全文获取类型
收费全文 | 667篇 |
免费 | 41篇 |
专业分类
电工技术 | 5篇 |
综合类 | 2篇 |
化学工业 | 198篇 |
金属工艺 | 18篇 |
机械仪表 | 9篇 |
建筑科学 | 50篇 |
矿业工程 | 2篇 |
能源动力 | 17篇 |
轻工业 | 39篇 |
水利工程 | 2篇 |
无线电 | 55篇 |
一般工业技术 | 134篇 |
冶金工业 | 34篇 |
原子能技术 | 6篇 |
自动化技术 | 137篇 |
出版年
2023年 | 16篇 |
2022年 | 18篇 |
2021年 | 20篇 |
2020年 | 12篇 |
2019年 | 11篇 |
2018年 | 12篇 |
2017年 | 17篇 |
2016年 | 28篇 |
2015年 | 15篇 |
2014年 | 32篇 |
2013年 | 33篇 |
2012年 | 34篇 |
2011年 | 43篇 |
2010年 | 47篇 |
2009年 | 46篇 |
2008年 | 38篇 |
2007年 | 43篇 |
2006年 | 16篇 |
2005年 | 25篇 |
2004年 | 25篇 |
2003年 | 14篇 |
2002年 | 6篇 |
2001年 | 9篇 |
2000年 | 15篇 |
1999年 | 13篇 |
1998年 | 6篇 |
1997年 | 12篇 |
1996年 | 11篇 |
1995年 | 2篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1985年 | 2篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1966年 | 3篇 |
1964年 | 1篇 |
排序方式: 共有708条查询结果,搜索用时 23 毫秒
691.
Bauer IW Li SP Han YC Yuan L Yin MZ 《Journal of materials science. Materials in medicine》2008,19(3):1091-1095
Hydroxyapatite (HAP) is the main inorganic component of hard tissues and shows excellent biocompatibility and osteoconductivity
properties. Nanoparticles of HAP can be synthesised by the precipitation method in distilled water. The needle shaped particles
are below 100 nm in size with low-crystallinity and high-surfacial activation. Recent studies showed toxic effects of HAP
nanoparticles on cancer cells. Other studies focus on the application of HAP nanoparticles as drug and gene delivery system
or cell marker. However, to date, the exact internalization pathway of HAP nanoparticles into cells has not been determined.
When HAP nanoparticles were added to cell culture medium, the particles immediately became instable and formed agglomerates
with a size of about 500–700 nm. Hence, cells seldom encounter single HAP nanoparticles in the environment of cell culture
or body fluid. The TEM showed internalized HAP captured by vacuoles in the cytoplasm of the hepatocellular carcinoma cells.
The invaginations in the cell membrane before nanoparticle uptake suggested endocytic pathways as internalization mechanism.
This study revealed that agglomerated HAP nanoparticles were internalized by cells through the energy-dependent process of
clathrin-mediated endocytosis. Depletion of intracellular potassium arrested the formation of coated pit, which inhibited
the uptake of HAP. 相似文献
692.
Luman Haris Ralf Biehl Martin Dulle Aurel Radulescu Olaf Holderer Ingo Hoffmann Andreas M. Stadler 《International journal of molecular sciences》2022,23(13)
Myelin basic protein (MBP) is intrinsically disordered in solution and is considered as a conformationally flexible biomacromolecule. Here, we present a study on perturbation of MBP structure and dynamics by the denaturant guanidinium chloride (GndCl) using small-angle scattering and neutron spin–echo spectroscopy (NSE). A concentration of 0.2 M GndCl causes charge screening in MBP resulting in a compact, but still disordered protein conformation, while GndCl concentrations above 1 M lead to structural expansion and swelling of MBP. NSE data of MBP were analyzed using the Zimm model with internal friction (ZIF) and normal mode (NM) analysis. A significant contribution of internal friction was found in compact states of MBP that approaches a non-vanishing internal friction relaxation time of approximately 40 ns at high GndCl concentrations. NM analysis demonstrates that the relaxation rates of internal modes of MBP remain unaffected by GndCl, while structural expansion due to GndCl results in increased amplitudes of internal motions. Within the model of the Brownian oscillator our observations can be rationalized by a loss of friction within the protein due to structural expansion. Our study highlights the intimate coupling of structural and dynamical plasticity of MBP, and its fundamental difference to the behavior of ideal polymers in solution. 相似文献
693.
High-dimensional index structures are a means to accelerate database query processing in high-dimensional data, like multimedia feature vectors. A particular interest in many application scenarios is to rank data items with respect to a certain distance function and, thus, identifying the nearest neighbor(s) of a query item.
In this paper, we propose a novel ranking algorithm that (1) operates on arbitrary high-dimensional filter indexes, like the VA-file, the VA+-file, the LPC-file, or the AV-method. Our ranking algorithm (2) exhibits a nearly balanced I/O load to retrieve subsequent items. Finally, it (3) strictly obeys a predefined main memory threshold and even (4) terminates successfully when memory restrictions are very tight. 相似文献
694.
695.
