−VCl2 systems and appeared to decompose at T ∼ 190 °C and is assumed to be a new vanadium borohydride. Crystalline Li2VCl4 was observed, but a major fraction of the decomposition products appeared to be amorphous. The KBH4−VCl2 system revealed formation of well-crystalline solid solutions of K(BH4)1−xClx. 相似文献
74.
The two-dimensional electron systems in graphene and in topological insulators are described by massless Dirac equations. Although the two systems have similar Hamiltonians, they are polar opposites in terms of spin-orbit coupling strength. We briefly review the status of efforts to achieve long spin-relaxation times in graphene with its weak spin-orbit coupling, and to achieve large current-induced spin polarizations in topological-insulator surface states that have strong spin-orbit coupling. We also comment on differences between the magnetic responses and dilute-moment coupling properties of the two systems, and on the pseudospin analogue of giant magnetoresistance in bilayer graphene. 相似文献
75.
Petukhova A Greener J Liu K Nykypanchuk D Nicolaÿ R Matyjaszewski K Kumacheva E 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(5):731-737
Nanomaterials with vectoral electromagnetic properties have potential applications in solar cells, plasmonic cavity resonators, light polarizers, and biosensing. Here a new, simple, solution-based method for producing nanomaterials comprising vertically aligned standing arrays of gold nanorods (NRs) end-functionalized with polymer ligands is reported. The method utilizes the side-by-side assembly of the NRs into large 2D superlattices, followed by the precipitation of the lattices on a solid substrate. The critical design rules for the self-assembly of superlattices are demonstrated, and they show the generality of the method by forming standing arrays from the NRs end-tethered with poly(N-vinylcarbazole) or with polystyrene molecules. 相似文献
76.
Reversible Switching Phenomenon in Diarylethene Molecular Devices with Reduced Graphene Oxide Electrodes on Flexible Substrates
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dongku Kim Hyunhak Jeong Wang‐Taek Hwang Yeonsik Jang Dmytro Sysoiev Elke Scheer Thomas Huhn Misook Min Hyoyoung Lee Takhee Lee 《Advanced functional materials》2015,25(37):5918-5923
Photoswitching molecular electronic devices with reduced graphene oxide (rGO) top electrodes on flexible substrates are fabricated and characterized. It has been reported previously that diarylethene molecular devices with poly‐(3,4‐ethylenedioxythiophene) stabilized with poly‐(4‐styrenesulfonic acid)/Au top electrodes can hold two stable electrical conductance states when the devices are exposed to UV or visible light during device fabrication. However, those devices fail to show the reversible switching phenomenon in response to illumination after device fabrication. By employing conducting and transparent rGO top electrodes, it is demonstrated that the diarylethene molecular devices show a reversible switching phenomenon, i.e., the fabricated devices change their conductance state in response to the alternating illumination with UV and visible light. Furthermore, the molecular devices with rGO top electrodes also exhibit good longtime stability and reliable electrical characteristics when subjected to various mechanical stresses (bending radius down to 5 mm and bending cycle over 104). 相似文献
77.
Petre Badica Hanna Borodianska Shumao Xie Ting Zhao Dmytro Demirskyi Peifeng Li Alfred I.Y. Tok Yoshio Sakka Oleg Vasylkiv 《Ceramics International》2014
Boron carbide ceramic was prepared by reactive Spark Plasma Sintering under N2-atmosphere and for different heating times and maximum pressure regimes. Split-Hopkinson Pressure Bar (SHPB), indentation, XRD and microscopy measurements were performed for samples characterization. It is shown that SHPB toughness control depending on SPS regime is possible and the main reason is introduction of nitrogen into B4C ceramic. Complex relationships between processing conditions, sintering mechanism, material's specifics, static and dynamic mechanical properties are discussed. Improvement of dynamic toughness is through mechanisms resembling those working for static load conditions such as cracks deflection and pull out, but there are also significant differences. 相似文献
78.
