全文获取类型
收费全文 | 339篇 |
免费 | 21篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 20篇 |
化学工业 | 99篇 |
金属工艺 | 1篇 |
机械仪表 | 8篇 |
建筑科学 | 10篇 |
能源动力 | 14篇 |
轻工业 | 21篇 |
水利工程 | 7篇 |
无线电 | 31篇 |
一般工业技术 | 51篇 |
冶金工业 | 30篇 |
原子能技术 | 1篇 |
自动化技术 | 72篇 |
出版年
2023年 | 3篇 |
2022年 | 18篇 |
2021年 | 26篇 |
2020年 | 6篇 |
2019年 | 9篇 |
2018年 | 12篇 |
2017年 | 13篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 20篇 |
2013年 | 19篇 |
2012年 | 18篇 |
2011年 | 13篇 |
2010年 | 11篇 |
2009年 | 20篇 |
2008年 | 20篇 |
2007年 | 12篇 |
2006年 | 6篇 |
2005年 | 15篇 |
2004年 | 9篇 |
2003年 | 16篇 |
2002年 | 8篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 15篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1972年 | 2篇 |
1961年 | 1篇 |
1959年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有365条查询结果,搜索用时 29 毫秒
11.
12.
Umberto De Rossi Johannes Moll Monika Spieles Günther Bach Siegfried Dhne Jrg Kriwanek Maria Lisk 《Advanced Synthesis \u0026amp; Catalysis》1995,337(1):203-208
Cyanine dyes ( 1a–d ) with the 5,5′,6,6′-tetrachloro-1,1′-dialkyl-3,3′-di-(3-carboxypropyl)-benzimidocarbocyanine chromophore differing only in the chain length of their alkyl groups in 1,1′-position have been synthesized, spectroscopically characterized, and compared with 5,5′6,6′-tetrachloro-1,1′-diethyl-3,3′-di-(4-sulfobutyl)-benzimidocarbocyanine( TDBC ). In aqueous solution the dyes form J-aggregates which, depending on the alkyl group chain length, exhibit J-bands differing in spectral positions, bandwidth, and in the number of peaks. 相似文献
13.
The substitution of the traditional analogic measurement and processing techniques with sampling methods is a trend in modern metrology. Many commercial instruments perform this determination by means of their internal firmware. An analysis is necessary when sampling instruments are employed within a laboratory, for the determination of one or more quantities. However, this analysis is possible only under some specific circumstances, where both the characteristics of the samples and the processing algorithms have to be known.The paper will consider the samples as input for the determination of given quantities and the methods to evaluate the uncertainty of the results from the uncertainty of the samples and their correlation. The example is derived by the uncertainty evaluation of the INRIM system for the precision measurement of the power, where the determination of the accuracy has been accomplished both by an almost analytical approach followed by a numerical evaluation. 相似文献
14.
Daniele Penchini Giovanni Cinti Gabriele Discepoli Umberto Desideri 《International Journal of Hydrogen Energy》2014
High temperature steam electrolyzers, taking advantage of high temperature heat, can produce more hydrogen by using less electrical energy than low temperature electrolyzers. This paper presents an experimental study on hydrogen production by using a 200 W solid oxide stack working in reverse mode. A thermodynamic study of the process was performed by measuring the heat and mass balance of stack at different operating conditions. Different definitions of efficiency were used to highlight the limit and potential of the process. The I–V curve, the flow rate measurements and the GC analysis on outlet flows were used to calculate the hydrogen and oxygen productions. In addition, the influence of steam dilution, water utilization and operating temperature on conversion efficiency and stack's thermal balance was evaluated. With this aim, the tests were performed at three operating temperature (700 °C, 750 °C and 800 °C) over a range of steam inlet concentration from 50% to 90% and water utilization up to 70%. The hydrogen and oxygen flows produced by electrolysis, at different loads, were directly measured after water condensation: net flows up to 2.4 ml/(min cm2) of hydrogen and 1.2 ml/(min cm2) of oxygen were measured and compared to the theoretical ones, showing a good agreement. 相似文献
15.
16.
