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71.
Ioannis Karatasios Vassilis Kilikoglou Panagiotis Theoulakis 《Cement and Concrete Research》2007,37(6):886-893
This paper presents the effect of barium hydroxide on the setting mechanism of lime-based conservation mortars, when used as an additive material. The study focuses on the monitoring of the setting process and the identification of the mineral phases formed, which are essential for furthering the study of the durability of barium mixtures against chemical degradation. X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and thermal analysis (DTA-TG) were used to monitor the setting processes of these mixtures and identify new phases formed. The results suggest that barium hydroxide is evenly distributed within the lime and produces a homogeneous binding material, consisting of calcite (CaCO3), witherite (BaCO3) and barium-calcium carbonate [BaCa(CO3)2]. Finally, it was found that barium carbonate can be directly bonded to calcitic aggregates and therefore increases its chemical compatibility with the binding material. 相似文献
72.
Roger Nahas Dennis Abatis Maria A. Anagnostopoulou Panagiotis Kefalas Constantinos Vagias Vassilios Roussis 《Food chemistry》2007,102(3):577-581
In the present work, thirteen algae from the Aegean Sea were examined for radical-scavenging activity (RSA) using the DPPH and chemiluminescence (CL) tests. Extracts of the brown alga Taonia atomaria exhibited the best RSA in comparison to the extracts of the other investigated species and approached the activity of powerful antioxidant standards. Column chromatography separation of T. atomaria extract, followed by preparative HPLC, resulted in the isolation of six metabolites, which were identified by spectral analyses (1H NMR, 13C NMR and MS). The isolated metabolites taondiol, isoepitaondiol, stypodiol, stypoldione, sargaquinone and sargaol were found to possess marked RSA. 相似文献
73.
Aristidis Stournaras Konstantinos Salonitis Panagiotis Stavropoulos George Chryssolouris 《The International Journal of Advanced Manufacturing Technology》2009,44(1-2):114-124
A theoretical model has been developed for simulating the laser grooving process. It takes into account the interaction among subsequent pulses, the required time for the melting temperature to be reached and the subsequent removal of a finite volume of material during each laser pulse. The model predicts the maximum groove depth that can be achieved for a specified set of process parameters, such as laser power, pulsing frequency, and scanning velocity. The theoretical predictions have been experimentally tested with a medium-power laser beam. 相似文献
74.
Stelios Spaniolas Christos Bazakos Thessaloniki Ntourou Saadia Bihmidine Andreas Georgousakis Panagiotis Kalaitzis 《European Food Research and Technology》2008,227(1):175-179
Filtered olive oil samples spiked with three different concentrations of λDNA were stored at 25 °C under a 12 h photoperiod for up to a year. These samples were used for DNA extraction and PCR amplification
of λDNA amplicons of 107, 415 and 691 bp length. The amplification signal was gradually decreased with longer storage periods,
while the strength of the signal was related to the initial concentration of spiking λDNA particularly during longer storage periods. The 107 bp amplicon was the only one successfully amplified from all the samples,
regardless of both concentration of spiking λDNA and storage period. The amplification of 415 and 691 bp amplicons was not successful for samples stored longer than a
threshold period of 20 and 10 days, respectively. These results suggest that detection of polymorphic markers requiring DNA
templates shorter than 100 bp might have a wider range of applications in DNA fingerprinting of olive oil. In addition, the
DNA extracts were tested for the presence of inhibitors in PCR amplification reactions of yeast DNA amplicons. The inhibitory
effect of olive DNA extracts was partial and gradually increased with the storage period of the olive oil samples used for
the DNA extraction. 相似文献
75.
Forces Driving Adoption of New Information Technologies 总被引:1,自引:0,他引:1
This paper investigates the forces that drive construction firms to adopt new information technologies. The research focuses on CAD and electronic data interchange technologies and studies in-depth eight innovation adoption decisions. The paper presents the findings regarding the forces that created the managerial stimuli for innovation and the organizational characteristics that played an important role in the adoption. The investigation identified four forces that drive innovation: competitive advantage, process problems, technological opportunity, and institutional requirements. These forces change over time and drive the diffusion of a technology in the industry. The study also found that different organizational characteristics determine a company's sensitivity to each force. The paper proposes a new model of diffusion of new technologies and presents the implications for increasing the rate of innovation in the industry. 相似文献
76.