Ingo Schlachter Ronald Frhlich Jochen Mattay 《Advanced Synthesis \u0026amp; Catalysis》1997,339(1):66-70
A new chiral olefin 4 was synthesized starting from L -aspartic acid. The structures of the intermediate oxazolidinones 6 and 7 were proven by X-ray analysis to be diastereomers. It was shown that 4 is unreactive in Diels-Alder reactions with cyclopentadiene and 1,3-diphenyliso-benzofuran because of its steric overloading (M.M. calculations) rather than by electronic effects (FMO by AM1 calculations). 相似文献
696.
Effects of electrospraying parameters on deposition of La0.3Sr0.7Fe0.7Cr0.3O3−δ cathode layer on GDC
Sedat Akkurt Can Sındıraç Tuğçe Özmen Egesoy Gökçe Atıcı Elif Erişman Emre Erğen Aligül Büyükaksoy 《International Journal of Applied Ceramic Technology》2023,20(3):1512-1525
High performance in intermediate temperature solid oxide fuel cells requires improvements especially in the microstructure of the cathode layer. New cobalt-free cathode materials are used because cobalt-containing cathodes have higher thermal expansion coefficients, poor long-term chemical stability, and lower mechanical stability. Recently cobalt-free cathodes have been proposed to solve these issues by using deposition methods other than electrospray deposition (ESD). In this study, ESD method is used to develop a cobalt-free cathode layer. The electrolyte layer is gadolinium-doped ceria that is deposited with La0.3Sr0.7Fe0.7 Cr0.3O3−δ (LSFCr) prepared by 2-butoxyethanol and ethylene glycol solvents as opposed to conventional solvents. Experimental ESD parameters are tested at different levels and combinations by applying statistical experimental design methods to optimize the microstructure. Coating deposited as such demonstrated higher electrochemical performance than similar electrodes fabricated by other methods. 相似文献
697.
Alexander Baer Ingo Hoffmann Najet Mahmoudi Alexandre Poulhazan Matthew J. Harrington Georg Mayer Stephan Schmidt Emanuel Schneck 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(22):2300516
For prey capture and defense, velvet worms eject an adhesive slime which has been established as a model system for recyclable complex liquids. Triggered by mechanical agitation, the liquid bio-adhesive rapidly transitions into solid fibers. In order to understand this mechanoresponsive behavior, here, the nanostructural organization of slime components are studied using small-angle scattering with neutrons and X-rays. The scattering intensities are successfully described with a three-component model accounting for proteins of two dominant molecular weight fractions and nanoscale globules. In contrast to the previous assumption that high molecular weight proteins—the presumed building blocks of the fiber core—are contained in the nanoglobules, it is found that the majority of slime proteins exist freely in solution. Only less than 10% of the slime proteins are contained in the nanoglobules, necessitating a reassessment of their function in fiber formation. Comparing scattering data of slime re-hydrated with light and heavy water reveals that the majority of lipids in slime are contained in the nanoglobules with homogeneous distribution. Vibrating mechanical impact under exclusion of air neither leads to formation of fibers nor alters the bulk structure of slime significantly, suggesting that interfacial phenomena and directional shearing are required for fiber formation. 相似文献
698.
699.
This article focuses on the vacuum equipment used in vacuum degassing (VD) and vacuum oxygen decarburization (VOD) processes. Despite harsh process conditions caused by outgassing and the process gases themselves, there are various pumping principles and designs of vacuum pumps that can be used. Through clever pump selection there is an opportunity to realize substantial energy and operating resource savings on the vacuum pumping side. Last but not least, a new pump series will be presented that further contributes to cost reduction through higher efficiency. 相似文献
700.
Basundhara Dasgupta Jan Niklas Hausmann Rodrigo Beltrán-Suito Shweta Kalra Konstantin Laun Ingo Zebger Matthias Driess Prashanth Wilfred Menezes 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(33):2301258
The low-temperature molecular precursor approach can be beneficial to conventional solid-state methods, which require high temperatures and lead to relatively large crystalline particles. Herein, a novel, single-step, room-temperature preparation of amorphous nickel pnictide (NiE; EP, As) nanomaterials is reported, starting from NaOCE(dioxane)n and NiBr2(thf)1.5. During application for the oxygen evolution reaction (OER), the pnictide anions leach, and both materials fully reconstruct into nickel(III/IV) oxide phases (similar to γ-NiOOH) comprising edge-sharing (NiO6) layers with intercalated potassium ions and a d-spacing of 7.27 Å. Remarkably, the intercalated γ-NiOOHx phases are nanocrystalline, unlike the amorphous nickel pnictide precatalysts. This unconventional reconstruction is fast and complete, which is ascribed to the amorphous nature of the nanostructured NiE precatalysts. The obtained γ-NiOOHx can effectively catalyse the OER for 100 h at a high current density (400 mA cm−2) and achieves outstandingly high current densities (>600 mA cm−2) for the selective, value-added oxidation of 5-hydroxymethylfurfural (HMF). The NiP-derived γ-NiOOHx shows a higher activity for both processes due to more available active sites. It is anticipated that the herein developed, effective, room-temperature molecular synthesis of amorphous nickel pnictide nanomaterials can be applied to other functional transition-metal pnictides. 相似文献