全文获取类型
收费全文 | 746篇 |
免费 | 42篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 149篇 |
金属工艺 | 13篇 |
机械仪表 | 37篇 |
建筑科学 | 27篇 |
矿业工程 | 3篇 |
能源动力 | 59篇 |
轻工业 | 41篇 |
水利工程 | 8篇 |
石油天然气 | 3篇 |
无线电 | 59篇 |
一般工业技术 | 133篇 |
冶金工业 | 144篇 |
原子能技术 | 1篇 |
自动化技术 | 109篇 |
出版年
2023年 | 14篇 |
2022年 | 13篇 |
2021年 | 23篇 |
2020年 | 19篇 |
2019年 | 18篇 |
2018年 | 28篇 |
2017年 | 18篇 |
2016年 | 28篇 |
2015年 | 21篇 |
2014年 | 34篇 |
2013年 | 49篇 |
2012年 | 36篇 |
2011年 | 69篇 |
2010年 | 42篇 |
2009年 | 39篇 |
2008年 | 44篇 |
2007年 | 41篇 |
2006年 | 24篇 |
2005年 | 24篇 |
2004年 | 17篇 |
2003年 | 20篇 |
2002年 | 12篇 |
2001年 | 6篇 |
2000年 | 10篇 |
1999年 | 4篇 |
1998年 | 14篇 |
1997年 | 7篇 |
1996年 | 12篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 10篇 |
1992年 | 12篇 |
1991年 | 4篇 |
1989年 | 3篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1970年 | 3篇 |
排序方式: 共有793条查询结果,搜索用时 15 毫秒
11.
This paper compares two dynamic, one-dimensional models of a planar anode-supported intermediate temperature (IT) direct internal reforming (DIR) solid oxide fuel cell (SOFC): one where the flow properties (pressure, gas stream densities, heat capacities, thermal conductivities, and viscosity) and gas velocities are taken as constant throughout the system, based on inlet conditions, and one where this assumption is removed to focus on the effect of considering the variation of local flow properties on the prediction of the fuel cell performance. The refined model consists of mass, energy, and momentum balances, and of an electrochemical model that relates the fuel and air gas compositions and temperatures to voltage, current density, and other relevant fuel cell variables. Simulations for steady-state and dynamic conditions have been carried out and the results obtained from the two models compared. For a co-flow SOFC operating on a 10% pre-reformed methane fuel mixture, with 75% fuel utilisation, inlet fuel and air temperatures of 1023 K, average current density of , and an air ratio of 8.5, the results show that, although the error incurred in the prediction of the flow properties in the first model is significant, there is good agreement between both models in terms of the overall cell performance: the maximum difference in the local temperature values is about 7 K and the cell efficiency differs by less than 1%. However, the discrepancies between the two models increase, especially in the fuel channel, when higher current density values are assigned to the cell. 相似文献
12.
A program to demonstrate high temperature hyperfiltration to renovate hot industrial wastewater for direct recycle is in Phase 2; the installation of a ~10m /hr membrane system to achieve closed cycle operation of a textile dye range. Hydrous-zirconium oxide-polyacrylate (ZOPA) membranes dynamically formed on porous sintered stainless steel tubes arranged in a Single Pass system will be supplied by the Mott-Brandon Corporation. Phase I of the program involved on-site pilot testing of several membranes, the procurement of competitive bids for the membrane system and the complete installation including all interface controls required for the dye operation.The 180°F (82°C) dye wash water contains residual dyes, auxiliary detergent and wetting agents, and guar gum. The total solids in the wash water range from 130 to 7000mg/l with the suspended solids ranging from 2 to 90 mg/l. The membrane system will be operated at 96% recovery. The concentrated residue is being studied for reuse or ultimate disposal through evaporation and/ or incineration. The performance of the membranes during the pilot tests, the laboratory evaluation of the reuse, and the complete recovery system are described. 相似文献
13.
