全文获取类型
收费全文 | 475篇 |
免费 | 33篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 97篇 |
金属工艺 | 26篇 |
机械仪表 | 8篇 |
建筑科学 | 2篇 |
能源动力 | 18篇 |
轻工业 | 4篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 68篇 |
一般工业技术 | 201篇 |
冶金工业 | 15篇 |
原子能技术 | 4篇 |
自动化技术 | 61篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 16篇 |
2019年 | 9篇 |
2018年 | 11篇 |
2017年 | 13篇 |
2016年 | 14篇 |
2015年 | 14篇 |
2014年 | 31篇 |
2013年 | 41篇 |
2012年 | 35篇 |
2011年 | 54篇 |
2010年 | 40篇 |
2009年 | 41篇 |
2008年 | 41篇 |
2007年 | 24篇 |
2006年 | 23篇 |
2005年 | 22篇 |
2004年 | 17篇 |
2003年 | 5篇 |
2002年 | 15篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1985年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有511条查询结果,搜索用时 0 毫秒
81.
Lutich AA Mauser C Da Como E Huang J Vaneski A Talapin DV Rogach AL Feldmann J 《Nano letters》2010,10(11):4646-4650
CdSe/CdS semiconductor nanocrystal heterostructures are currently of high interest for the peculiar electronic structure offering unique optical properties. Here, we show that nanorods and tetrapods made of such material combination enable efficient multiexcitonic emission, when the volume of the nanoparticle is maximized. This condition is fulfilled by tetrapods with an arm length of 55 nm and results in a dual emission with comparable intensities from the CdS arms and CdSe core. The relative intensities of the dual emission, originating from exciton phase-space filling and reduced Auger recombination, can be effectively modulated by the photon fluence of the pump laser. The results, obtained under steady-state detection conditions, highlight the properties of tetrapods as multiexciton dual-color emitters. 相似文献
82.
Dmitri A. Molodov Tatiana Gorkaya Christoph Günster Günter Gottstein 《Frontiers of Materials Science in China》2010,4(3):291-305
Recent research on the dynamics of planar grain boundaries is reviewed. Novel measuring techniques developed for in situ observation and recording of magnetically and stress driven grain boundary migration are presented. The results of migration
measurements obtained on bismuth, zinc and aluminum bicrystals are addressed. The experiments revealed that the inclination
of a 〈112〉 tilt boundary in Bi has a very strong influence on its mobility. The migration of planar 〈10$
\bar 1
$
\bar 1
0〉 tilt grain boundaries with different misorientation angles was measured in situ in bicrystals of high purity zinc. The
results proved that there is a pronounced misorientation dependence of grain boundary mobility in the investigated angular
range. The shear stress induced migration of planar symmetric 〈100〉 tilt boundaries in aluminum bicrystals was observed to
be accompanied by a lateral translation of the adjacent grains. The coupling between boundary motion and shearing is not confined
to low angle and some low Σ high angle boundaries, but occurs also for noncoincidence high angle 〈100〉 tilt boundaries. It
has been found that also for stress induced grain boundary motion there is a misorientation dependence of the migration activation
parameters. Lower values of the activation enthalpy and the pre-exponential mobility factor can be associated with boundaries
with tilt angles close to low Σ CSL orientation relationships. 相似文献
83.
Parameter estimation of an electrochemistry‐based lithium‐ion battery model using a two‐step procedure and a parameter sensitivity analysis 下载免费PDF全文
Lithium‐ion batteries are indispensable in various applications owing to their high specific energy and long service life. Lithium‐ion battery models are used for investigating the behavior of the battery and enabling power control in applications. The Doyle‐Fuller‐Newman (DFN) model is a popular electrochemistry‐based model, which characterizes the dynamics in the battery through diffusions in solid and electrolyte and predicts current/voltage response. However, the DFN model contains a large number of parameters that need to be estimated to obtain an accurate battery model. In this paper, a computationally feasible two‐step estimation approach is proposed that only uses voltage and current measurements of the battery under consideration. In the two‐step procedure, the parameters are divided into 2 groups. The first group contains thermodynamic parameters, which are estimated using low‐current discharges, while the second group contains kinetic parameters, which are estimated using a well‐designed highly‐dynamic pulse (dis‐)charge current. A parameter sensitivity analysis is done to find a subset of parameters that can be reliably estimated using current and voltage measurements only. Experimental data are collected for 12 Ah nickel cobalt aluminum pouch lithium‐ion cell. The voltage predictions of the identified model are compared with several experimental data sets to validate the model. A root mean square error between model predictions and experimental data smaller than 16 mV is achieved. 相似文献
84.
85.
Pedro M. F. J. Costa Dmitri Golberg Guozhen Shen Masanori Mitome Yoshio Bando 《Journal of Materials Science》2008,43(4):1460-1470
The electrical properties of wurtzite-type ZnO low-dimensional structures were analysed using a scanning tunnelling microscopy
(STM) in situ holder for transmission electron microscopes (TEM). Compared to similar studies in the literature employing
nanowires or nanobelts, our work illustrates that rather complex structures can be reliably analysed with this technique.
