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171.
Yoong Lee Yeong Min Hahm Shigeki Matsuya Masaharu Nakagawa Kunio Ishikawa 《Journal of Materials Science》2007,42(18):7843-7849
Bone mineral of human is different in composition from the stoichiometric hydroxyapatite (Ca10(PO4)6(OH)2) in that it contains additional ions, of which CO32− is the most abundant species. Carbonate-substituted hydroxyapatite (CHA) bodies were prepared by the hydrothermal treatment
of highly porous calcium carbonate (CaCO3) body at 120 °C in 1 M M2HPO4 and M3PO4 solutions (M = NH4 or K). It was found that CaCO3 body was almost transformed into CHA body after hydrothermal treatment for 24 h irrespective of type of phosphate solution.
However, a small amount of CaCO3 still remained after the treatment in K3PO4 for 48 h. Crystal shape of CHA bodies prepared in those solutions except for K2HPO4 was flake-like, which was different from that (stick-like) of original CaCO3 body used for the preparation of CHA body. CHA prepared in the K2HPO4 showed globule-like crystal. Average pore size and hole size of the CHA bodies were 150, 70 μm and their porosities were
about 89% irrespective of the solution. Carbonate content was slightly higher in the CHA bodies obtained from potassium phosphate
solutions than in those obtained from ammonium phosphate solutions. Mostly B-type CHA was obtained after the hydrothermal
treatment in the potassium phosphate solutions. On the other hand, mixed A- and B-type CHA (ca. 1–2 in molar ratio) was obtained
in the ammonium phosphate solutions. The content of CO32− in the CHA body depended on the type of phosphate solution and was slightly larger in the potassium phosphate solutions. 相似文献
172.
We performed a first principles study to investigate the interaction of tetrakis-ethylmethylaminohafnium (4[(C2H5)(CH3)N]Hf, TEMAHf) precursors with an OH-terminated Si (001) surface that is the initial stage of atomic layer deposition (ALD). When TEMAHf reacted on the OH-terminated Si surface, there were two reaction mechanisms. One was the reaction with one -OH, and the other was the reaction with two -OH's. When TEMAHf reacted with an -OH on the Si (001) surface, an ethylmethylamine ((C2H5)(CH3)NH, EMA) was produced as a by-product and the trikis-ethylmethylaminohafnium group (3[(C2H5)(CH3)N]Hf) was attached to the O atom of the -OH. There were five reaction sites for TEMAHf to react with two -OH's to form the dikis-ethylmethylaminohafnium group (2[(C2H5)(CH3)N]Hf): Inter-dimer, intra-dimer, inter-row, cross-dimer, and cross-row. The reaction with two -OH's on the inter-dimer, intra-dimer, and inter-row sites were more favorable than the reaction with one -OH. Since the inter-dimer reaction was the most favorable, the energy barrier on the inter-dimer site for the reaction of the trikis-ethylmethylaminohafnium group with -OH to form the dikis-ethylmethylaminohafnium group was calculated, and the result was 0.19 eV. An extra energy of 0.25 eV was needed to remove EMA from the surface. Four TEMAHf's reacted with the surface and these reactions were exothermic by -7.77 eV, and the calculated Hf coverage of the first-half ALD cycle was 1.67 x 10(14)/cm2. 相似文献
173.
ABSTRACT: The production of xanthan gum, an industrially important microbial exopolysaccharide, was enhanced by using Xanthomonas campestris cells adsorbed to cotton fibers. However, the function of xanthan polymers during cell adsorption has not been elucidated. Polyethylenimine (PEI), a cationic polyelectrolyte, was employed to investigate respective effects of fiber surface properties and xanthan polymers during cell adsorption. Adsorption of X. campestris cells to fiber was independent of fiber roughness and hairiness, and the effect of electrostatic interactions between cells and fiber was insignificant. Fiber hydrophilicity was critical in initiating cell-fiber contacts, whereas xanthan polymers enhanced retention of cells on fiber surface. The untreated cotton showed the highest immobilization efficiency and xanthan production. 相似文献
174.
