全文获取类型
收费全文 | 290篇 |
免费 | 12篇 |
专业分类
电工技术 | 3篇 |
综合类 | 1篇 |
化学工业 | 73篇 |
金属工艺 | 5篇 |
机械仪表 | 9篇 |
建筑科学 | 15篇 |
矿业工程 | 1篇 |
能源动力 | 21篇 |
轻工业 | 43篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
无线电 | 18篇 |
一般工业技术 | 61篇 |
冶金工业 | 10篇 |
自动化技术 | 37篇 |
出版年
2024年 | 5篇 |
2023年 | 7篇 |
2022年 | 7篇 |
2021年 | 12篇 |
2020年 | 11篇 |
2019年 | 10篇 |
2018年 | 14篇 |
2017年 | 7篇 |
2016年 | 21篇 |
2015年 | 7篇 |
2014年 | 14篇 |
2013年 | 27篇 |
2012年 | 16篇 |
2011年 | 24篇 |
2010年 | 23篇 |
2009年 | 26篇 |
2008年 | 15篇 |
2007年 | 13篇 |
2006年 | 4篇 |
2005年 | 11篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有302条查询结果,搜索用时 15 毫秒
281.
B Kasapgil Ince A Selcuk O Ince 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2002,77(6):711-719
The performance of an upflow anaerobic filter (UAF) treating a chemical synthesis‐based pharmaceutical wastewater was evaluated under various operating conditions. During start‐up, the UAF was initially fed by glucose till an organic loading rate (OLR) of approximately 7.5 kg COD m?3 day?1 with a hydraulic retention time of 2.3 days. A soluble COD removal efficiency of 98% was achieved before the addition of the wastewater. Initially, the filter inertia was acclimatized to the wastewater by sequential feeding of 10% (w/v), 30% (w/v) and 70% (w/v) of the pre‐aerated wastewater mixed with glucose followed by a 100% (w/v) pre‐aerated wastewater. During the operation, the COD removal efficiency and methane yield decreased to 75% and 0.30 m3 CH4 kg?1 CODremoved respectively. As the UAF became accustomed to the pre‐aerated wastewater, raw wastewater was fed in increasing ratios of 20% (w/v), 60% (w/v) and 80% (w/v) with the pre‐aerated wastewater as the remaining part. During this stage of the operation, a COD removal efficiency in a range of 77–86% was achieved and the methane yield decreased to 0.24 m3 CH4 kg?1 CODremoved. Finally, 100% (w/v) raw wastewater was fed and a COD removal efficiency of 65% was achieved with a methane yield of 0.20 m3 CH4 kg?1 CODremoved. At the end of the operation, acetoclastic methanogenic activity was only measured in the bottom section of the UAF, this showed a 90% reduction in comparison with activity of inoculation sludge. Microscopic examinations revealed that rod‐shaped methanogens remained as the dominant species whereas Methanosarcina‐like species and filaments were present only in insignificant numbers along the UAF. © 2002 Society of Chemical Industry 相似文献
282.
Ozlem Sahin Serkan Eymur Arzu Uyanik Ezgi Akceylan 《Polycyclic Aromatic Compounds》2018,38(2):168-179
The chiral calix[4]arene derivative (6) bearing an L-prolinamido group has been designed and proved to be a water compatible efficient organocatalysts for a direct enantioselective aldol reaction. Compound 6 catalyzes the aldol reaction of cyclohexanone and a variety of aromatic aldehydes yielding anti-aldol products in high yield with enantioselectivities of up to 93% and diastereoselectivity of up to 95:5. 相似文献
283.