Through controlled contact manipulations it was possible to alter the systems I–V characteristics and, in separate experiments, to follow their electrical response to cycles of induced stress. Analysis of
the I–V curves showed higher than expected resistances which, according to the detailed TEM characterisation, could be correlated
with the considerable density of defects present. These defects accumulate in specific areas of the complex structural arrays
of ZnO and represent high resistance points responsible for structural failure, when the systems are subjected to extreme
current flows.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
86.
Based on the self-ordering behavior of ionic liquids on solid surface, a gold ion containing ionic liquid was employed to obtain a uniform pattern of gold nanoparticles on Si substrate. Using this catalytic pattern, super-dense, centimetre long, well-crystallized and vertically-aligned ZnS nanowire arrays were then generated. It was found that the densely-packed gold nanoparticles played a key role in the nanowire alignment. Furthermore, the field-emission measurements show that the present ultralong ZnS nanowires arrays possess a low turn-on field of 3.69 V μm(-1) and a high field-enhancement factor of 1215.4, indicating they are valuable field emitters. 相似文献
87.
Koren K Dmitriev RI Borisov SM Papkovsky DB Klimant I 《Chembiochem : a European journal of chemical biology》2012,13(8):1184-1190
Ir(III)-porphyrins are a relatively new group of phosphorescent dyes that have potential for oxygen sensing and labeling of biomolecules. The requirement of two axial ligands for the Ir(III) ion permits simple linkage of biomolecules by a one-step ligand-exchange reaction, for example, using precursor carbonyl chloride complexes and peptides containing histidine residue(s). Using this approach, we produced three complexes of Ir(III)-octaethylporphyrin with cell-penetrating (Ir1 and Ir2) and tumor-targeting (Ir3) peptides and studied their photophysical properties. All of the complexes were stable and possessed bright, long-decay (unquenched lifetimes exceeding 45 μs) phosphorescence at around 650 nm, with moderate sensitivity to oxygen. The Ir1 and Ir2 complexes showed positive staining of a number of mammalian cell types, thus demonstrating localization similar to endoplasmic reticulum and ATP- and temperature-independent intracellular accumulation (direct translocation mechanism). Their low photo- and cytotoxicity allows intracellular oxygen to be probed. 相似文献
88.
Noboru Yoshikawa Guoqiang XieZiping Cao Dmitri V. Louzguine 《Journal of the European Ceramic Society》2012,32(2):419-424
An Fe3O4 powder compact was irradiated with a 2.45 GHz microwave single-mode applicator at the magnetic field maximum position. Selectively heated regions (hot spot region) having several hundred micrometers to millimeter scale were formed. They exhibited metallic color. The SEM/EDX observations showed no appreciable difference in the compositions between the hot spot regions and the matrix. However, micro-XRD revealed that the hot spot region had a larger fraction of FeO than the matrix did, although the major consisting phase was Fe3O4 with a little Fe2O3. TEM observations indicated that the observed hot spot regions comprise these oxide phases separated in nano-sized grains, which agrees with our previous report. The larger fraction of FeO phase and flat surface might be related with the metallic color of the hot spot region. Their formation mechanisms and phase constitution were discussed. 相似文献
89.
Ding Wang Dmitri Donetsky Seungyong Jung Gregory Belenky 《Journal of Electronic Materials》2012,41(11):3027-3030
Minority carrier lifetime in long-wave infrared (LWIR) type?II InAs/GaSb superlattices was studied using the optical modulation response (OMR) technique in wide ranges of excitation and temperature. The measured carrier lifetime was found to increase superexponentially with decreasing excitation power density below the level of 1?mW/cm2 to 2?mW/cm2. The phenomenon was qualitatively explained by the presence of shallow trapping centers. 相似文献
90.
Xi Wang Xinqiang Cao Laure Bourgeois Hasigaowa Guan Shimou Chen Yeteng Zhong Dai‐Ming Tang Huiqiao Li Tianyou Zhai Liang Li Yoshio Bando Dmitri Golberg 《Advanced functional materials》2012,22(13):2682-2690
A new facile route to fabricate N‐doped graphene‐SnO2 sandwich papers is developed. The 7,7,8,8‐tetracyanoquinodimethane anion (TCNQ?) plays a key role for the formation of such structures as it acts as both the nitrogen source and complexing agent. If used in lithium‐ion batteries (LIBs), the material exhibits a large capacity, high rate capability, and excellent cycling stability. The superior electrochemical performance of this novel material is the result from its unique features: excellent electronic conductivity related to the sandwich structure, short transportation length for both lithium ions and electrons, and elastomeric space to accommodate volume changes upon Li insertion/extraction. 相似文献