Mi Kyoung Seo Jung An Lee Sehoon Jeong Dae-Hyun Seog Jung Goo Lee Sung Woo Park 《International journal of molecular sciences》2022,23(12)
In several rodent models, acute administration of the metabotropic glutamate 2/3 (mGlu2/3) receptor antagonist LY341495 induced antidepressant-like effects via a mechanism of action similar to that of ketamine. However, the effects of chronic mGlu2/3 antagonism have not yet been explored. Therefore, we investigated the effects of chronic LY341495 treatment on the mechanistic target of rapamycin complex 1 (mTORC1) signaling and the levels of synaptic proteins in mice subjected to chronic unpredictable stress (CUS). LY341495 (1 mg/kg) was administered daily for 4 weeks to mice with and without CUS exposure. After the final treatment, the forced swimming test (FST) was used to assess antidepressant-like effects. The hippocampal levels of mTORC1-related proteins were derived by Western blotting. Chronic LY341495 treatment reversed the CUS-induced behavioral effects of FST. CUS significantly reduced the phosphorylation of mTORC1 and downstream effectors [eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP-1) and small ribosomal protein 6 (S6)], as well as the expression of synaptic proteins postsynaptic density-95 (PSD-95) and AMPA receptor subunit GluR1 (GluA1) in the hippocampus. However, chronic LY341495 treatment rescued these deficits. Our results suggest that the activation of hippocampal mTORC1 signaling is related to the antidepressant effect of chronic LY341495 treatment in an animal model of CUS-induced depression. 相似文献
175.
André Wählisch Rainer Unterumsberger Philipp Hönicke Janin Lubeck Yves Kayser Jan Weser Gaoliang Dai Kai Hahm Thomas Weimann Christian Seim Stefan Rehbein Burkhard Beckhoff 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(9):2204943
A reliable and quantitative material analysis is crucial for assessing new technological processes, especially to facilitate a quantitative understanding of advanced material properties at the nanoscale. To this end, X-ray fluorescence microscopy techniques can offer an element-sensitive and non-destructive tool for the investigation of a wide range of nanotechnological materials. Since X-ray radiation provides information depths of up to the microscale, even stratified or buried arrangements are easily accessible without invasive sample preparation. However, in terms of the quantification capabilities, these approaches are usually restricted to a qualitative or semi-quantitative analysis at the nanoscale. Relying on comparable reference nanomaterials is often not straightforward or impossible because the development of innovative nanomaterials has proven to be more fast-paced than any development process for appropriate reference materials. The present work corroborates that a traceable quantification of individual nanoobjects can be realized by means of an X-ray fluorescence microscope when utilizing rather conventional but well-calibrated instrumentation instead of reference materials. As a proof of concept, the total number of atoms forming a germanium nanoobject is quantified using soft X-ray radiation. Furthermore, complementary dimensional parameters of such objects are reconstructed. 相似文献
176.
Kunsik An Chaewon Kim Sunkuk Kim Taesoo Lee Dongyeol Shin Jaemin Lim Donghyo Hahm Wan Ki Bae Jun Young Kim Jeonghun Kwak Jaehoon Kim Kyung-Tae Kang 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(20):2206133
The quantum dot light-emitting diode (QLED) represents one of the strongest display technologies and has unique advantages like a shallow emission spectrum and superior performance based on the cumulative studies of state-of-the-art quantum dot (QD) synthesis and interfacial engineering. However, research on managing the device's light extraction has been lacking compared to the conventional LED field. Moreover, relevant studies on top-emitting QLEDs (TE-QLEDs) have been severely lacking compared to bottom-emitting QLEDs (BE-QLEDs). This paper demonstrates a novel light extraction structure called the randomly disassembled nanostructure (RaDiNa). The RaDiNa is formed by detaching polydimethylsiloxane (PDMS) film from a ZnO nanorod (ZnO NR) layer and laying it on top of the TE-QLED. The RaDiNa-attached TE-QLED shows significantly widened angular-dependent electroluminescence (EL) intensities over the pristine TE-QLED, confirming the effective light extraction capability of the RaDiNa layer. Consequently, the optimized RaDiNa-attached TE-QLED achieves enhanced external quantum efficiency (EQE) over the reference device by 60%. For systematic analyses, current–voltage–luminance (J–V–L) characteristics are investigated using scanning electron microscopy (SEM) and optical simulation based on COMSOL Multiphysics. It is believed that this study's results provide essential information for the commercialization of TE-QLEDs. 相似文献