Results are reported of experiments and modelling of cathodic Pb and anodic PbO2 electrodeposition, aimed at developing a process using both reactions simultaneously for treating aqueous effluents from lead–acid battery recycling plants. Pb(II) solubilities and equilibrium potentials were calculated as functions of pH and sulfate activities. Using kinetic parameters from the literature or determined experimentally, models were developed for current density–potential and current efficiency–potential relationships, together with the current density dependence of specific electrical energy consumptions for Pb(II) recovery. Experimental current density–potential and charge efficiency–potential relationships were in broad agreement with model predictions, with near unity current efficiencies for mass transport controlled PbO2 deposition from electrolytes containing 1 mol Pb(II) m–3 at pH 12. However, charge efficiencies for cathodic deposition of lead were typically 0.2 for 1 mol Pb(II) m–3 + 1 mol O2 (aq) m–3; removal of dissolved oxygen was predicted and determined to increase current efficiencies to near unity. Pb(II) concentrations were depleted to <60 ppb in a batch recycle reactor system with graphite felt anodes and graphite or titanium felt cathodes. Simultaneous cathodic Pb and anodic PbO2 electrodeposition resulted in more rapid Pb(II) depletion than for either reaction separately. 相似文献
14.
Cleland LG Proudman SM Hall C Stamp LK McWilliams L Wylie N Neumann M Gibson RA James MJ 《Lipids》2003,38(4):419-424
Dietary fish oil supplements have been shown to have benefits in rheumatoid arthritis (RA), other inflammatory diseases, and
in cardiovascular disease. As with any medical advice, variability will exist with regard to adherence and consequent biochemical
or pharmacophysiologic effects. The aim was to explore the utility of plasma phospholipid EPA as a measure of n−3 PUFA intake
and response to standardized therapeutic advice given in an outpatient or office practice setting, to increase dietary n−3
PUFA, including a fish oil supplement. Patients with early RA were given verbal and written advice to alter their dietary
n−3 PUFA intake, including ingestion of 20 mL of bottled fish oil on juice daily. The advice included instructions to increase
n−3 PUFA and to avoid foods rich in n−6 PUFA. Every 3 mon, blood samples were obtained for analysis of plasma phospholipid
FA. Plasma phospholipid EPA was used as the primary index of n−3 PUFA intake. A diverse response was seen, with about one-third
of patients achieving a substantial elevation of plasma phospholipid EPA over the 12-mon study period. A third had little
change, with the remainder achieving intermediate levels. Data obtained longitudinally from individual patients indicated
that substantial elevations of EPA (>5% total plasma phospholipid FA) could be maintained for more than 3 yr. Plasma phospholipid
EPA is a convenient measure of adherence to advice to take a dietary n−3 PUFA-rich fish oil supplement. This measure may prove
a useful adjunct to intention to treat analyses in determining the effect of dietary fish oil supplements on long-term outcomes
in arthritis and other chronic inflammatory diseases. It may also provide a guide to the effectiveness of therapeutic and
preventive messages designed to increase n−3 PUFA intake. 相似文献
15.
The growth kinetics of electrogenerated hydrogen, oxygen and chlorine gas bubbles formed at microelectrodes, were determined photographically and fitted by regression analysis to the equation;r(t)=t
x
, wherer(t) is the bubble radius at timet after nucleation, the growth coefficient, andx the time coefficient. The coefficientx was found to decrease from a short time (< 10 ms) value near unity, typical of inertia controlled growth, through 0.5, characteristic of diffusional control, to 0.3, expected for Faradaic growth, at long times (\s> 100 ms). The current efficiency for bubble growth increased with bubble lifetime, reflecting the decrease in local dissolved gas supersaturation. The pH dependency of the bubble departure diameter indicated that, in surfactant-free electrolytes, double layer interaction forces between the negatively charged hydrogen evolving cathode or positively charged oxygen/chlorine evolving anode and positively (pH \s< 2) or negatively (pH \s> 3) charged bubbles, were the determining factor. The effect of addition of an increasing concentration of cationic (DoTAB) or anionic (SDoS) surfactant was to progressively reduce the pH effect on departure diameter, due to surfactant adsorption on the bubble and, to a lesser extent, on the electrode.Nomenclature
C
coefficient [3]
-
D
diffusion coefficient (m2 s–1)
-
I
current (A)
-
P
pressure (kN m–2)
-
R
universal gas constant (8.314 J mol–1 K–1)
-
r
bubble radius (m)
-
T
absolute temperature (K)
-
t
time (ms)
-
x
time coefficient
-
zF
molar charge (96 487z C mol–1)
-
growth coefficient (m s–0.33)
- P
Laplace excess pressure (kN m–2)
-
surface tension (mN m–1)
-
electrolyte density (kg m–3)
-
contact angle ()
Paper presented at the International Meeting on Electrolytic Bubbles organized by the Electrochemical Technology Group of the Society of Chemical Industry, and held at Imperial College, London, 13–14 September 1984. 相似文献
16.