The mechanisms of chronic infections caused by opportunistic pathogens are of keen interest to both researchers and health professionals globally. Typically, chronic infectious disease can be characterized by an elevation in immune response, a process that can often lead to further destruction. Reactive-Oxygen-Species (ROS) have been strongly implicated in the aforementioned detrimental response by host that results in self-damage. Unlike excessive ROS production resulting in robust cellular death typically induced by acute infection or inflammation, lower levels of ROS produced by host cells are increasingly recognized to play a critical physiological role for regulating a variety of homeostatic cellular functions including growth, apoptosis, immune response, and microbial colonization. Sources of cellular ROS stimulation can include "danger-signal-molecules" such as extracellular ATP (eATP) released by stressed, infected, or dying cells. Particularly, eATP-P2X(7) receptor mediated ROS production has been lately found to be a key modulator for controlling chronic infection and inflammation. There is growing evidence that persistent microbes can alter host cell ROS production and modulate eATP-induced ROS for maintaining long-term carriage. Though these processes have yet to be fully understood, exploring potential positive traits of these "injurious" molecules could illuminate how opportunistic pathogens maintain persistence through physiological regulation of ROS signaling. 相似文献
284.
Bekir Sari Nihan Yavas Mehmet Makulogullari Ozlem Erol Halil Ibrahim Unal 《Reactive and Functional Polymers》2009,69(11):808-815
In this study, polyindole (PIN) and polyindole/polyethylene (PIN/PE) conducting composites, having various amounts of PIN, were synthesized by chemical polymerization using FeCl3 as an oxidizing agent and taking the ratio of salt:monomer as 3:1. The samples of PIN and PIN/PE composites were characterized by FTIR, UV–vis, TGA, SEM, Gouy scale magnetic susceptibility, conductivity (1.2 × 10−3 S cm−1 > σ > 1.96 × 10−6 S cm−1, at T = 25 °C) and density measurements. FTIR analysis suggested a 2,3-propagation mechanism for PIN formation. The ground milled samples were subjected to particle size analysis by dynamic light scattering (DLS) and a micron-sized particle distribution was obtained. A series of volume fractions ( = 10–25%) were prepared from the materials in silicone oil (SO) and their sedimentation stabilities determined. The most stable composite [PIN(89%)/PE(11%)] against gravitational sedimentation was subjected to flow-rate measurements under externally applied electric field strength (E) and an electrorheological (ER) activity was observed; threshold energies (Et) were calculated. The effects of volume fraction, shear rate, external E, frequency and temperature onto ER activities of the suspensions were investigated. Enhancement in the electric field viscosities and shear thinning viscoelastic behaviors were observed for all the samples studied. Recoverable viscoelastic deformations were determined from the creep tests under external E. 相似文献
285.
Efficient clustering and categorizing of video are becoming more and more vital in various applications including video summarization, content-based representation and so on. The large volume of video data is the biggest challenge that this task presents, for most the clustering techniques suffer from high dimensional data in terms of both accuracy and efficiency. In addition to this, most video applications require online processing; therefore, clustering should also be done online for such tasks. This paper presents an online video scene clustering/segmentation method that is based on incremental nonnegative matrix factorization (INMF), which has been shown to be a powerful content representation tool for high dimensional data. The proposed algorithm (Comp-INMF) enables online representation of video content and increases efficiency significantly by integrating a competitive learning scheme into INMF. It brings a systematic solution to the issue of rank selection in nonnegative matrix factorization, which is equivalent to specifying the number of clusters. The clustering performance is evaluated by tests on TRECVID video sequences, and a performance comparison to baseline methods including Adaptive Resonance Theory (ART) is provided in order to demonstrate the efficiency and efficacy of the proposed video clustering scheme. Clustering performance reported in terms of recall, precision and F1 measures shows that the labeling accuracy of the algorithm is notable, especially at edit effect regions that constitute a challenging point in video analysis. 相似文献
286.
Due to recent advances in wireless communication technologies, there has been a rapid growth in wireless sensor networks research during the past few decades. Many novel architectures, protocols, algorithms, and applications have been proposed and implemented. The efficiency of these networks is highly dependent on routing protocols directly affecting the network life-time. Clustering is one of the most popular techniques preferred in routing operations. In this paper, a novel energy efficient clustering mechanism, based on artificial bee colony algorithm, is presented to prolong the network life-time. Artificial bee colony algorithm, simulating the intelligent foraging behavior of honey bee swarms, has been successfully used in clustering techniques. The performance of the proposed approach is compared with protocols based on LEACH and particle swarm optimization, which are studied in several routing applications. The results of the experiments show that the artificial bee colony algorithm based clustering can successfully be applied to WSN routing protocols. 相似文献
287.