Summary The principle of Minimum Relative Entropy (MRE), given fully decomposable subset and aggregate mean queue length, utilisation and flow-balance constraints, is used in conjunction with asymptotic connections to infinite capacity queues, to derive new analytic approximations for the conditional and marginal state probabilities of single class general closed queueing network models (QNMs) in the context of a multilevel variable aggregation scheme. The concept of subparallelism is applied to preserve the flow conservation and a universal MRE hierarchical decomposition algorithm is proposed for the approximate analysis of arbitrary closed queueing networks with single server queues and general service-times. Heuristic criteria towards an optimal coupling of network's units at each level of aggregation are suggested. As an illustration, the MRE algorithm is implemented iteratively by using the Generalised Exponential (GE) distributional model to approximate the service and asymptotic flow processes in the network. This algorithm captures the exact solution of separable queueing networks, while for general queueing networks it compares favourably against exact solutions and known approximations.This work is sponsored by the Science and Engineering Research Council (SERC), UK, under grant GR/F29271 相似文献
77.
78.
Panagiotis Dallas Jiri Tucek Dalibor Jancik Milan Kolar Ales Panacek Radek Zboril 《Advanced functional materials》2010,20(14):2347-2354
A recently developed multi‐functional phosphotriazine‐based polymer is used as a matrix for embedding γ‐Fe2O3 nanoparticles as well as a suitable chemical template for surface modification with silver nanoparticles. For the primary magnetic modification, maghemite nanoparticles are surface modified with oleic acid in order to render them organophilic and to prevent the aggregation of the nanoparticles. This aggregation could occur as the polymer synthesis, based on reaction of phosphonitrilic chlorine and 1,4‐phenylenediamine, takes place in toluene. The surface active amine units of the polymer structure enable the reduction of silver cations to silver nanoparticles, which are well attached and finely dispersed on its surface. The developed nanocomposite represents one of the few magnetically controllable antibacterial agents based on silver nanoparticles. Magnetic measurements reveal the completely suppressed interactions among maghemite nanoparticles because of their perfect surface coating with an organic surfactant and fine dispersion inside the polymer matrix. This magnetic nanocomposite exhibits a high antibacterial and antifungal activity as proven by tests with nine bacterial strains and four candida (yeast genus) species. For the majority of the tested species, the minimum‐inhibition concentrations are below 100 mg L?1, which is comparable to their equivalent minimum‐inhibition concentrations in colloidal silver systems. 相似文献
79.
80.
Borrell A Cantos G Aguilar A Androukaki E Dendrinos P 《The Science of the total environment》2007,381(1-3):316-325
Blubber from Mediterranean monk seals (Monachus monachus) from the Western Sahara coast (Atlantic), sampled during 1996-1999, and from the Greek coast (Mediterranean), sampled during 1995-1999, was analyzed for organochlorine pollutants (OCs). In both populations, no significant difference was found between sexes. In the Atlantic population, mature females presented greater percentages of higher chlorinated PCB (polychlorinated biphenyl) congeners in relation to total PCBs (sum of 25 congeners) than pups, indicating a differential transfer of PCB congeners through lactation. In the Mediterranean, the reduced sample size of adult individuals precluded proper statistical investigation of age-related variation. Significant differences in concentrations and pollutant patterns were found between populations. Thus, Mediterranean individuals presented significantly higher levels of HCB (hexachlorobenzene), tPCB, and DDTs (dichlorodiphenyltrichloroethane) concentrations and DDE/tDDT and tDDT/tPCB ratios than their counterparts from the Atlantic. Moreover, the relative proportion of different congeners in relation to the total PCB load (congener/tPCB) was also different between the two areas. The 100*tDDT/tPCB ratio in Atlantic seals was 38.46, which indicates a predominance of industrial inputs over those associated with agriculture. Conversely, in the Mediterranean seal population, the 100*tDDT/tPCB ratio was 177.1, denoting a proportionally higher contribution of pollutants of agricultural origin. 相似文献