Dielectric Relaxation Processes,Electronic Structure,and Band Gap Engineering of MFU‐4‐type Metal‐Organic Frameworks: Towards a Rational Design of Semiconducting Microporous Materials
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Pit Sippel Dmytro Denysenko Alois Loidl Peter Lunkenheimer German Sastre Dirk Volkmer 《Advanced functional materials》2014,24(25):3885-3896
The electronic structures and band gaps of MFU‐4‐type metal‐organic frameworks can be systematically engineered leading to a family of isostructural microporous solids. Electrical properties of the microcrystalline samples are investigated by temperature‐dependent broad‐band dielectric and optical spectroscopy, which are corroborated by full band structure calculations performed for framework and cluster model compounds at multiple levels of density functional theory. The combined results glean a detailed picture of relative shifts and dispersion of molecular orbitals when going from zero‐dimensional clusters to three‐dimensional periodic solids, thus allowing to develop guidelines for tailoring the electronic properties of this class of semiconducting microporous solids via a versatile building block approach. Thus, engineering of the band gap in MFU‐4 type compounds can be achieved by adjusting the degree of conjugation of the organic ligand or by choosing an appropriate metal whose partially occupied d‐orbitals generate bands below the LUMO energy of the ligand which, for example, is accomplished by octahedral Co(II) ions in Co‐MFU‐4. 相似文献
79.
Ranjith Krishna Pai Lihua Zhang Dmytro Nykpanchuk Mircea Cotlet Chad S. Korach 《Advanced Engineering Materials》2011,13(10):B415-B422
Complex microstructures of biominerals such as seashell nacre, bone, and teeth are awe‐inspiring. Nature has devised schemes to combine hard inorganic platelets of aragonite (CaCO3) and an organic matrix that produce tough biocomposites. The ability of the organic‐inorganic components to “slide” internally leads to the toughening of the materials, though a recreation of this system at the nanoscale has yet to be shown. Here, we implement a poly(KAMPS)‐based assembly, which is carried out entirely from dilute aqueous solutions of the materials to create a “brick and mortar”‐type aragonite structure that mimics the platelet sliding and exhibits toughening. The negatively charged poly(KAMPS) chains are attracted to the positively charged divalent cations, by which addition of NaHCO3 to an aqueous mixture of Ca2+‐poly(KAMPS), results in the growth of aragonite nanorods with a width of 120 nm. The reversible nature of the physical gel formation of poly(KAMPS) in solution results in adhesion of the nanorods into a microscale structure. The new nacre‐like carbonate composite, has a modulus (44 GPa) and hardness (2.8 GPa) on a similar order as to that of nacre and other bio‐composites, exhibits limited creep, and demonstrates a mechanism with nanoscale deformation. 相似文献
80.
The templated sol-gel synthesis of ultrabright fluorescent nanoporous silica particles based on the use of organic silica sources has previously been reported. The use of organosilanes as the main silica precursors has a number of issues, in particular, the low robustness of the synthesis due to instability of the organic silica source. Here we report on a novel synthesis of ultrabright fluorescent nanoporous silica discoids (a specific shape in-between the sphere and disk) of 3.1 ± 0.7 microns in size, which were prepared using a stable inorganic sodium silicate silica source. Organic fluorescent dye Rhodamine 6G (R6G) was physically (non-covalently) entrapped inside cylindrical nanochannels of ~4-5 nm in diameter. In contrast to the synthesis with organic silica precursors, the obtained particles showed an excessive leakage of dye. To prevent this leakage, we modified the synthesis by adding a small amount of a secondary silica source. The synthesized particles show virtually no leakage, high photostability, and a brightness equivalent to the fluorescence of up to 7 × 10(7) free R6G molecules. This is about 7 times higher than the fluorescent brightness of particles of the same size made of CdSe/ZnS quantum dots, and 420 times higher than the brightness of the same volume of aqueous solution of free R6G dye. 相似文献