Sartori Luisa; Becchio Cristina; Bulgheroni Maria; Castiello Umberto 《Canadian Metallurgical Quarterly》2009,35(5):1490
Four experiments investigated the influence of a sudden social request on the kinematics of a preplanned action. In Experiment 1, participants were requested to grasp an object and then locate it within a container (unperturbed trials). On 20% of trials, a human agent seated nearby the participant unexpectedly stretched out her arm and unfolded her hand as if to ask for the object (perturbed trials). In the remaining 3 experiments, similar procedures were adopted except that (a) the human was replaced by a robotic agent, (b) the gesture performed by the human agent did not imply a social request, and (c) the gaze of the human agent was not available. Only when the perturbation was characterized by a social request involving a human agent were there kinematic changes to the action directed toward the target. Conversely, no effects on kinematics were evident when the perturbation was caused by the robotic agent or by a human agent performing a nonsocial gesture. These findings are discussed in the light of current theories proposed to explain the effects of social context on the control of action. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
17.
18.
The cell wall is essential to preserve osmotic integrity of yeast cells. Some phenotypic traits of cell wall mutants suggest that, as a result of a weakening of the cell wall, hypo-osmotic stress-like conditions are created. Consequent expansion of the cell wall and stretching of the plasma membrane trigger a complex response to prevent cell lysis. In this work we examined two conditions that generate a cell wall and membrane stress: one is represented by the cell wall mutant gas1Delta and the other by a hypo-osmotic shock. We examined the actin cytoskeleton and the role of the cell wall sensors Wsc1p and Mid2p in these stress conditions. In the gas1 null mutant cells, which lack a beta(1,3)-glucanosyltransferase activity required for cell wall assembly, a constitutive marked depolarization of actin cytoskeleton was found. In a hypo-osmotic shock wild-type cells showed a transient depolarization of actin cytoskeleton. The percentage of depolarized cells was maximal at 30 min after the shift and then progressively decreased until cells reached a new steady-state condition. The maximal response was proportional to the magnitude of the difference in the external osmolarity before and after the shift within a given range of osmolarities. Loss of Wsc1p specifically delayed the repolarization of the actin cytoskeleton, whereas Wsc1p and Mid2p were essential for the maintenance of cell integrity in gas1Delta cells. The control of actin cytoskeleton is an important element in the context of the compensatory response to cell wall weakening. Wsc1p appears to be an important regulator of the actin network rearrangements in conditions of cell wall expansion and membrane stretching. 相似文献
19.
The properties of a GaN Metal-Semiconductor Field Effect Transistor were studied based on two-dimensional full band Monte Carlo simulations. The dependences of the distributions of the electric potential, electron concentration, electric field, drift velocity, and average electron energy on the gate-source voltage (VGS) and drain-source voltage (VDS) were obtained, then the characteristics of the drain current (IDS) versus the drain-source voltage (VDS) and the transconductance (Gm) versus VGS characteristics were determined. At and IDS is 5.03 A/cm, which is higher value. The Gm−VGS curve shows bell shaped and the maximum Gm is 112 ms/mm at and The current gain cutoff frequency (fT) is 98 GHz at and 相似文献
20.
Comparing effects of 2-D and 3-D visual cues during aurally aided target acquisition 总被引:1,自引:0,他引:1
The aim of the present study was to investigate interactions between vision and audition during a visual target acquisition task performed in a virtual environment. In two experiments, participants were required to perform an acquisition task guided by auditory and/or visual cues. In both experiments the auditory cues were constructed using virtual 3-D sound techniques based on nonindividualized head-related transfer functions. In Experiment 1 the visual cue was constructed in the form of a continuously updated 2-D arrow. In Experiment 2 the visual cue was a nonstereoscopic, perspective-based 3-D arrow. The results suggested that virtual spatial auditory cues reduced acquisition time but were not as effective as the virtual visual cues. Experiencing the 3-D perspective-based arrow rather than the 2-D arrow produced a faster acquisition time not only in the visually aided conditions but also when the auditory cues were presented in isolation. Suggested novel applications include providing 3-D nonstereoscopic, perspective-based visual information on radar displays, which may lead to a better integration with spatial virtual auditory information. 相似文献