Ozlem Sel Aurélien Soulès Bruno Améduri Bernard Boutevin Christel Laberty‐Robert Gérard Gebel Clément Sanchez 《Advanced functional materials》2010,20(7):1090-1098
Hybrid organic/inorganic membranes that include a functionalized (‐SO3H), interconnected silica network, a non‐porogenic organic matrix, and a ‐SO3H‐functionalized terpolymer are synthesized through a sol–gel‐based strategy. The use of a novel crosslinkable poly(vinylidene fluoride‐ter‐perfluoro(4‐methyl‐3,6‐dioxaoct‐7‐ene sulfonyl fluoride)‐ter‐vinyltriethoxysilane) (poly(VDF‐ter‐PFSVE‐ter‐VTEOS)) terpolymer allows a multiple tuning of the different interfaces to produce original hybrid membranes with improved properties. The synthesized terpolymer and the composite membranes are characterized, and the proton conductivity of a hybrid membrane in the absence of the terpolymer is promising, since 8 mS cm?1 is reached at room temperature, immersed in water, with an experimental ion‐exchange‐capacity (IECexp) value of 0.4 meq g?1. Furthermore, when the composite membranes contain the interfaced terpolymer, they exhibit both a higher proton conductivity (43 mS cm?1 at 65 °C under 100% relative humidity) and better stability than the standard hybrid membrane, arising from the occurrence of a better interface between the inorganic silica and the poly[(vinylidene fluoride)‐co‐hexafluoropropylene] (poly(VDF‐co‐HFP)) copolymer network. Accordingly, the hybrid SiO2‐SO3H/terpolymer/poly(VDF‐co‐HFP) copolymer membrane has potential use as an electrolyte in a polymer‐electrolyte‐membrane fuel cell operating at intermediate temperatures. 相似文献
288.
Ayduk Ozlem; Mendoza-Denton Rodolfo; Mischel Walter; Downey Geraldine; Peake Philip K.; Rodriguez Monica 《Canadian Metallurgical Quarterly》2000,79(5):776
People high in rejection sensitivity (RS) anxiously expect rejection and are at risk for interpersonal and personal distress. Two studies examined the role of self-regulation through strategic attention deployment in moderating the link between RS and maladaptive outcomes. Self-regulation was assessed by the delay of gratification (DG) paradigm in childhood. In Study 1, preschoolers from the Stanford University community who participated in the DG paradigm were assessed 20 years later. Study 2 assessed low-income, minority middle school children on comparable measures. DG ability buffered high-RS people from interpersonal difficulties (aggression, peer rejection) and diminished well-being (e.g., low self-worth, higher drug use). The protective effect of DG ability on high-RS children's self-worth is explained by reduced interpersonal problems. Attentional mechanisms underlying the interaction between RS and strategic self-regulation are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
289.
Summary The retention diagrams of poly(ether imide) for ethyl benzene, n-propyl benzene, isopropyl benzene, chloro benzene, n-butyl acetate, tert-butyl acetate, isoamyl acetate, n-nonane, n-decane, n-undecane, n-dodecane and n-tridecane were obtained by inverse gas chromatography technique. In this work, the slope changes on the diagram were assigned as secondary transitions. The secondary transition temperatures obtained by inverse gas chromatography technique are in good agreement with the ones obtained by thermally stimulated depolarization current in the literature. Specific retention volume, Vg0, the weight fraction activity coefficients of the solvents at infinite solution, Ω1∞, Flory-Huggins polymer-solvent interaction parameters,χ12∞, equation-of-state polymer-solvent interaction parameters,χ12*, effective exchange energy parameters, Xeff were determined. Later, the partial molar heat of sorption,
and the partial molar heat of mixing,
were obtained. The solubility parameter of poly(ether imide), δ2 was determined as 10.7 (cal/cm3)1/2 by extrapolation of the δ2 values obtained by considering the free volume effects from studied temperature range to room temperature. 相似文献
290.