Evaluating the Wisdom of Strangers: The Perceived Credibility of Online Consumer Reviews on Yelp
下载免费PDF全文
![点击此处可从《Journal of Computer-Mediated Communication》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This study examined the effects of review valence, the reviewer profile, and the receiver's familiarity with the platform (user/nonuser) on the perceived credibility of a review on Yelp.com and on the receiver's attitude toward the reviewed object. The results demonstrated a difference in cue‐taking between users and nonusers. For users, there was an interaction effect of 2 profile cues (number of friends and number of reviews) on competence. Users interpreted the cues in combination, whereas non‐users were not influenced by them. The friends × reviews × platform familiarity interaction indirectly affected attitude through competence. Further, review valence was positively associated with perceived credibility and attitude. The findings support and extend the social information processing theory and cue combination literature. 相似文献
17.
Bioinspired Nacre‐Like Ceramic with Nickel Inclusions Fabricated by Electroless Plating and Spark Plasma Sintering
下载免费PDF全文
![点击此处可从《Advanced Engineering Materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zhe Xu Jiacheng Huang Cheng Zhang Soheil Daryadel Ali Behroozfar Brandon McWilliams Benjamin Boesl Arvind Agarwal Majid Minary‐Jolandan 《Advanced Engineering Materials》2018,20(5)
18.
Alireza Tadayoni Wen-Fang Xie Brandon W. Gordon 《International Journal of Control, Automation and Systems》2011,9(1):50-59
In this paper, an adaptive controller with structurally dynamic wavelet network is developed for a harmonic drive subject
to parameter varying friction. The control architecture integrates a proportional controller, a feedback adaptive component
and sliding component to adaptively compensate for the friction to achieve accurate position tracking. Global asymptotic stability
of the algorithm is proved by using Lyapunov function. In parallel to the adaptive controller, a fuzzy reconfiguration scheme
is devised to change the structure of the network along with weights updating to improve the system tracking performance and
robustness. Experimental tests on a harmonic drive manipulator verify the effectiveness of the proposed control method. 相似文献
19.
Blanchet-Sadri et al. have shown that Avoidability, or the problem of deciding the avoidability of a finite set of partial words over an alphabet of size k≥2, is NP-hard [F. Blanchet-Sadri, R. Jungers, J. Palumbo, Testing avoidability on sets of partial words is hard, Theoret. Comput. Sci. 410 (2009) 968-972]. Building on their work, we analyze in this paper the complexity of natural variations on the problem. While some of them are NP-hard, others are shown to be efficiently decidable. Using some combinatorial properties of de Bruijn graphs, we establish a correspondence between lengths of cycles in such graphs and periods of avoiding words, resulting in a tight bound for periods of avoiding words. We also prove that Avoidability can be solved in polynomial space, and reduces in polynomial time to the problem of deciding the avoidability of a finite set of partial words of equal length over the binary alphabet. We give a polynomial bound on the period of an infinite avoiding word, in the case of sets of full words, in terms of two parameters: the length and the number of words in the set. We give a polynomial space algorithm to decide if a finite set of partial words is avoided by a non-ultimately periodic infinite word. The same algorithm also decides if the number of words of length n avoiding a given finite set of partial words grows polynomially or exponentially with n. 相似文献
20.